Thanks a lot! That helped.
Using hw:0 instead of plughw:0 did not make a difference. However, capturing 12 channels instead of 8 did. If I capture 12 channels, I use only 21% of the CPU. 8 channels use 50%. This happens regardless of whether I use plughw or hw. This is a huge improvement. Apparently the additional 30% CPU was used to reformat the 12interleaved samples into a stream with 8 interleaved samples.
The CPU is still a function of sampling rate: sampling at 48khz takes 10% cpu, whereas 96Khz uses 21%. So I suspect there is still some unnecessary processing going on, since both 96k and 48k are supported sampling rates. Would you have any other leads to follow?
Many thanks again, Bhiksha
Jaroslav Kysela wrote:
On Sat, 27 Dec 2003, bhiksha wrote:
Hi Jaroslav,
Thanks a ton for replying.
Re recording with the delta 1010 : Ive tried every sample type :
S16_LE, U16_LE, S16_BE, U16_BE, S24_LE, U24_LE, S24_BE, U24_BE,
S32_LE, U32_LE, S32_BE, U32_BE.
T he delta1010 does 24 bit sampling, so at least one of the 24
bit formats above must have been native.
No, the S32_LE format is native because low eight bits are padded with zero. 24-bit formats are used only with USB and PCMCIA devices.
Regardless, capturing 8 channels of audio at 96Khz
(which is a native sampling freq. for the delta1010) consumes
50% of the CPU on my 3.06 Ghz machine.
You may simply check that the conversion is not used. Use 'hw:0' device name. Then no conversions are active.
Anyway, the problem might be also in the route plugin. The ICE1712 chip
captures always 12 channels simultaneously. So try to capture 12 channels.
And yes, hardware is assymetric: 10 playback channels and 12 capture channels.
Jaroslav
----- Jaroslav Kysela <[EMAIL PROTECTED]> Linux Kernel Sound Maintainer ALSA Project, SuSE Labs
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