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• avformat/matroskaenc : Check for failure when writing SeekHead

  29 décembre 2019, par Andreas Rheinhardt

  avformat/matroskaenc : Check for failure when writing SeekHead
  mkv_write_seekhead() would up until now try to seek to the position where
  
  the SeekHead ought to be written, write the SeekHead and seek back. The
  
  first of these seeks was checked as was writing, yet the seek back was
  
  unchecked. Moreover the return value of mkv_write_seekhead() was unchecked
  
  (the ordinary return value was the position where the SeekHead was written).
  This commit changes this : Everything is checked. In the unseekable case
  
  (where the first seek may nevertheless work when it happens in the buffer)
  
  a failure at the first seek is not considered an error. In any case,
  
  failure to seek back is an error.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavformat/matroskaenc.c

• movenc : Add an option for delaying writing the moov with empty_moov

  3 novembre 2014, par Martin Storsjö

  movenc : Add an option for delaying writing the moov with empty_moov
  This delays writing the moov until the first fragment is written,
  
  or can be flushed by the caller explicitly when wanted. If the first
  
  sample in all streams is available at this point, we can write
  
  a proper editlist at this point, allowing streams to start at
  
  something else than dts=0. For AC3 and DNXHD, a packet is
  
  needed in order to write the moov header properly.
  This isn’t added to the normal behaviour for empty_moov, since
  
  the behaviour that ftyp+moov is written during avformat_write_header
  
  would be changed. Callers that split the output stream into header+segments
  
  (either by flushing manually, with the custom_frag flag set, or by
  
  just differentiating between data written during avformat_write_header
  
  and the rest) will need to be adjusted to take this option into use.
  For handling streams that start at something else than dts=0, an
  
  alternative would be to use different kinds of heuristics for
  
  guessing the start dts (using AVCodecContext delay or has_b_frames
  
  together with the frame rate), but this is not reliable and doesn’t
  
  necessarily work well with stream copy, and wouldn’t work for getting
  
  the right initialization data for AC3 or DNXHD either.
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavformat/movenc.c
  • [DH] libavformat/movenc.h
  • [DH] libavformat/version.h

• How to use Mozilla DeepSpeech to generate subtitle from video file ?

  31 mars 2022, par SingularitySG

  I'm currently trying to generate subtitles file .srt using Mozilla DeepSpeech libraries.

  


  Confusion I'm having :

  


  I'm following this guide but I'm completely lost at the part where he uses pyAudioAnalysis to trim out the silence portion of the .wav files.

  


  Another is the portion where he processes the audio file via calling the ds model & ds scorer
I've downloaded both deepspeech-0.9.3-models.scorer and deepspeech-0.9.3-models.pbmm from https://github.com/mozilla/DeepSpeech/releases Do I just reference the model and scorer to the downloaded file path instead ?

  


  def ds_process_audio(audio_file, file_handle): 
    ds = Model(ds_model)
    ds.enableExternalScorer(ds_scorer)


  


  At the moment, I'm able to extract out .wav files from .mp4, .mkv video format.

  


  I've tried pip install pyAudioAnalysis but I'm not sure how to call the functions that are related to it as per his guide in trimming out the silence portion of the .wav file. Below is the code I'm currently working with as of now.

  


  video_name = "Videos\Gintama_EP342.mkv"
audio_name = video_name + ".wav"


def extractAudio(input_file, audio_file_name):
    # Extract audio from input video file and save to audio/ in root dir
    # Args:
    #    input_file : input video file
    #    audio_file_name : save audio WAV file with same filename as video file

    command = ["ffmpeg", "-hide_banner", "-loglevel", "warning", "-i", input_file, "-ac", "1", "-ar", "16000", "-vn", "-f", "wav", audio_file_name]    
    try:
        ret = sp.call(command, shell=True)
        print("Extracted audio to audio/{}".format(audio_file_name.split("/")[-1]))
    except Exception as e:
        print("Error: ", str(e))
        exit(1)


  


  Appreciate any help given. Thank you