ffmpeg: Do not fail if a demuxer and decoder use the same option identifer

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

ffmpeg.c

@@ -532,6 +532,15 @@ static void ffmpeg_cleanup(int ret)
     term_exit();
 }
 
+void remove_avoptions(AVDictionary **a, AVDictionary *b)
+{
+    AVDictionaryEntry *t = NULL;
+
+    while ((t = av_dict_get(b, "", t, AV_DICT_IGNORE_SUFFIX))) {
+        av_dict_set(a, t->key, NULL, AV_DICT_MATCH_CASE);
+    }
+}
+
 void assert_avoptions(AVDictionary *m)
 {
     AVDictionaryEntry *t;

ffmpeg.h

@@ -502,6 +502,7 @@ void show_usage(void);
 
 void opt_output_file(void *optctx, const char *filename);
 
+void remove_avoptions(AVDictionary **a, AVDictionary *b);
 void assert_avoptions(AVDictionary *m);
 
 int guess_input_channel_layout(InputStream *ist);

ffmpeg_opt.c

@@ -872,6 +872,7 @@ static int open_input_file(OptionsContext *o, const char *filename)
         print_error(filename, err);
         exit_program(1);
     }
+    remove_avoptions(&o->g->format_opts, o->g->codec_opts);
     assert_avoptions(o->g->format_opts);
 
     /* apply forced codec ids */