At Mon, 24 Feb 2014 13:13:44 +0100, Maarten Baert wrote:
On 24/02/14 10:17, Takashi Iwai wrote:
Can S32 work instead of S16? Then we won't lose the accuracy so much. Of course, handling float directly would be the best option.
The samplerate and speexrate plugins currently take S16 (see pcm_src_convert_s16 in alsa-plugins/rate/rate_samplerate.c and alsa-plugins/rate/rate_speexrate.c), so just using S32 will not improve the accuracy.
Ah, I forgot it. We should fix these plugins to allow S32 if available, too...
It would be easy to replace those functions with pcm_src_convert_float (both resampler libraries have functions that take float directly), but that will break the plugin ABI. Is that acceptable? The same would have to be done for the channel remapping (route conversion) plugin.
It's fine as long as the plugin is backward compatible. That is, pcm_rate.c checks the plugin version and uses the new ops only for objects advertising the newer version. See pcm_extplug.c. There are some codes checking version numbers.
In anyway, could you give your acked-by tag?
Sorry, I don't know what you mean - this is the first time I've submitted a patch here.
Just give a line "Signed-off-by: Your Name your@mail" in the patch changelog. See Documentation/SubmittingPatches (section "sign your work") for details. This is a standard procedure required for linux-kernel patch management, and we follow it for alsa-lib and others in general.
thanks,
Takashi