[FFmpeg-devel] [PATCH v2] avformat/mpegts: add merge_pmt_versions option
Aman Gupta
aman at tmm1.net
Wed May 16 02:12:10 EEST 2018
On Tue, May 15, 2018 at 12:23 PM, Aman Gupta <ffmpeg at tmm1.net> wrote:
> From: Aman Gupta <aman at tmm1.net>
>
> This new optional flag makes it easier to deal with mpegts
> samples where the PMT is updated and elementary streams move
> to different PIDs in the middle of playback.
>
> Previously, new AVStreams were created per PID, and it was up
> to the user to figure out which streams had migrated to a new PID
> (by iterating over the list of AVProgram and making guesses), and
> switch seamlessly to the new AVStream during playback.
>
> Transcoding or remuxing these streams with ffmpeg on the CLI was
> also quite painful, and the user would need to extract each set of
> PIDs into a separate file and then stitch them back together.
>
> With this new option, the mpegts demuxer will automatically detect
> PMT changes and feed data from the new PID to the original AVStream
> that was created for the orignal PID. For mpegts samples with
> stream_identifier_descriptor available, the unique ID is used to merge
> PIDs together. If the stream id is not available, the demuxer attempts
> to map PIDs based on their order and relation to the PCR pid.
>
> With this change, I am able to playback and transcode/remux these
> two samples which previously caused issues:
>
> https://tmm1.s3.amazonaws.com/pmt-version-change.ts
> https://kuroko.fushizen.eu/videos/pid_switch_sample.ts
>
> I also have another longer sample which contains multiple PMT
> changes, some of which change the ES pids and others which do not:
>
> https://tmm1.s3.amazonaws.com/multiple-pmt-change.ts
>
> Demuxing this sample with the new option shows several new log
> messages as the PMT changes are handled:
>
> [mpegts @ 0x7ffe18801200] detected PMT change (version=3/4,
> pcr_pid=0xf98/0xf9b)
> [mpegts @ 0x7ffe18801200] re-using existing video stream 0 (pid=0xf98)
> for new pid=0xf9b
> [mpegts @ 0x7ffe18801200] re-using existing audio stream 1 (pid=0xf99)
> for new pid=0xf9c
> [mpegts @ 0x7ffe18801200] re-using existing audio stream 2 (pid=0xf9a)
> for new pid=0xf9d
> [mpegts @ 0x7ffe18801200] detected PMT change (version=4/5,
> pcr_pid=0xf9b/0xfa9)
> [mpegts @ 0x7ffe18801200] re-using existing video stream 0 (pid=0xf98)
> for new pid=0xfa9
> [mpegts @ 0x7ffe18801200] re-using existing audio stream 1 (pid=0xf99)
> for new pid=0xfaa
> [mpegts @ 0x7ffe18801200] re-using existing audio stream 2 (pid=0xf9a)
> for new pid=0xfab
>
One issue I found with this patch: if you seek around aggressively
sometimes you may encounter a
new ES before a PMT, which causes it not to get merged in as expected. I'm
adding the following change
locally to fix the issue.
diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
index f16eae3235..3d8e9da66f 100644
--- a/libavformat/mpegts.c
+++ b/libavformat/mpegts.c
@@ -1077,6 +1077,8 @@ static int mpegts_push_data(MpegTSFilter *filter,
if (!pes->st) {
if (ts->skip_changes)
goto skip;
+ if (ts->merge_pmt_versions)
+ goto skip; /* wait for PMT to merge new stream
*/
if (!pes->st)
pes->st = avformat_new_stream(ts->stream,
NULL);
This has the side-effect that any pids not advertised in a PMT will be
ignored, but I think that's acceptable behavior
if you're opting-in to this new feature.
