lavf/rtpdec: Constify several pointers.

Fixes two warnings:
libavformat/rtpdec.c:155:20: warning: return discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]
libavformat/rtpdec.c:168:20: warning: return discards 'const' qualifier from pointer target type [-Wdiscarded-qualifiers]

libavformat/rdt.c

@@ -53,7 +53,7 @@ struct RDTDemuxContext {
 
 RDTDemuxContext *
 ff_rdt_parse_open(AVFormatContext *ic, int first_stream_of_set_idx,
-                  void *priv_data, RTPDynamicProtocolHandler *handler)
+                  void *priv_data, const RTPDynamicProtocolHandler *handler)
 {
     RDTDemuxContext *s = av_mallocz(sizeof(RDTDemuxContext));
     if (!s)

libavformat/rdt.h

@@ -41,7 +41,7 @@ typedef struct RDTDemuxContext RDTDemuxContext;
 RDTDemuxContext *ff_rdt_parse_open(AVFormatContext *ic,
                                    int first_stream_of_set_idx,
                                    void *priv_data,
-                                   RTPDynamicProtocolHandler *handler);
+                                   const RTPDynamicProtocolHandler *handler);
 void ff_rdt_parse_close(RDTDemuxContext *s);
 
 /**

libavformat/rtpdec.c

@@ -143,7 +143,7 @@ const RTPDynamicProtocolHandler *ff_rtp_handler_iterate(void **opaque)
     return r;
 }
 
-RTPDynamicProtocolHandler *ff_rtp_handler_find_by_name(const char *name,
+const RTPDynamicProtocolHandler *ff_rtp_handler_find_by_name(const char *name,
                                                        enum AVMediaType codec_type)
 {
     void *i = 0;
@@ -157,7 +157,7 @@ RTPDynamicProtocolHandler *ff_rtp_handler_find_by_name(const char *name,
     return NULL;
 }
 
-RTPDynamicProtocolHandler *ff_rtp_handler_find_by_id(int id,
+const RTPDynamicProtocolHandler *ff_rtp_handler_find_by_id(int id,
                                                      enum AVMediaType codec_type)
 {
     void *i = 0;
@@ -572,7 +572,7 @@ RTPDemuxContext *ff_rtp_parse_open(AVFormatContext *s1, AVStream *st,
 }
 
 void ff_rtp_parse_set_dynamic_protocol(RTPDemuxContext *s, PayloadContext *ctx,
-                                       RTPDynamicProtocolHandler *handler)
+                                       const RTPDynamicProtocolHandler *handler)
 {
     s->dynamic_protocol_context = ctx;
     s->handler                  = handler;

libavformat/rtpdec.h

@@ -43,7 +43,7 @@ typedef struct RTPDemuxContext RTPDemuxContext;
 RTPDemuxContext *ff_rtp_parse_open(AVFormatContext *s1, AVStream *st,
                                    int payload_type, int queue_size);
 void ff_rtp_parse_set_dynamic_protocol(RTPDemuxContext *s, PayloadContext *ctx,
-                                       RTPDynamicProtocolHandler *handler);
+                                       const RTPDynamicProtocolHandler *handler);
 void ff_rtp_parse_set_crypto(RTPDemuxContext *s, const char *suite,
                              const char *params);
 int ff_rtp_parse_packet(RTPDemuxContext *s, AVPacket *pkt,
@@ -208,7 +208,7 @@ const RTPDynamicProtocolHandler *ff_rtp_handler_iterate(void **opaque);
  * @param name name of the requested rtp dynamic protocol handler
  * @return A rtp dynamic protocol handler if one was found, NULL otherwise.
  */
-RTPDynamicProtocolHandler *ff_rtp_handler_find_by_name(const char *name,
+const RTPDynamicProtocolHandler *ff_rtp_handler_find_by_name(const char *name,
                                                   enum AVMediaType codec_type);
 /**
  * Find a registered rtp dynamic protocol handler with a matching codec ID.
@@ -216,7 +216,7 @@ RTPDynamicProtocolHandler *ff_rtp_handler_find_by_name(const char *name,
  * @param id AVCodecID of the requested rtp dynamic protocol handler.
  * @return A rtp dynamic protocol handler if one was found, NULL otherwise.
  */
-RTPDynamicProtocolHandler *ff_rtp_handler_find_by_id(int id,
+const RTPDynamicProtocolHandler *ff_rtp_handler_find_by_id(int id,
                                                 enum AVMediaType codec_type);
 
 /* from rtsp.c, but used by rtp dynamic protocol handlers. */

libavformat/rtsp.c

@@ -211,7 +211,7 @@ static int get_sockaddr(AVFormatContext *s,
 }
 
 #if CONFIG_RTPDEC
-static void init_rtp_handler(RTPDynamicProtocolHandler *handler,
+static void init_rtp_handler(const RTPDynamicProtocolHandler *handler,
                              RTSPStream *rtsp_st, AVStream *st)
 {
     AVCodecParameters *par = st ? st->codecpar : NULL;
@@ -271,7 +271,7 @@ static int sdp_parse_rtpmap(AVFormatContext *s,
     }
 
     if (par->codec_id == AV_CODEC_ID_NONE) {
-        RTPDynamicProtocolHandler *handler =
+        const RTPDynamicProtocolHandler *handler =
             ff_rtp_handler_find_by_name(buf, par->codec_type);
         init_rtp_handler(handler, rtsp_st, st);
         /* If no dynamic handler was found, check with the list of standard
@@ -495,7 +495,7 @@ static void sdp_parse_line(AVFormatContext *s, SDPParseState *s1,
                 if (CONFIG_RTPDEC && !rt->ts)
                     rt->ts = avpriv_mpegts_parse_open(s);
             } else {
-                RTPDynamicProtocolHandler *handler;
+                const RTPDynamicProtocolHandler *handler;
                 handler = ff_rtp_handler_find_by_id(
                               rtsp_st->sdp_payload_type, AVMEDIA_TYPE_DATA);
                 init_rtp_handler(handler, rtsp_st, NULL);
@@ -513,7 +513,7 @@ static void sdp_parse_line(AVFormatContext *s, SDPParseState *s1,
             rtsp_st->stream_index = st->index;
             st->codecpar->codec_type = codec_type;
             if (rtsp_st->sdp_payload_type < RTP_PT_PRIVATE) {
-                RTPDynamicProtocolHandler *handler;
+                const RTPDynamicProtocolHandler *handler;
                 /* if standard payload type, we can find the codec right now */
                 ff_rtp_get_codec_info(st->codecpar, rtsp_st->sdp_payload_type);
                 if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&

libavformat/rtsp.h

@@ -458,7 +458,7 @@ typedef struct RTSPStream {
     /** The following are used for dynamic protocols (rtpdec_*.c/rdt.c) */
     //@{
     /** handler structure */
-    RTPDynamicProtocolHandler *dynamic_handler;
+    const RTPDynamicProtocolHandler *dynamic_handler;
 
     /** private data associated with the dynamic protocol */
     PayloadContext *dynamic_protocol_context;