w3c / w3c/webcodecs

value of optimizeForLatency in emitted decoder configuration

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Description

It seems odd that the value of optimizeForLatency in the decoder configuration spit out by the encoder does not reflect the value of latencyMode set in the encoder configuration.

In the encode-decode sample, I had expected (but not checked) that setting latencyMode: "realtime" in the encoder config would result in optimizeForLatency: true in the decoder config. Because the decoder config didn't automatically set optimizeForLatency: true, the measured decoder latencies for VP8 and AV1 were considerably higher (~ 100 ms) than expected (and higher than the encoder latencies).

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Research direction

Start with the encode-decode sample and inspect how latencyMode and optimizeForLatency are represented in the encoder and emitted decoder configurations. Compare the VP8 and AV1 latency measurements, then determine the expected relationship and document or test the behavior so the configuration and measured latency are consistent.

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Assessment

Domain
api
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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