OPUS_SET_DRED_DURATION was hardcoded to 2 (20 ms), meaning DRED only
covered 1/3 of a lost 60 ms frame and was useless above 20 ms channels.
Now computed as max(2, ceil(frame_ms/10)) so DRED always embeds enough
redundancy to reconstruct one full previous frame regardless of frame size.
The floor of 2 preserves two-frame burst-loss coverage at 10 ms channels.
Decoder side and server are unaffected (server relays payloads verbatim).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Talon
04bdb70d47