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Fix: improve timestamp calculation for st20 st40 st41 #1224

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Fix: improve timestamp calculation for st20 st40 st41 #1224

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b3ca2ea
Fix RTP imestamp calculation for St40 and St41 in a same way as St30
tszumski Jul 28, 2025
7946156
Fix: Refactor pacing_first_pkt_time and update pacing_time_stamp to h…
tszumski Jul 29, 2025
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4 changes: 0 additions & 4 deletions lib/src/st2110/st_header.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1054,8 +1054,6 @@ struct st_tx_ancillary_session_pacing {
uint64_t cur_epochs; /* epoch of current frame */
/* timestamp for rtp header */
uint32_t rtp_time_stamp;
/* timestamp for pacing */
uint32_t pacing_time_stamp;
uint64_t cur_epoch_time;
double tsc_time_cursor; /* in ns, tsc time cursor for packet pacing */
/* ptp time may onward */
Expand Down Expand Up @@ -1224,8 +1222,6 @@ struct st_tx_fastmetadata_session_pacing {
uint64_t cur_epochs; /* epoch of current frame */
/* timestamp for rtp header */
uint32_t rtp_time_stamp;
/* timestamp for pacing */
uint32_t pacing_time_stamp;
uint64_t cur_epoch_time;
double tsc_time_cursor; /* in ns, tsc time cursor for packet pacing */
/* ptp time may onward */
Expand Down
18 changes: 13 additions & 5 deletions lib/src/st2110/st_tx_ancillary_session.c
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Expand Up @@ -260,7 +260,7 @@ static int tx_ancillary_session_sync_pacing(struct mtl_main_impl* impl,
bool sync, uint64_t required_tai,
bool second_field) {
struct st_tx_ancillary_session_pacing* pacing = &s->pacing;
double frame_time = pacing->frame_time;
long double frame_time = pacing->frame_time;
/* always use MTL_PORT_P for ptp now */
uint64_t ptp_time = mt_get_ptp_time(impl, MTL_PORT_P);
uint64_t next_epochs = pacing->cur_epochs + 1;
Expand Down Expand Up @@ -309,12 +309,20 @@ static int tx_ancillary_session_sync_pacing(struct mtl_main_impl* impl,
if (epochs < next_epochs) s->stat_epoch_onward += (next_epochs - epochs);

pacing->cur_epochs = epochs;
pacing->cur_epoch_time = tx_ancillary_pacing_time(pacing, epochs);
pacing->pacing_time_stamp = tx_ancillary_pacing_time_stamp(pacing, epochs);
pacing->rtp_time_stamp = pacing->pacing_time_stamp;

if (required_tai) {
pacing->cur_epoch_time = required_tai + frame_time;
pacing->rtp_time_stamp =
((uint64_t)((required_tai / frame_time) * pacing->frame_time_sampling) &
0xffffffff);
} else {
pacing->cur_epoch_time = tx_ancillary_pacing_time(pacing, epochs);
pacing->rtp_time_stamp = tx_ancillary_pacing_time_stamp(pacing, epochs);
}

pacing->tsc_time_cursor = (double)mt_get_tsc(impl) + to_epoch;
dbg("%s(%d), epochs %" PRIu64 " time_stamp %u time_cursor %f to_epoch %f\n", __func__,
s->idx, pacing->cur_epochs, pacing->pacing_time_stamp, pacing->tsc_time_cursor,
s->idx, pacing->cur_epochs, pacing->rtp_time_stamp, pacing->tsc_time_cursor,
to_epoch);

