diff --git a/CMakeLists.txt b/CMakeLists.txt
index c32423e..e0ba082 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -202,7 +202,9 @@ set(MYNTEYE_SRCS
   src/mynteye/types.cc
   src/mynteye/util/files.cc
   src/mynteye/util/strings.cc
-  src/mynteye/device/channels/channels.cc
+  src/mynteye/device/channel/bytes.cc
+  src/mynteye/device/channel/channels.cc
+  src/mynteye/device/channel/file_channel.cc
   src/mynteye/device/config.cc
   src/mynteye/device/context.cc
   src/mynteye/device/device.cc
diff --git a/include/mynteye/device/callbacks.h b/include/mynteye/device/callbacks.h
index 91cf934..b1601e3 100644
--- a/include/mynteye/device/callbacks.h
+++ b/include/mynteye/device/callbacks.h
@@ -30,20 +30,6 @@ MYNTEYE_BEGIN_NAMESPACE
 
 namespace device {
 
-typedef struct ImgParams {
-  bool ok;
-  std::shared_ptr<IntrinsicsBase> in_left;
-  std::shared_ptr<IntrinsicsBase> in_right;
-  Extrinsics ex_right_to_left;
-} img_params_t;
-
-typedef struct ImuParams {
-  bool ok;
-  ImuIntrinsics in_accel;
-  ImuIntrinsics in_gyro;
-  Extrinsics ex_left_to_imu;
-} imu_params_t;
-
 /**
  * @ingroup datatypes
  * Frame with raw data.
diff --git a/include/mynteye/device/device.h b/include/mynteye/device/device.h
index 50e1d50..6dded7a 100644
--- a/include/mynteye/device/device.h
+++ b/include/mynteye/device/device.h
@@ -51,6 +51,26 @@ class StreamsAdapter;
 template <class Data>
 class AsyncCallback;
 
+namespace device {
+
+typedef struct ImgParams {
+  bool ok;
+  std::string version;
+  std::shared_ptr<IntrinsicsBase> in_left;
+  std::shared_ptr<IntrinsicsBase> in_right;
+  Extrinsics ex_right_to_left;
+} img_params_t;
+
+typedef struct ImuParams {
+  bool ok;
+  std::string version;
+  ImuIntrinsics in_accel;
+  ImuIntrinsics in_gyro;
+  Extrinsics ex_left_to_imu;
+} imu_params_t;
+
+}  // namespace device
+
 /**
  * The Device class to communicate with MYNT® EYE device.
  */
@@ -266,7 +286,7 @@ class MYNTEYE_API Device {
    */
   device::StreamData GetStreamData(const Stream &stream);
 
-  /** 
+  /**
    * @deprecated Replaced by GetStreamData(const Stream &stream)
    */
   device::StreamData GetLatestStreamData(const Stream &stream);
diff --git a/src/mynteye/device/channel/bytes.cc b/src/mynteye/device/channel/bytes.cc
new file mode 100644
index 0000000..d08164a
--- /dev/null
+++ b/src/mynteye/device/channel/bytes.cc
@@ -0,0 +1,208 @@
+// Copyright 2018 Slightech Co., Ltd. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#include "mynteye/device/channel/bytes.h"
+
+#include "mynteye/util/strings.h"
+
+MYNTEYE_BEGIN_NAMESPACE
+
+namespace bytes {
+
+// from
+
+std::string _from_data(const std::uint8_t *data, std::size_t count) {
+  std::string s(reinterpret_cast<const char *>(data), count);
+  strings::trim(s);
+  return s;
+}
+
+// from types
+
+std::size_t from_data(IntrinsicsPinhole *in, const std::uint8_t *data) {
+  std::size_t i = 0;
+
+  // width, 2
+  in->width = _from_data<std::uint16_t>(data + i);
+  i += 2;
+  // height, 2
+  in->height = _from_data<std::uint16_t>(data + i);
+  i += 2;
+  // fx, 8
+  in->fx = _from_data<double>(data + i);
+  i += 8;
+  // fy, 8
+  in->fy = _from_data<double>(data + i);
+  i += 8;
+  // cx, 8
+  in->cx = _from_data<double>(data + i);
+  i += 8;
+  // cy, 8
+  in->cy = _from_data<double>(data + i);
+  i += 8;
+  // model, 1
+  in->model = data[i];
+  i += 1;
+  // coeffs, 40
+  for (std::size_t j = 0; j < 5; j++) {
+    in->coeffs[j] = _from_data<double>(data + i + j * 8);
+  }
+  i += 40;
+
+  return i;
+}
+
+std::size_t from_data(ImuIntrinsics *in, const std::uint8_t *data) {
+  std::size_t i = 0;
+
+  // scale
+  for (std::size_t j = 0; j < 3; j++) {
+    for (std::size_t k = 0; k < 3; k++) {
+      in->scale[j][k] = _from_data<double>(data + i + (j * 3 + k) * 8);
+    }
+  }
+  i += 72;
+  // drift
+  for (std::size_t j = 0; j < 3; j++) {
+    in->drift[j] = _from_data<double>(data + i + j * 8);
+  }
+  i += 24;
+  // noise
+  for (std::size_t j = 0; j < 3; j++) {
+    in->noise[j] = _from_data<double>(data + i + j * 8);
+  }
+  i += 24;
+  // bias
+  for (std::size_t j = 0; j < 3; j++) {
+    in->bias[j] = _from_data<double>(data + i + j * 8);
+  }
+  i += 24;
+
+  return i;
+}
+
+std::size_t from_data(Extrinsics *ex, const std::uint8_t *data) {
+  std::size_t i = 0;
+
+  // rotation
+  for (std::size_t j = 0; j < 3; j++) {
+    for (std::size_t k = 0; k < 3; k++) {
+      ex->rotation[j][k] = _from_data<double>(data + i + (j * 3 + k) * 8);
+    }
+  }
+  i += 72;
+  // translation
+  for (std::size_t j = 0; j < 3; j++) {
+    ex->translation[j] = _from_data<double>(data + i + j * 8);
+  }
+  i += 24;
+
+  return i;
+}
+
+// to
+
+std::size_t _to_data(std::string value, std::uint8_t *data, std::size_t count) {
+  std::copy(value.begin(), value.end(), data);
+  for (std::size_t i = value.size(); i < count; i++) {
+    data[i] = ' ';
+  }
+  return count;
+}
+
+// to types
+
+std::size_t to_data(const IntrinsicsPinhole *in, std::uint8_t *data) {
+  std::size_t i = 0;
+
+  // width, 2
+  _to_data(in->width, data + i);
+  i += 2;
+  // height, 2
+  _to_data(in->height, data + i);
+  i += 2;
+  // fx, 8
+  _to_data(in->fx, data + i);
+  i += 8;
+  // fy, 8
+  _to_data(in->fy, data + i);
+  i += 8;
+  // cx, 8
+  _to_data(in->cx, data + i);
+  i += 8;
+  // cy, 8
+  _to_data(in->cy, data + i);
+  i += 8;
+  // model, 1
+  data[i] = in->model;
+  i += 1;
+  // coeffs, 40
+  for (std::size_t j = 0; j < 5; j++) {
+    _to_data(in->coeffs[j], data + i + j * 8);
+  }
+  i += 40;
+
+  return i;
+}
+
+std::size_t to_data(const ImuIntrinsics *in, std::uint8_t *data) {
+  std::size_t i = 0;
+
+  // scale
+  for (std::size_t j = 0; j < 3; j++) {
+    for (std::size_t k = 0; k < 3; k++) {
+      _to_data(in->scale[j][k], data + i + (j * 3 + k) * 8);
+    }
+  }
+  i += 72;
+  // drift
+  for (std::size_t j = 0; j < 3; j++) {
+    _to_data(in->drift[j], data + i + j * 8);
+  }
+  i += 24;
+  // noise
+  for (std::size_t j = 0; j < 3; j++) {
+    _to_data(in->noise[j], data + i + j * 8);
+  }
+  i += 24;
+  // bias
+  for (std::size_t j = 0; j < 3; j++) {
+    _to_data(in->bias[j], data + i + j * 8);
+  }
+  i += 24;
+
+  return i;
+}
+
+std::size_t to_data(const Extrinsics *ex, std::uint8_t *data) {
+  std::size_t i = 0;
+
+  // rotation
+  for (std::size_t j = 0; j < 3; j++) {
+    for (std::size_t k = 0; k < 3; k++) {
+      _to_data(ex->rotation[j][k], data + i + (j * 3 + k) * 8);
+    }
+  }
+  i += 72;
+  // translation
+  for (std::size_t j = 0; j < 3; j++) {
+    _to_data(ex->translation[j], data + i + j * 8);
+  }
+  i += 24;
+
+  return i;
+}
+
+}  // namespace bytes
+
+MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/device/channel/bytes.h b/src/mynteye/device/channel/bytes.h
new file mode 100644
index 0000000..5014e05
--- /dev/null
+++ b/src/mynteye/device/channel/bytes.h
@@ -0,0 +1,89 @@
+// Copyright 2018 Slightech Co., Ltd. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#ifndef MYNTEYE_DEVICE_CHANNEL_BYTES_H_
+#define MYNTEYE_DEVICE_CHANNEL_BYTES_H_
+#pragma once
+
+#include <algorithm>
+#include <string>
+
+#include "mynteye/mynteye.h"
+#include "mynteye/types.h"
+#include "mynteye/device/channel/def.h"
+#include "mynteye/device/types.h"
+
+MYNTEYE_BEGIN_NAMESPACE
+
+namespace bytes {
+
+// from
+
+template <typename T>
+T _from_data(const std::uint8_t *data) {
+  std::size_t size = sizeof(T) / sizeof(std::uint8_t);
+  T value = 0;
+  for (std::size_t i = 0; i < size; i++) {
+    value |= data[i] << (8 * (size - i - 1));
+  }
+  return value;
+}
+
+template <>
+inline double _from_data(const std::uint8_t *data) {
+  return *(reinterpret_cast<const double *>(data));
+}
+
+std::string _from_data(const std::uint8_t *data, std::size_t count);
+
+// from types
+
+std::size_t from_data(IntrinsicsPinhole *in, const std::uint8_t *data);
+
+std::size_t from_data(ImuIntrinsics *in, const std::uint8_t *data);
+
+std::size_t from_data(Extrinsics *ex, const std::uint8_t *data);
+
+// to
+
+template <typename T>
+std::size_t _to_data(T value, std::uint8_t *data) {
+  std::size_t size = sizeof(T) / sizeof(std::uint8_t);
+  for (std::size_t i = 0; i < size; i++) {
+    data[i] = static_cast<std::uint8_t>((value >> (8 * (size - i - 1))) & 0xFF);
+  }
+  return size;
+}
+
+template <>
+inline std::size_t _to_data(double value, std::uint8_t *data) {
+  std::uint8_t *val = reinterpret_cast<std::uint8_t *>(&value);
+  std::copy(val, val + 8, data);
+  return 8;
+}
+
+std::size_t _to_data(std::string value, std::uint8_t *data, std::size_t count);
+
+// to types
+
+std::size_t to_data(const IntrinsicsPinhole *in, std::uint8_t *data);
+
+std::size_t to_data(const ImuIntrinsics *in, std::uint8_t *data);
+
+std::size_t to_data(const Extrinsics *ex, std::uint8_t *data);
+
+}  // namespace bytes
+
+MYNTEYE_END_NAMESPACE
+
+#endif  // MYNTEYE_DEVICE_CHANNEL_BYTES_H_
diff --git a/src/mynteye/device/channels/channels.cc b/src/mynteye/device/channel/channels.cc
similarity index 72%
rename from src/mynteye/device/channels/channels.cc
rename to src/mynteye/device/channel/channels.cc
index 6a73fd0..f29ccf0 100644
--- a/src/mynteye/device/channels/channels.cc
+++ b/src/mynteye/device/channel/channels.cc
@@ -11,7 +11,7 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
-#include "mynteye/device/channels/channels.h"
+#include "mynteye/device/channel/channels.h"
 
