avformat: Mark argument in av_{i|o}format_next/ffurl_protocol_next as const

libavformat/avformat.h

@@ -1286,14 +1286,14 @@ int avformat_network_deinit(void);
  * if f is non-NULL, returns the next registered input format after f
  * or NULL if f is the last one.
  */
-AVInputFormat  *av_iformat_next(AVInputFormat  *f);
+AVInputFormat  *av_iformat_next(const AVInputFormat  *f);
 
 /**
  * If f is NULL, returns the first registered output format,
  * if f is non-NULL, returns the next registered output format after f
  * or NULL if f is the last one.
  */
-AVOutputFormat *av_oformat_next(AVOutputFormat *f);
+AVOutputFormat *av_oformat_next(const AVOutputFormat *f);
 
 /**
  * Allocate an AVFormatContext.

libavformat/avio.c

@@ -32,7 +32,7 @@
 
 static URLProtocol *first_protocol = NULL;
 
-URLProtocol *ffurl_protocol_next(URLProtocol *prev)
+URLProtocol *ffurl_protocol_next(const URLProtocol *prev)
 {
     return prev ? prev->next : first_protocol;
 }

libavformat/format.c

@@ -32,7 +32,7 @@ static AVInputFormat *first_iformat = NULL;
 /** head of registered output format linked list */
 static AVOutputFormat *first_oformat = NULL;
 
-AVInputFormat *av_iformat_next(AVInputFormat *f)
+AVInputFormat *av_iformat_next(const AVInputFormat *f)
 {
     if (f)
         return f->next;
@@ -40,7 +40,7 @@ AVInputFormat *av_iformat_next(AVInputFormat *f)
         return first_iformat;
 }
 
-AVOutputFormat *av_oformat_next(AVOutputFormat *f)
+AVOutputFormat *av_oformat_next(const AVOutputFormat *f)
 {
     if (f)
         return f->next;

libavformat/url.h

@@ -238,7 +238,7 @@ int ff_check_interrupt(AVIOInterruptCB *cb);
  *
  * @param prev result of the previous call to this functions or NULL.
  */
-URLProtocol *ffurl_protocol_next(URLProtocol *prev);
+URLProtocol *ffurl_protocol_next(const URLProtocol *prev);
 
 /* udp.c */
 int ff_udp_set_remote_url(URLContext *h, const char *uri);