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• How much of modern FFmpeg is written by Fabrice Bellard ?

  17 décembre 2022, par Hashim Aziz

  FFmpeg is considered by many to be the work of Fabrice Bellard, and maybe even his magnum opus, but since he stopped contributing to the project (under the pseudonym Gérard Lantau) in 2004, I wondered how much of it can actually still be said to be his. By comparison, Linus Torvalds' Wikipedia page states :

  


  


  As of 2006, approximately 2% of the Linux kernel was written by
Torvalds himself.[28] Because thousands have contributed to it, his
percentage is still one of the largest. However, he said in 2012 that
his own personal contribution is now mostly merging code written by
others, with little programming.

  


  


  This despite the fact that Torvalds is still an active contributor to the Linux kernel, whereas Bellard hasn't been an active contributor to FFmpeg for almost two decades.

  


  FFmpeg being an open-source project tracked with Git, it seems like the question should be technically and objectively answerable, but as someone who hates mailing lists and the generally archaic ways that big open-source projects like to do things, I wouldn't know where to start in doing so.

  


  Just how much of the modern FFmpeg codebase is Fabrice Bellard actually responsible for, in comparison to the other FFmpeg devs ?

  


• 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)

  


• bash script with conditional arguments and output pipe not working [duplicate]

  19 décembre 2022, par Pavel

  Can u please help me with bash script for ffmpeg ?
Trying to create condition based on args to play OR save media to file, so I've created this kind of IF :

  


  #!/bin/bash

if [ "$1" == "play" ]; then
    POSTFIX="-f matroska - | mpv -"
else
    POSTFIX="-y $OUTPUT"
fi

ffmpeg \
  # skipped personal ffmpeg stuff
  "$POSTFIX"


  


  Now when I try to run it with "play" argument it says :

  


  Unrecognized option 'f matroska - | mpv -'.


  


  So if I add this POSTFIX both variants to command everything works fine...

  


  It looks like something in my bash screens this args or something like that ? Also I don't see in error this dash symbol before f option