From: Timo Wischer <twischer@xxxxxxxxxxxxxx>
Without this change an interval of (x x+1] will be interpreted as an
empty interval but the right value would be x+1.
This leads to a failing snd_pcm_hw_params() call which returns -EINVAL.
An example issue log is given in the following:
snd_pcm_hw_params failed with err -22 (Invalid argument)
ACCESS: MMAP_NONINTERLEAVED
FORMAT: S16_LE
SUBFORMAT: STD
SAMPLE_BITS: 16
FRAME_BITS: 16
CHANNELS: 1
RATE: 16000
PERIOD_TIME: (15999 16000]
PERIOD_SIZE: (255 256]
PERIOD_BYTES: (510 512]
PERIODS: [2 3)
BUFFER_TIME: 32000
BUFFER_SIZE: 512
BUFFER_BYTES: 1024
In case of (x x+1) we have to interpret it anyway as a single value of x to
compensate rounding issues.
For example the period size will result in an interval of (352 353) when
the period time is 16ms and the sample rate 22050 Hz
(16ms * 22,05 kHz = 352,8 frames). But 352 has to be chosen to allow a
buffer size of 705 (32ms * 22,05 kHz = 705,6 frames) which has to be >= 2x
period size to avoid Xruns. The buffer size will not end up with an
interval of (705 706) similar to the period size because
snd_pcm_rate_hw_refine_cchange() calls snd_interval_floor() for the buffer
size. Therefore this value will be interpreted as an integer interval
instead of a real interval further on.
This issue seems to exist since the change of 9bb985c38 ("pcm:
snd_interval_refine_first/last: exclude value only if also excluded
before")
Signed-off-by: Timo Wischer <twischer@xxxxxxxxxxxxxx>
diff --git a/src/pcm/interval_inline.h b/src/pcm/interval_inline.h
index a68e292..5e59d72 100644
--- a/src/pcm/interval_inline.h
+++ b/src/pcm/interval_inline.h
@@ -51,12 +51,14 @@ INTERVAL_INLINE int snd_interval_single(const snd_interval_t *i)
{
assert(!snd_interval_empty(i));
return (i->min == i->max ||
- (i->min + 1 == i->max && i->openmax));
+ (i->min + 1 == i->max && (i->openmin || i->openmax)));
}
INTERVAL_INLINE int snd_interval_value(const snd_interval_t *i)
{
assert(snd_interval_single(i));
+ if (!i->openmax)
+ return i->max;
return i->min;
}
--
2.7.4
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