YouTube Opus and Eclipsa Audio uploads vs Sume's WAV and MP3
YouTube now lists Opus and Eclipsa Audio beside AAC-LC for uploads. Sume audio outputs are wav (pcm_s16le) and mp3 only; neither is Opus or Eclipsa.
YouTube's upload page now lists three audio codecs: AAC-LC, Opus and Eclipsa Audio. Sume's standalone audio outputs include neither of the newer two; they are wav or mp3.
Read 2026-10-01: YouTube Help, Sume's audio detach and Timeline audio docs.
What does YouTube list for audio?
Audio codec: AAC-LC or Opus or Eclipsa Audio. Channels: stereo, stereo plus 5.1, or stereo plus Eclipsa Audio. Sample rate: 48kHz. A note says Eclipsa Audio (immersive audio) is recommended at 128 kbps per channel.
Where does each Sume surface stand?
So AAC-LC is the one YouTube-listed codec that a Sume surface writes into an MP4, and only through trim.
| Surface | Audio codec it emits | Opus or Eclipsa |
|---|---|---|
| YouTube upload list | AAC-LC, Opus, Eclipsa Audio | Listed |
| Audio detach | wav or mp3 | No |
| Timeline audio output | wav (default) or mp3 | No |
Video trim, audio: keep | AAC (exact mode remux) | No |
Is wav or mp3 a problem for YouTube?
The page shown here does not say what YouTube does with a standalone wav or mp3, because those are not upload containers; its list is for audio inside an MP4. Treat those files as intermediates and encode the delivery audio in your own muxing step.
Timeline's docs advise keeping wav when the file will be joined again or drives lip-sync, since mp3 re-adds priming padding at each edge.
Can I get Opus or Eclipsa by asking for a codec?
No. The docs list no codec field, and sending codec is refused with ffmpeg_fields_rejected. The mapping from raw ffmpeg flags to the fields that do exist is in audio detach: ffmpeg flags to API fields.
Sources
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