lavf: factor out freeing an AVStream

It will be needed in other functions.

libavformat/utils.c

@@ -2442,32 +2442,24 @@ int av_read_pause(AVFormatContext *s)
     return AVERROR(ENOSYS);
 }
 
-void avformat_free_context(AVFormatContext *s)
+static void free_stream(AVStream **pst)
 {
-    int i, j;
-    AVStream *st;
+    AVStream *st = *pst;
+    int i;
 
-    if (!s)
+    if (!st)
         return;
 
-    av_opt_free(s);
-    if (s->iformat && s->iformat->priv_class && s->priv_data)
-        av_opt_free(s->priv_data);
-
-    for (i = 0; i < s->nb_streams; i++) {
-        /* free all data in a stream component */
-        st = s->streams[i];
-
-        for (j = 0; j < st->nb_side_data; j++)
-            av_freep(&st->side_data[j].data);
+    for (i = 0; i < st->nb_side_data; i++)
+        av_freep(&st->side_data[i].data);
     av_freep(&st->side_data);
-        st->nb_side_data = 0;
 
-        if (st->parser) {
+    if (st->parser)
         av_parser_close(st->parser);
-        }
+
     if (st->attached_pic.data)
         av_packet_unref(&st->attached_pic);
+
     av_dict_free(&st->metadata);
     av_freep(&st->probe_data.buf);
     av_free(st->index_entries);
@@ -2476,8 +2468,24 @@ void avformat_free_context(AVFormatContext *s)
     av_free(st->codec);
     av_free(st->priv_data);
     av_free(st->info);
-        av_free(st);
-    }
+
+    av_freep(pst);
+}
+
+void avformat_free_context(AVFormatContext *s)
+{
+    int i;
+
+    if (!s)
+        return;
+
+    av_opt_free(s);
+    if (s->iformat && s->iformat->priv_class && s->priv_data)
+        av_opt_free(s->priv_data);
+
+    for (i = 0; i < s->nb_streams; i++)
+        free_stream(&s->streams[i]);
+
     for (i = s->nb_programs - 1; i >= 0; i--) {
         av_dict_free(&s->programs[i]->metadata);
         av_freep(&s->programs[i]->stream_index);