if (sync) {
Expand Down
18 changes: 13 additions & 5 deletions lib/src/st2110/st_tx_fastmetadata_session.c
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Expand Up @@ -260,7 +260,7 @@ static int tx_fastmetadata_session_sync_pacing(struct mtl_main_impl* impl,
bool sync, uint64_t required_tai,
bool second_field) {
struct st_tx_fastmetadata_session_pacing* pacing = &s->pacing;
double frame_time = pacing->frame_time;
long double frame_time = pacing->frame_time;
/* always use MTL_PORT_P for ptp now */
uint64_t ptp_time = mt_get_ptp_time(impl, MTL_PORT_P);
uint64_t next_epochs = pacing->cur_epochs + 1;
Expand Down Expand Up @@ -309,12 +309,20 @@ static int tx_fastmetadata_session_sync_pacing(struct mtl_main_impl* impl,
if (epochs < next_epochs) s->stat_epoch_onward += (next_epochs - epochs);

pacing->cur_epochs = epochs;
pacing->cur_epoch_time = tx_fastmetadata_pacing_time(pacing, epochs);
pacing->pacing_time_stamp = tx_fastmetadata_pacing_time_stamp(pacing, epochs);
pacing->rtp_time_stamp = pacing->pacing_time_stamp;

if (required_tai) {
pacing->cur_epoch_time = required_tai + frame_time;
pacing->rtp_time_stamp =
((uint64_t)((required_tai / frame_time) * pacing->frame_time_sampling) &
0xffffffff);
} else {
pacing->cur_epoch_time = tx_fastmetadata_pacing_time(pacing, epochs);
pacing->rtp_time_stamp = tx_fastmetadata_pacing_time_stamp(pacing, epochs);
}

pacing->tsc_time_cursor = (double)mt_get_tsc(impl) + to_epoch;
dbg("%s(%d), epochs %" PRIu64 " time_stamp %u time_cursor %f to_epoch %f\n", __func__,
s->idx, pacing->cur_epochs, pacing->pacing_time_stamp, pacing->tsc_time_cursor,
s->idx, pacing->cur_epochs, pacing->rtp_time_stamp, pacing->tsc_time_cursor,
to_epoch);

if (sync) {
Expand Down
66 changes: 44 additions & 22 deletions lib/src/st2110/st_tx_video_session.c
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Original file line number Diff line number Diff line change
Expand Up @@ -18,9 +18,8 @@ static inline double pacing_time(struct st_tx_video_pacing* pacing, uint64_t epo
return epochs * pacing->frame_time;
}

static inline double pacing_first_pkt_time(struct st_tx_video_pacing* pacing,
uint64_t epochs) {
return pacing_time(pacing, epochs) + pacing->tr_offset - (pacing->vrx * pacing->trs);
static inline double pacing_first_pkt_time(struct st_tx_video_pacing* pacing) {
return pacing->tr_offset - (pacing->vrx * pacing->trs);
}

/* pacing start time(warmup pkt if has warmup stage) of the frame */
Expand All @@ -33,25 +32,26 @@ static inline double pacing_start_time(struct st_tx_video_pacing* pacing,
/* time stamp on the first pkt video pkt(not the warmup) */
static inline uint32_t pacing_time_stamp(struct st_tx_video_session_impl* s,
struct st_tx_video_pacing* pacing,
uint64_t epochs) {
uint64_t epochs, uint64_t tai) {
uint64_t tmstamp64;
double time;
if (s->ops.flags & ST20_TX_FLAG_RTP_TIMESTAMP_EPOCH) {
/* the start of epoch */
time = pacing_first_pkt_time(pacing, epochs);
} else if (s->ops.flags & ST20_TX_FLAG_RTP_TIMESTAMP_FIRST_PKT) {
long double frame_time = pacing->frame_time;
double time = pacing_time(pacing, epochs);

if (s->ops.flags & ST20_TX_FLAG_USER_TIMESTAMP) {
time = tai;
} else if (s->ops.flags & ST20_TX_FLAG_RTP_TIMESTAMP_EPOCH) {
time += pacing_first_pkt_time(pacing);
} else { // if (s->ops.flags & ST20_TX_FLAG_RTP_TIMESTAMP_FIRST_PKT) {
/* the start of first pkt */
time = pacing_first_pkt_time(pacing, epochs);
if (pacing->warm_pkts) time -= 3 * pacing->trs; /* deviation for VRX */
} else if (s->ops.rtp_timestamp_delta_us) {
int32_t rtp_timestamp_delta_us = s->ops.rtp_timestamp_delta_us;
time = pacing_time(pacing, epochs) + (rtp_timestamp_delta_us * NS_PER_US);
} else {
/* default to the start of first pkt */
time = pacing_first_pkt_time(pacing, epochs);
time += pacing_first_pkt_time(pacing);
if (pacing->warm_pkts) time -= 3 * pacing->trs; /* deviation for VRX */
}
tmstamp64 = (time / pacing->frame_time) * pacing->frame_time_sampling;

