On Wed, 21 Nov 2007, Takashi Iwai wrote:
At Wed, 21 Nov 2007 12:40:54 +0100, I wrote:
At Tue, 20 Nov 2007 01:51:51 +0100, Lennart Poettering wrote:
- If I open an audio device with "plughw:" i can disable the software resampling that takes place via "snd_pcm_hw_params_get_rate_resample()". However, there is no equivalent for disabling the channel number adjustment or the sample format conversion. This would be very useful in PA however, since this would allow me to use only the parts of plughw I am interested in (softvol), and disable all the rest (resampling, conversion, channel remixing).
Hmm.. It's a bit difficult to implement in a clean way. For example, what would be the reason to disable softvol? It's basically irrelevant with the PCM parameters. It's added just because of lack of hardware volume controls.
One idea I have is to make an API like
snd_pcm_alias_plugin(src, dst);
For example,
snd_pcm_alias_plugin("softvol", "passthru");
I don't like this idea nor implementation much. It will be much better to design a run-time communication with plugins to change configuration parameters / behaviour (something like ioctl on opened pcm handle).
Jaroslav
----- Jaroslav Kysela perex@perex.cz Linux Kernel Sound Maintainer ALSA Project