Собственно, сабж: https://www.phoronix.com/news/FFmpeg-FLV-Improvements
Thanks to the work of open-source developer Timo Rothenpieler (plus two patches from Dennis Sädtler) there is now multi-track audio/video support and modern codec support with the enhanced FLV v2 support added to FFmpeg.
The FFmpeg FLV decoder now supports for demuxing and handling all multi-track modes, enhanced audio codec support, parsing enhanced RTMP multi-channel information, and other «flvdec» improvements.
Over on the FLV encode «flvenc» side there is multi-track video support based on the enhanced RTMP v2 specification, writing multi-track audio, and other related work.