 #include <bitset>
 #include <chrono>
@@ -19,10 +19,10 @@
 #include <iterator>
 #include <sstream>
 #include <stdexcept>
+#include <string>
 #include <vector>
 
 #include "mynteye/logger.h"
-#include "mynteye/util/strings.h"
 #include "mynteye/util/times.h"
 
 #define IMU_TRACK_PERIOD 25  // ms
@@ -432,7 +432,7 @@ void Channels::StopImuTracking() {
 
 bool Channels::GetFiles(
     device_info_t *info, img_params_t *img_params, imu_params_t *imu_params,
-    Version *spec_version) const {
+    Version *spec_version) {
   if (info == nullptr && img_params == nullptr && imu_params == nullptr) {
     LOG(WARNING) << "Files are not provided to get";
     return false;
@@ -486,7 +486,8 @@ bool Channels::GetFiles(
       i += 3;
       switch (file_id) {
         case FID_DEVICE_INFO: {
-          CHECK_EQ(bytes::from_data(info, data + i), file_size)
+          auto &&n = file_channel_.GetDeviceInfoFromData(data + i, info);
+          CHECK_EQ(n, file_size)
               << "The firmware not support getting device info, you could "
                  "upgrade to latest";
           spec_ver = &info->spec_version;
@@ -495,8 +496,7 @@ bool Channels::GetFiles(
         case FID_IMG_PARAMS: {
           if (file_size > 0) {
             CheckSpecVersion(spec_ver);
-            auto &&n = adapter_->GetImgParamsFromData(
-                data + i, spec_ver, img_params);
+            auto &&n = file_channel_.GetImgParamsFromData(data + i, img_params);
             CHECK_EQ(n, file_size);
           }
         } break;
@@ -504,8 +504,7 @@ bool Channels::GetFiles(
           imu_params->ok = file_size > 0;
           if (imu_params->ok) {
             CheckSpecVersion(spec_ver);
-            auto &&n = adapter_->GetImuParamsFromData(
-                data + i, spec_ver, imu_params);
+            auto &&n = file_channel_.GetImuParamsFromData(data + i, imu_params);
             CHECK_EQ(n, file_size);
           }
         } break;
@@ -544,15 +543,15 @@ bool Channels::SetFiles(
   std::uint16_t size = 0;
   if (info != nullptr) {
     header[0] = true;
-    size += bytes::to_data(info, data + 3 + size, spec_ver);
+    size += file_channel_.SetDeviceInfoToData(info, data + 3 + size);
   }
   if (img_params != nullptr) {
     header[1] = true;
-    size += adapter_->SetImgParamsToData(img_params, spec_ver, data + 3 + size);
+    size += file_channel_.SetImgParamsToData(img_params, data + 3 + size);
   }
   if (imu_params != nullptr) {
     header[2] = true;
-    size += adapter_->SetImuParamsToData(imu_params, spec_ver, data + 3 + size);
+    size += file_channel_.SetImuParamsToData(imu_params, data + 3 + size);
   }
 
   data[0] = static_cast<std::uint8_t>(header.to_ulong());
@@ -737,309 +736,4 @@ Channels::control_info_t Channels::XuControlInfo(Option option) const {
   return {min, max, def};
 }
 
