Default the generate key frame algorithm to all layers. #276
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What is the purpose of blocking the return until all requested key frames have been generated? This was previously required/done to get "a" timestamp but no longer serves any purpose? See also #145 on the overall broken assumptions |
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This issue had an associated resolution in WebRTC September 2025 meeting – 16 September 2025 (PR #276: Default the generate key frame algorithm to all layers):
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Note that RIDs are optional, we only know that either all encodings have RIDs or none of them have RIDs, but we don't know that no RIDs equals singlecast - you could have multiple encodings without RIDs. The alternative would be encodingIndex but we can say that rids are a prerequisite |
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Note I also cleaned up the language a bit: "encoder" was being used at two different conceptual levels: A) as the owner of all layers, and B) per layer. I reworked/replaced the latter with "layer" consistent with existing text in 4.10: "When transform’s [[encoder]] receives a keyframe request, ... Set rid to the RID of the appropriate layer, or undefined if the request is not for a specific layer." |
| 1. If |encoder|.`[[pendingKeyFrameTasks]]` is undefined, initialize |encoder|.`[[pendingKeyFrameTasks]]` to an empty set. | ||
| 1. Let |shouldTriggerKeyFrame| be <code>false</code> if |encoder|.`[[pendingKeyFrameTasks]]` contains a task whose `[[rid]]` | ||
| value is equal to |rid|, and <code>true</code> otherwise. | ||
| 1. Remove from |layers| all layers already [=list/contained|found=] in any `[[layers]]` of any tasks in |encoder|.`[[pendingKeyFrameTasks]]`. |
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Maybe we can do that step first before creating the pending key frame task.
| 1. If |frame| was generated by a video encoder identified by |task|.`[[rid]]`, run the following steps: | ||
| 1. If |frame| was generated for a layer | ||
| [=list/contained=] in |task|.`[[layers]]`, remove that layer from |task|.`[[layers]]`. | ||
| If this causes |task|.`[[layers]]` to become empty, then run the following steps: |
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Let's resolve the promise as soon as we have a frame, that way, whether there are multiple key frames or just one, it is consistent.
From #143 (comment)
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