Sound per channel

[Oldes]

I have a sound card with 7 channels and I need to play separate mono sounds in these channels.
Is it possible to use some api to achieve it?

[mackron]

Yes, this is just normal sound output. Set your channel count to 0 in the device config to use the device's native channel count. After ma_device_init() returns, inspect device.playback.channelMap to get an idea of the order of your channels. Then in the data callback simply copy your per-channel audio data into the output buffer, remembering that you need to interleave the per-channel data before copying it into the output buffer.

[Oldes]

So I must use the low-level API?

[mackron]

I assumed you were using the low-level API. For the high level API it's a bit trickier, but still possible. You'll need to make use of the node graph. Several ways to do it, but here's one way. Initialize your sound with ma_sound_init_ex() and set the channelsOut member of ma_sound_config to MA_SOUND_SOURCE_CHANNEL_COUNT. That will result in the output of the sound having the same channel count as the underlying data source instead of the engine's channel count. Then connect the output of each one of your sounds to an input of a ma_channel_combiner_node (https://github.com/mackron/miniaudio/tree/master/extras/nodes/ma_channel_combiner_node). Set the channel count of the combiner node to that of your engine (ignore the incorrect comment in the ma_channel_combiner_node.h file - was a copy/paste error). Then connect the output of your combiner to the engine's endpoint. You

The combiner node takes separated mono channels as input and on output produces interleaved audio data suitable for playback. It's in a separate file so you'll need to take that from the extras folder that I linked to above.

What's your use case for this out of curiosity? Unless you need mixing and/or advanced effect processing, the high level API might be overkill for what you're trying to do and it might be simpler to just use the low-level API. You can still make use of the resource manager and decoders and whatnot with the low-level API.

[Oldes]

My exact use case is a multimedia installation where I need to play separate audio outputs from multiple speakers from a Raspberry PI.
I may try the low-level API.. But it is just my second day since I started playing with your library:)

Meanwhile I want to use MiniAudio as an audio extension to Rebol.

[mackron]

The low-level API isn't too hard to use - and in some cases can actually be easier depending on what you need. The hardest thing is keeping everything thread-safe since your audio data is transferred on a separate thread via a callback.