-
-std::size_t ChannelsAdapter::GetImuParamsFromData(
-    const std::uint8_t *data, const Version *version,
-    Channels::imu_params_t *imu_params) {
-  std::size_t i = 0;
-  i += bytes::from_data(&imu_params->in_accel, data + i, version);
-  i += bytes::from_data(&imu_params->in_gyro, data + i, version);
-  i += bytes::from_data(&imu_params->ex_left_to_imu, data + i, version);
-  return i;
-}
-
-std::size_t ChannelsAdapter::SetImuParamsToData(
-    const Channels::imu_params_t *imu_params, const Version *version,
-    std::uint8_t *data) {
-  std::size_t i = 3;  // skip id, size
-  i += bytes::to_data(&imu_params->in_accel, data + i, version);
-  i += bytes::to_data(&imu_params->in_gyro, data + i, version);
-  i += bytes::to_data(&imu_params->ex_left_to_imu, data + i, version);
-  // others
-  std::size_t size = i - 3;
-  data[0] = Channels::FID_IMU_PARAMS;
-  data[1] = static_cast<std::uint8_t>((size >> 8) & 0xFF);
-  data[2] = static_cast<std::uint8_t>(size & 0xFF);
-  return size + 3;
-}
-
-
-namespace bytes {
-
-// from
-
-std::string _from_data(const std::uint8_t *data, std::size_t count) {
-  std::string s(reinterpret_cast<const char *>(data), count);
-  strings::trim(s);
-  return s;
-}
-
-std::size_t from_data(Channels::device_info_t *info, const std::uint8_t *data) {
-  std::size_t i = 4;  // skip vid, pid
-  // name, 16
-  info->name = _from_data(data + i, 16);
-  i += 16;
-  // serial_number, 16
-  info->serial_number = _from_data(data + i, 16);
-  i += 16;
-  // firmware_version, 2
-  info->firmware_version.set_major(data[i]);
-  info->firmware_version.set_minor(data[i + 1]);
-  i += 2;
-  // hardware_version, 3
-  info->hardware_version.set_major(data[i]);
-  info->hardware_version.set_minor(data[i + 1]);
-  info->hardware_version.set_flag(std::bitset<8>(data[i + 2]));
-  i += 3;
-  // spec_version, 2
-  info->spec_version.set_major(data[i]);
-  info->spec_version.set_minor(data[i + 1]);
-  i += 2;
-  // lens_type, 4
-  info->lens_type.set_vendor(_from_data<std::uint16_t>(data + i));
-  info->lens_type.set_product(_from_data<std::uint16_t>(data + i + 2));
-  i += 4;
-  // imu_type, 4
-  info->imu_type.set_vendor(_from_data<std::uint16_t>(data + i));
-  info->imu_type.set_product(_from_data<std::uint16_t>(data + i + 2));
-  i += 4;
-  // nominal_baseline, 2
-  info->nominal_baseline = _from_data<std::uint16_t>(data + i);
-  i += 2;
-
-  return i;
-}
-
-std::size_t from_data(IntrinsicsPinhole *in, const std::uint8_t *data,
-    const Version *spec_version) {
-  std::size_t i = 0;
-
-  // width, 2
-  in->width = _from_data<std::uint16_t>(data + i);
-  i += 2;
-  // height, 2
-  in->height = _from_data<std::uint16_t>(data + i);
-  i += 2;
-  // fx, 8
-  in->fx = _from_data<double>(data + i);
-  i += 8;
-  // fy, 8
-  in->fy = _from_data<double>(data + i);
-  i += 8;
-  // cx, 8
-  in->cx = _from_data<double>(data + i);
-  i += 8;
-  // cy, 8
-  in->cy = _from_data<double>(data + i);
-  i += 8;
-  // model, 1
-  in->model = data[i];
-  i += 1;
-  // coeffs, 40
-  for (std::size_t j = 0; j < 5; j++) {
-    in->coeffs[j] = _from_data<double>(data + i + j * 8);
-  }
-  i += 40;
-
-  MYNTEYE_UNUSED(spec_version)
-  return i;
-}
-
-std::size_t from_data(ImuIntrinsics *in, const std::uint8_t *data,
-    const Version *spec_version) {
-  std::size_t i = 0;
-
-  // scale
-  for (std::size_t j = 0; j < 3; j++) {
-    for (std::size_t k = 0; k < 3; k++) {
-      in->scale[j][k] = _from_data<double>(data + i + (j * 3 + k) * 8);
-    }
-  }
-  i += 72;
-  // drift
-  for (std::size_t j = 0; j < 3; j++) {
-    in->drift[j] = _from_data<double>(data + i + j * 8);
-  }
-  i += 24;
-  // noise
-  for (std::size_t j = 0; j < 3; j++) {
-    in->noise[j] = _from_data<double>(data + i + j * 8);
-  }
-  i += 24;
-  // bias
-  for (std::size_t j = 0; j < 3; j++) {
-    in->bias[j] = _from_data<double>(data + i + j * 8);
-  }
-  i += 24;
-
-  MYNTEYE_UNUSED(spec_version)
-  return i;
-}
-
-std::size_t from_data(Extrinsics *ex, const std::uint8_t *data,
-    const Version *spec_version) {
-  std::size_t i = 0;
-
-  // rotation
-  for (std::size_t j = 0; j < 3; j++) {
-    for (std::size_t k = 0; k < 3; k++) {
-      ex->rotation[j][k] = _from_data<double>(data + i + (j * 3 + k) * 8);
-    }
-  }
-  i += 72;
-  // translation
-  for (std::size_t j = 0; j < 3; j++) {
-    ex->translation[j] = _from_data<double>(data + i + j * 8);
-  }
-  i += 24;
-
-  MYNTEYE_UNUSED(spec_version)
-  return i;
-}
-
-// to
-
-std::size_t _to_data(std::string value, std::uint8_t *data, std::size_t count) {
-  std::copy(value.begin(), value.end(), data);
-  for (std::size_t i = value.size(); i < count; i++) {
-    data[i] = ' ';
-  }
-  return count;
-}
-
-std::size_t to_data(const Channels::device_info_t *info, std::uint8_t *data,
-    const Version *spec_version) {
-  std::size_t i = 3;  // skip id, size
-  i += 4;             // skip vid, pid
-  // name, 16
-  _to_data(info->name, data + i, 16);
-  i += 16;
-  // serial_number, 16
-  _to_data(info->serial_number, data + i, 16);
-  i += 16;
-  // firmware_version, 2
-  data[i] = info->firmware_version.major();
-  data[i + 1] = info->firmware_version.minor();
-  i += 2;
-  // hardware_version, 3
-  data[i] = info->hardware_version.major();
-  data[i + 1] = info->hardware_version.minor();
-  data[i + 2] =
-      static_cast<std::uint8_t>(info->hardware_version.flag().to_ulong());
-  i += 3;
-  // spec_version, 2
-  data[i] = info->spec_version.major();
-  data[i + 1] = info->spec_version.minor();
-  i += 2;
-  // lens_type, 4
-  _to_data(info->lens_type.vendor(), data + i);
-  _to_data(info->lens_type.product(), data + i + 2);
-  i += 4;
-  // imu_type, 4
-  _to_data(info->imu_type.vendor(), data + i);
-  _to_data(info->imu_type.product(), data + i + 2);
-  i += 4;
-  // nominal_baseline, 2
-  _to_data(info->nominal_baseline, data + i);
-  i += 2;
-
-  MYNTEYE_UNUSED(spec_version)
-
-  // others
-  std::size_t size = i - 3;
-  data[0] = Channels::FID_DEVICE_INFO;
-  data[1] = static_cast<std::uint8_t>((size >> 8) & 0xFF);
-  data[2] = static_cast<std::uint8_t>(size & 0xFF);
-  return size + 3;
-}
-
-std::size_t to_data(const IntrinsicsPinhole *in, std::uint8_t *data,
-    const Version *spec_version) {
-  std::size_t i = 0;
-
-  // width, 2
-  _to_data(in->width, data + i);
-  i += 2;
-  // height, 2
-  _to_data(in->height, data + i);
-  i += 2;
-  // fx, 8
-  _to_data(in->fx, data + i);
-  i += 8;
-  // fy, 8
-  _to_data(in->fy, data + i);
-  i += 8;
-  // cx, 8
-  _to_data(in->cx, data + i);
-  i += 8;
-  // cy, 8
-  _to_data(in->cy, data + i);
-  i += 8;
-  // model, 1
-  data[i] = in->model;
-  i += 1;
-  // coeffs, 40
-  for (std::size_t j = 0; j < 5; j++) {
-    _to_data(in->coeffs[j], data + i + j * 8);
-  }
-  i += 40;
-
-  MYNTEYE_UNUSED(spec_version)
-  return i;
-}
-
-std::size_t to_data(const ImuIntrinsics *in, std::uint8_t *data,
-    const Version *spec_version) {
-  std::size_t i = 0;
-
-  // scale
-  for (std::size_t j = 0; j < 3; j++) {
-    for (std::size_t k = 0; k < 3; k++) {
-      _to_data(in->scale[j][k], data + i + (j * 3 + k) * 8);
-    }
-  }
-  i += 72;
-  // drift
-  for (std::size_t j = 0; j < 3; j++) {
-    _to_data(in->drift[j], data + i + j * 8);
-  }
-  i += 24;
-  // noise
-  for (std::size_t j = 0; j < 3; j++) {
-    _to_data(in->noise[j], data + i + j * 8);
-  }
-  i += 24;
-  // bias
-  for (std::size_t j = 0; j < 3; j++) {
-    _to_data(in->bias[j], data + i + j * 8);
-  }
-  i += 24;
-
-  MYNTEYE_UNUSED(spec_version)
-  return i;
-}
-
-std::size_t to_data(const Extrinsics *ex, std::uint8_t *data,
-    const Version *spec_version) {
-  std::size_t i = 0;
-
-  // rotation
-  for (std::size_t j = 0; j < 3; j++) {
-    for (std::size_t k = 0; k < 3; k++) {
-      _to_data(ex->rotation[j][k], data + i + (j * 3 + k) * 8);
-    }
-  }
-  i += 72;
-  // translation
-  for (std::size_t j = 0; j < 3; j++) {
-    _to_data(ex->translation[j], data + i + j * 8);
-  }
-  i += 24;
-
-  MYNTEYE_UNUSED(spec_version)
-  return i;
-}
-
-}  // namespace bytes
-
 MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/device/channels/channels.h b/src/mynteye/device/channel/channels.h
similarity index 56%
rename from src/mynteye/device/channels/channels.h
rename to src/mynteye/device/channel/channels.h
index 371f3af..1ab453e 100644
--- a/src/mynteye/device/channels/channels.h
+++ b/src/mynteye/device/channel/channels.h
@@ -11,20 +11,19 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
-#ifndef MYNTEYE_DEVICE_CHANNELS_CHANNELS_H_
-#define MYNTEYE_DEVICE_CHANNELS_CHANNELS_H_
+#ifndef MYNTEYE_DEVICE_CHANNEL_CHANNELS_H_
+#define MYNTEYE_DEVICE_CHANNEL_CHANNELS_H_
 #pragma once
 
