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new ad53728984 avformat/mpegtsenc: add mpegts_pcr_pid option for separate
PCR PID
ad53728984 is described below
commit ad53728984531cebdb027e70e78d7165a6bdfe20
Author: shadowcaster3 <[email protected]>
AuthorDate: Fri Jul 31 01:20:26 2026 +0300
Commit: Marton Balint <[email protected]>
CommitDate: Fri Jul 31 06:25:59 2026 +0000
avformat/mpegtsenc: add mpegts_pcr_pid option for separate PCR PID
Add a new muxer option mpegts_pcr_pid that generates PCR on a dedicated
adaptation-field-only PID, separate from any elementary stream.
ISDB-T 1seg receivers require PCR on a standalone PID. When PCR shares
the video PID, these receivers acquire the service but refuse to decode
video and audio. This is standard practice in Japanese digital
terrestrial broadcasting per ARIB TR-B14.
When mpegts_pcr_pid is set to a valid PID value:
- PCR packets are generated as adaptation-field-only packets on the
specified PID at the interval set by pcr_period
- The video stream adaptation fields do not carry PCR flags
- The PMT PCR_PID field is set to the specified PID
When mpegts_pcr_pid is -1 (default): existing behavior is unchanged.
The existing mpegts_insert_pcr_only function is refactored into a
parameterized mpegts_insert_pcr_only_pid(s, pid, cc, discontinuity)
to avoid code duplication.
Fixes: https://code.ffmpeg.org/FFmpeg/FFmpeg/issues/23649
Signed-off-by: shadowcaster3 <[email protected]>
---
doc/muxers.texi | 6 ++++
libavformat/mpegtsenc.c | 73 ++++++++++++++++++++++++++++++++++++++++---------
2 files changed, 66 insertions(+), 13 deletions(-)
diff --git a/doc/muxers.texi b/doc/muxers.texi
index 5dc46ff291..99584e2b8d 100644
--- a/doc/muxers.texi
+++ b/doc/muxers.texi
@@ -3228,6 +3228,12 @@ Override the default PCR retransmission time in
milliseconds. Default is
20 ms is used for CBR streams, the highest multiple of the frame duration which
is less than 100 ms is used for VBR streams.
+@item mpegts_pcr_pid @var{integer}
+Set a separate PID for PCR packets. When set to a valid PID value, PCR is
+carried in adaptation-field-only packets on the specified PID, separate from
+the elementary stream PIDs. This is required for example by ARIB TR-B14.
+Default is @code{-1} which means PCR is placed on the elementary stream PIDs.
+
@item pat_period @var{duration}
Maximum time in seconds between PAT/PMT tables. Default is @code{0.1}.
diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
index 7f76883531..c7733f65e3 100644
--- a/libavformat/mpegtsenc.c
+++ b/libavformat/mpegtsenc.c
@@ -132,6 +132,10 @@ typedef struct MpegTSWrite {
uint8_t provider_name[256];
int omit_video_pes_length;
+
+ int pcr_pid; ///< user-specified separate PCR PID (-1 = use
video PID)
+ int64_t pcr_stream_pcr_period; ///< PCR period for the dedicated stream
+ int64_t pcr_stream_last_pcr; ///< last PCR sent on the dedicated PID
} MpegTSWrite;
/* a PES packet header is generated every DEFAULT_PES_HEADER_FREQ packets */
