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
`AVCodecParameters` contains values from the codec detected by
avformat_find_stream_info(), but after avcodec_open2(), a different
codec might be selected with a different `AVSampleFormat`. This leads
to misinterpretation of data returned from FFmpeg, leading to random
noise or silence.
This was observed with FFmpeg 4.0.2 and a TS container file containing
MP2. A mp3-float codec was detected returning `AV_SAMPLE_FMT_FLTP`,
but finally the `mpegaudiodec_fixed.c` was used, returning
`AV_SAMPLE_FMT_S16`.
By using the audio format from `AVCodecContext`, we ensure that MPD
and FFmpeg always agree on the actual audio format in the buffer.
This removes the FFmpeg bug workaround from commit e1b032cbad which I
assume is obsolete after 7 years.
Fixes#380
ensure that valid mixer values are set also when the ALSA driver
does not report a valid dB range ('set_raw' fallback)
correct a bug in which volume is assumed to lie in [0..100]
instead of [0..1]
The protocol documentation says that the difference between `find` and
`search` is that `search` is case insensitive, but that's only half
the truth: `search` also searches for sub strings instead of matching
the whole string. This part is undocumented and unfortunate, but at
this point, we can't change it.
However leaking this surprising behavior to the new filter expressions
was a bad idea; the "==" operator should never match substrings. For
people who need that, we should add a new operator.
Max Kellermann