-#include <algorithm>
 #include <map>
 #include <memory>
 #include <set>
-#include <string>
 #include <thread>
 #include <vector>
 
 #include "mynteye/mynteye.h"
-#include "mynteye/types.h"
+#include "mynteye/device/channel/def.h"
+#include "mynteye/device/channel/file_channel.h"
 #include "mynteye/device/device.h"
 #include "mynteye/device/types.h"
 #include "mynteye/uvc/uvc.h"
@@ -42,15 +41,6 @@ class ChannelsAdapter;
 
 class MYNTEYE_API Channels {
  public:
-  typedef enum Channel {
-    CHANNEL_CAM_CTRL = 1,
-    CHANNEL_HALF_DUPLEX = 2,
-    CHANNEL_IMU_WRITE = 3,
-    CHANNEL_IMU_READ = 4,
-    CHANNEL_FILE = 5,
-    CHANNEL_LAST
-  } channel_t;
-
   typedef struct ControlInfo {
     std::int32_t min;
     std::int32_t max;
@@ -63,19 +53,11 @@ class MYNTEYE_API Channels {
     XU_CMD_LAST
   } xu_cmd_t;
 
-  typedef enum FileId {
-    FID_DEVICE_INFO = 1,  // device info
-    FID_IMG_PARAMS = 2,   // image intrinsics & extrinsics
-    FID_IMU_PARAMS = 4,   // imu intrinsics & extrinsics
-    FID_LAST,
-  } file_id_t;
-
   using imu_callback_t = std::function<void(const ImuPacket &packet)>;
 
-  using device_info_t = DeviceInfo;
-
-  using img_params_t = std::map<Resolution, device::img_params_t>;
-  using imu_params_t = device::imu_params_t;
+  using device_info_t = FileChannel::device_info_t;
+  using img_params_t = FileChannel::img_params_t;
+  using imu_params_t = FileChannel::imu_params_t;
 
   Channels(const std::shared_ptr<uvc::device> &device,
            const std::shared_ptr<ChannelsAdapter> &adapter);
@@ -101,7 +83,7 @@ class MYNTEYE_API Channels {
 
   bool GetFiles(
       device_info_t *info, img_params_t *img_params, imu_params_t *imu_params,
-      Version *spec_version = nullptr) const;
+      Version *spec_version = nullptr);
   bool SetFiles(
       device_info_t *info, img_params_t *img_params, imu_params_t *imu_params,
       Version *spec_version = nullptr);
@@ -142,6 +124,8 @@ class MYNTEYE_API Channels {
   std::shared_ptr<uvc::device> device_;
   std::shared_ptr<ChannelsAdapter> adapter_;
 
+  FileChannel file_channel_;
+
   std::map<Option, control_info_t> control_infos_;
 
   bool is_imu_tracking_;
@@ -165,88 +149,8 @@ class ChannelsAdapter {
   virtual std::vector<std::int32_t> GetGyroRangeValues() = 0;
 
   virtual void GetImuResPacket(const std::uint8_t *data, ImuResPacket *res) = 0;
-
-  virtual std::size_t GetImgParamsFromData(
-      const std::uint8_t *data, const Version *version,
-      Channels::img_params_t *img_params) = 0;
-  virtual std::size_t SetImgParamsToData(
-      const Channels::img_params_t *img_params, const Version *version,
-      std::uint8_t *data) = 0;
-
-  virtual std::size_t GetImuParamsFromData(
-      const std::uint8_t *data, const Version *version,
-      Channels::imu_params_t *imu_params);
-  virtual std::size_t SetImuParamsToData(
-      const Channels::imu_params_t *imu_params, const Version *version,
-      std::uint8_t *data);
 };
 
-namespace bytes {
-
-// from
-
-template <typename T>
-T _from_data(const std::uint8_t *data) {
-  std::size_t size = sizeof(T) / sizeof(std::uint8_t);
-  T value = 0;
-  for (std::size_t i = 0; i < size; i++) {
-    value |= data[i] << (8 * (size - i - 1));
-  }
-  return value;
-}
-
-template <>
-inline double _from_data(const std::uint8_t *data) {
-  return *(reinterpret_cast<const double *>(data));
-}
-
-std::string _from_data(const std::uint8_t *data, std::size_t count);
-
-std::size_t from_data(Channels::device_info_t *info, const std::uint8_t *data);
-
-std::size_t from_data(IntrinsicsPinhole *in, const std::uint8_t *data,
-    const Version *spec_version);
-
-std::size_t from_data(ImuIntrinsics *in, const std::uint8_t *data,
-    const Version *spec_version);
-
-std::size_t from_data(Extrinsics *ex, const std::uint8_t *data,
-    const Version *spec_version);
-
-// to
-
-template <typename T>
-std::size_t _to_data(T value, std::uint8_t *data) {
-  std::size_t size = sizeof(T) / sizeof(std::uint8_t);
-  for (std::size_t i = 0; i < size; i++) {
-    data[i] = static_cast<std::uint8_t>((value >> (8 * (size - i - 1))) & 0xFF);
-  }
-  return size;
-}
-
-template <>
-inline std::size_t _to_data(double value, std::uint8_t *data) {
-  std::uint8_t *val = reinterpret_cast<std::uint8_t *>(&value);
-  std::copy(val, val + 8, data);
-  return 8;
-}
-
-std::size_t _to_data(std::string value, std::uint8_t *data, std::size_t count);
-
-std::size_t to_data(const Channels::device_info_t *info, std::uint8_t *data,
-    const Version *spec_version);
-
-std::size_t to_data(const IntrinsicsPinhole *in, std::uint8_t *data,
-    const Version *spec_version);
-
-std::size_t to_data(const ImuIntrinsics *in, std::uint8_t *data,
-    const Version *spec_version);
-
-std::size_t to_data(const Extrinsics *ex, std::uint8_t *data,
-    const Version *spec_version);
-
-}  // namespace bytes
-
 MYNTEYE_END_NAMESPACE
 