@@ -1088,7 +1092,14 @@ static void select_pcr_streams(AVFormatContext *s)
}
}
- if (pcr_st) {
+ if (ts->pcr_pid >= FIRST_OTHER_PID) {
+ int pcr_period_ms = ts->pcr_period_ms == -1 ? PCR_RETRANS_TIME :
ts->pcr_period_ms;
+ service->pcr_pid = ts->pcr_pid;
+ ts->pcr_stream_pcr_period = av_rescale(pcr_period_ms,
PCR_TIME_BASE, 1000);
+ ts->pcr_stream_last_pcr = ts->first_pcr -
ts->pcr_stream_pcr_period;
+ av_log(s, AV_LOG_VERBOSE, "service %i using separate PCR pid=%d,
pcr_period=%"PRId64"ms\n",
+ service->sid, ts->pcr_pid, (int64_t)pcr_period_ms);
+ } else if (pcr_st) {
MpegTSWriteStream *ts_st = pcr_st->priv_data;
service->pcr_pid = ts_st->pid;
enable_pcr_generation_for_stream(s, pcr_st);
@@ -1130,6 +1141,12 @@ static int mpegts_init(AVFormatContext *s)
if (s->max_delay < 0) /* Not set by the caller */
s->max_delay = 0;
+ if (ts->pcr_pid != -1 && ts->pcr_pid < FIRST_OTHER_PID) {
+ av_log(s, AV_LOG_ERROR, "Invalid PCR PID %d, must be in range [%d,
%d]\n",
+ ts->pcr_pid, FIRST_OTHER_PID, LAST_OTHER_PID);
+ return AVERROR(EINVAL);
+ }
+
// round up to a whole number of TS packets
ts->pes_payload_size = (ts->pes_payload_size + 14 + 183) / 184 * 184 - 14;
@@ -1378,25 +1395,23 @@ static void mpegts_insert_null_packet(AVFormatContext
*s)
}
/* Write a single transport stream packet with a PCR and no payload */
-static void mpegts_insert_pcr_only(AVFormatContext *s, AVStream *st)
+static void mpegts_insert_pcr_only_pid(AVFormatContext *s, int pid, int cc,
+ int discontinuity)
{
MpegTSWrite *ts = s->priv_data;
- MpegTSWriteStream *ts_st = st->priv_data;
uint8_t *q;
uint8_t buf[TS_PACKET_SIZE];
q = buf;
*q++ = SYNC_BYTE;
- *q++ = ts_st->pid >> 8;
- *q++ = ts_st->pid;
- *q++ = 0x20 | ts_st->cc; /* Adaptation only */
+ *q++ = (pid >> 8) & 0x1f;
+ *q++ = pid & 0xff;
+ *q++ = 0x20 | (cc & 0xf); /* Adaptation only */
/* Continuity Count field does not increment (see 13818-1 section 2.4.3.3)
*/
*q++ = TS_PACKET_SIZE - 5; /* Adaptation Field Length */
*q++ = 0x10; /* Adaptation flags: PCR present */
- if (ts_st->discontinuity) {
+ if (discontinuity)
q[-1] |= 0x80;
- ts_st->discontinuity = 0;
- }
/* PCR coded into 6 bytes */
q += write_pcr_bits(q, get_pcr(ts));
@@ -1406,6 +1421,13 @@ static void mpegts_insert_pcr_only(AVFormatContext *s,
AVStream *st)
write_packet(s, buf);
}
+static void mpegts_insert_pcr_only(AVFormatContext *s, AVStream *st)
+{
+ MpegTSWriteStream *ts_st = st->priv_data;
+ mpegts_insert_pcr_only_pid(s, ts_st->pid, ts_st->cc, ts_st->discontinuity);
+ ts_st->discontinuity = 0;
+}
+
static void write_pts(uint8_t *q, int fourbits, int64_t pts)
{
int val;
@@ -1534,7 +1556,15 @@ static void mpegts_write_pes(AVFormatContext *s,
AVStream *st,
if (ts->mux_rate > 1) {
/* Send PCR packets for all PCR streams if needed */
pcr = get_pcr(ts);
- if (pcr >= ts->next_pcr) {
+ if (ts->pcr_pid >= FIRST_OTHER_PID) {
+ /* Dedicated PCR PID: send adaptation-only packets on that PID
*/
+ if (pcr - ts->pcr_stream_last_pcr >=
ts->pcr_stream_pcr_period) {
