thermalcam_decoder/decode.py

# coding: utf-8

from os import system
import numpy as np
from tqdm import tqdm
import pandas as pd
import pcapng
from struct import unpack
from PIL import Image
import cv2


pd.options.display.max_colwidth = 150

scanner = pcapng.scanner.FileScanner(open('in.pcap', 'rb'))
blocks = list(tqdm(scanner))


def tryget(obj, att):
    if hasattr(obj, att):
        return getattr(obj, att)
    return None


df = pd.DataFrame([{'index': i, 'length': tryget(obj, 'packet_len')} for i, obj in enumerate(blocks)])
# get udp packets
data = [blocks[i] for i in df[df.length == 6972.0].index]
# remove udp header
raw = [d.packet_data[0x2a:] for d in data]


def parse(data):
    hdr = 4 + 2 * 7
    c1, c2, part, a, ffaa, b, c, d = unpack('>Lhhhhhhh', data[:hdr])
    ret = locals()
    del ret['data']
    del ret['hdr']
    ret['data'] = data[hdr:]
    return ret


df = pd.DataFrame([parse(d) for d in raw])
df2 = df[[c for c in df.columns if c != 'data']]


def getframes(df):
    frames = []
    current = []
    for i, row in df.iterrows():
        if row.part == 0:
            # roll over
            if len(current) > 0:
                frames.append(current)
            current = []
        current.append(row['data'])
    if len(current) > 0:
        frames.append(current)
    return [b''.join(parts) for parts in frames]


def image16(frame, width, height, pixelformat='>H'):
    return [
        Image.fromarray(np.frombuffer(frame, dtype=pixelformat).reshape(width, height)) for frame in frames
        if len(frame) == 2 * width * height
        ]


def showvideo(images):
    # wip
    videodims = images[0].size
    fourcc = cv2.VideoWriter_fourcc(*'avc1')
    video = cv2.VideoWriter("test.mp4", fourcc, 60, videodims)
    img = Image.new('RGB', videodims, color='darkred')
    # draw stuff that goes on every frame here
    for i in range(0, 60*60):
        imtemp = img.copy()
        # draw frame specific stuff here.
        video.write(cv2.cvtColor(np.array(imtemp), cv2.COLOR_RGB2BGR))
    video.release()

# def shape(frames, width, height, mode='RGB'):
# return [Image.frombytes('RGB', (width, height), frame) for frame in frames if len(frame) == width * height * 3]


frames = getframes(df)
images = image16(frames, 384, 288)
for i, img in enumerate(tqdm(images)):
    img.save(f'{i:04}.png')
# frame = b''.join(df.iloc[:32]['data'])
# Image.frombytes('RGB', (288, 256), frame).show()
start_len = len(b'T=(-1.665884e-08)*X^4+(1.347094e-05)*X^3+(-4.396264e-03)*X^2+(9.506939e-01)*X+(-6.353247e+01)\r\n')

# 250 bytes at start of frame
equations = {x[:250].decode().strip() for x in df[df.part == 0]['data']}
# seen only a single equation on all packets
assert len(equations) == 1

assert list(equations)[0] == 'T=(-1.665884e-08)*X^4+(1.347094e-05)*X^3+(-4.396264e-03)*X^2+(9.506939e-01)*X+(-6.353247e+01)'

# we have 6372 packets
assert df.shape[0] == 6372

# produce a video
system('ffmpeg -f image2 -framerate 25 -i %04d.png -vf "transpose=1" -s 384x288 -vcodec libx264 -pix_fmt yuv420p thermal.mp4')
print('to play: ffplay thermal.mp4')