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• Why doesn't FFmpeg work when using yt-dlp in python script ?

  11 mai 2022, par spelle

  I'm trying to download a video using yt-dlp in python.

  


  ydl_opts = {'format': 'bv+ba/b'}
with YoutubeDL(ydl_opts) as ydl:
     ydl.download('https://www.reddit.com/r/cats/comments/re37dn/weve_been_feeding_this_stray_for_several_years/')


  


  But I'm reaching an FFmpeg error in the log

  


  [generic] 1o8t9ollwx481: Requesting header
[redirect] Following redirect to https://www.reddit.com/r/cats/comments/re37dn/weve_been_feeding_this_stray_for_several_years/
[Reddit] re37dn: Downloading JSON metadata
[Reddit] re37dn: Downloading m3u8 information
[Reddit] re37dn: Downloading MPD manifest
[info] 1o8t9ollwx481: Downloading 1 format(s): dash-video_4419291+dash-audio_0_133951
WARNING: You have requested merging of multiple formats but ffmpeg is not installed. The formats won't be merged.
[download] Destination: We’ve been feeding this stray for several years, but she’s lost a lot of weight and I don’t think she would last outside for another winter, so I brought her in. [1o8t9ollwx481].fdash-video_4419291.mp4
[download] 100% of 5.18MiB in 00:00               
[download] Destination: We’ve been feeding this stray for several years, but she’s lost a lot of weight and I don’t think she would last outside for another winter, so I brought her in. [1o8t9ollwx481].fdash-audio_0_133951.m4a
[download] 100% of 161.32KiB in 00:00


  


  FFmpeg is installed through pip and added in PATH.

  


• ffmpeg_opt : restore documented stream selection behaviour

  28 juillet 2021, par Gyan Doshi

  ffmpeg_opt : restore documented stream selection behaviour
  11d3b03fcb added consideration of default stream disposition for audio
  
  and video when choosing the 'best' stream among all the inputs. This can
  
  lead to video streams with lower resolution or audio streams with fewer
  
  channels being selected.
  Stream disposition, however, only sets a priority for a stream
  
  among all other streams in the *same input*. It cannot set a priority
  
  for a stream across all inputs.
  This patch sets a middle-way and selects the best stream from each file
  
  with default disposition considered. Then it discards disposition weight
  
  and selects best stream as per the original criteria of highest
  
  resolution for video and most channels for audio.
  

  • [DH] fftools/ffmpeg_opt.c

• FFmpeg trim filter fails to use sexagisimal time specification and the output stream is empty. Is it a bug and is there a fix ?

  29 novembre 2020, par Link-akro

  With ffmpeg the trim filter (or its audio variant atrim) malfunctions whenever i try to write a sexagesimal time specification for the boundaries or duration parameters of the filter : the result is always an empty stream.

  


  According to the documentation i already linked, which was generated on November 26, 2020 so far, the time duration specification should be supported.

  


  


  start, end, and duration are expressed as time duration specifications

  


  


  Quote of the spec.

  


  


  [-][HH :]MM:SS[.m...]

  


  


  


  [-]S+[.m...][s|ms|us]

  


  


  I am working in a Windows_10-64bit and scripting in its CMD.exe command-line, should it matter.

  


  Here is an instance of trimming a video stream out of a media file with hardcoded value for simplicity. The audio is retained unless i use atrim as well.
We may or may not append the setpts filter as recommended in the documentation henceforth setpts=PTS-STARTPTS if we want to shift the stream to start at the beginning of the cut range.

  


      ffmpeg -i sample-counter.mp4 -vf "trim=start=start='1:2':end='1:5'" sample-counter-trimmed.mp4


  


  If i use decimal it works as intended.

  


      ffmpeg -i sample-counter.mp4 -vf "trim=start=start='2':end='5'" sample-counter-trimmed.mp4


  


  This is the banner of my ffmpeg build. We may see it is the latest build by gyan.dev at the moment i post this.

  


      ffmpeg version 4.3.1-2020-11-19-full_build-www.gyan.dev Copyright (c) 2000-2020 the FFmpeg developers
      built with gcc 10.2.0 (Rev5, Built by MSYS2 project)
      configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-lzma --enable-libsnappy --enable-zlib --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libzvbi --enable-librav1e --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libaom --enable-libopenjpeg --enable-libvpx --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame --enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint


  


  The incorrect stream is always reported as 0kB weight in the output of ffmpeg. I confirmed with ffprobe Movie_Countdown-trim-2-5.mov -show_streams -show_entries format=duration that the incorrect stream is duration zero.

  


  Should i report it as a bug ? Is there some correction or workaround ?

  


  I would rather a solution with the trim filter itself, but if not possible a CMD batch scripting.
We should not need a different filter like select or seeking option like there are tutorials and questions/answers everywhere already. Scripting would be straight-forward in a proper *nix shell+distrib and taught everywhere so it is not worth caring while CMD answers on the other hand are rare so a scripting workaround for CMD would have some microcosmic worth since making one is considerably less straight-forward than a shell with modern mathematics and parsing abilities built-in or packaged.