Re: [Alsa-devel] Problem deducing buffer time with non-integer samplerate?

[Arve Knudsen]

Maybe I should add that this is after a successful call to 
snd_pcm_hw_params (hardwarespace configured), in case it wasn't clear. 
Does the driver return wrong approximation thresholds (delta > 1), or is 
it supposed to work this way?? I mean, can't ALSA deduce a single 
approximate value which can be returned?

Regards

Arve Knudsen

On Thu, 04 Mar 2004 14:30:08 +0100, Arve Knudsen <[EMAIL PROTECTED]> 
wrote:

Hi

A PortAudio user has been experiencing a problem with his SB128 (Ensoniq 
AudioPCI driver), which we tracked down to a call to 
snd_pcm_hw_params_get_buffer_time returning -EINVAL. A dump of the 
current hw configuration space looks like this:
ACCESS:  MMAP_INTERLEAVED
FORMAT:  S16_LE
SUBFORMAT:  STD
SAMPLE_BITS: 16
FRAME_BITS: 32
CHANNELS: 2
RATE: (44099 44100)
PERIOD_TIME: (5804 5805)
PERIOD_SIZE: 256
PERIOD_BYTES: 1024
PERIODS: 5
BUFFER_TIME: (29024 29026)
BUFFER_SIZE: 1280
BUFFER_BYTES: 5120
TICK_TIME: 10000

Is the problem that the delta between min and max BUFFER_TIME exceeds 
one (1)? The exact samplerate is 44099.81 which should correlate with 
the integer min/max values. While I'm at it, is it correct to translate 
samplerate fractions from 0.5 and upwards to dir == -1 and 1 for 
fractions less than 0.5 (ie. 44099.81 translates to 44100 with dir == 
-1)? There's also a "bug" in the documentation for 
snd_pcm_hw_params_set_buffer_size, which mentions "dir", although its 
not part of the function signature.

Thanks

Arve Knudsen




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