-#endif  // MYNTEYE_DEVICE_CHANNELS_CHANNELS_H_
+#endif  // MYNTEYE_DEVICE_CHANNEL_CHANNELS_H_
diff --git a/src/mynteye/device/channel/def.h b/src/mynteye/device/channel/def.h
new file mode 100644
index 0000000..7e5d39e
--- /dev/null
+++ b/src/mynteye/device/channel/def.h
@@ -0,0 +1,40 @@
+// Copyright 2018 Slightech Co., Ltd. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#ifndef MYNTEYE_DEVICE_CHANNEL_DEF_H_
+#define MYNTEYE_DEVICE_CHANNEL_DEF_H_
+#pragma once
+
+#include "mynteye/mynteye.h"
+
+MYNTEYE_BEGIN_NAMESPACE
+
+typedef enum Channel {
+  CHANNEL_CAM_CTRL = 1,
+  CHANNEL_HALF_DUPLEX = 2,
+  CHANNEL_IMU_WRITE = 3,
+  CHANNEL_IMU_READ = 4,
+  CHANNEL_FILE = 5,
+  CHANNEL_LAST
+} channel_t;
+
+typedef enum FileId {
+  FID_DEVICE_INFO = 1,  // device info
+  FID_IMG_PARAMS = 2,   // image intrinsics & extrinsics
+  FID_IMU_PARAMS = 4,   // imu intrinsics & extrinsics
+  FID_LAST,
+} file_id_t;
+
+MYNTEYE_END_NAMESPACE
+
+#endif  // MYNTEYE_DEVICE_CHANNEL_DEF_H_
diff --git a/src/mynteye/device/channel/file_channel.cc b/src/mynteye/device/channel/file_channel.cc
new file mode 100644
index 0000000..d3b4da1
--- /dev/null
+++ b/src/mynteye/device/channel/file_channel.cc
@@ -0,0 +1,403 @@
+// Copyright 2018 Slightech Co., Ltd. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#include "mynteye/device/channel/file_channel.h"
+
+#include "mynteye/logger.h"
+
+MYNTEYE_BEGIN_NAMESPACE
+
+// FileChannel
+
+FileChannel::FileChannel() {
+  dev_info_parser_ = std::make_shared<DeviceInfoParser>();
+  img_params_parser_ = std::make_shared<ImgParamsParser>();
+  imu_params_parser_ = std::make_shared<ImuParamsParser>();
+}
+
+FileChannel::~FileChannel() {
+}
+
+std::size_t FileChannel::GetDeviceInfoFromData(
+    const std::uint8_t *data, device_info_t *info) {
+  auto n = dev_info_parser_->GetFromData(data, info);
+  auto spec_version = info->spec_version;
+  img_params_parser_->SetSpecVersion(spec_version);
+  imu_params_parser_->SetSpecVersion(spec_version);
+  return n;
+}
+
+std::size_t FileChannel::SetDeviceInfoToData(
+    const device_info_t *info, std::uint8_t *data) {
+  auto spec_version = info->spec_version;
+  img_params_parser_->SetSpecVersion(spec_version);
+  imu_params_parser_->SetSpecVersion(spec_version);
+  return dev_info_parser_->SetToData(info, data);
+}
+
+std::size_t FileChannel::GetImgParamsFromData(
+    const std::uint8_t *data, img_params_t *img_params) {
+  CHECK_NOTNULL(img_params_parser_);
+  return img_params_parser_->GetFromData(data, img_params);
+}
+
+std::size_t FileChannel::SetImgParamsToData(
+    const img_params_t *img_params, std::uint8_t *data) {
+  CHECK_NOTNULL(img_params_parser_);
+  return img_params_parser_->SetToData(img_params, data);
+}
+
+std::size_t FileChannel::GetImuParamsFromData(
+    const std::uint8_t *data, imu_params_t *imu_params) {
+  return imu_params_parser_->GetFromData(data, imu_params);
+}
+
+std::size_t FileChannel::SetImuParamsToData(
+    const imu_params_t *imu_params, std::uint8_t *data) {
+  return imu_params_parser_->SetToData(imu_params, data);
+}
+
+// DeviceInfoParser
+
+DeviceInfoParser::DeviceInfoParser() {
+}
+
+DeviceInfoParser::~DeviceInfoParser() {
+}
+
+std::size_t DeviceInfoParser::GetFromData(
+    const std::uint8_t *data, device_info_t *info) const {
+  std::size_t i = 4;  // skip vid, pid
+  // name, 16
+  info->name = bytes::_from_data(data + i, 16);
+  i += 16;
+  // serial_number, 16
+  info->serial_number = bytes::_from_data(data + i, 16);
+  i += 16;
+  // firmware_version, 2
+  info->firmware_version.set_major(data[i]);
+  info->firmware_version.set_minor(data[i + 1]);
+  i += 2;
+  // hardware_version, 3
+  info->hardware_version.set_major(data[i]);
+  info->hardware_version.set_minor(data[i + 1]);
+  info->hardware_version.set_flag(std::bitset<8>(data[i + 2]));
+  i += 3;
+  // spec_version, 2
+  info->spec_version.set_major(data[i]);
+  info->spec_version.set_minor(data[i + 1]);
+  i += 2;
+  // lens_type, 4
+  info->lens_type.set_vendor(bytes::_from_data<std::uint16_t>(data + i));
+  info->lens_type.set_product(bytes::_from_data<std::uint16_t>(data + i + 2));
+  i += 4;
+  // imu_type, 4
+  info->imu_type.set_vendor(bytes::_from_data<std::uint16_t>(data + i));
+  info->imu_type.set_product(bytes::_from_data<std::uint16_t>(data + i + 2));
+  i += 4;
+  // nominal_baseline, 2
+  info->nominal_baseline = bytes::_from_data<std::uint16_t>(data + i);
+  i += 2;
+
+  // get other infos according to spec_version
+
+  return i;
+}
+
+std::size_t DeviceInfoParser::SetToData(
+    const device_info_t *info, std::uint8_t *data) const {
+  std::size_t i = 3;  // skip id, size
+  i += 4;             // skip vid, pid
+  // name, 16
+  bytes::_to_data(info->name, data + i, 16);
+  i += 16;
+  // serial_number, 16
+  bytes::_to_data(info->serial_number, data + i, 16);
+  i += 16;
+  // firmware_version, 2
+  data[i] = info->firmware_version.major();
+  data[i + 1] = info->firmware_version.minor();
+  i += 2;
+  // hardware_version, 3
+  data[i] = info->hardware_version.major();
+  data[i + 1] = info->hardware_version.minor();
+  data[i + 2] =
+      static_cast<std::uint8_t>(info->hardware_version.flag().to_ulong());
+  i += 3;
+  // spec_version, 2
+  data[i] = info->spec_version.major();
+  data[i + 1] = info->spec_version.minor();
+  i += 2;
+  // lens_type, 4
+  bytes::_to_data(info->lens_type.vendor(), data + i);
+  bytes::_to_data(info->lens_type.product(), data + i + 2);
+  i += 4;
+  // imu_type, 4
+  bytes::_to_data(info->imu_type.vendor(), data + i);
+  bytes::_to_data(info->imu_type.product(), data + i + 2);
+  i += 4;
+  // nominal_baseline, 2
+  bytes::_to_data(info->nominal_baseline, data + i);
+  i += 2;
+
+  // set other infos according to spec_version
+
+  // others
+  std::size_t size = i - 3;
+  data[0] = FID_DEVICE_INFO;
+  data[1] = static_cast<std::uint8_t>((size >> 8) & 0xFF);
+  data[2] = static_cast<std::uint8_t>(size & 0xFF);
+  return size + 3;
+}
+
+// ImgParamsParser
+
+ImgParamsParser::ImgParamsParser() {
+}
+
+ImgParamsParser::~ImgParamsParser() {
+}
+
+std::size_t ImgParamsParser::GetFromData(
+    const std::uint8_t *data, img_params_t *img_params) const {
+  if (spec_version_ == Version(1, 0) || spec_version_ == Version(1, 1)) {
+    // get img params without version header
+    if (spec_version_ == Version(1, 0)) {
+      return GetFromData_v1_0(data, img_params);
+    } else {
+      return GetFromData_v1_1(data, img_params);
+    }
+  } else {
+    // get img params with version header
+    return GetFromData_new(data, img_params);
+  }
+}
+
+std::size_t ImgParamsParser::SetToData(
+    const img_params_t *img_params, std::uint8_t *data) const {
+  if (spec_version_ == Version(1, 0) || spec_version_ == Version(1, 1)) {
+    // set img params without version header
+    if (spec_version_ == Version(1, 0)) {
+      return SetToData_v1_0(img_params, data);
+    } else {
+      return SetToData_v1_1(img_params, data);
+    }
+  } else {
+    // set img params with version header
+    return SetToData_new(img_params, data);
+  }
+}
+
+std::size_t ImgParamsParser::GetFromData_v1_0(
+    const std::uint8_t *data, img_params_t *img_params) const {
+  std::size_t i = 0;
+
+  auto in_left = std::make_shared<IntrinsicsPinhole>();
+  auto in_right = std::make_shared<IntrinsicsPinhole>();
+  Extrinsics ex_right_to_left;
+
+  i += bytes::from_data(in_left.get(), data + i);
+  i += bytes::from_data(in_right.get(), data + i);
+  i += bytes::from_data(&ex_right_to_left, data + i);
+  (*img_params)[{752, 480}] = {true, spec_version_.to_string(),
+      in_left, in_right, ex_right_to_left};
+
+  return i;
+}
+
+std::size_t ImgParamsParser::SetToData_v1_0(
+    const img_params_t *img_params, std::uint8_t *data) const {
+  std::size_t i = 3;  // skip id, size
+
+  auto params = (*img_params).at({752, 480});
+  auto in_left = std::dynamic_pointer_cast<IntrinsicsPinhole>(params.in_left);
+  auto in_right = std::dynamic_pointer_cast<IntrinsicsPinhole>(params.in_right);
+  i += bytes::to_data(in_left.get(), data + i);
+  i += bytes::to_data(in_right.get(), data + i);
+  i += bytes::to_data(&params.ex_right_to_left, data + i);
+
+  // others
+  std::size_t size = i - 3;
+  data[0] = FID_IMG_PARAMS;
+  data[1] = static_cast<std::uint8_t>((size >> 8) & 0xFF);
+  data[2] = static_cast<std::uint8_t>(size & 0xFF);
+  return size + 3;
+}
+
+std::size_t ImgParamsParser::GetFromData_v1_1(
+    const std::uint8_t *data, img_params_t *img_params) const {
+  std::size_t i = 0;
+
+  Extrinsics ex_right_to_left;
+  {
+    auto in_left = std::make_shared<IntrinsicsPinhole>();
+    auto in_right = std::make_shared<IntrinsicsPinhole>();
+    i += bytes::from_data(in_left.get(), data + i);
+    i += bytes::from_data(in_right.get(), data + i);
+    (*img_params)[{1280, 400}] = {true, spec_version_.to_string(),
+        in_left, in_right, ex_right_to_left};
+  }
+  {
+    auto in_left = std::make_shared<IntrinsicsPinhole>();
+    auto in_right = std::make_shared<IntrinsicsPinhole>();
+    i += bytes::from_data(in_left.get(), data + i);
+    i += bytes::from_data(in_right.get(), data + i);
+    (*img_params)[{2560, 800}] = {true, spec_version_.to_string(),
