Support two cases of transmuxing without re-encoding:

• HLS (static m3u8) to mp4
• format-only relacement (e.g. mkv to mp4)

• fix when channelLayout is 0
• fix when Audio FIFO size=0
• add GOP for WebEncoder.encode (seekable)
• remove trim range restriction
• Filterer.filter only allow necessary frames

• decode->canvas->encode
• MediaRecorder -> wav file
• audio: trim + loop + concat

• Unify WebCodecs and FFmpeg wasm into one file codec.ts.
• Support ReadableStream<VideoFrame/AudioData> as source.
• Support Output chunk.videoFrame / chunk.audioData

• move worker js file inline, when bundle.
• fetch wasm file from CDN (unpkg) when production.

Build a audio/video stream processing library, based on WebAssembly and FFmpeg.

• Custom read/write for Demuxer and Muxer.
• Support URL and Blob(File) as input in browser.
• Support three basic export ways.
• add trim and format filter.