Pass the composition and ancillary ID for DVB subtitles via extradata instead

of sub_id, this allows detecting when that information is not available and
just decode everything.
In addition extradata is required for many codecs and thus in contrast to
sub_id generally already passed on by any programs using libav*.
Also ask for a sample if we encounter a stream with multiple/changing IDs.

Originally committed as revision 24238 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/dvbsubdec.c

@@ -358,8 +358,14 @@ static av_cold int dvbsub_init_decoder(AVCodecContext *avctx)
     int i, r, g, b, a = 0;
     DVBSubContext *ctx = avctx->priv_data;
 
-    ctx->composition_id = avctx->sub_id & 0xffff;
-    ctx->ancillary_id = avctx->sub_id >> 16;
+    if (!avctx->extradata || avctx->extradata_size != 4) {
+        av_log(avctx, AV_LOG_WARNING, "Invalid extradata, subtitle streams may be combined!\n");
+        ctx->composition_id = -1;
+        ctx->ancillary_id   = -1;
+    } else {
+        ctx->composition_id = AV_RB16(avctx->extradata);
+        ctx->ancillary_id   = AV_RB16(avctx->extradata + 2);
+    }
 
     default_clut.id = -1;
     default_clut.next = NULL;
@@ -1434,7 +1440,8 @@ static int dvbsub_decode(AVCodecContext *avctx,
         segment_length = AV_RB16(p);
         p += 2;
 
-        if (page_id == ctx->composition_id || page_id == ctx->ancillary_id) {
+        if (page_id == ctx->composition_id || page_id == ctx->ancillary_id ||
+            ctx->composition_id == -1 || ctx->ancillary_id == -1) {
             switch (segment_type) {
             case DVBSUB_PAGE_SEGMENT:
                 dvbsub_parse_page_segment(avctx, p, segment_length);

libavformat/mpegts.c

@@ -860,7 +860,6 @@ static void pmt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
     const uint8_t *p, *p_end, *desc_list_end, *desc_end;
     int program_info_length, pcr_pid, pid, stream_type;
     int desc_list_len, desc_len, desc_tag;
-    int comp_page, anc_page;
     char language[4];
     uint32_t prog_reg_desc = 0; /* registration descriptor */
 
@@ -981,9 +980,17 @@ static void pmt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
                 language[2] = get8(&p, desc_end);
                 language[3] = 0;
                 get8(&p, desc_end);
-                comp_page = get16(&p, desc_end);
-                anc_page = get16(&p, desc_end);
-                st->codec->sub_id = (anc_page << 16) | comp_page;
+                if (st->codec->extradata) {
+                    if (st->codec->extradata_size == 4 && memcmp(st->codec->extradata, p, 4))
+                        av_log_ask_for_sample(ts->stream, "DVB sub with multiple IDs\n");
+                } else {
+                    st->codec->extradata = av_malloc(4 + FF_INPUT_BUFFER_PADDING_SIZE);
+                    if (st->codec->extradata) {
+                        st->codec->extradata_size = 4;
+                        memcpy(st->codec->extradata, p, 4);
+                    }
+                }
+                p += 4;
                 av_metadata_set2(&st->metadata, "language", language, 0);
                 break;
             case 0x0a: /* ISO 639 language descriptor */