Use a bitstream filter for converting the extradata syntax when generating an SDP.

This allows to generate correct SDPs for H.264 video in "MP4 syntax".

Originally committed as revision 23572 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/sdp.c

@@ -149,6 +149,19 @@ static char *extradata2psets(AVCodecContext *c)
 
         return NULL;
     }
+    if (c->extradata[0] == 1) {
+        uint8_t *dummy_p;
+        int dummy_int;
+        AVBitStreamFilterContext *bsfc= av_bitstream_filter_init("h264_mp4toannexb");
+
+        if (!bsfc) {
+            av_log(c, AV_LOG_ERROR, "Cannot open the h264_mp4toannexb BSF!\n");
+
+            return NULL;
+        }
+        av_bitstream_filter_filter(bsfc, c, NULL, &dummy_p, &dummy_int, NULL, 0, 0);
+        av_bitstream_filter_close(bsfc);
+    }
 
     psets = av_mallocz(MAX_PSET_SIZE);
     if (psets == NULL) {