[Protux-devel] Status/implementation multiple bitdepth/samplerate etc. support

[Remon Sijrier]

Hi Luciano,

I've mentioned this earlier but as it is important for me, I'll ask it again.

My soundcard (based on the ice1712 chipset) works only under the following 
conditions with hardwaredescripter: "hw"

1.
SND_PCM_FORMAT_S32_LE --- the actual bitdepth can be (16?? or) 24 bits, but 
stored in a "word". The card internally handles all samples with 32 bits at a 
time. There is no "real" 32 bit support (DAC, ADC are 24 bits)

2.
Any of the following rates can be used both in stereo and mono:
44100,
48000
96000

3.
And last but not least, the card can handle up to:
10 channels.

Setting the hw_param values must be done with one of the values from the 
points 1-3

This card has physically only 2 channels, but the chip can handle 10 channels, 
so the "hw" wants to have it set to 10!!

MADM and MustuxAudioBus are still not prepared to handle this situation.

So my suggestion in this is:
Detect the cards "real" bitdepth, channels, and rate support, test these 
values with MustuxAudioBus::supports (or place this detection code in this 
method).
Then we have a "real supported" bitdepths, rate and channels for MADM, and if 
a given samplerate from Mixer doesn't match the "real supported" etc, then 
convert it to a rate which is supported by MADM (and thus by the audio card)
Only in this way we can use the "hw" descriptor, else I have to use "plughw" 
for ever, even if protux has internal 24 bits, etc... support.

Plughw is less robust, (that's what they say on the alsa-devel and sound-devel 
mailing lists) and if we do it internally in MADM, or MustuxAudioBus, I 
really should be happy, as I still get alsa-lib errors when I start a 
recording.

Greetz,

Remon