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• take audio from mp4 video using ffmpeg

  11 avril 2022, par Nakem1

  I'm trying to use the go wrapper over ffmpeg https://github.com/u2takey/ffmpeg-go

  


  to take audio from an mp4 video. I don't want to create extra local files, but I can't pass the input otherwise.

  


  I transfer the created file and return the audio to io.Reader(audio var) :

  


      telegramFile, err := r.bot.GetFile(&msg.VideoNote.File)
    if err != nil {
        // handling error
    }
    fileBytes, err := io.ReadAll(telegramFile)
    if err != nil {
        // handling error
    }

    inputFile := fmt.Sprintf("%s.mp4", msg.VideoNote.File.FileID)
    err = ioutil.WriteFile(inputFile, fileBytes, 0o600)
    if err != nil {
        // handling error
    }

    audio := bytes.NewBuffer(nil)
    err = ffmpeg.Input(
        inputFile,
    ).
        Output("pipe:1", ffmpeg.KwArgs{"format": "wav"}).WithOutput(audio).Run()
    if err != nil {
        // handling error
    }


  


  I am sending io.Reader(telegramFile var) and get io.Reader(audio var) :

  


      telegramFile, err := r.bot.GetFile(&msg.VideoNote.File)
    if err != nil {
        // handling error
    }

    audio := bytes.NewBuffer(nil)
    err = ffmpeg.Input(
        "pipe:0", ffmpeg.KwArgs{"format": "mp4"},
    ).
        Output("pipe:1", ffmpeg.KwArgs{"format": "wav"}).WithInput(telegramFile).WithOutput(audio).Run()
    if err != nil {
        // handling error
    }


  


  the first code works, but I need the second one. The conversion is performed, but the audio is invalid. Too few bytes.

  


  here is an example of using input -> output https://github.com/u2takey/ffmpeg-go/blob/8af5c3849807dcda756406a7b2b3631a5c90d53b/ffmpeg_test.go#L330

  


• lavf/http: add support for reading streamcast metadata

  26 juin 2013, par wm4

  lavf/http: add support for reading streamcast metadata
  Allow applications to request reading streamcast metadata. This uses
  
  AVOptions as API, and requires the application to explicitly request
  
  and read metadata. Metadata can be updated mid-stream ; if an
  
  application is interested in that, it has to poll for the data by
  
  reading the "icy_metadata_packet" option in regular intervals.
  There doesn’t seem to be a nice way to transfer the metadata in a nicer
  
  way. Converting the metadata to ID3v2 tags might be a nice idea, but
  
  the libavformat mp3 demuxer doesn’t seem to read these tags mid-stream,
  
  and even then we couldn’t guarantee that tags are not inserted in the
  
  middle of mp3 packet data.
  This commit provides the minimum to enable applications to retrieve
  
  this information at all.
  Signed-off-by : Stefano Sabatini <stefasab@gmail.com>
  

  • [DH] doc/protocols.texi
  • [DH] libavformat/http.c
  • [DH] libavformat/version.h

• cinepakenc : fixes and improvements

  27 juin 2017, par addr-see-the-website@aetey.se

  cinepakenc : fixes and improvements
  version 2013-02-08 Rl
  
   fixes/optimization in multistrip encoding and codebook size choice,
  
    quality/bitrate is now better than that of the binary proprietary encoder
  version 2013-02-12 Rl
  
   separated codebook training sets, avoided the transfer of wasted bytes,
  
    which yields both better quality and smaller files
  
   now using the correct colorspace (TODO : move conversion to libswscale)
  version 2013-02-14 Rl "Valentine’s Day" version :
  
   made strip division more robust
  
   minimized bruteforcing the number of strips,
  
    (costs some R/D but speeds up compession a lot), the heuristic
  
    assumption is that score as a function of the number of strips has
  
    one wide minimum which moves slowly, of course not fully true
  
   simplified codebook generation,
  
    the old code was meant for other optimizations than we actually do
  
   optimized the codebook generation / error estimation for MODE_MC
  version 2013-04-28 Rl
  
   bugfixed codebook optimization logic
  version 2014-01-20 Rl
  
   made the encoder compatible with vintage decoders
  
    and added some yet unused code for possible future
  
    incremental codebook updates
  
   fixed a small memory leak
  version 2014-01-21 Rl
  
   believe it or not, now we get even smaller files, with better quality
  
    (which means I missed an optimization earlier :)
  Signed-off-by : Diego Biurrun <diego@biurrun.de>
  

  • [DBH] libavcodec/cinepakenc.c