[wip] mpv patch to enable playback of mpegts with mid-stream pid changes, like https://s3.amazonaws.com/tmm1/pmt-version-change.ts

mpv-mpegts-pid-switch.diff

diff --git a/demux/demux.c b/demux/demux.c
index 0c45083e2d..61e45be90b 100644
--- a/demux/demux.c
+++ b/demux/demux.c
@@ -268,6 +268,7 @@ struct sh_stream *demux_alloc_sh_stream(enum stream_type type)
         .index = -1,
         .ff_index = -1,     // may be overwritten by demuxer
         .demuxer_id = -1,   // ... same
+        .program_num = -1,  // ...
         .codec = talloc_zero(sh, struct mp_codec_params),
         .tags = talloc_zero(sh, struct mp_tags),
     };
@@ -1505,6 +1506,25 @@ void demuxer_select_track(struct demuxer *demuxer, struct sh_stream *stream,
     pthread_mutex_unlock(&in->lock);
 }
 
+void demuxer_select_track2(struct demuxer *demuxer, struct sh_stream *stream,
+                          double ref_pts, bool selected)
+{
+    struct demux_internal *in = demuxer->in;
+    pthread_mutex_lock(&in->lock);
+    // don't flush buffers if stream is already selected / unselected
+    if (stream->ds->selected != selected) {
+        stream->ds->selected = selected;
+        ds_flush(stream->ds);
+        in->tracks_switched = true;
+        if (in->threading) {
+            pthread_cond_signal(&in->wakeup);
+        } else {
+            execute_trackswitch(in);
+        }
+    }
+    pthread_mutex_unlock(&in->lock);
+}
+
 void demux_set_stream_autoselect(struct demuxer *demuxer, bool autoselect)
 {
     assert(!demuxer->in->threading); // laziness
diff --git a/demux/demux.h b/demux/demux.h
index 8a1da4e400..650eaaf7b1 100644
--- a/demux/demux.h
+++ b/demux/demux.h
@@ -272,6 +272,8 @@ void demux_set_ts_offset(struct demuxer *demuxer, double offset);
 
 int demux_control(struct demuxer *demuxer, int cmd, void *arg);
 
+void demuxer_select_track2(struct demuxer *demuxer, struct sh_stream *stream,
+                          double ref_pts, bool selected);
 void demuxer_select_track(struct demuxer *demuxer, struct sh_stream *stream,
                           double ref_pts, bool selected);
 void demux_set_stream_autoselect(struct demuxer *demuxer, bool autoselect);
diff --git a/demux/demux_lavf.c b/demux/demux_lavf.c
index 8371985419..cf4e30381d 100644
--- a/demux/demux_lavf.c
+++ b/demux/demux_lavf.c
@@ -183,6 +183,12 @@ static const struct format_hack format_hacks[] = {
     {0}
 };
 
+typedef struct {
+    int num;
+    int pcr_pid;
+    unsigned int nb_stream_indexes;
+} lavf_program_t;
+
 typedef struct lavf_priv {
     struct stream *stream;
     bool own_stream;
@@ -200,6 +206,9 @@ typedef struct lavf_priv {
     char *mime_type;
     double seek_delay;
 
+    lavf_program_t program;
+    struct sh_stream *video_stream;
+
     struct demux_lavf_opts *opts;
     double mf_fps;
 } lavf_priv_t;
@@ -551,6 +560,15 @@ static void select_tracks(struct demuxer *demuxer, int start)
         bool selected = stream && demux_stream_is_selected(stream) &&
                         !stream->attached_picture;
         st->discard = selected ? AVDISCARD_DEFAULT : AVDISCARD_ALL;
+
+        if (stream && stream->type == STREAM_VIDEO) {
+            if (selected) {
+                priv->program.num = stream->program_num;
+                priv->video_stream = stream;
+            }
+            if (!selected && stream->program_num == priv->program.num)
+                st->discard = AVDISCARD_DEFAULT;
+        }
     }
 }
 
