Support generating multiple videotracks and single audio from from a mp4 file using FFmpeg

[TilsonJoji]

Hello Mike @englishm ,

Re-opening this PR that had raised in Luke's repo , along with the code and description here.

In context to the PR in moq-js , this PR holds the changes done to ./dev/pub to enable us to create 3 video renditions for a video file that could be ingested for a single namespace via moq-pub.

I have tried to optimize FFmpeg args to help us get the best of video quality and latency and also tried to make the config parameters in the script readable, at times occasionally I have observed video artefacts at higher video quality track. Since the context is the same I added the changes in ./dev/pub , please let me know if you would like me to keep this as a separate file like ./dev/pub_multi

Script usage scenarios:

• Scenario 1: Legacy single track

  • ./dev/pub

• Scenario 2:

  • Multi-track , 3 video tracks and 1 audio track will be ingested into moq-pub
  • Default video quality parameters are:

    • 1920x1080:6000K:60

    • 1280x720:5000K:30

    • 640x480:4000K:25

    • ./dev/pub_multi_track

• Scenario 3

  • With argument multi and video quality of the 3 tracks specified in arguments
    - ./dev/pub_multi_track 1920x1080:6000K:60 1280x720:5000K:30 360x480:4000K:25

All the arguments that are not in this 1920x1080:6000K:60 format will be passed to cargo

With pub_multi_track script , a realtime live video track stream will be simulated and the video will be watermarked/overlayed with real-time UTC clock from the server on the top left corner that can be visually compared with https://time.is/UTC to check real-time latency and the videoresolition-bitrate will be watermarked/overlayed at the bottom right corner to assist in visually identifying the track.

[Outdated para.] ./dev/pub script had an "$@" as the last argument to moq-pub , which passes all the arguments to the script to moq-pub , had to remove it to incorporate the current implementation and legacy flow works without it, to my understanding moq-pub usage is moq-pub --name , so we can safely remove "$@" . Kindly advise if I overlooked this.

Kindly review and let me know your thoughts and amendments to be done.

[TilsonJoji]

UT

trackswap-UT-draft05.mp4

[englishm]

Thank you, @TilsonJoji!

As for the dev/pub script, I do think it would be best to leave the current script as-is and supporting $@ and have a separate script for this new multi-track mode for now. We could always roll it back in to the main script again later, but I know that I often make use of the $@ to pass in additional arguments, and others may, too.

[TilsonJoji]

Thank you, @TilsonJoji!

As for the dev/pub script, I do think it would be best to leave the current script as-is and supporting $@ and have a separate script for this new multi-track mode for now. We could always roll it back in to the main script again later, but I know that I often make use of the $@ to pass in additional arguments, and others may, too.

Thank you for your comment/advise , as desired , I have separated the multi-track script into a new one and retained $@ .

[TilsonJoji]

Please hold-on your review , there is one more check required in my commit will update shortly

[TilsonJoji]

Done with addressing your comment/advise @englishm , kindly review and let me know your thoughts and amendments to be done.

[englishm]

Thanks, @TilsonJoji!