+ ts->pcr_stream_last_pcr = FFMAX(pcr -
ts->pcr_stream_pcr_period, ts->pcr_stream_last_pcr + ts->pcr_stream_pcr_period);
+ mpegts_insert_pcr_only_pid(s, ts->pcr_pid, 0, 0);
+ pcr = get_pcr(ts);
+ }
+ ts->next_pcr = ts->pcr_stream_last_pcr +
ts->pcr_stream_pcr_period;
+ } else if (pcr >= ts->next_pcr) {
int64_t next_pcr = INT64_MAX;
for (int i = 0; i < s->nb_streams; i++) {
/* Make the current stream the last, because for that we
@@ -1559,13 +1589,28 @@ static void mpegts_write_pes(AVFormatContext *s,
AVStream *st,
}
if (dts != AV_NOPTS_VALUE && (dts - pcr /
SYSTEM_CLOCK_FREQUENCY_DIVISOR) > delay) {
/* pcr insert gets priority over null packet insert */
- if (write_pcr)
+ if (ts->pcr_pid >= FIRST_OTHER_PID) {
+ int64_t cur_pcr = get_pcr(ts);
+ if (cur_pcr - ts->pcr_stream_last_pcr >=
ts->pcr_stream_pcr_period) {
+ ts->pcr_stream_last_pcr = FFMAX(cur_pcr -
ts->pcr_stream_pcr_period, ts->pcr_stream_last_pcr + ts->pcr_stream_pcr_period);
+ mpegts_insert_pcr_only_pid(s, ts->pcr_pid, 0, 0);
+ } else {
+ mpegts_insert_null_packet(s);
+ }
+ } else if (write_pcr) {
mpegts_insert_pcr_only(s, st);
- else
+ } else {
mpegts_insert_null_packet(s);
+ }
/* recalculate write_pcr and possibly retransmit si_info */
continue;
}
+ } else if (ts->pcr_pid >= FIRST_OTHER_PID && pcr != AV_NOPTS_VALUE) {
+ /* VBR mode with dedicated PCR PID */
+ if (pcr - ts->pcr_stream_last_pcr >= ts->pcr_stream_pcr_period &&
is_start) {
+ ts->pcr_stream_last_pcr = FFMAX(pcr -
ts->pcr_stream_pcr_period, ts->pcr_stream_last_pcr + ts->pcr_stream_pcr_period);
+ mpegts_insert_pcr_only_pid(s, ts->pcr_pid, 0, 0);
+ }
} else if (ts_st->pcr_period && pcr != AV_NOPTS_VALUE) {
if (pcr - ts_st->last_pcr >= ts_st->pcr_period && is_start) {
ts_st->last_pcr = FFMAX(pcr - ts_st->pcr_period,
ts_st->last_pcr + ts_st->pcr_period);
@@ -1594,7 +1639,7 @@ static void mpegts_write_pes(AVFormatContext *s, AVStream
*st,
key && is_start && pts != AV_NOPTS_VALUE &&
!is_dvb_teletext /* adaptation+payload forbidden for teletext
(ETSI EN 300 472 V1.3.1 4.1) */) {
// set Random Access for key frames
- if (ts_st->pcr_period)
+ if (ts_st->pcr_period && ts->pcr_pid < FIRST_OTHER_PID)
write_pcr = 1;
set_af_flag(buf, 0x40);
q = get_ts_payload_start(buf);
@@ -2389,6 +2434,8 @@ static const AVOption options[] = {
OFFSET(omit_video_pes_length), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, ENC
},
{ "pcr_period", "PCR retransmission time in milliseconds",
OFFSET(pcr_period_ms), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, INT_MAX, ENC
},
+ { "mpegts_pcr_pid", "Set a separate PCR PID (-1 means PCR on video PID)",
+ OFFSET(pcr_pid), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, LAST_OTHER_PID, ENC
},
{ "pat_period", "PAT/PMT retransmission time limit in seconds",
OFFSET(pat_period_us), AV_OPT_TYPE_DURATION, { .i64 = PAT_RETRANS_TIME *
1000LL }, 0, INT64_MAX, ENC },
{ "sdt_period", "SDT retransmission time limit in seconds",
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