PCM input splitter

Updated: May 06, 2022

A PCM input splitter is a virtual, capture-only device that directly overlays a PCM capture device to enable support for multiple subchannels on hardware that would otherwise support only a single subchannel. The PCM input splitter supports up to 10 concurrently attached subchannels.

The PCM splitter allows multiple processes and threads to concurrently capture audio from the same hardware device. For example, you could use different processes to capture audio for both voice recognition and file recording from the same capture device. The PCM input splitter can be enabled for a PCM capture device via the audio configuration file using the input_splitter_enable key. By default, the PCM input splitter is disabled.

Both the PCM input splitter and PCM software mixer must operate at the same data fragment size, which you set via the sw_mixer_ms option. Because you cannot use a samples value to specify the fragment size the PCM input splitter uses, you cannot size the PCM software mixer fragments using samples (the sw_mixer_samples option) when you use the input splitter.

For information about using an input splitter, see description for the input_splitter_enable key in the “Audio configuration file” section of io-audio in the QNX Neutrino Utilities Reference guide.