Draining will always playback somewhat beyond the end of the filled
buffer. This would produce artifacts if the user did not set up the
auto-silencing machinery, which is an extremely easy mistake to make, as
the API strongly suggests convenient fire-and-forget semantics. This
patch makes it work out of the box.
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@xxxxxx>
---
you are NOT expected to apply this. i just needed it for my testing
(it's easier to deploy as i'm hacking on the kernel anyway) and wanted
to post it for posterity.
v3:
- rebased to updated silencing code
- intro period alignment to reduce redundant fill
- cut down commit message again, as it's disabled by default now
v2:
- fill only up to two periods, to avoid undue load with big buffers
- added discussion to commit message
---
sound/core/pcm_lib.c | 35 ++++++++++++++++++++++++++++++++++-
sound/core/pcm_native.c | 3 ++-
2 files changed, 36 insertions(+), 2 deletions(-)
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index 9c121a921b04..46e63e653789 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -67,6 +67,11 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram
snd_pcm_uframes_t frames, ofs, transfer;
int err;
+ if (runtime->silence_size == 0 &&
+ (runtime->state != SNDRV_PCM_STATE_DRAINING ||
+ (runtime->info & SNDRV_PCM_HW_PARAMS_NO_DRAIN_SILENCE) ||
+ (runtime->hw.info & SNDRV_PCM_INFO_PERFECT_DRAIN)))
+ return;
if (runtime->silence_size < runtime->boundary) {
snd_pcm_sframes_t noise_dist;
snd_pcm_uframes_t appl_ptr = READ_ONCE(runtime->control->appl_ptr);
@@ -80,6 +85,33 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram
noise_dist += runtime->boundary;
/* total noise distance */
noise_dist += runtime->silence_filled;
+ if (runtime->state == SNDRV_PCM_STATE_DRAINING) {
+ snd_pcm_uframes_t slack = runtime->rate / 10;
+ snd_pcm_sframes_t threshold;
+ snd_pcm_uframes_t ps = runtime->period_size;
+ snd_pcm_uframes_t silence_size = ps;
+ // Round down to start of next period. This is disabled
+ // if the period count is not integer.
+ if (runtime->periods * ps == runtime->buffer_size)
+ silence_size = ps - (appl_ptr + ps - 1) % ps - 1;
+ // Add overshoot to accomodate FIFOs and IRQ delays.
+ // The default 1/10th secs is very generous. But more than one
+ // period doesn't make sense; the driver would set the minimum
+ // period size accordingly.
+ slack = min(slack, ps);
+ silence_size += slack;
+ // This catches the periods == 1 case.
+ silence_size = min(silence_size, runtime->buffer_size);
+
+ threshold = ps + slack;
+ if (noise_dist >= threshold)
+ return;
+ frames = threshold - noise_dist;
+ if (frames > silence_size)
+ frames = silence_size;
+
+ goto avoid_reindent;
+ }
if (noise_dist >= (snd_pcm_sframes_t) runtime->silence_threshold)
return;
frames = runtime->silence_threshold - noise_dist;
@@ -118,6 +150,7 @@ void snd_pcm_playback_silence(struct snd_pcm_substream *substream, snd_pcm_ufram
*/
frames = runtime->buffer_size - runtime->silence_filled;
}
+avoid_reindent:
if (snd_BUG_ON(frames > runtime->buffer_size))
return;
if (frames == 0)
@@ -465,7 +498,7 @@ static int snd_pcm_update_hw_ptr0(struct snd_pcm_substream *substream,
}
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
- runtime->silence_size > 0)
+ (runtime->silence_size > 0 || runtime->state == SNDRV_PCM_STATE_DRAINING))
snd_pcm_playback_silence(substream, new_hw_ptr);
if (in_interrupt) {
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 39a65d1415ab..913dae449ba0 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -1454,7 +1454,7 @@ static void snd_pcm_post_start(struct snd_pcm_substream *substream,
runtime->rate;
__snd_pcm_set_state(runtime, state);
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
- runtime->silence_size > 0)
+ (runtime->silence_size > 0 || state == SNDRV_PCM_STATE_DRAINING))
snd_pcm_playback_silence(substream, ULONG_MAX);
snd_pcm_timer_notify(substream, SNDRV_TIMER_EVENT_MSTART);
}
@@ -2045,6 +2045,7 @@ static int snd_pcm_do_drain_init(struct snd_pcm_substream *substream,
break;
case SNDRV_PCM_STATE_RUNNING:
__snd_pcm_set_state(runtime, SNDRV_PCM_STATE_DRAINING);
+ snd_pcm_playback_silence(substream, ULONG_MAX);
break;
case SNDRV_PCM_STATE_XRUN:
__snd_pcm_set_state(runtime, SNDRV_PCM_STATE_SETUP);
--
2.40.0.152.g15d061e6df
