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core: adjust playing_for and underrun_for at rewind

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A rewind may erase data that sink_input counted in playing_for or
underrun_for earlier. Add code adjusting those values after a rewind.

One visible symptom of this bug was problems recovering from an
underrun. When a client calls pa_stream_write() with a large block of
memory, the function can split that into smaller pieces before sending
it to the server. When receiving new data for a stream that had
silence queued due to underrun, the server would do a rewind to
replace the queued-but-not-played silence with the new data. Because
of the bug, this rewind itself would not change underrun_for. It's
possible for multiple rewinds to be done without filling the sink
buffer in between (which is what would eventually reset underrun_for).
In this case, the server rapidly processing the split packets would
rewind the stream for _each_ of them (as underrun_for would stay set),
erasing valid audio as a result.
This commit is contained in:
Uoti Urpala 2012-07-28 23:51:46 +03:00 • committed by Arun Raghavan
parent 94039790f8
commit 5bc6cadcb2
1 changed files with 22 additions and 4 deletions
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26
src/pulsecore/sink-input.c
View file

@ -970,6 +970,15 @@ void pa_sink_input_drop(pa_sink_input *i, size_t nbytes /* in sink sample spec *
pa_memblockq_drop(i->thread_info.render_memblockq, nbytes);
}
static void subtract_helper(size_t *p, size_t amount)
{
if (*p == (size_t) -1)
return;
if (*p < amount)
*p = 0;
*p -= amount;
}
/* Called from thread context */
void pa_sink_input_process_rewind(pa_sink_input *i, size_t nbytes /* in sink sample spec */) {
size_t lbq;
@ -996,8 +1005,12 @@ void pa_sink_input_process_rewind(pa_sink_input *i, size_t nbytes /* in sink sam
/* We were asked to drop all buffered data, and rerequest new
* data from implementor the next time peek() is called */
size_t s = pa_memblockq_get_length(i->thread_info.render_memblockq);
if (i->thread_info.resampler)
s = pa_resampler_request(i->thread_info.resampler, s);
pa_memblockq_flush_write(i->thread_info.render_memblockq, TRUE);
subtract_helper(&i->thread_info.underrun_for, s);
subtract_helper(&i->thread_info.playing_for, s);
} else if (i->thread_info.rewrite_nbytes > 0) {
size_t max_rewrite, amount;
@ -1012,6 +1025,8 @@ void pa_sink_input_process_rewind(pa_sink_input *i, size_t nbytes /* in sink sam
amount = PA_MIN(i->thread_info.rewrite_nbytes, max_rewrite);
if (amount > 0) {
size_t samount = amount;
pa_log_debug("Have to rewind %lu bytes on implementor.", (unsigned long) amount);
/* Tell the implementor */
@ -1021,11 +1036,14 @@ void pa_sink_input_process_rewind(pa_sink_input *i, size_t nbytes /* in sink sam
/* Convert back to to sink domain */
if (i->thread_info.resampler)
amount = pa_resampler_result(i->thread_info.resampler, amount);
samount = pa_resampler_result(i->thread_info.resampler, amount);
if (amount > 0)
if (samount > 0) {
/* Ok, now update the write pointer */
pa_memblockq_seek(i->thread_info.render_memblockq, - ((int64_t) amount), PA_SEEK_RELATIVE, TRUE);
pa_memblockq_seek(i->thread_info.render_memblockq, - ((int64_t) samount), PA_SEEK_RELATIVE, TRUE);
subtract_helper(&i->thread_info.underrun_for, amount);
subtract_helper(&i->thread_info.playing_for, amount);
}
if (i->thread_info.rewrite_flush)
pa_memblockq_silence(i->thread_info.render_memblockq);