Subject: Re: [linux-audio-dev] MMAP + RTC excellent performance , 2.9ms latency during playback !
From: maarten de boer (maarten.deboer_AT_iua.upf.es)
Date: Mon Mar 13 2000 - 05:42:16 EST
On Tue, 07 Mar 2000, sbenno_AT_gardena.net wrote:
> Good news folks:
> The results of my preliminary using ALSA MMAP mode + RTC tests look promising
>
> For the tests I used my Celeron366 + SB Live! card
> I am using 512 bytes buffesize at 44100kHz stereo ( 2.9ms buffer)
> basically I am donig the following: (for now playback only)
When I try to use a SB Live at 44100, I have a problem that
read and write seem to get out of sync. Jaroslav said this is
a hardware issue of the SB Live.
But it seems that Benno doesn't have that problem. How come?
Is mmap more reliable than read/write ?
> - write some docs how to use high-performance realtime audio under ALSA
> (of course with working examples)
>
> - write a new version of latencytest (almost from scratch) which will support
> OSS , ALSA and the benchmarking of timers like RTC and others.
In addition to that, I think it would be great to provide some template
applications, that people can use as a base for RT audio IO applications.
What features should go into these template apps? I thought of
- OSS and ALSA support
- demonstrate the use of multithreading (pthread) with different priorities
- standard set of command line options for sample rate, fragment size, etc
- midi control of the audio processing
For now, the alsa latency.c test is what comes closest to this.
Maarten
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