decoders: Add stateful decoder API #62
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Add an initial version of stateful decoder API.
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@InternetOfTofu can you provide at least one implementation so that we know this works? Also, IIRC, someone from @Gnurou 's team was already working on something similar |
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That someone is actually @InternetOfTofu :) Sorry for the delay, I'll try to review this this week! |
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Since ccdec has a similar enum, we should probably have a single declaration in lib.rs since we already have DecodedFormat there.
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| pub enum ColorGamut { |
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Right now we don't have any way to manage color properties, even for stateless decoders. Let's drop this for now as it is not needed for basic decoding.
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| pub enum StatefulDecoderEvent { |
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I suspect you can reuse DecoderEvent (and the DecodedHandle trait) as-is for the stateful decoder. It will align the interfaces and make the code simpler somehow.
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| /// The format of the stream has changed and action is required. A VideoFrame | ||
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| FormatChanged(VideoFrame), |
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Why do we need to return a videoframe here?
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| pub struct StatefulDecoder<C, B> |
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The first use of the stateful decoder interface should be as a stateful wrapper to any stateless decoder, i.e. an adapter that turns a stateless decoder into a stateful one. That adapter maybe be implemented as a StatefulDecoderBackend, but for simplicity I'd recommend writing it as an implementation of StatefulDecoder first and see what parts we can share with other stateful decoder implementations.
So I'd suggest starting with the design of this wrapper first to guide the interface. Starting from any stateless decoder, the stateful wrapper should
- Accept input buffers and queue them until they can be processed,
- Try to submit work to the stateless decoder, hold if the work cannot be submitted to retry later, and process the events of the stateless decoder, forwarding them to the caller if needed (e.g. decoded frames),
... and I think that's mostly it. The simple_playback_loop should give a good example of how things should work, as its purpose is to provide some stateful-ish behavior to our stateless decoders. I will be replaced it by the stateful decoder once it is available.
Add an initial version of stateful decoder API.