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pulse: Fix hole handling in pa_stream_peek().

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Previously, if there was a hole in a recording stream,
pa_stream_peek() would crash. Holes could be handled silently inside
pa_stream_peek() by generating silence (wouldn't work for compressed
streams, though) or by skipping any holes. However, I think it's
better to let the caller decide how the holes should be handled, so
in case of holes, pa_stream_peek() will return NULL data pointer and
the length of the hole in the nbytes argument.

This change is technically an interface break, because previously the
documentation didn't mention the possibility of holes that need
special handling. However, since holes caused crashing anyway in the
past, it's not a regression if applications keep misbehaving due to
not handing holes properly.

Some words about when holes can appear in recording streams: I think
it would be reasonable behavior if overruns due to the application
reading data too slowly would cause holes. Currently that's not the
case - overruns will just cause audio to be skipped. But the point is
that this might change some day. I'm not sure how holes can occur
with the current code, but as the linked bug shows, they can happen.
It's most likely due to recording from a monitor source where the
thing being monitored has holes in its playback stream.

BugLink: http://bugs.launchpad.net/bugs/1058200
This commit is contained in:
Tanu Kaskinen 2012-11-07 16:52:37 +02:00 • committed by David Henningsson
parent 38c650dca9
commit dfd44036b5
2 changed files with 31 additions and 9 deletions
Download patch file Download diff file Expand all files Collapse all files

20
src/pulse/stream.c
View file

@ -1593,9 +1593,17 @@ int pa_stream_peek(pa_stream *s, const void **data, size_t *length) {
if (!s->peek_memchunk.memblock) {
if (pa_memblockq_peek(s->record_memblockq, &s->peek_memchunk) < 0) {
/* record_memblockq is empty. */
*data = NULL;
*length = 0;
return 0;
} else if (!s->peek_memchunk.memblock) {
/* record_memblockq isn't empty, but it doesn't have any data at
* the current read index. */
*data = NULL;
*length = s->peek_memchunk.length;
return 0;
}
s->peek_data = pa_memblock_acquire(s->peek_memchunk.memblock);
@ -1614,7 +1622,7 @@ int pa_stream_drop(pa_stream *s) {
PA_CHECK_VALIDITY(s->context, !pa_detect_fork(), PA_ERR_FORKED);
PA_CHECK_VALIDITY(s->context, s->state == PA_STREAM_READY, PA_ERR_BADSTATE);
PA_CHECK_VALIDITY(s->context, s->direction == PA_STREAM_RECORD, PA_ERR_BADSTATE);
PA_CHECK_VALIDITY(s->context, s->peek_memchunk.memblock, PA_ERR_BADSTATE);
PA_CHECK_VALIDITY(s->context, s->peek_memchunk.length > 0, PA_ERR_BADSTATE);
pa_memblockq_drop(s->record_memblockq, s->peek_memchunk.length);
@ -1622,9 +1630,13 @@ int pa_stream_drop(pa_stream *s) {
if (s->timing_info_valid && !s->timing_info.read_index_corrupt)
s->timing_info.read_index += (int64_t) s->peek_memchunk.length;
pa_assert(s->peek_data);
pa_memblock_release(s->peek_memchunk.memblock);
pa_memblock_unref(s->peek_memchunk.memblock);
if (s->peek_memchunk.memblock) {
pa_assert(s->peek_data);
s->peek_data = NULL;
pa_memblock_release(s->peek_memchunk.memblock);
pa_memblock_unref(s->peek_memchunk.memblock);
}
pa_memchunk_reset(&s->peek_memchunk);
return 0;