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module-rtp: add rate matching for the source

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correlate the timestamps against the graph clock and calculate a rate
correction. this smooths out the timestamps.
This commit is contained in:
Wim Taymans 2023-02-17 11:22:29 +01:00
parent aca5755c91
commit 8eaf46a678
1 changed files with 64 additions and 9 deletions
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69
src/modules/module-rtp-source.c
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@ -237,11 +237,15 @@ struct session {
struct spa_io_rate_match *rate_match;
struct spa_io_position *position;
struct spa_dll dll;
double corr;
uint32_t target_buffer;
float max_error;
unsigned first:1;
unsigned receiving:1;
unsigned direct_timestamp:1;
float last_timestamp;
float last_time;
};
static void session_touch(struct session *sess)
@ -409,16 +413,15 @@ static void process_midi(struct session *sess)
maxsize = d[0].maxsize;
/* we always use the graph position to select events, the receiver side is
* responsible for smoothing out the RTP timestamps to graph time */
duration = sess->position->clock.duration;
if (sess->position && sess->direct_timestamp)
if (sess->position)
timestamp = sess->position->clock.position;
else
timestamp = 0;
/* we copy events into the buffer based on the rtp timestamp + delay.
* With direct timestamp we lock them to the graph position. Otherwise
* we fill the current cycle with events we have. The first event offset
* might be wrong, in this case. */
/* we copy events into the buffer based on the rtp timestamp + delay. */
spa_pod_builder_init(&b, d[0].data, maxsize);
spa_pod_builder_push_sequence(&b, &f[0], 0);
@ -511,6 +514,16 @@ static int get_midi_size(uint8_t *p, uint32_t avail)
return size;
}
static double get_time(struct session *sess)
{
struct timespec ts;
double t;
clock_gettime(CLOCK_MONOTONIC, &ts);
t = sess->position->clock.position / (double) sess->position->clock.rate.denom;
t += (SPA_TIMESPEC_TO_NSEC(&ts) - sess->position->clock.nsec) / (double)SPA_NSEC_PER_SEC;
return t;
}
static void receive_midi(struct session *sess, uint8_t *packet,
uint32_t timestamp, uint32_t payload_offset, uint32_t plen)
{
@ -523,10 +536,51 @@ static void receive_midi(struct session *sess, uint8_t *packet,
uint32_t offs = payload_offset, len, end;
bool first = true;
if (sess->direct_timestamp) {
/* in direct timestamp we attach the RTP timestamp directly on the
* midi events and render them in the corresponding cycle */
if (!sess->have_sync) {
pw_log_info("sync to timestamp %u direct:%d", timestamp, sess->direct_timestamp);
pw_log_info("sync to timestamp %u/ direct:%d", timestamp,
sess->direct_timestamp);
sess->have_sync = true;
}
} else {
/* in non-direct timestamp mode, we relate the graph clock against
* the RTP timestamps */
double ts = timestamp / (float) sess->info.rate;
double t = get_time(sess);
double elapsed, estimated, diff;
/* the elapsed time between RTP timestamps */
elapsed = ts - sess->last_timestamp;
/* for that elapsed time, our clock should have advanced
* by this amount since the last estimation */
estimated = sess->last_time + elapsed * sess->corr;
/* calculate the diff between estimated and current clock time in
* samples */
diff = (estimated - t) * sess->info.rate;
/* no sync or we drifted too far, resync */
if (!sess->have_sync || fabs(diff) > sess->target_buffer) {
sess->corr = 1.0;
spa_dll_set_bw(&sess->dll, SPA_DLL_BW_MIN, 256, sess->info.rate);
pw_log_info("sync to timestamp %u/%f direct:%d", timestamp, t,
sess->direct_timestamp);
sess->have_sync = true;
} else {
/* update our new rate correction */
sess->corr = spa_dll_update(&sess->dll, diff);
/* our current time is now the estimated time */
t = estimated;
}
pw_log_debug("%f %f %f %f", t, estimated, diff, sess->corr);
timestamp = t * sess->info.rate;
sess->last_timestamp = ts;
sess->last_time = t;
}
filled = spa_ringbuffer_get_write_index(&sess->ring, &write);
if (filled > (int32_t)BUFFER_SIZE2)
@ -558,7 +612,7 @@ static void receive_midi(struct session *sess, uint8_t *packet,
else
offs += parse_varlen(&packet[offs], end - offs, &delta);
timestamp += delta;
timestamp += delta * sess->corr;
spa_pod_builder_control(&b, timestamp, SPA_CONTROL_Midi);
size = get_midi_size(&packet[offs], end - offs);
@ -946,6 +1000,7 @@ static int session_new(struct impl *impl, struct sdp_info *info)
spa_dll_init(&session->dll);
spa_dll_set_bw(&session->dll, SPA_DLL_BW_MIN, 128, info->rate);
session->corr = 1.0;
if (info->channelmap[0]) {
pw_properties_set(props, PW_KEY_NODE_CHANNELNAMES, info->channelmap);