It seems there is interest in using the P2 Pro as a USB camera on PC and interpreting the content of the video stream, so I will share the experiments I made after receiving mine.
Basically I played with ffmpeg to extract raw data from the video stream.
The main finding is that the USB UVC device is exporting 2 video streams
- a 256x192 yuyv422 stream that contains a grayscale 8 bits normalized video that is directly exploitable (the 8 bits luminance channel is the temperature data and both chrominance channels are fixed values to give a colorless/grayscale result)
- a 256x384 yuyv422 stream that contains an exact copy of the previous stream in the upper half of the image and a greenish picture in the bottom half. This greenish picture is actually the raw non-normalized sensor values that are actually encoded in gray16le format (just 16 bits per pixel, in one grayscale channel, little-endian).
Examples playing with those video streams on a linux box:
# First of, find the device corresponding to your IR camera
v4l2-ctl --list-devices
# Check that the normalized stream works fine
ffplay -input_format yuyv422 -video_size 256x192 -i /dev/video4
# Look a the combined streams
ffplay -input_format yuyv422 -video_size 256x384 -i /dev/video4
# Use ffmpeg to grab the combined stream, crop to keep only the bottom half
# then pipe the raw data to ffplay and reinterpret it as gray16le.
# The resulting picture will be almost uniform gray due to the low range of
# the raw values in the 16 bits dynamic range.
# The raw values in a 0°C to 100°C environment ranges around 19000 to 24000
# (in a 0 to 65535 dynamic range).
ffmpeg -input_format yuyv422 -video_size 256x384 -i /dev/video4 -vf 'crop=h=(ih/2):y=(ih/2)' -pix_fmt yuyv422 -f rawvideo - | ffplay -pixel_format gray16le -video_size 256x192 -f rawvideo -i -
# To make the resulting raw stream more useful, you can add a normalization filter
# followed by a pseudocolor filter with typical IR camera colors
ffmpeg -input_format yuyv422 -video_size 256x384 -i /dev/video4 -vf 'crop=h=(ih/2):y=(ih/2)' -pix_fmt yuyv422 -f rawvideo - | ffplay -pixel_format gray16le -video_size 256x192 -f rawvideo -i - -vf 'normalize=smoothing=10, format=pix_fmts=rgb48, pseudocolor=p=inferno'
# You can then play with pretty much infinitely long ffmpeg command lines
# For example, you can upscale the video stream, display the min and max raw
# values in the top left corner and add a time graph of the min and max values
# at the bottom
ffmpeg -input_format yuyv422 -video_size 256x384 -i /dev/video4 -vf 'crop=h=(ih/2):y=(ih/2)' -pix_fmt yuyv422 -f rawvideo - | ffplay -pixel_format gray16le -video_size 256x192 -f rawvideo -i - -vf 'signalstats, split [main][secondary]; [main] normalize=smoothing=10, format=pix_fmts=rgb48, pseudocolor=p=inferno, scale=w=2*iw:h=2*ih, drawtext=x=3:y=3:borderw=1:bordercolor=white:fontfile=FreeSerif.ttf:text=MIN\\: %{metadata\\:lavfi.signalstats.YMIN} MAX\\: %{metadata\\:lavfi.signalstats.YMAX} [thermal]; [secondary] drawgraph=m1=lavfi.signalstats.YMIN:fg1=0xFFFF9040:m2=lavfi.signalstats.YMAX:fg2=0xFF0000FF:bg=0x303030:min=18500:max=24500:slide=scroll:size=512x64 [graph]; [thermal][graph] vstack'
So the raw data from the sensor are very easily accessible. The only missing part is the conversion from raw values to actual temperatures. I don't know if some kind of calibration needs to be applied or if the raw values can be converted directly to temperatures with a simple fixed (linear ?) equation.
In my quick tests I derived the following equation to convert raw to °C but this is only a rough guesstimate: f(x) = (x - 19295) / 51.2857
Hi sorry to drag up an old post however trying the P2Pro software on an RPI4 and while I can get the bw thermal, the bw and green to come up I cant get the inferno color pallet option to work with your command, it just errors out for me.
This just does not work and I get Option P not found, error initiating filter pseudocolour
# To make the resulting raw stream more useful, you can add a normalization filter
# followed by a pseudocolor filter with typical IR camera colors
ffmpeg -input_format yuyv422 -video_size 256x384 -i /dev/video4 -vf 'crop=h=(ih/2):y=(ih/2)' -pix_fmt yuyv422 -f rawvideo - | ffplay -pixel_format gray16le -video_size 256x192 -f rawvideo -i - -vf 'normalize=smoothing=10, format=pix_fmts=rgb48, pseudocolor=p=inferno'
Any help would be amasing.
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