Aman
> Signed-off-by: Aman Gupta <aman at tmm1.net>
> ---
> doc/demuxers.texi | 4 ++
> libavformat/mpegts.c | 106 ++++++++++++++++++++++++++++++
> ++--
> tests/fate/mpegts.mak | 5 ++
> tests/ref/fate/mpegts-probe-pmt-merge | 32 ++++++++++
> 4 files changed, 143 insertions(+), 4 deletions(-)
> create mode 100644 tests/ref/fate/mpegts-probe-pmt-merge
>
> diff --git a/doc/demuxers.texi b/doc/demuxers.texi
> index e7c2abce57..2f7d7e0f3a 100644
> --- a/doc/demuxers.texi
> +++ b/doc/demuxers.texi
> @@ -552,6 +552,10 @@ Show the detected raw packet size, cannot be set by
> the user.
> Scan and combine all PMTs. The value is an integer with value from -1
> to 1 (-1 means automatic setting, 1 means enabled, 0 means
> disabled). Default value is -1.
> +
> + at item merge_pmt_versions
> +Re-use existing streams when a PMT's version is updated and elementary
> +streams move to different PIDs. Default value is 0.
> @end table
>
> @section mpjpeg
> diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
> index 27b1c30a44..f16eae3235 100644
> --- a/libavformat/mpegts.c
> +++ b/libavformat/mpegts.c
> @@ -84,6 +84,8 @@ typedef struct MpegTSSectionFilter {
> unsigned int end_of_section_reached : 1;
> SectionCallback *section_cb;
> void *opaque;
> + int orig_pcr_pid; /* pmt specific */
> + int last_pcr_pid;
> } MpegTSSectionFilter;
>
> struct MpegTSFilter {
> @@ -147,6 +149,7 @@ struct MpegTSContext {
> int scan_all_pmts;
>
> int resync_size;
> + int merge_pmt_versions;
>
> /******************************************/
> /* private mpegts data */
> @@ -172,6 +175,8 @@ static const AVOption options[] = {
> {.i64 = 0}, 0, 0, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_EXPORT |
> AV_OPT_FLAG_READONLY },
> {"scan_all_pmts", "scan and combine all PMTs",
> offsetof(MpegTSContext, scan_all_pmts), AV_OPT_TYPE_BOOL,
> {.i64 = -1}, -1, 1, AV_OPT_FLAG_DECODING_PARAM },
> + {"merge_pmt_versions", "re-use streams when PMT's version/pids
> change", offsetof(MpegTSContext, merge_pmt_versions), AV_OPT_TYPE_BOOL,
> + {.i64 = 0}, 0, 1, AV_OPT_FLAG_DECODING_PARAM },
> {"skip_changes", "skip changing / adding streams / programs",
> offsetof(MpegTSContext, skip_changes), AV_OPT_TYPE_BOOL,
> {.i64 = 0}, 0, 1, 0 },
> {"skip_clear", "skip clearing programs", offsetof(MpegTSContext,
> skip_clear), AV_OPT_TYPE_BOOL,
> @@ -1073,7 +1078,8 @@ static int mpegts_push_data(MpegTSFilter *filter,
> if (ts->skip_changes)
> goto skip;
>
> - pes->st = avformat_new_stream(ts->stream, NULL);
> + if (!pes->st)
> + pes->st = avformat_new_stream(ts->stream,
> NULL);
> if (!pes->st)
> return AVERROR(ENOMEM);
> pes->st->id = pes->pid;
> @@ -1983,6 +1989,69 @@ int ff_parse_mpeg2_descriptor(AVFormatContext *fc,
> AVStream *st, int stream_type
> return 0;
> }
>
> +static AVStream *find_matching_stream(MpegTSContext *ts, int pid,
> + int stream_id,
> + int pcr_pid, int orig_pcr_pid)
> +{
