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• Streaming video frame by frame using Python and SRT

  25 avril 2023, par skylighty

  Almost every implementation of exposing a video stream in Python that I could find find is based on opencv and then writing frame (numpy.ndarrays) converted to bytes to FFMPEG stream, which goes to RTMP exposed on nginx server which works pretty fine, however now I have to expose SRT.

  


  Would anyone be so kind to tell me if it's possible using FFMPEG (I already have ffmpeg recompiled with libsrt), and if it is what command should I use ?

  


  Basically, the whole pipeline at the moment looks like this : RTMP (stream source) -> Python processing frame by frame -> process.stdin.write(frames.tobytes()) -> RTMP (stream out).

  


  Where the process is FFMPEG process opened with subprocess lib, the direct command is :

  


  command = [
    'ffmpeg',
    '-y',
    '-f', 'rawvideo',
    '-vcodec', 'rawvideo',
    '-pix_fmt', 'bgr24',
    '-s', "{}x{}".format(1920, 1080),
    '-r', str(30),
    '-i', '-',
    '-c:v', 'libx264',
    '-pix_fmt', 'yuv420p',
    '-preset', 'ultrafast',
    '-f', 'flv',
    url
]
process = subprocess.Popen(command, stdin=subprocess.PIPE)


  


  I'd also like to ask if any other server will be necessary, because I had to get rtmp module for nginx to make this pipeline work as it should, so I'm pretty sure that there's work to do too.

  


  Of course I could grab the output RTMP, put it to OBS and configure it to spit out the SRT, but I'd like to expose SRT stream directly from Python code, as correct output.

  


  I'll be really grateful for any help.

  


• FFMPEG : Set Opacity of audio waveform color

  13 août 2018, par Software Development Consultan

  I was trying to do transparency in waveform generated. It seems there is not direct option in ’showwaves’ filter so I came across ’colorkey’ which might help.

  I am trying with following :

  ffmpeg -y -loop 1 -threads 0 -i background.png -i input.mp3 -filter_complex "[1:a]aformat=channel_layouts=mono,showwaves=s=1280x100:rate=7:mode=cline:scale=sqrt:colors=0x0000ff,colorkey=color=0x0000ff:similarity=0.01:blend=0.1[v] ; [0:v][v] overlay=0:155 [v1]" -map "[v1]" -map 1:a -c:v libx264 -crf 35 -ss 0 -t 5 -c:a copy -shortest -pix_fmt yuv420p -threads 0 test_org.mp4

  So I wanted to blue color waveform and wanted to set opacity of that 1 to 0 let say. But it seems this generates blackbox which is actual background of ’1280x100’. I want to keep background of waveform transparent and just wanted to change opacity of waveform only.

  Result of my command : enter image description here

  

  Can you please let me know your suggestion

  @Gyan, this is with reference to following question which you have answered.

  Related last question

  Thanks, Hardik

• How to create an animated AVIF from images

  17 mai 2023, par Undone

  I have 6 images in .avif format I want to encode to a a single animated avif file.

  


  I could create a .gif from images easily with ffmpeg and convert the generated .gif to .avif But I still want a more direct method

  


  I've tried the following but it only reencodes the .avif images one by one without making a single animated AVIF file

  


  ffmpeg -i *.avif -f yuv4mpegpipe -strict -1 - | avifenc --stdin --fps 13 output.avif


  


  and with :

  


  ffmpeg  -pattern_type glob -i '*.avif' -strict -1 -pix_fmt yuv420p10 -f yuv4mpegpipe - | avifenc --stdin --fps 13 output.avif


  


  With the above command I receive an error :

  


  *.avif: No such file or directory
[1]    901919 exit 1                            ffmpeg -pattern_type glob -i '*.avif' -strict -1 -pix_fmt yuv420p10 -f  - | 
       901920 segmentation fault (core dumped)  avifenc --stdin --fps 13 output.avif