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AAC_LC_CODEC_STRING

codec::codec_strings

Constant AAC_LC_CODEC_STRING 

Source 
pub const AAC_LC_CODEC_STRING: &str = "mp4a.40.2";
Expand description

AAC-LC in MP4 codec string. Always mp4a.40.2:

  • mp4a = ISO/IEC 14496 sample entry fourcc
  • 40 = ObjectTypeIndication for MPEG-4 Audio (decimal 64, hex 0x40)
  • 2 = Audio Object Type 2 (AAC-LC) per ISO/IEC 14496-3 Table 1.16

HE-AAC v1 = mp4a.40.5, HE-AAC v2 = mp4a.40.29. We don’t emit those today — the audio rendition is always AAC-LC stereo at 48 kHz per the CMAF ladder defaults — but if the worker ever passes-through HE-AAC source, this needs to inspect the AOT signaled in the AudioSpecificConfig and switch. Until then, callers using the constant string are correct.