clean and comment

decode.py

@@ -1,5 +1,3 @@
-# coding: utf-8
-
 from os import system
 import numpy as np
 from tqdm import tqdm
@@ -7,30 +5,34 @@ import pandas as pd
 import pcapng
 from struct import unpack
 from PIL import Image
-import cv2
-
-
-pd.options.display.max_colwidth = 150
 
+# Read packets from a pcap file
 scanner = pcapng.scanner.FileScanner(open('in.pcap', 'rb'))
 blocks = list(tqdm(scanner))
 
 
+# Helper function to safely get an attribute from an object
 def tryget(obj, att):
     if hasattr(obj, att):
         return getattr(obj, att)
     return None
 
 
+# Create a DataFrame with packet lengths
 df = pd.DataFrame([{'index': i, 'length': tryget(obj, 'packet_len')} for i, obj in enumerate(blocks)])
-# get udp packets
+
+
+# Filter and extract data packets of a specific length
 data = [blocks[i] for i in df[df.length == 6972.0].index]
-# remove udp header
+
+# Remove the UDP header from the packets
 raw = [d.packet_data[0x2a:] for d in data]
 
 
+# Function to parse packet data
 def parse(data):
-    hdr = 4 + 2 * 7
+    hdr = 4 + 2 * 7  # Header length
+    # Unpack data into variables
     c1, c2, part, a, ffaa, b, c, d = unpack('>Lhhhhhhh', data[:hdr])
     ret = locals()
     del ret['data']
@@ -39,16 +41,17 @@ def parse(data):
     return ret
 
 
+# Parse each packet and create a DataFrame
 df = pd.DataFrame([parse(d) for d in raw])
 df2 = df[[c for c in df.columns if c != 'data']]
 
 
+# Function to group data into frames
 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 = []
@@ -58,48 +61,22 @@ def getframes(df):
     return [b''.join(parts) for parts in frames]
 
 
+# Function to convert binary frame data into images
 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]
 
 
+# Get frames and convert them to images
 frames = getframes(df)
 images = image16(frames, 384, 288)
+
+# Save each image as a PNG file
 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
+# Produce a video from the saved images
-equations = {x[:250].decode().strip() for x in df[df.part == 0]['data']}
+system('ffmpeg -hide_banner -loglevel info -y -f image2 -framerate 25 -i %04d.png -vf "transpose=1" -s 384x288 -vcodec libx264 -pix_fmt yuv420p thermal.mp4')
-# 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')