if (s->ops.rtp_timestamp_delta_us) {
time += (s->ops.rtp_timestamp_delta_us * NS_PER_US);
}

tmstamp64 = (time / frame_time) * pacing->frame_time_sampling;
uint32_t tmstamp32 = tmstamp64;

return tmstamp32;
Expand Down Expand Up @@ -600,14 +600,16 @@ static int tv_sync_pacing(struct mtl_main_impl* impl, struct st_tx_video_session
int idx = s->idx;
struct st_tx_video_pacing* pacing = &s->pacing;
double frame_time = pacing->frame_time;
double to_epoch;
/* always use MTL_PORT_P for ptp now */
uint64_t ptp_time = mt_get_ptp_time(impl, MTL_PORT_P);
uint64_t next_epochs = pacing->cur_epochs + 1;
uint64_t epochs;
uint64_t ptp_epochs;
bool interlaced = s->ops.interlaced;

if (required_tai) {
uint64_t ptp_epochs = ptp_time / frame_time;
ptp_epochs = ptp_time / frame_time;
epochs = required_tai / frame_time;
dbg("%s(%d), required tai %" PRIu64 " ptp_epochs %" PRIu64 " epochs %" PRIu64 "\n",
__func__, idx, required_tai, ptp_epochs, epochs);
Expand Down Expand Up @@ -638,7 +640,22 @@ static int tv_sync_pacing(struct mtl_main_impl* impl, struct st_tx_video_session

/* epoch resolved */
double start_time_ptp = pacing_start_time(pacing, epochs);
double to_epoch = start_time_ptp - ptp_time;
if (required_tai) {
to_epoch = (double)required_tai - ptp_time;
if (to_epoch > NS_PER_S) {
dbg("%s(%d), required tai %" PRIu64 " ptp_epochs %" PRIu64 " epochs %" PRIu64 "\n",
__func__, s->idx, required_tai, ptp_epochs, epochs);
s->stat_error_user_timestamp++;
to_epoch = NS_PER_S; // do our best to slow down
}
if (to_epoch < 0) {
/* time bigger than the assigned epoch time */
to_epoch = 0; /* send asap */
}
} else {
to_epoch = start_time_ptp - ptp_time;
}

if (to_epoch < 0) {
/* time larger than the next assigned epoch time */
dbg("%s(%d), to_epoch %f, ptp epochs %" PRIu64 " cur_epochs %" PRIu64
Expand All @@ -665,8 +682,13 @@ static int tv_sync_pacing(struct mtl_main_impl* impl, struct st_tx_video_session
}
if (epochs < next_epochs) s->stat_epoch_onward += (next_epochs - epochs);
pacing->cur_epochs = epochs;
pacing->cur_epoch_time = pacing_time(pacing, epochs);
pacing->rtp_time_stamp = pacing_time_stamp(s, pacing, epochs);
if (s->ops.flags & ST20_TX_FLAG_USER_TIMESTAMP) {
pacing->cur_epoch_time = required_tai;
} else {
pacing->cur_epoch_time = pacing_time(pacing, epochs);
}

pacing->rtp_time_stamp = pacing_time_stamp(s, pacing, epochs, required_tai);
dbg("%s(%d), old time_cursor %fms\n", __func__, idx,
pacing->tsc_time_cursor / 1000 / 1000);
pacing->tsc_time_cursor = (double)mt_get_tsc(impl) + to_epoch;
Expand Down