FFmpegAVDemuxer is a muxer dependent on FFmpeg lib, which can mux video stream and audio stream to media files. Currently, only mux MP4/FMP4 is supported（Currently, only Video Stream is supported.）, and we will add support for more types of files in the future.
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This is a sample of how to record MP4 dependent on FFmpegH264Provider and FFmpegAVMuxer.
the flow of record MP4:
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