> + AVFormatContext *s = ts->stream;
> + int i, orig_pid = orig_pcr_pid + (pid - pcr_pid);
> + AVStream *found = NULL;
> +
> + for (i = 0; i < s->nb_streams; i++) {
> + AVStream *st = s->streams[i];
> + if (stream_id != -1) {
> + if (st->stream_identifier == stream_id+1) {
> + found = st;
> + break;
> + }
> + } else if (pcr_pid != orig_pcr_pid && st->id == orig_pid) {
> + found = st;
> + break;
> + }
> + }
> +
> + if (found) {
> + av_log(ts->stream, AV_LOG_DEBUG, "re-using existing %s stream %d
> (pid=0x%x) for new pid=0x%x\n",
> + av_get_media_type_string(found->codecpar->codec_type), i,
> found->id, pid);
> + }
> +
> + return found;
> +}
> +
> +static int parse_stream_identifier_desc(const uint8_t *p, const uint8_t
> *p_end)
> +{
> + const uint8_t **pp = &p;
> + const uint8_t *desc_list_end;
> + const uint8_t *desc_end;
> + int desc_list_len;
> + int desc_len, desc_tag;
> +
> + desc_list_len = get16(pp, p_end);
> + if (desc_list_len < 0)
> + return -1;
> + desc_list_len &= 0xfff;
> + desc_list_end = p + desc_list_len;
> + if (desc_list_end > p_end)
> + return -1;
> +
> + while (1) {
> + desc_tag = get8(pp, desc_list_end);
> + if (desc_tag < 0)
> + return -1;
> + desc_len = get8(pp, desc_list_end);
> + if (desc_len < 0)
> + return -1;
> + desc_end = *pp + desc_len;
> + if (desc_end > desc_list_end)
> + return -1;
> +
> + if (desc_tag == 0x52) {
> + return get8(pp, desc_end);
> + }
> + *pp = desc_end;
> + }
> +}
> +
> static int is_pes_stream(int stream_type, uint32_t prog_reg_desc)
> {
> return !(stream_type == 0x13 ||
> @@ -2000,6 +2069,8 @@ static void pmt_cb(MpegTSFilter *filter, const
> uint8_t *section, int section_len
> int program_info_length, pcr_pid, pid, stream_type;
> int desc_list_len;
> uint32_t prog_reg_desc = 0; /* registration descriptor */
> + int last_ver = tssf->last_ver;
> + int stream_id = -1;
>
> int mp4_descr_count = 0;
> Mp4Descr mp4_descr[MAX_MP4_DESCR_COUNT] = { { 0 } };
> @@ -2032,6 +2103,14 @@ static void pmt_cb(MpegTSFilter *filter, const
> uint8_t *section, int section_len
> pcr_pid &= 0x1fff;
> add_pid_to_pmt(ts, h->id, pcr_pid);
> set_pcr_pid(ts->stream, h->id, pcr_pid);
> + if (!tssf->orig_pcr_pid)
> + tssf->orig_pcr_pid = pcr_pid;
> +
> + if (last_ver != -1 && h->version != last_ver) {
> + av_log(ts->stream, AV_LOG_DEBUG, "detected PMT change
> (version=%d/%d, pcr_pid=0x%x/0x%x)\n",
> + last_ver, h->version, tssf->last_pcr_pid, pcr_pid);
> + }
> + tssf->last_pcr_pid = pcr_pid;
>
> av_log(ts->stream, AV_LOG_TRACE, "pcr_pid=0x%x\n", pcr_pid);
>
> @@ -2083,14 +2162,22 @@ static void pmt_cb(MpegTSFilter *filter, const
> uint8_t *section, int section_len
> if (pid < 0)
> goto out;
> pid &= 0x1fff;
> + stream_id = parse_stream_identifier_desc(p, p_end);
> if (pid == ts->current_pid)
> goto out;
>
> /* now create stream */
> if (ts->pids[pid] && ts->pids[pid]->type == MPEGTS_PES) {
> pes = ts->pids[pid]->u.pes_filter.opaque;
