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• FFMPEG Streaming, using list for multiple presentations

  3 janvier 2021, par JJ The Second

  I am currently using a third party library to transcode videos from mp4 to HLS. https://video.aminyazdanpanah.com/python/start?r=hls#hls Great documentation and works fine however I have an issue by passing a list to hls.representations() that I think is something wrong I do. Here is how I run my code.

  


  presetList = []
rep_1  = Representation(Size(1920,1080), Bitrate(4096 * 1024, 320 * 1024))
                    presetList.append(rep_1)
rep_2 = Representation(Size(1440, 900), Bitrate(2048 * 1024, 320 * 1024))
                    presetList.append(rep_2)

video =  "file.mp4"
video = ffmpeg_streaming.input(video)
completed_destination = "completed.m3u8"
hls = video.hls(Formats.h264())
hls.representations(presetList)
hls.output(completed_destination)


  


  When I run this I get following error, that is triggered by library meaning values in my list not passed properly ?

  


    File "/var/www/transcoder/transcoder/env/lib/python3.8/site-packages/ffmpeg_streaming/_hls_helper.py", line 87, in stream_info
    f'BANDWIDTH={rep.bitrate.calc_overall}',
AttributeError: 'list' object has no attribute 'bitrate'


  


  if I instead run the same code with only change as below, works like a charm :

  


  hls.representations(rep_1, rep_2)


  


  What am I doing wrong here ? Thanks

  


• lavc/hevcdec : only set no_rasl_output_flag for IRAP frames

  1er juin 2024, par Anton Khirnov

  lavc/hevcdec : only set no_rasl_output_flag for IRAP frames
  Its meaning is only specified for IRAP frames.
  As it's currently never used otherwise, this should not change decoder
  
  behaviour, but will be useful in future commits.
  

  • [DH] libavcodec/hevc/hevcdec.c
  • [DH] libavcodec/hevc/hevcdec.h

• ffmpeg not reading stdin fast enough

  5 mars 2019, par Joshua Walsh

  I have a NodeJS program which launches ffmpeg (with child_process) and then provides realtime video data via stdin, using the pipe protocol.

  ffmpeg -nostdin -i pipe:0 -codec libx264 -preset veryfast -tune zerolatency -acodec aac -b:a 128k output/index.m3u8

  ffmpeg transcodes the video into h264 and muxes it into an HLS live stream.

  The issue that I have is that sometimes ffmpeg refuses to accept more input. The default behaviour of NodeJS is to buffer input until the child process can accept it, but after a while this causes my application to run out of memory.

  I tried a naive solution where if ffmpeg wasn’t able to read the input (if proc.stdin.write returns false) I would start discarding data until the drain event was raised on the stream, but this unsurprisingly led to badly degraded video output, with terrible artifacting.

  The nature of the source of the data makes it impossible for me to block, my application has to deal with it in realtime.

  ffmpeg is using only a fraction of the available resources on the system (35% CPU, 1% disk), so I’m not sure why it’s blocking stdin. If I specify a more demanding preset then it happily uses more CPU, so CPU speed shouldn’t be a limiting factor.

  Does anyone know why ffmpeg would be blocking stdin ? Is there a way I can tell ffmpeg to drop frames if it starts falling behind ?