The string av01.0.08M.08 is a technical descriptor for the codec, while 399 is the specific YouTube internal format code (itag) for a 1080p AV1 video stream. Compression Efficiency: AV1 provides better compression than its predecessor, VP9. Technical String Breakdown: av01 : The AV1 codec identifier. 0 : Profile 0 (Main profile for consumer devices). 08M : Level 3.0 (indicated by 8), Main tier (M). 08 : 8-bit color depth.
ffmpeg -i input.mp4 -c:v libaom-av1 -crf 30 \ -c:a libopus -b:a 128k \ -map 0:v:0 -map 0:a:0 \ -metadata:s:v:0 title="av01008m08" \ -metadata:s:a:0 title="opus 251 new" \ output.mp4 codecs av01008m08 399 opus 251 new
Understanding these codecs is the key to knowing why your 4K stream looks sharp and your audio sounds clear even on a shaky mobile connection. Decoding the Video: AV01 (AV1) The string av01