> + if (ts->merge_pmt_versions && !pes->st) {
> + st = find_matching_stream(ts, pid, stream_id, pcr_pid,
> tssf->orig_pcr_pid);
> + if (st) {
> + pes->st = st;
> + pes->stream_type = stream_type;
> + }
> + }
> if (!pes->st) {
> - pes->st = avformat_new_stream(pes->stream, NULL);
> + pes->st = avformat_new_stream(pes->stream, NULL);
> if (!pes->st)
> goto out;
> pes->st->id = pes->pid;
> @@ -2100,7 +2187,14 @@ static void pmt_cb(MpegTSFilter *filter, const
> uint8_t *section, int section_len
> if (ts->pids[pid])
> mpegts_close_filter(ts, ts->pids[pid]); // wrongly added
> sdt filter probably
> pes = add_pes_stream(ts, pid, pcr_pid);
> - if (pes) {
> + if (ts->merge_pmt_versions && pes && !pes->st) {
> + st = find_matching_stream(ts, pid, stream_id, pcr_pid,
> tssf->orig_pcr_pid);
> + if (st) {
> + pes->st = st;
> + pes->stream_type = stream_type;
> + }
> + }
> + if (pes && !pes->st) {
> st = avformat_new_stream(pes->stream, NULL);
> if (!st)
> goto out;
> @@ -2110,7 +2204,11 @@ static void pmt_cb(MpegTSFilter *filter, const
> uint8_t *section, int section_len
> int idx = ff_find_stream_index(ts->stream, pid);
> if (idx >= 0) {
> st = ts->stream->streams[idx];
> - } else {
> + }
> + if (ts->merge_pmt_versions && !st) {
> + st = find_matching_stream(ts, pid, stream_id, pcr_pid,
> tssf->orig_pcr_pid);
> + }
> + if (!st) {
> st = avformat_new_stream(ts->stream, NULL);
> if (!st)
> goto out;
> diff --git a/tests/fate/mpegts.mak b/tests/fate/mpegts.mak
> index 2b128492e0..bbcbfc47b2 100644
> --- a/tests/fate/mpegts.mak
> +++ b/tests/fate/mpegts.mak
> @@ -15,6 +15,11 @@ fate-mpegts-probe-program: SRC =
> $(TARGET_SAMPLES)/mpegts/loewe.ts
> fate-mpegts-probe-program: CMD = run $(PROBE_CODEC_NAME_COMMAND)
> -select_streams p:769:v:0 -i "$(SRC)"
>
>
> +FATE_MPEGTS_PROBE-$(call DEMDEC, MPEGTS) += fate-mpegts-probe-pmt-merge
> +fate-mpegts-probe-pmt-merge: SRC = $(TARGET_SAMPLES)/mpegts/pmtchange.ts
> +fate-mpegts-probe-pmt-merge: CMD = run $(PROBE_CODEC_NAME_COMMAND)
> -merge_pmt_versions 1 -i "$(SRC)"
> +
> +
> FATE_SAMPLES_FFPROBE += $(FATE_MPEGTS_PROBE-yes)
>
> fate-mpegts: $(FATE_MPEGTS_PROBE-yes)
> diff --git a/tests/ref/fate/mpegts-probe-pmt-merge
> b/tests/ref/fate/mpegts-probe-pmt-merge
> new file mode 100644
> index 0000000000..6e424af5d2
> --- /dev/null
> +++ b/tests/ref/fate/mpegts-probe-pmt-merge
> @@ -0,0 +1,32 @@
> +[PROGRAM]
> +[STREAM]
> +codec_name=ac3
> +[/STREAM]
> +[STREAM]
> +codec_name=ac3
> +[/STREAM]
> +[STREAM]
> +codec_name=ac3
> +[/STREAM]
> +[STREAM]
> +codec_name=mpeg2video
> +[/STREAM]
> +[STREAM]
> +codec_name=scte_35
> +[/STREAM]
> +[/PROGRAM]
> +[STREAM]
> +codec_name=ac3
> +[/STREAM]
> +[STREAM]
> +codec_name=ac3
> +[/STREAM]
> +[STREAM]
> +codec_name=ac3
> +[/STREAM]
> +[STREAM]
> +codec_name=mpeg2video
> +[/STREAM]
> +[STREAM]
> +codec_name=scte_35
> +[/STREAM]
> --
> 2.14.2
>
>
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