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| author | Oswald Buddenhagen <oswald.buddenhagen@gmx.de> | 2023-04-20 14:33:23 +0300 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2023-04-21 13:21:04 +0300 |
| commit | 9f656705c5faa18afb26d922cfc64f9fd103c38d (patch) | |
| tree | e3ded34bd862102da4bab1f1329e9a3f31e186a3 /Documentation/sound | |
| parent | 0d19bd4df75eee7df20377ffa2b62a4adedd19ff (diff) | |
| download | linux-9f656705c5faa18afb26d922cfc64f9fd103c38d.tar.xz | |
ALSA: pcm: rewrite snd_pcm_playback_silence()
The auto-silencer supports two modes: "thresholded" to fill up "just
enough", and "top-up" to fill up "as much as possible". The two modes
used rather distinct code paths, which this patch unifies. The only
remaining distinction is how much we actually want to fill.
This fixes a bug in thresholded mode, where we failed to use new_hw_ptr,
resulting in under-fill.
Top-up mode is now more well-behaved and much easier to understand in
corner cases.
This also updates comments in the proximity of silencing-related data
structures.
Signed-off-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
Reviewed-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230420113324.877164-1-oswald.buddenhagen@gmx.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'Documentation/sound')
| -rw-r--r-- | Documentation/sound/kernel-api/writing-an-alsa-driver.rst | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst index a368529e8ed3..e37d9dba320d 100644 --- a/Documentation/sound/kernel-api/writing-an-alsa-driver.rst +++ b/Documentation/sound/kernel-api/writing-an-alsa-driver.rst @@ -1577,14 +1577,19 @@ are the contents of this file: unsigned int period_step; unsigned int sleep_min; /* min ticks to sleep */ snd_pcm_uframes_t start_threshold; - snd_pcm_uframes_t stop_threshold; - snd_pcm_uframes_t silence_threshold; /* Silence filling happens when - noise is nearest than this */ - snd_pcm_uframes_t silence_size; /* Silence filling size */ + /* + * The following two thresholds alleviate playback buffer underruns; when + * hw_avail drops below the threshold, the respective action is triggered: + */ + snd_pcm_uframes_t stop_threshold; /* - stop playback */ + snd_pcm_uframes_t silence_threshold; /* - pre-fill buffer with silence */ + snd_pcm_uframes_t silence_size; /* max size of silence pre-fill; when >= boundary, + * fill played area with silence immediately */ snd_pcm_uframes_t boundary; /* pointers wrap point */ - snd_pcm_uframes_t silenced_start; - snd_pcm_uframes_t silenced_size; + /* internal data of auto-silencer */ + snd_pcm_uframes_t silence_start; /* starting pointer to silence area */ + snd_pcm_uframes_t silence_filled; /* size filled with silence */ snd_pcm_sync_id_t sync; /* hardware synchronization ID */ |