+        in_left, in_right, ex_right_to_left};
+  }
+  {
+    i += bytes::from_data(&ex_right_to_left, data + i);
+    (*img_params)[{1280, 400}].ex_right_to_left = ex_right_to_left;
+    (*img_params)[{2560, 800}].ex_right_to_left = ex_right_to_left;
+  }
+
+  return i;
+}
+
+std::size_t ImgParamsParser::SetToData_v1_1(
+    const img_params_t *img_params, std::uint8_t *data) const {
+  std::size_t i = 3;  // skip id, size
+
+  {
+    auto params = (*img_params).at({1280, 400});
+    auto in_left = std::dynamic_pointer_cast<IntrinsicsPinhole>(params.in_left);
+    auto in_right = std::dynamic_pointer_cast<IntrinsicsPinhole>(
+        params.in_right);
+    i += bytes::to_data(in_left.get(), data + i);
+    i += bytes::to_data(in_right.get(), data + i);
+  }
+  {
+    auto params = (*img_params).at({2560, 800});
+    auto in_left = std::dynamic_pointer_cast<IntrinsicsPinhole>(params.in_left);
+    auto in_right = std::dynamic_pointer_cast<IntrinsicsPinhole>(
+        params.in_right);
+    i += bytes::to_data(in_left.get(), data + i);
+    i += bytes::to_data(in_right.get(), data + i);
+    i += bytes::to_data(&params.ex_right_to_left, data + i);
+  }
+
+  // others
+  std::size_t size = i - 3;
+  data[0] = FID_IMG_PARAMS;
+  data[1] = static_cast<std::uint8_t>((size >> 8) & 0xFF);
+  data[2] = static_cast<std::uint8_t>(size & 0xFF);
+  return size + 3;
+}
+
+std::size_t ImgParamsParser::GetFromData_new(
+    const std::uint8_t *data, img_params_t *img_params) const {
+  return 0;
+}
+std::size_t ImgParamsParser::SetToData_new(
+    const img_params_t *img_params, std::uint8_t *data) const {
+  return 0;
+}
+
+// ImuParamsParser
+
+ImuParamsParser::ImuParamsParser() {
+}
+
+ImuParamsParser::~ImuParamsParser() {
+}
+
+std::size_t ImuParamsParser::GetFromData(
+    const std::uint8_t *data, imu_params_t *imu_params) const {
+  if (spec_version_ == Version(1, 0) || spec_version_ == Version(1, 1)) {
+    // get imu params without version header
+    return GetFromData_old(data, imu_params);
+  } else {
+    // get imu params with version header
+    return GetFromData_new(data, imu_params);
+  }
+}
+
+std::size_t ImuParamsParser::SetToData(
+    const imu_params_t *imu_params, std::uint8_t *data) const {
+  if (spec_version_ == Version(1, 0) || spec_version_ == Version(1, 1)) {
+    // set imu params without version header
+    return SetToData_old(imu_params, data);
+  } else {
+    // set imu params with version header
+    return SetToData_new(imu_params, data);
+  }
+}
+
+std::size_t ImuParamsParser::GetFromData_old(
+    const std::uint8_t *data, imu_params_t *imu_params) const {
+  std::size_t i = 0;
+  i += bytes::from_data(&imu_params->in_accel, data + i);
+  i += bytes::from_data(&imu_params->in_gyro, data + i);
+  i += bytes::from_data(&imu_params->ex_left_to_imu, data + i);
+  return i;
+}
+
+std::size_t ImuParamsParser::SetToData_old(
+    const imu_params_t *imu_params, std::uint8_t *data) const {
+  std::size_t i = 3;  // skip id, size
+  i += bytes::to_data(&imu_params->in_accel, data + i);
+  i += bytes::to_data(&imu_params->in_gyro, data + i);
+  i += bytes::to_data(&imu_params->ex_left_to_imu, data + i);
+  // others
+  std::size_t size = i - 3;
+  data[0] = FID_IMU_PARAMS;
+  data[1] = static_cast<std::uint8_t>((size >> 8) & 0xFF);
+  data[2] = static_cast<std::uint8_t>(size & 0xFF);
+  return size + 3;
+}
+
+std::size_t ImuParamsParser::GetFromData_new(
+    const std::uint8_t *data, imu_params_t *imu_params) const {
+  std::size_t i = 0;
+  // version, 2
+  Version version(data[i], data[i + 1]);
+  imu_params->version = version.to_string();
+  i += 2;
+  // get imu params according to version
+  if (version == Version(1, 2)) {  // v1.2
+    i += bytes::from_data(&imu_params->in_accel, data + i);
+    i += bytes::from_data(&imu_params->in_gyro, data + i);
+    i += bytes::from_data(&imu_params->ex_left_to_imu, data + i);
+  } else {
+    LOG(FATAL) << "Could not get imu params of version "
+        << version.to_string() << ", please use latest SDK.";
+  }
+  return i;
+}
+
+std::size_t ImuParamsParser::SetToData_new(
+    const imu_params_t *imu_params, std::uint8_t *data) const {
+  std::size_t i = 3;  // skip id, size
+  // version, 2
+  Version version(imu_params->version);
+  data[i] = version.major();
+  data[i + 1] = version.minor();
+  i += 2;
+  // set imu params according to version
+  if (version == Version(1, 2)) {  // v1.2
+    i += bytes::to_data(&imu_params->in_accel, data + i);
+    i += bytes::to_data(&imu_params->in_gyro, data + i);
+    i += bytes::to_data(&imu_params->ex_left_to_imu, data + i);
+  } else {
+    LOG(FATAL) << "Could not set imu params of version "
+        << version.to_string() << ", please use latest SDK.";
+  }
+  // others
+  std::size_t size = i - 3;
+  data[0] = FID_IMU_PARAMS;
+  data[1] = static_cast<std::uint8_t>((size >> 8) & 0xFF);
+  data[2] = static_cast<std::uint8_t>(size & 0xFF);
+  return size + 3;
+}
+
+MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/device/channel/file_channel.h b/src/mynteye/device/channel/file_channel.h
new file mode 100644
index 0000000..2058124
--- /dev/null
+++ b/src/mynteye/device/channel/file_channel.h
@@ -0,0 +1,142 @@
+// Copyright 2018 Slightech Co., Ltd. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+#ifndef MYNTEYE_DEVICE_CHANNEL_FILE_CHANNEL_H_
+#define MYNTEYE_DEVICE_CHANNEL_FILE_CHANNEL_H_
+#pragma once
+
+#include <map>
+#include <memory>
+
+#include "mynteye/mynteye.h"
+#include "mynteye/device/device.h"
+#include "mynteye/device/channel/bytes.h"
+
+MYNTEYE_BEGIN_NAMESPACE
+
+class DeviceInfoParser;
+class ImgParamsParser;
+class ImuParamsParser;
+
+class FileChannel {
+ public:
+  using device_info_t = DeviceInfo;
+
+  using img_params_t = std::map<Resolution, device::img_params_t>;
+  using imu_params_t = device::imu_params_t;
+
+  FileChannel();
+  ~FileChannel();
+
+  std::size_t GetDeviceInfoFromData(
+      const std::uint8_t *data, device_info_t *info);
+  std::size_t SetDeviceInfoToData(
+      const device_info_t *info, std::uint8_t *data);
+
+  std::size_t GetImgParamsFromData(
+      const std::uint8_t *data, img_params_t *img_params);
+  std::size_t SetImgParamsToData(
+      const img_params_t *img_params, std::uint8_t *data);
+
+  std::size_t GetImuParamsFromData(
+      const std::uint8_t *data, imu_params_t *imu_params);
+  std::size_t SetImuParamsToData(
+      const imu_params_t *imu_params, std::uint8_t *data);
+
+ private:
+  std::shared_ptr<DeviceInfoParser> dev_info_parser_;
+  std::shared_ptr<ImgParamsParser> img_params_parser_;
+  std::shared_ptr<ImuParamsParser> imu_params_parser_;
+};
+
+class DeviceInfoParser {
+ public:
+  using device_info_t = FileChannel::device_info_t;
+
+  DeviceInfoParser();
+  ~DeviceInfoParser();
+
+  std::size_t GetFromData(
+      const std::uint8_t *data, device_info_t *info) const;
+  std::size_t SetToData(
+      const device_info_t *info, std::uint8_t *data) const;
+};
+
+class ImgParamsParser {
+ public:
+  using img_params_t = FileChannel::img_params_t;
+
+  ImgParamsParser();
+  ~ImgParamsParser();
+
+  void SetSpecVersion(const Version& spec_version) {
+    spec_version_ = spec_version;
+  }
+
+  std::size_t GetFromData(
+      const std::uint8_t *data, img_params_t *img_params) const;
+  std::size_t SetToData(
+      const img_params_t *img_params, std::uint8_t *data) const;
+
+  std::size_t GetFromData_v1_0(
+      const std::uint8_t *data, img_params_t *img_params) const;
+  std::size_t SetToData_v1_0(
+      const img_params_t *img_params, std::uint8_t *data) const;
+
+  std::size_t GetFromData_v1_1(
+      const std::uint8_t *data, img_params_t *img_params) const;
+  std::size_t SetToData_v1_1(
+      const img_params_t *img_params, std::uint8_t *data) const;
+
+  std::size_t GetFromData_new(
+      const std::uint8_t *data, img_params_t *img_params) const;
+  std::size_t SetToData_new(
+      const img_params_t *img_params, std::uint8_t *data) const;
+
+ private:
+  Version spec_version_;
+};
+
+class ImuParamsParser {
+ public:
+  using imu_params_t = FileChannel::imu_params_t;
+
+  ImuParamsParser();
+  ~ImuParamsParser();
+
+  void SetSpecVersion(const Version& spec_version) {
+    spec_version_ = spec_version;
+  }
+
+  std::size_t GetFromData(
+      const std::uint8_t *data, imu_params_t *imu_params) const;
+  std::size_t SetToData(
+      const imu_params_t *imu_params, std::uint8_t *data) const;
+
+  std::size_t GetFromData_old(
+      const std::uint8_t *data, imu_params_t *imu_params) const;
+  std::size_t SetToData_old(
+      const imu_params_t *imu_params, std::uint8_t *data) const;
+
+  std::size_t GetFromData_new(
+      const std::uint8_t *data, imu_params_t *imu_params) const;
+  std::size_t SetToData_new(
+      const imu_params_t *imu_params, std::uint8_t *data) const;
+
+ private:
+  Version spec_version_;
+};
+
+MYNTEYE_END_NAMESPACE
+
+#endif  // MYNTEYE_DEVICE_CHANNEL_FILE_CHANNEL_H_
diff --git a/src/mynteye/device/device.cc b/src/mynteye/device/device.cc
index beb58a2..b1a6295 100644
--- a/src/mynteye/device/device.cc
+++ b/src/mynteye/device/device.cc
@@ -21,7 +21,7 @@
 
