avformat/flac_picture: Avoid allocation of AVIOContext

Put an AVIOContext whose lifetime doesn't extend beyond the function
where it is allocated on the stack instead of allocating and freeing it.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavformat/flac_picture.c

@@ -26,6 +26,7 @@
 #include "flac_picture.h"
 #include "id3v2.h"
 #include "internal.h"
+#include "avio_internal.h"
 
 int ff_flac_parse_picture(AVFormatContext *s, uint8_t *buf, int buf_size)
 {
@@ -33,15 +34,13 @@ int ff_flac_parse_picture(AVFormatContext *s, uint8_t *buf, int buf_size)
     enum AVCodecID id = AV_CODEC_ID_NONE;
     AVBufferRef *data = NULL;
     uint8_t mimetype[64], *desc = NULL;
-    AVIOContext *pb = NULL;
+    AVIOContext pb0, *pb = &pb0;
     AVStream *st;
     int width, height, ret = 0;
     int len;
     unsigned int type;
 
-    pb = avio_alloc_context(buf, buf_size, 0, NULL, NULL, NULL, NULL);
-    if (!pb)
-        return AVERROR(ENOMEM);
+    ffio_init_context(pb, buf, buf_size, 0, NULL, NULL, NULL, NULL);
 
     /* read the picture type */
     type = avio_rb32(pb);
@@ -145,14 +144,11 @@ int ff_flac_parse_picture(AVFormatContext *s, uint8_t *buf, int buf_size)
     if (desc)
         av_dict_set(&st->metadata, "title", desc, AV_DICT_DONT_STRDUP_VAL);
 
-    avio_context_free(&pb);
-
     return 0;
 
 fail:
     av_buffer_unref(&data);
     av_freep(&desc);
-    avio_context_free(&pb);
 
     return ret;
 }