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• ffmpeg transcoding one input video stream and multiple output video streams in the same file

  28 janvier 2020, par user2165262

  I am trying to transcode a single video file with 1 video stream and several audio streams to the file having same video stream in different bitrates/sizes with correct padding at the same time.

  the command I use is :

      ffmpeg -y -ss 600 -t 600 -i "INPUT.mkv" -map_chapters -1 -map 0:0 -c:v libx264 -keyint_min 48 -g 96 -bufsize 350k -b:v 350k -minrate 300k -maxrate 400k -profile:v baseline -level 3.0 -preset slow -vf "scale=iw*min(480/iw\,272/ih):ih*min(480/iw\,272/ih),pad=480:272 :(480-iw)/2 :(272-ih)/2" -map 0:0 -c:v libx264 -keyint_min 48 -g 96 -bufsize 650k -b:v 650k -minrate 500k -maxrate 800k -profile:v baseline -level 3.1 -preset slow -vf "scale=iw*min(640/iw\,360/ih):ih*min(640/iw\,360/ih),pad=640:360 :(640-iw)/2 :(360-ih)/2" -map 0:1 -c:a libfaac -b:a 32k -ar 44100 -f mpegts OUTPUT.m2ts
  

  ffmpeg creates two video streams, however the bitrate and resolution for all of them are taken from the last video arguments - i.e. both streams are 640x360 :

      Output #0, mpegts, to ’OUTPUT.m2ts’ :
      Stream #0:0(eng) : Video : h264, yuv420p, 640x360 [SAR 559:560 DAR 559:315], q=-1—1, 650 kb/s,     Stream #0:1(eng) : Video : h264, yuv420p, 640x360 [SAR 559:560 DAR 559:315], q=-1—1, 650 kb/s, 90k tbn, 23.98 tbc (default)
      Stream #0:2(rus) : Audio : aac, 44100 Hz, 5.1, s16, 32 kb/s (default)
      Stream mapping :
      Stream #0:0 -> #0:0 (h264 -> libx264)
      Stream #0:0 -> #0:1 (h264 -> libx264)
      Stream #0:1 -> #0:2 (aac -> libfaac)
      Press [q] to stop, [?] for help
  

  Is it practically possible to make transcoding to several bitrates to the same file ?

• How to catch a FFMPEG exception with subprocess ?

  13 mai 2022, par Faindirnomainzein

  I'm doing some work on subtitles and some videos have 1 subtitle track, others have 2 subtitle tracks. For those that have 2, I use the 2nd one (index = 1). I'm trying to automate it with python.

  


  For files with with 2 subtitle tracks, I use :

  


  


  -vf "subtitles='file.mkv':si=1

  


  


  and for those with 1 subtitle track, I use :

  


  


  -vf "subtitles='file.mkv':si=0

  


  


  I'm using this code :

  


  for mkv in all_mkvs:
    try:
      subprocess.call(f'ffmpeg -i ... -vf "subtitles='file.mkv':si=1 ...')
    except:
      subprocess.call(f'ffmpeg -i ... -vf "subtitles='file.mkv':si=0 ...')


  


  But it doesn't seem to care about the exception and just ends the loop whenever it meets a file with 1 subtitle and gives me the error anyway.

  


  Press [q] to stop, [?] for help
[Parsed_subtitles_0 @ 0000011af4912880] Shaper: FriBidi 1.0.10 (SIMPLE) HarfBuzz-ng 2.7.2 (COMPLEX)
[Parsed_subtitles_0 @ 0000011af4912880] Unable to locate subtitle stream in ./test/349.mkv
[AVFilterGraph @ 0000011af623d880] Error initializing filter 'subtitles' with args './test/349.mkv:si=1'
Error reinitializing filters!
Failed to inject frame into filter network: Operation not permitted
Error while processing the decoded data for stream #0:3
Conversion failed!


  


  As you can see in the error message above, it says : "Error initializing filter .... si=1" because it should be si=0 in the case of that specific file, which is why I added the exception, but it doesn't seem to care about it.

  


  

  


  So I'm trying to catch that error and say "ok, in that case, let's do si=0 instead".

  


• ffmpeg get only audio Error parsing NAL unit [closed]

  3 juin 2021, par smail saa

  hello i am new here for first questions i have stream work with token this stream have multibitrate and auto quality

  


  http://host:port/cam1@720 ?auto=1?token=123123123 this work perfect but only 576
but if we modifai stream to http://host:port/cam1@720?token=123123123 work only sound
and it work perfect in android only
in ffmpeg i get :

  


  ffmpeg reponse

  


  [hevc @ 0x3f0b840] Error parsing NAL unit #2. [hevc @ 0x3f0b840] PPS id out of range : 0 [mpegts @ 0x3efca80] decoding for stream 0 failed [mpegts @ 0x3efca80] Could not find codec parameters for stream 0 (Video : hevc (HEVC / 0x43564548), none) : unspecified size Consider increasing the value for the 'analyzeduration' and 'probesize' options Input #0, mpegts, from 'http://host:port/cam1@720?token=123123123' : Duration : N/A, start : 23229.541289, bitrate : N/A Program 1 Stream #0:0[0x100] : Video : hevc (HEVC / 0x43564548), none, 25 tbr, 90k tbn, 90k tbc Stream #0:10x101 : Audio : aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp, 100 kb/s Stream mapping : Stream #0:0 -> #0:0 (hevc (native) -> hevc (libx265)) Stream #0:1 -> #0:1 (aac (native) -> pcm_mulaw (native)) Press [q] to stop, [?] for help [hevc @ 0x3f062c0] PPS id out of range : 0 [hevc @ 0x3f062c0] Error parsing NAL unit #2.

  


  thanks for answer and help