 #include "mynteye/logger.h"
 #include "mynteye/device/async_callback.h"
-#include "mynteye/device/channels/channels.h"
+#include "mynteye/device/channel/channels.h"
 #include "mynteye/device/config.h"
 #include "mynteye/device/motions.h"
 #include "mynteye/device/standard/device_s.h"
diff --git a/src/mynteye/device/motions.cc b/src/mynteye/device/motions.cc
index d5a0719..71c40ab 100644
--- a/src/mynteye/device/motions.cc
+++ b/src/mynteye/device/motions.cc
@@ -14,7 +14,7 @@
 #include "mynteye/device/motions.h"
 
 #include "mynteye/logger.h"
-#include "mynteye/device/channels/channels.h"
+#include "mynteye/device/channel/channels.h"
 
 MYNTEYE_BEGIN_NAMESPACE
 
diff --git a/src/mynteye/device/standard/channels_adapter_s.cc b/src/mynteye/device/standard/channels_adapter_s.cc
index ea013c9..a2fc0ee 100644
--- a/src/mynteye/device/standard/channels_adapter_s.cc
+++ b/src/mynteye/device/standard/channels_adapter_s.cc
@@ -126,41 +126,4 @@ void StandardChannelsAdapter::GetImuResPacket(
   unpack_imu_res_packet(data, res);
 }
 
-std::size_t StandardChannelsAdapter::GetImgParamsFromData(
-    const std::uint8_t *data, const Version *version,
-    Channels::img_params_t *img_params) {
-  std::size_t i = 0;
-
-  auto in_left = std::make_shared<IntrinsicsPinhole>();
-  auto in_right = std::make_shared<IntrinsicsPinhole>();
-  Extrinsics ex_right_to_left;
-
-  i += bytes::from_data(in_left.get(), data + i, version);
-  i += bytes::from_data(in_right.get(), data + i, version);
-  i += bytes::from_data(&ex_right_to_left, data + i, version);
-  (*img_params)[{752, 480}] = {true, in_left, in_right, ex_right_to_left};
-
-  return i;
-}
-
-std::size_t StandardChannelsAdapter::SetImgParamsToData(
-    const Channels::img_params_t *img_params, const Version *version,
-    std::uint8_t *data) {
-  std::size_t i = 3;  // skip id, size
-
-  auto params = (*img_params).at({752, 480});
-  auto in_left = std::dynamic_pointer_cast<IntrinsicsPinhole>(params.in_left);
-  auto in_right = std::dynamic_pointer_cast<IntrinsicsPinhole>(params.in_right);
-  i += bytes::to_data(in_left.get(), data + i, version);
-  i += bytes::to_data(in_right.get(), data + i, version);
-  i += bytes::to_data(&params.ex_right_to_left, data + i, version);
-
-  // others
-  std::size_t size = i - 3;
-  data[0] = Channels::FID_IMG_PARAMS;
-  data[1] = static_cast<std::uint8_t>((size >> 8) & 0xFF);
-  data[2] = static_cast<std::uint8_t>(size & 0xFF);
-  return size + 3;
-}
-
 MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/device/standard/channels_adapter_s.h b/src/mynteye/device/standard/channels_adapter_s.h
index b768c22..54205a3 100644
--- a/src/mynteye/device/standard/channels_adapter_s.h
+++ b/src/mynteye/device/standard/channels_adapter_s.h
@@ -19,7 +19,7 @@
 #include <set>
 #include <vector>
 
-#include "mynteye/device/channels/channels.h"
+#include "mynteye/device/channel/channels.h"
 
 MYNTEYE_BEGIN_NAMESPACE
 
@@ -37,13 +37,6 @@ class StandardChannelsAdapter : public ChannelsAdapter {
   std::vector<std::int32_t> GetGyroRangeValues() override;
 
   void GetImuResPacket(const std::uint8_t *data, ImuResPacket *res) override;
-
-  std::size_t GetImgParamsFromData(
-      const std::uint8_t *data, const Version *version,
-      Channels::img_params_t *img_params) override;
-  std::size_t SetImgParamsToData(
-      const Channels::img_params_t *img_params, const Version *version,
-      std::uint8_t *data) override;
 };
 
 MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/device/standard2/channels_adapter_s2.cc b/src/mynteye/device/standard2/channels_adapter_s2.cc
index dc91636..3257039 100644
--- a/src/mynteye/device/standard2/channels_adapter_s2.cc
+++ b/src/mynteye/device/standard2/channels_adapter_s2.cc
@@ -122,64 +122,4 @@ void Standard2ChannelsAdapter::GetImuResPacket(
   unpack_imu_res_packet(data, res);
 }
 
