Serialize mixer output frame ordering via AsyncStream.#1890
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shogo4405 merged 1 commit intoHaishinKit:mainfrom Mar 22, 2026
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Replace unstructured Task {} in MediaMixerOutput and StreamOutput
conformances with AsyncStream channels that preserve FIFO ordering.
The previous pattern created a new Task for each audio/video callback,
which provides no ordering guarantee when entering an actor's serial
executor. This caused adjacent frames to arrive out of order, resulting
in RTMPTimestamp.invalidSequence errors (silent frame drops) and
AVAssetWriter failures in StreamRecorder.
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Replace unstructured Task {} in MediaMixerOutput and StreamOutput
conformances with AsyncStream channels that preserve FIFO ordering.
The previous pattern created a new Task for each audio/video callback,
which provides no ordering guarantee when entering an actor's serial
executor. This caused adjacent frames to arrive out of order, resulting
in RTMPTimestamp.invalidSequence errors (silent frame drops) and
AVAssetWriter failures in StreamRecorder.
Collaborator
|
Thank you for your patience. I haven’t been able to come up with a solid design yet, so I’d like to merge this PR and proceed with testing. |
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Fixes #1889
Replace unstructured Task {} in MediaMixerOutput and StreamOutput conformances with AsyncStream channels that preserve FIFO ordering.
Problem
The nonisolated mixer delegate methods in RTMPStream, SRTStream, and StreamRecorder each create a new Task {} per callback to hop into the actor. Swift provides no ordering guarantee for unstructured tasks entering an actor's serial executor, so adjacent frames can arrive out of order.
This causes:
Changes
Continuations are declared nonisolated(unsafe) since AsyncStream.Continuation.yield is thread-safe and mutations only occur from within the actor.