avformat/mpegts: use stream index based lookup with merge_pmt_versions if stream identifier matches multiple streams

Also make sure we are checking the old state of the streams because otherwise
some streams might already have the newly parsed stream identifiers which
corrupts matching.

Fixes streams having the same identifier mixed up on pmt version change.

Fixes ticket #9006.

Signed-off-by: Marton Balint <cus@passwd.hu>

libavformat/mpegts.c

@@ -107,11 +107,19 @@ struct MpegTSFilter {
     } u;
 };
 
-#define MAX_PIDS_PER_PROGRAM 64
+struct Stream {
+    int idx;
+    int stream_identifier;
+};
+
+#define MAX_STREAMS_PER_PROGRAM 128
+#define MAX_PIDS_PER_PROGRAM (MAX_STREAMS_PER_PROGRAM + 2)
 struct Program {
     unsigned int id; // program id/service id
     unsigned int nb_pids;
     unsigned int pids[MAX_PIDS_PER_PROGRAM];
+    unsigned int nb_streams;
+    struct Stream streams[MAX_STREAMS_PER_PROGRAM];
 
     /** have we found pmt for this program */
     int pmt_found;
@@ -291,6 +299,7 @@ static void clear_program(struct Program *p)
     if (!p)
         return;
     p->nb_pids = 0;
+    p->nb_streams = 0;
     p->pmt_found = 0;
 }
 
@@ -2193,25 +2202,20 @@ int ff_parse_mpeg2_descriptor(AVFormatContext *fc, AVStream *st, int stream_type
 }
 
 static AVStream *find_matching_stream(MpegTSContext *ts, int pid, unsigned int programid,
-                                      int stream_identifier, int pmt_stream_idx)
+                                      int stream_identifier, int pmt_stream_idx, struct Program *p)
 {
     AVFormatContext *s = ts->stream;
     int i;
     AVStream *found = NULL;
 
-    for (i = 0; i < s->nb_streams; i++) {
-        AVStream *st = s->streams[i];
-        if (st->program_num != programid)
-            continue;
-        if (stream_identifier != -1) { /* match based on "stream identifier descriptor" if present */
-            if (st->stream_identifier == stream_identifier+1) {
-                found = st;
-                break;
-            }
-        } else if (st->pmt_stream_idx == pmt_stream_idx) { /* match based on position within the PMT */
-            found = st;
-            break;
+    if (stream_identifier) { /* match based on "stream identifier descriptor" if present */
+        for (i = 0; i < p->nb_streams; i++) {
+            if (p->streams[i].stream_identifier == stream_identifier)
+                if (!found || pmt_stream_idx == i) /* fallback to idx based guess if multiple streams have the same identifier */
+                    found = s->streams[p->streams[i].idx];
         }
+    } else if (pmt_stream_idx < p->nb_streams) { /* match based on position within the PMT */
+        found = s->streams[p->streams[pmt_stream_idx].idx];
     }
 
     if (found) {
@@ -2270,6 +2274,7 @@ static void pmt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
 {
     MpegTSContext *ts = filter->u.section_filter.opaque;
     MpegTSSectionFilter *tssf = &filter->u.section_filter;
+    struct Program old_program;
     SectionHeader h1, *h = &h1;
     PESContext *pes;
     AVStream *st;
@@ -2303,6 +2308,10 @@ static void pmt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
         return;
 
     prg = get_program(ts, h->id);
+    if (prg)
+        old_program = *prg;
+    else
+        clear_program(&old_program);
 
     if (ts->skip_unknown_pmt && !prg)
         return;
@@ -2360,7 +2369,7 @@ static void pmt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
     if (prg)
         prg->pmt_found = 1;
 
-    for (i = 0; ; i++) {
+    for (i = 0; i < MAX_STREAMS_PER_PROGRAM; i++) {
         st = 0;
         pes = NULL;
         stream_type = get8(&p, p_end);
@@ -2373,14 +2382,13 @@ static void pmt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
         if (pid == ts->current_pid)
             goto out;
 
-        if (ts->merge_pmt_versions)
-            stream_identifier = parse_stream_identifier_desc(p, p_end);
+        stream_identifier = parse_stream_identifier_desc(p, p_end) + 1;
 
         /* 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, h->id, stream_identifier, i);
+                st = find_matching_stream(ts, pid, h->id, stream_identifier, i, &old_program);
                 if (st) {
                     pes->st = st;
                     pes->stream_type = stream_type;
@@ -2402,7 +2410,7 @@ static void pmt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
                 mpegts_close_filter(ts, ts->pids[pid]); // wrongly added sdt filter probably
             pes = add_pes_stream(ts, pid, pcr_pid);
             if (ts->merge_pmt_versions && pes && !pes->st) {
-                st = find_matching_stream(ts, pid, h->id, stream_identifier, i);
+                st = find_matching_stream(ts, pid, h->id, stream_identifier, i, &old_program);
                 if (st) {
                     pes->st = st;
                     pes->stream_type = stream_type;
@@ -2424,7 +2432,7 @@ static void pmt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
                 st = ts->stream->streams[idx];
             }
             if (ts->merge_pmt_versions && !st) {
-                st = find_matching_stream(ts, pid, h->id, stream_identifier, i);
+                st = find_matching_stream(ts, pid, h->id, stream_identifier, i, &old_program);
             }
             if (!st) {
                 st = avformat_new_stream(ts->stream, NULL);
@@ -2449,6 +2457,11 @@ static void pmt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
             mpegts_set_stream_info(st, pes, stream_type, prog_reg_desc);
 
         add_pid_to_program(prg, pid);
+        if (prg) {
+            prg->streams[i].idx = st->index;
+            prg->streams[i].stream_identifier = stream_identifier;
+            prg->nb_streams++;
+        }
 
         av_program_add_stream_index(ts->stream, h->id, st->index);