-std::size_t Standard2ChannelsAdapter::GetImgParamsFromData(
-    const std::uint8_t *data, const Version *version,
-    Channels::img_params_t *img_params) {
-  std::size_t i = 0;
-
-  Extrinsics ex_right_to_left;
-  {
-    auto in_left = std::make_shared<IntrinsicsPinhole>();
-    auto in_right = std::make_shared<IntrinsicsPinhole>();
-    i += bytes::from_data(in_left.get(), data + i, version);
-    i += bytes::from_data(in_right.get(), data + i, version);
-    (*img_params)[{1280, 400}] = {true, in_left, in_right, ex_right_to_left};
-  }
-  {
-    auto in_left = std::make_shared<IntrinsicsPinhole>();
-    auto in_right = std::make_shared<IntrinsicsPinhole>();
-    i += bytes::from_data(in_left.get(), data + i, version);
-    i += bytes::from_data(in_right.get(), data + i, version);
-    (*img_params)[{2560, 800}] = {true, in_left, in_right, ex_right_to_left};
-  }
-  {
-    i += bytes::from_data(&ex_right_to_left, data + i, version);
-    (*img_params)[{1280, 400}].ex_right_to_left = ex_right_to_left;
-    (*img_params)[{2560, 800}].ex_right_to_left = ex_right_to_left;
-  }
-
-  return i;
-}
-
-std::size_t Standard2ChannelsAdapter::SetImgParamsToData(
-    const Channels::img_params_t *img_params, const Version *version,
-    std::uint8_t *data) {
-  std::size_t i = 3;  // skip id, size
-
-  {
-    auto params = (*img_params).at({1280, 400});
-    auto in_left = std::dynamic_pointer_cast<IntrinsicsPinhole>(params.in_left);
-    auto in_right = std::dynamic_pointer_cast<IntrinsicsPinhole>(
-        params.in_right);
-    i += bytes::to_data(in_left.get(), data + i, version);
-    i += bytes::to_data(in_right.get(), data + i, version);
-  }
-  {
-    auto params = (*img_params).at({2560, 800});
-    auto in_left = std::dynamic_pointer_cast<IntrinsicsPinhole>(params.in_left);
-    auto in_right = std::dynamic_pointer_cast<IntrinsicsPinhole>(
-        params.in_right);
-    i += bytes::to_data(in_left.get(), data + i, version);
-    i += bytes::to_data(in_right.get(), data + i, version);
-    i += bytes::to_data(&params.ex_right_to_left, data + i, version);
-  }
-
-  // others
-  std::size_t size = i - 3;
-  data[0] = Channels::FID_IMG_PARAMS;
-  data[1] = static_cast<std::uint8_t>((size >> 8) & 0xFF);
-  data[2] = static_cast<std::uint8_t>(size & 0xFF);
-  return size + 3;
-}
-
 MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/device/standard2/channels_adapter_s2.h b/src/mynteye/device/standard2/channels_adapter_s2.h
index d9a5e1a..375ba3e 100644
--- a/src/mynteye/device/standard2/channels_adapter_s2.h
+++ b/src/mynteye/device/standard2/channels_adapter_s2.h
@@ -19,7 +19,7 @@
 #include <set>
 #include <vector>
 
-#include "mynteye/device/channels/channels.h"
+#include "mynteye/device/channel/channels.h"
 
 MYNTEYE_BEGIN_NAMESPACE
 
@@ -37,13 +37,6 @@ class Standard2ChannelsAdapter : public ChannelsAdapter {
   std::vector<std::int32_t> GetGyroRangeValues() override;
 
   void GetImuResPacket(const std::uint8_t *data, ImuResPacket *res) override;
-
-  std::size_t GetImgParamsFromData(
-      const std::uint8_t *data, const Version *version,
-      Channels::img_params_t *img_params) override;
-  std::size_t SetImgParamsToData(
-      const Channels::img_params_t *img_params, const Version *version,
-      std::uint8_t *data) override;
 };
 
 MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/device/standard2/channels_adapter_s210a.cc b/src/mynteye/device/standard2/channels_adapter_s210a.cc
index 6283c8a..e2ff9af 100644
--- a/src/mynteye/device/standard2/channels_adapter_s210a.cc
+++ b/src/mynteye/device/standard2/channels_adapter_s210a.cc
@@ -122,64 +122,4 @@ void Standard210aChannelsAdapter::GetImuResPacket(
   unpack_imu_res_packet(data, res);
 }
 
-std::size_t Standard210aChannelsAdapter::GetImgParamsFromData(
-    const std::uint8_t *data, const Version *version,
-    Channels::img_params_t *img_params) {
-  std::size_t i = 0;
-
-  Extrinsics ex_right_to_left;
-  {
-    auto in_left = std::make_shared<IntrinsicsPinhole>();
-    auto in_right = std::make_shared<IntrinsicsPinhole>();
-    i += bytes::from_data(in_left.get(), data + i, version);
-    i += bytes::from_data(in_right.get(), data + i, version);
-    (*img_params)[{1280, 400}] = {true, in_left, in_right, ex_right_to_left};
-  }
-  {
-    auto in_left = std::make_shared<IntrinsicsPinhole>();
-    auto in_right = std::make_shared<IntrinsicsPinhole>();
-    i += bytes::from_data(in_left.get(), data + i, version);
-    i += bytes::from_data(in_right.get(), data + i, version);
-    (*img_params)[{2560, 800}] = {true, in_left, in_right, ex_right_to_left};
-  }
-  {
-    i += bytes::from_data(&ex_right_to_left, data + i, version);
-    (*img_params)[{1280, 400}].ex_right_to_left = ex_right_to_left;
-    (*img_params)[{2560, 800}].ex_right_to_left = ex_right_to_left;
-  }
-
-  return i;
-}
-
-std::size_t Standard210aChannelsAdapter::SetImgParamsToData(
-    const Channels::img_params_t *img_params, const Version *version,
-    std::uint8_t *data) {
-  std::size_t i = 3;  // skip id, size
-
-  {
-    auto params = (*img_params).at({1280, 400});
-    auto in_left = std::dynamic_pointer_cast<IntrinsicsPinhole>(params.in_left);
-    auto in_right = std::dynamic_pointer_cast<IntrinsicsPinhole>(
-        params.in_right);
-    i += bytes::to_data(in_left.get(), data + i, version);
-    i += bytes::to_data(in_right.get(), data + i, version);
-  }
-  {
-    auto params = (*img_params).at({2560, 800});
-    auto in_left = std::dynamic_pointer_cast<IntrinsicsPinhole>(params.in_left);
-    auto in_right = std::dynamic_pointer_cast<IntrinsicsPinhole>(
-        params.in_right);
-    i += bytes::to_data(in_left.get(), data + i, version);
-    i += bytes::to_data(in_right.get(), data + i, version);
-    i += bytes::to_data(&params.ex_right_to_left, data + i, version);
-  }
-
-  // others
-  std::size_t size = i - 3;
-  data[0] = Channels::FID_IMG_PARAMS;
-  data[1] = static_cast<std::uint8_t>((size >> 8) & 0xFF);
-  data[2] = static_cast<std::uint8_t>(size & 0xFF);
-  return size + 3;
-}
-
 MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/device/standard2/channels_adapter_s210a.h b/src/mynteye/device/standard2/channels_adapter_s210a.h
index 0de7d28..b63e4dc 100644
--- a/src/mynteye/device/standard2/channels_adapter_s210a.h
+++ b/src/mynteye/device/standard2/channels_adapter_s210a.h
@@ -19,7 +19,7 @@
 #include <set>
 #include <vector>
 
-#include "mynteye/device/channels/channels.h"
+#include "mynteye/device/channel/channels.h"
 
 MYNTEYE_BEGIN_NAMESPACE
 
@@ -37,13 +37,6 @@ class Standard210aChannelsAdapter : public ChannelsAdapter {
   std::vector<std::int32_t> GetGyroRangeValues() override;
 
   void GetImuResPacket(const std::uint8_t *data, ImuResPacket *res) override;
-
-  std::size_t GetImgParamsFromData(
-      const std::uint8_t *data, const Version *version,
-      Channels::img_params_t *img_params) override;
-  std::size_t SetImgParamsToData(
-      const Channels::img_params_t *img_params, const Version *version,
-      std::uint8_t *data) override;
 };
 
 MYNTEYE_END_NAMESPACE
diff --git a/src/mynteye/device/types.h b/src/mynteye/device/types.h
index 44efaf5..41b372a 100644
--- a/src/mynteye/device/types.h
+++ b/src/mynteye/device/types.h
@@ -51,6 +51,10 @@ class MYNTEYE_API Version {
       : major_(parse_part(name, 0)), minor_(parse_part(name, 1)) {}
   virtual ~Version() {}
 
+  bool empty() const {
+    return major_ == 0 && minor_ == 0;
+  }
+
   bool operator==(const Version &other) const {
     return major_ == other.major_ && minor_ == other.minor_;
   }
diff --git a/tools/writer/device_writer.cc b/tools/writer/device_writer.cc
index 9352c3c..a609222 100644
--- a/tools/writer/device_writer.cc
+++ b/tools/writer/device_writer.cc
@@ -232,7 +232,9 @@ void DeviceWriter::SaveAllInfos(const std::string &dir) {
   auto &&m_in = device_->GetMotionIntrinsics();
   SaveImuParams(
       {
-          false, m_in.accel, m_in.gyro,
+          false,
+          device_->GetInfo()->spec_version.to_string(),
+          m_in.accel, m_in.gyro,
           device_->GetMotionExtrinsics(Stream::LEFT),
       },
       dir + MYNTEYE_OS_SEP "imu.params");
diff --git a/tools/writer/device_writer.h b/tools/writer/device_writer.h
index ac4b2a5..de942fc 100644
--- a/tools/writer/device_writer.h
+++ b/tools/writer/device_writer.h
@@ -20,7 +20,7 @@
 #include <string>
 
 #include "mynteye/mynteye.h"
-#include "mynteye/device/channels/channels.h"
+#include "mynteye/device/channel/channels.h"
 #include "mynteye/device/types.h"
 
 MYNTEYE_BEGIN_NAMESPACE