This patch refactors RDT packet header parsing so that it can be used in

rtsp.c to detect the ID of the packet source also in case of TCP streams.
This allows proper playback of RDT streams with multiple stream types, e.g.
audio + video. Accepted by LucaB in "RDT/Realmedia patches #2" thread on ML.

Originally committed as revision 15496 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/rdt.c

@@ -140,27 +140,25 @@ rdt_load_mdpr (rdt_data *rdt, AVStream *st, int rule_nr)
  * Actual data handling.
  */
 
-static int rdt_parse_header(struct RTPDemuxContext *s, const uint8_t *buf,
-                            int len, int *seq, uint32_t *timestamp, int *flags)
+int
+ff_rdt_parse_header(const uint8_t *buf, int len,
+                    int *sn, int *seq, int *rn, uint32_t *ts)
 {
-    rdt_data *rdt = s->dynamic_protocol_context;
-    int consumed = 0, sn;
+    int consumed = 10;
 
-    if (buf[0] < 0x40 || buf[0] > 0x42) {
+    if (len > 0 && (buf[0] < 0x40 || buf[0] > 0x42)) {
         buf += 9;
         len -= 9;
         consumed += 9;
     }
-    sn = (buf[0]>>1) & 0x1f;
-    *seq = AV_RB16(buf+1);
-    *timestamp = AV_RB32(buf+4);
-    if (!(buf[3] & 1) && (sn != rdt->prev_sn || *timestamp != rdt->prev_ts)) {
-        *flags |= PKT_FLAG_KEY;
-        rdt->prev_sn = sn;
-        rdt->prev_ts = *timestamp;
-    }
+    if (len < 10)
+        return -1;
+    if (sn)  *sn  = (buf[0]>>1) & 0x1f;
+    if (seq) *seq = AV_RB16(buf+1);
+    if (ts)  *ts  = AV_RB32(buf+4);
+    if (rn)  *rn  = buf[3] & 0x3f;
 
-    return consumed + 10;
+    return consumed;
 }
 
 /**< return 0 on packet, no more left, 1 on packet, 1 on partial packet... */
@@ -208,7 +206,8 @@ int
 ff_rdt_parse_packet(RTPDemuxContext *s, AVPacket *pkt,
                     const uint8_t *buf, int len)
 {
-    int seq, flags = 0;
+    rdt_data *rdt = s->dynamic_protocol_context;
+    int seq, flags = 0, rule, sn;
     uint32_t timestamp;
     int rv= 0;
 
@@ -221,9 +220,14 @@ ff_rdt_parse_packet(RTPDemuxContext *s, AVPacket *pkt,
 
     if (len < 12)
         return -1;
-    rv = rdt_parse_header(s, buf, len, &seq, &timestamp, &flags);
+    rv = ff_rdt_parse_header(buf, len, &sn, &seq, &rule, &timestamp);
     if (rv < 0)
         return rv;
+    if (!(rule & 1) && (sn != rdt->prev_sn || timestamp != rdt->prev_ts)) {
+        flags |= PKT_FLAG_KEY;
+        rdt->prev_sn = sn;
+        rdt->prev_ts = timestamp;
+    }
     buf += rv;
     len -= rv;
     s->seq = seq;

libavformat/rdt.h

@@ -56,6 +56,20 @@ void ff_rdt_subscribe_rule(char *cmd, int size,
 void ff_rdt_subscribe_rule2(RTPDemuxContext *s, char *cmd, int size,
                             int stream_nr, int rule_nr);
 
+/**
+ * Parse RDT-style packet header.
+ *
+ * @param buf input buffer
+ * @param len length of input buffer
+ * @param sn will be set to the stream number this packet belongs to
+ * @param seq will be set to the sequence number this packet belongs to
+ * @param rn will be set to the rule number this packet belongs to
+ * @param ts will be set to the timestamp of the packet
+ * @return the amount of bytes consumed, or <0 on error
+ */
+int ff_rdt_parse_header(const uint8_t *buf, int len,
+                        int *sn, int *seq, int *rn, uint32_t *ts);
+
 /**
  * Parse RDT-style packet data (header + media data).
  * Usage similar to rtp_parse_packet().

libavformat/rtsp.c

@@ -1265,6 +1265,9 @@ static int tcp_read_packet(AVFormatContext *s, RTSPStream **prtsp_st,
     ret = url_readbuf(rt->rtsp_hd, buf, len);
     if (ret != len)
         return -1;
+    if (rt->transport == RTSP_TRANSPORT_RDT &&
+        ff_rdt_parse_header(buf, len, &id, NULL, NULL, NULL) < 0)
+        return -1;
 
     /* find the matching stream */
     for(i = 0; i < rt->nb_rtsp_streams; i++) {