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• How do I get audio files of a specific file size ?

  16 juillet 2018, par Houseman

  Is there any way to use ffmpeg to accurately break audio files into smaller files of a specific file size, or pull a specific number of samples from a file ?

  I’m working with a speech-to-text API that needs audio chunks in exactly 160,000 bytes, or 80,000 16-bit samples.

  I have a video stream, and I have an ffmpeg command to extract audio from it :

  ffmpeg -i "rtmp://MyFMSWorkspace/ingest/test/mp4:test_1000 live=1" -ar 16000 -f segment -segment_time 10 out%04d.wav

  So now I have 10 second audio chunks with a sample rate of 16 kHz. Is there any way to break this into exactly 160kb, 5 second files using ffmpeg ?

  I tried this :

  ffmpeg -t 00:00:05.00 -i out0000.wav outCropped.wav

  But the output was this :

  Input #0, wav, from 'out0000.wav':
  
    Metadata:
  
      encoder         : Lavf56.40.101
  
    Duration: 00:00:10.00, bitrate: 256 kb/s
  
      Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 16000 Hz, 1 channels, s16, 256 kb/s
  
  Output #0, wav, to 'outCropped.wav':
  
    Metadata:
  
      ISFT            : Lavf56.40.101
  
      Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 16000 Hz, mono, s16, 256 kb/s
  
      Metadata:
  
        encoder         : Lavc56.60.100 pcm_s16le
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (pcm_s16le (native) -> pcm_s16le (native))
  
  Press [q] to stop, [?] for help
  
  size=     156kB time=00:00:05.00 bitrate= 256.1kbits/s

  but now the size is 156kb

  EDIT :

  My finished command is :

  ffmpeg -i "url" -map 0:1 -af aresample=16000,asetnsamples=16000 -f segment -segment_time 5 -segment_format sw out%04d.sw

• Does anybody know about the ".ms" video format, and how I might be able to convert it ? [closed]

  2 octobre 2024, par Jim Miller

  I'm trying to deal with some very old video files from a Mac OS 8-era CD. They have a ".ms" file extension, and can be played with the old "Movie Player" distributed with OS 8. But Movie Player won't export them to .mp4 or anything currently useful, and I haven't found a modern-day player/converter (VLC, etc), on either Mac or Windows, that will open them. I could update my old testing Mac to QuickTime 3, but I've long ago misplaced my QT 3 Pro key(!), and the free version of QT 3 doesn't do exports. Those were the days... BTW, these ".ms" files are not the same as ".dvr-ms" files, so there's no help there.

  


  Any advice ? Maybe there are some settings for ffmpeg I've missed ? Thanks !

  


• hwcontext_vulkan : rewrite upload/download

  18 juillet 2024, par Lynne

  hwcontext_vulkan : rewrite upload/download
  This commit was long overdue. The old transfer dubiously tried to
  
  merge as much code as possible, and had very little in the way
  
  of optimizations, apart from basic host-mapping.
  The new code uses buffer pools for any temporary bufflers, and
  
  handles falling back to buffer-based uploads if host-mapping fails.
  Roundtrip performance difference :
  
  ffmpeg -init_hw_device "vulkan=vk:0,debug=0,disable_multiplane=1" -f lavfi \
  
   i color=red:s=3840x2160 -vf hwupload,hwdownload,format=yuv420p -f null -
  7900XTX :
  
  Before : 224fps
  
  After : 502fps
  Ada, with proprietary drivers :
  
  Before : 29fps
  
  After : 54fps
  Alder Lake :
  
  Before : 85fps
  
  After : 108fps
  With the host-mapping codepath disabled :
  
  Before : 32fps
  
  After : 51fps
  

  • [DH] libavutil/hwcontext_vulkan.c
  • [DH] libavutil/vulkan.c