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[client] audio: tune target latency

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The target latency is now based upon the device maximum period size
(which may be configured by setting the `PIPEWIRE_LATENCY` environment
variable if using PipeWire), with some allowance for timing jitter from
Spice and the audio device.

PipeWire can change the period size dynamically at any time which must be
taken into account when selecting the target latency to avoid underruns
when the period size is increased. This is explained in detail within the
commit body.
This commit is contained in:
Chris Spencer
2022-01-29 19:23:28 +00:00
committed by Geoffrey McRae
parent ca29fe80a6
commit e1e60fdaa6
4 changed files with 131 additions and 46 deletions
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73
client/audiodevs/PipeWire/pipewire.c
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@@ -104,16 +104,6 @@ static void pipewire_onPlaybackProcess(void * userdata)
if (pw.playback.rateMatch && pw.playback.rateMatch->size > 0)
frames = min(frames, pw.playback.rateMatch->size);
// stream was started just to get the initial period size
if (pw.playback.startFrames == -1)
{
pw.playback.startFrames = frames;
pw_stream_set_active(pw.playback.stream, false);
sbuf->datas[0].chunk->size = 0;
pw_stream_queue_buffer(pw.playback.stream, pbuf);
return;
}
frames = pw.playback.pullFn(dst, frames);
if (!frames)
{
@@ -189,7 +179,7 @@ static void pipewire_playbackStopStream(void)
}
static void pipewire_playbackSetup(int channels, int sampleRate,
LG_AudioPullFn pullFn)
int * maxPeriodFrames, LG_AudioPullFn pullFn)
{
const struct spa_pod * params[1];
uint8_t buffer[1024];
@@ -205,38 +195,71 @@ static void pipewire_playbackSetup(int channels, int sampleRate,
if (pw.playback.stream &&
pw.playback.channels == channels &&
pw.playback.sampleRate == sampleRate)
{
*maxPeriodFrames = pw.playback.startFrames;
return;
}
pipewire_playbackStopStream();
int bufferFrames = sampleRate / 10;
int maxLatencyFrames = bufferFrames / 2;
char maxLatency[32];
snprintf(maxLatency, sizeof(maxLatency), "%d/%d", maxLatencyFrames,
sampleRate);
int defaultLatencyFrames = 2048;
char defaultNodeLatency[32];
snprintf(defaultNodeLatency, sizeof(defaultNodeLatency), "%d/%d",
defaultLatencyFrames, sampleRate);
pw.playback.channels = channels;
pw.playback.sampleRate = sampleRate;
pw.playback.stride = sizeof(float) * channels;
pw.playback.pullFn = pullFn;
pw.playback.startFrames = -1;
pw_thread_loop_lock(pw.thread);
pw.playback.stream = pw_stream_new_simple(
pw.loop,
"Looking Glass",
pw_properties_new(
PW_KEY_NODE_NAME , "Looking Glass",
PW_KEY_MEDIA_TYPE , "Audio",
PW_KEY_MEDIA_CATEGORY , "Playback",
PW_KEY_MEDIA_ROLE , "Music",
PW_KEY_NODE_MAX_LATENCY, maxLatency,
PW_KEY_NODE_NAME , "Looking Glass",
PW_KEY_MEDIA_TYPE , "Audio",
PW_KEY_MEDIA_CATEGORY, "Playback",
PW_KEY_MEDIA_ROLE , "Music",
PW_KEY_NODE_LATENCY , defaultNodeLatency,
NULL
),
&events,
NULL
);
// The user can override the default node latency with the PIPEWIRE_LATENCY
// environment variable, so get the actual node latency value from the stream.
// The actual quantum size may be lower than this value depending on what else
// is using the audio device, but we can treat this value as a maximum
const struct pw_properties * properties =
pw_stream_get_properties(pw.playback.stream);
const char *actualNodeLatency =
pw_properties_get(properties, PW_KEY_NODE_LATENCY);
DEBUG_ASSERT(actualNodeLatency != NULL);
unsigned num, denom;
if (sscanf(actualNodeLatency, "%u/%u", &num, &denom) != 2 ||
denom != sampleRate)
{
DEBUG_WARN(
"PIPEWIRE_LATENCY value '%s' is invalid or does not match stream sample "
"rate; defaulting to %d/%d", actualNodeLatency, defaultLatencyFrames,
sampleRate);
struct spa_dict_item items[] = {
{ PW_KEY_NODE_LATENCY, defaultNodeLatency }
};
pw_stream_update_properties(pw.playback.stream,
&SPA_DICT_INIT_ARRAY(items));
pw.playback.startFrames = defaultLatencyFrames;
}
else
pw.playback.startFrames = num;
*maxPeriodFrames = pw.playback.startFrames;
if (!pw.playback.stream)
{
pw_thread_loop_unlock(pw.thread);
@@ -257,13 +280,11 @@ static void pipewire_playbackSetup(int channels, int sampleRate,
PW_ID_ANY,
PW_STREAM_FLAG_AUTOCONNECT |
PW_STREAM_FLAG_MAP_BUFFERS |
PW_STREAM_FLAG_RT_PROCESS,
PW_STREAM_FLAG_RT_PROCESS |
PW_STREAM_FLAG_INACTIVE,
params, 1);
pw_thread_loop_unlock(pw.thread);
while(pw.playback.startFrames == -1)
pw_thread_loop_wait(pw.thread);
}
static bool pipewire_playbackStart(int framesBuffered)