avformat/mp3dec: Add usetoc option to allow dlsabling the use of the xing TOC

The toc is inexact and not using it can thus make sense.
Using it is faster though, thus the opposite can similarly makes sense
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/mp3dec.c

@@ -19,6 +19,7 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "libavutil/opt.h"
 #include "libavutil/avstring.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/dict.h"
@@ -36,10 +37,12 @@
 #define XING_TOC_COUNT 100
 
 typedef struct {
+    AVClass *class;
     int64_t filesize;
     int xing_toc;
     int start_pad;
     int end_pad;
+    int usetoc;
 } MP3DecContext;
 
 /* mp3 read */
@@ -91,6 +94,9 @@ static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration
     int i;
     MP3DecContext *mp3 = s->priv_data;
 
+    if (!mp3->usetoc)
+        return;
+
     if (!filesize &&
         !(filesize = avio_size(s->pb))) {
         av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n");
@@ -316,6 +322,19 @@ static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
     return 0;
 }
 
+static const AVOption options[] = {
+    { "usetoc", "use table of contents", offsetof(MP3DecContext, usetoc), AV_OPT_TYPE_INT, {.i64 = -1}, -1, 1, AV_OPT_FLAG_DECODING_PARAM},
+    { NULL },
+};
+
+static const AVClass demuxer_class = {
+    .class_name = "mp3",
+    .item_name  = av_default_item_name,
+    .option     = options,
+    .version    = LIBAVUTIL_VERSION_INT,
+    .category   = AV_CLASS_CATEGORY_DEMUXER,
+};
+
 AVInputFormat ff_mp3_demuxer = {
     .name           = "mp3",
     .long_name      = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
@@ -326,4 +345,5 @@ AVInputFormat ff_mp3_demuxer = {
     .priv_data_size = sizeof(MP3DecContext),
     .flags          = AVFMT_GENERIC_INDEX,
     .extensions     = "mp2,mp3,m2a", /* XXX: use probe */
+    .priv_class     = &demuxer_class,
 };

libavformat/version.h

@@ -31,7 +31,7 @@
 
 #define LIBAVFORMAT_VERSION_MAJOR 55
 #define LIBAVFORMAT_VERSION_MINOR 11
-#define LIBAVFORMAT_VERSION_MICRO 100
+#define LIBAVFORMAT_VERSION_MICRO 101
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \