... | ... | @@ -104,6 +104,28 @@ Yes. Format conversions are not cheap and must be avoided. For audio processing |
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- Format conversions are done at the input/output nodes. This means that conversions are done to and from devices and also to and from clients that use the stream API.
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- This also means that the conversion code for clients runs in the context of the client and not the server. This also avoids issues with having complicated code such as decoders running in the server context.
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### What is the Pro Audio Profile
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In addition to the PulseAudio profiles, all audio cards now have an extra "Pro Audio" profile. Selecting this profile does the following things:
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* Exposes all the devices available on the card.
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* Exposes the maximum number of channels on all devices.
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* The channels are labeled as AUX0, AUX1, ...
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* Disables the hardware mixers, it only enables software volume/mute.
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* A session manager will configure streams to stereo and route to the first two channels (AUX0 and AUX1).
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This profile is meant to be used on audio cards with:
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* More than 8 channels for input or output. Channel assignment is probably wrong for these cards.
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* Cards with many instruments connected to each input. It makes sense to handle each channel as a separate unrelated stream.
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* Output Cards with many unrelated outputs, like speakers on the first 2 channels, headphones on the second channel-pair, additional speakers on the other channels.
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For consumer cards with stereo or surround configurations, it does not make sense to use this Profile.
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When using this profile, it might make sense to configure additional virtual sources to route applications to specific channels: https://gitlab.freedesktop.org/pipewire/pipewire/-/wikis/Virtual-Devices#behringer-umc404hd-speakersheadphones-virtual-sinks
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Note that this profile does *not* change any of the latency settings or configurations on the device.
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### What About Pro Video?
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- Similar to audio we have one common format: RGBA float32 premultiplied linear video. This should be easy to generate and manipulate on GPU/CPU and allow for HDR and simple compositing operations.
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