@@ -700,6 +718,9 @@ static void handle_new_stream(demuxer_t *demuxer, int i)
     MP_TARRAY_APPEND(priv, priv->streams, priv->num_streams, sh);
 
     if (sh) {
+        AVProgram *program = av_find_program_from_stream(priv->avfc, NULL, st->index);
+        if (program)
+            sh->program_num = program->program_num;
         sh->ff_index = st->index;
         sh->codec->codec = mp_codec_from_av_codec_id(codec->codec_id);
         sh->codec->codec_tag = codec->codec_tag;
@@ -736,6 +757,70 @@ static void handle_new_stream(demuxer_t *demuxer, int i)
     select_tracks(demuxer, i);
 }
 
+static void detect_program_changes(demuxer_t *demuxer)
+{
+    lavf_priv_t *priv = demuxer->priv;
+    struct sh_stream *old_stream = NULL, *new_stream = NULL;
+    AVProgram *program;
+    int i, j;
+
+    if (priv->avfc->nb_programs < 1)
+        return;
+    if (priv->program.num == 0)
+        return;
+
+    for (i = 0; i < priv->avfc->nb_programs; i++)
+        if (priv->avfc->programs[i]->id == priv->program.num)
+            break;
+    if (i == priv->avfc->nb_programs)
+        return;
+    program = priv->avfc->programs[i];
+
+    // skip unless program changed
+    if (program->pcr_pid == priv->program.pcr_pid &&
+        program->nb_stream_indexes == priv->program.nb_stream_indexes) {
+        return;
+    }
+
+    MP_VERBOSE(demuxer, "Detected program change for %d: "
+                        "(pcr=%d,nb=%d) -> (pcr=%d,nb=%d) \n",
+               program->program_num,
+               priv->program.pcr_pid, priv->program.nb_stream_indexes,
+               program->pcr_pid, program->nb_stream_indexes);
+
+    priv->program = (lavf_program_t){
+        .num = program->program_num,
+        .pcr_pid = program->pcr_pid,
+        .nb_stream_indexes = program->nb_stream_indexes,
+    };
+
+    for (i = 0; i < priv->num_streams; i++) {
+        struct sh_stream *stream = priv->streams[i];
+        if (!stream || stream->type != STREAM_AUDIO)
+            continue;
+
+        int found = 0;
+        for (j = 0; j < program->nb_stream_indexes; j++) {
+            if (program->stream_index[j] == stream->ff_index) {
+                found = 1;
+                break;
+            }
+        }
+
+        if (found) {
+            if (!new_stream) new_stream = stream;
+        } else if (demux_stream_is_selected(stream)) {
+            old_stream = stream;
+        }
+    }
+
+    if (old_stream && new_stream) {
+        MP_VERBOSE(demuxer, "Switching audio from %d to %d\n", old_stream->index, new_stream->index);
+        demuxer_select_track(demuxer, old_stream, MP_NOPTS_VALUE, false);
+        demuxer_select_track2(demuxer, new_stream, MP_NOPTS_VALUE, true);
+    }
+}
+
 // Add any new streams that might have been added
 static void add_new_streams(demuxer_t *demuxer)
 {
@@ -952,12 +1037,19 @@ static int demux_lavf_fill_buffer(demuxer_t *demux)
     }
 
     add_new_streams(demux);
+    detect_program_changes(demux);
     update_metadata(demux, pkt);
 
     assert(pkt->stream_index >= 0 && pkt->stream_index < priv->num_streams);
     struct sh_stream *stream = priv->streams[pkt->stream_index];
     AVStream *st = priv->avfc->streams[pkt->stream_index];
 
+    if (stream->type == STREAM_VIDEO &&
+        stream != priv->video_stream &&
+        priv->video_stream &&
+        priv->program.num == stream->program_num)
+        stream = priv->video_stream;
+
     if (!demux_stream_is_selected(stream)) {
         av_packet_unref(pkt);
         return 1; // don't signal EOF if skipping a packet
diff --git a/demux/stheader.h b/demux/stheader.h
index 26c1246d66..7280074605 100644
--- a/demux/stheader.h
+++ b/demux/stheader.h
@@ -41,6 +41,7 @@ struct sh_stream {
 
     struct mp_codec_params *codec;
 
+    int program_num;
     char *title;
     char *lang;                 // language code
     bool default_track;         // container default track flag