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• ffmpeg converting PCM data file to wav file getting distorted(noisy) data

  3 janvier 2015, par Mahendra

  I have raw pcm data in following form :

  0000 0000 0000 0000 0000 0000 0000 0000
  
  0000 0000 0000 0000 0000 0000 0000 0000
  
  0000 0000 0000 0000 0000 0000 0000 0000
  
  0000 0000 0000 0000 0000 0000 0000 0100
  
  0000 0000 0000 0000 0000 0000 0000 0000
  
  0000 0100 0100 0000 0000 efbf bdef bfbd
  
  0000 efbf bdef bfbd efbf bdef bfbd efbf
  
  bdef bfbd efbf bdef bfbd efbf bdef bfbd
  
  efbf bdef bfbd efbf bdef bfbd 0000 efbf
  
  bdef bfbd 0000 efbf bdef bfbd efbf bdef
  
  bfbd 2900 efbf bdef bfbd 0000 efbf bdef
  
  bfbd efbf bdef bfbd efbf bdef bfbd 0000

  and I want to make this data in wav file when I am converting by ffmpeg getting noisy data by this command :

  sox -V -t raw -b 16 -e signed -r 16000 -c 1 14_32_7_187.pcm  new.wav

  and :

  ffmpeg -f s16le -ar 16000 -ac 1 -i 14_32_7_187.pcm -ar 16000 -ac 1 oout.wav

  using both getting noisy data.

• Added handle_form_data method to ease handling of form data.

  1er mai 2012, par Sebastian Tschan

  m server/php/upload.class.php Added handle_form_data method to ease handling of form data. Added index as parameter passed to the handle_file_upload method. Refactored the file upload validation.

• How to send encoded video (or audio) data from server to client in a way that's decodable by webcodecs API using minimal latency and data overhead

  11 janvier 2023, par Tiger Yang

  My question (read entire post for context) :

  


  Given the unique circumstance of only ever decoding data from a specifically-configured encoder, what is the best way I can send the encoded bitstream along with the bare minimum extra bytes required to properly configure the decoder on the client's end (including only things that change per stream, and omitting things that don't, such as resolution) ? I'm a sucker for zero compromises, and I think I am willing to design my own minimal container format to accomplish this.

  


  Context and problem :

  


  I'm working on a remote desktop implementation that consists of a server that captures and encodes the display and speakers using FFmpeg and forwards it via pipe to a go (language) program which sends it on two unidirectional webtransport streams to my client, which I plan to decode using the webcodecs API. According to MDN, the video decoder needs to be fed via .configure() an object containing the following : https://developer.mozilla.org/en-US/docs/Web/API/VideoDecoder/configure before it's able to decode anything.

  


  same goes for the audio decoder : https://developer.mozilla.org/en-US/docs/Web/API/AudioDecoder/configure

  


  What I've tried so far :

  


  Because this remote desktop will be for my personal use only, it would only ever receive streams from a specific encoder configured in a specific way encoding video at a specific resolution, framerate, color space, etc.. Therefore, I took my video capture FFmpeg command...

  


  videoString := []string{
        "ffmpeg",
        "-init_hw_device", "d3d11va",
        "-filter_complex", "ddagrab=video_size=1920x1080:framerate=60",
        "-vcodec", "hevc_nvenc",
        "-tune", "ll",
        "-preset", "p7",
        "-spatial_aq", "1",
        "-temporal_aq", "1",
        "-forced-idr", "1",
        "-rc", "cbr",
        "-b:v", "500K",
        "-no-scenecut", "1",
        "-g", "216000",
        "-f", "hevc", "-",
    }


  


  ...and instructed it to write to an mp4 file instead of outputting to pipe, and then I had this webcodecs demo https://w3c.github.io/webcodecs/samples/video-decode-display/ demux it using mp4box.js. Knowing that the demo outputs a proper .configure() object, I blindly copied it and had my client configure using that every time. Sadly, it didn't work, and I since noticed that the "description" part of the configure object changes despite the encoder and parameters being the same.

  


  I knew that mp4 files worked via mp4box, but they can't be streamed with low latency over a network, and additionally, ffmpeg's -f parameters specifies the muxer to use, but there are so many different types.

  


  At this point, I think I'm completely out of my depth, so :

  


  Given the unique circumstance of only ever decoding data from a specifically-configured encoder, what is the best way I can send the encoded bitstream along with the bare minimum extra bytes required to properly configure the decoder on the client's end (including only things that change per stream, and omitting things that don't, such as resolution) ? I'm a sucker for zero compromises, and I think I am willing to design my own minimal container format to accomplish this. (copied above)