MPD's default is 100ms, which is too long for the real-time I/O
thread. The OutputThread has 100us, but the real-time I/O thread
might have tighter deadlines.
This change has currently no effect (I believe), because nobody uses
timers on the RTIO thread.
If our `ring_buffer` is smaller than the ALSA-PCM buffer (if the
latter has more than the 4 periods we allocate), it can happen that
the start threshold is crossed and ALSA switches to
`SND_PCM_STATE_RUNNING`, but the `ring_buffer` is empty. In this
case, MPDD will generate silence, even though the ALSA-PCM buffer has
enough data. This causes stuttering (#420).
This commit amends an older workaround for a similar problem (commit
e08598e7e2) by adding a snd_pcm_avail()
check, and only generate silence if there is less than one period of
data in the ALSA-PCM buffer.
Fixes#420
The method Cancel() assumes that the `period_buffer` must be empty
when `active==false`, but that is not the case when Play() fails.
Of course the assertion in Cancel() is not 100% correct, but I decided
to rather fix this in LockCaughtError() because the `period_buffer`
should only be accessed from within the RTIO thread, and this is the
only code path where `active` can be set to `false` with a non-empty
`period_buffer`.
Fixes#423
This check was added 9 years ago in commit
4dc25d3908 to work around a dmix bug
which I assume has been fixed long ago.
Removing this fixes another corner case: if draining is requested
before the start threshold is reached, the PCM is still in
SND_PCM_STATE_PREPARED but not yet SND_PCM_STATE_RUNNING, which means
the submitted data will never be played. This corner case is
realistic when playing songs shorter than the ALSA buffer (if the
buffer is very large).
This fixes a corner case which has probably never occurred and
probably never will: if Cancel() is called, and then Play() followed
by Drain(), the plugin should really play that data. However
currently, this never happens, because snd_pcm_prepare() is never
called.
I added this sentence in commit
5271e81ebe, but this was merely
documented the legacy status quo, which has always been undocumented
for old-style filters.
But for new filters, using "==" for sub strings was a surprising
"feature", which I removed in commit
ac0852b4e3.
When `metadata_sent` is `false`, the plugin assumes there is metadata
which must be sent, even if no metadata page was passed to the plugin.
Initializing it to `true` avoids dereferencing this `nullptr`.
Fixes#412
If the output is already open, the `current_chunk` pointer may be
bogus and out of sync with `SharedPipeConsumer::chunk`, leading to an
assertion failure in `SharedPipeConsumer::Consume()`.
Fixes#411
Meson always enables large file support on the compiler command line,
thus config.h doesn't need to be included anymore. We'll remove the
whole `check.h` header soon.
Closes#409
Max Kellermann