[PATCH] detect where trailing metadata begins in mp3 files so =
David Byron none
dbyron
Mon Sep 27 10:29:03 CEST 2010
it's=0A=
not returned from av_read_frame=0A=
=0A=
---=0A=
Changelog | 2 +=0A=
libavformat/mp3.c | 122 =
++++++++++++++++++++++++++++++++++++++++++++++++++++-=0A=
2 files changed, 123 insertions(+), 1 deletions(-)=0A=
=0A=
diff --git a/Changelog b/Changelog=0A=
index a76cec1..289466d 100644=0A=
--- a/Changelog=0A=
+++ b/Changelog=0A=
@@ -4,6 +4,8 @@ releases are sorted from youngest to oldest.=0A=
=0A=
version <next>:=0A=
=0A=
+- detect where trailing metadata begins in mp3 files so it's not=0A=
+ returned from av_read_frame=0A=
- WebM support in Matroska de/muxer=0A=
- low overhead Ogg muxing=0A=
- MMS-TCP support=0A=
diff --git a/libavformat/mp3.c b/libavformat/mp3.c=0A=
index c1622a3..b8f3734 100644=0A=
--- a/libavformat/mp3.c=0A=
+++ b/libavformat/mp3.c=0A=
@@ -19,9 +19,11 @@=0A=
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA =
02110-1301 USA=0A=
*/=0A=
=0A=
+#include <assert.h>=0A=
#include <strings.h>=0A=
#include "libavutil/avstring.h"=0A=
#include "libavutil/intreadwrite.h"=0A=
+#include "apetag.h"=0A=
#include "avformat.h"=0A=
#include "id3v2.h"=0A=
#include "id3v1.h"=0A=
@@ -31,8 +33,93 @@=0A=
#include "libavcodec/mpegaudio.h"=0A=
#include "libavcodec/mpegaudiodecheader.h"=0A=
=0A=
+/**=0A=
+ * Information used to demux mp3 files=0A=
+ */=0A=
+typedef struct {=0A=
+ /**=0A=
+ * -1 if no trailing metadata is detected, otherwise the=0A=
+ * offset where trailing metadata begins=0A=
+ */=0A=
+ int64_t trailing_metadata_offset;=0A=
+} MP3Context;=0A=
+=0A=
/* mp3 read */=0A=
=0A=
+/**=0A=
+ * Find the offset where trailing metadata begins. If there=0A=
+ * are multiple items of trailing metadata (e.g. APE +=0A=
+ * lyrics3 + id3v1), this function finds the offset of the=0A=
+ * beginning of them all. If there is space between the=0A=
+ * items, this function doesn't look before the space.=0A=
+ *=0A=
+ * @retval 0 successfully populated s->priv_data (an=0A=
+ * MP3Context)->trailing_metadata_offset with the offset of=0A=
+ * trailing metadata (-1 if there is none)=0A=
+ */=0A=
+static int ff_mp3_find_trailing_metadata(AVFormatContext *s)=0A=
+{=0A=
+ int64_t ape_offset;=0A=
+ uint64_t ape_size;=0A=
+ int64_t id3v1_offset;=0A=
+ int64_t trailing_offset;=0A=
+ int ret;=0A=
+ MP3Context *mp3 =3D s->priv_data;=0A=
+=0A=
+ mp3->trailing_metadata_offset =3D -1;=0A=
+=0A=
+ /* First look for the id3v1 tag at the end */=0A=
+ ret =3D ff_id3v1_offset(s,&id3v1_offset);=0A=
+ if (ret < 0)=0A=
+ goto done;=0A=
+=0A=
+ if (id3v1_offset !=3D -1)=0A=
+ av_log(s, AV_LOG_VERBOSE, "%s: \"%s\": id3v1 tag at offset %"=0A=
+ PRId64 "(0x%" PRIx64 ")\n", __FUNCTION__, s->filename,=0A=
+ id3v1_offset, id3v1_offset);=0A=
+=0A=
+ trailing_offset =3D id3v1_offset;=0A=
+=0A=
+ /* Because of the way ff_id3v1_offset works, we don't=0A=
+ need to make sure the id3v1 tag is at the very end of=0A=
+ the file. */=0A=
+=0A=
+ /* Now look for an APE tag. Pass 0 because we don't=0A=
+ care how many fields it's got. */=0A=
+ ret =3D ff_ape_offset(s,id3v1_offset,&ape_offset,&ape_size,0);=0A=
+ if (ret < 0)=0A=
+ goto done;=0A=
+=0A=
+ assert((id3v1_offset =3D=3D -1) || (ape_offset < id3v1_offset));=0A=
+=0A=
+ if (ape_offset !=3D -1) {=0A=
+ if (id3v1_offset !=3D -1) {=0A=
+ /* If the APE tag isn't immediately before the=0A=
+ id3v1 tag, we're done */=0A=
+ if ((ape_offset + ape_size) !=3D id3v1_offset) {=0A=
+ av_log(s, AV_LOG_WARNING, "%s: \"%s\": gap between end =
of "=0A=
+ "APE tag and start of id3v1 tag", __FUNCTION__,=0A=
+ s->filename);=0A=
+=0A=
+ /* Just give the offset of the id3v1 tag so=0A=
+ we don't ditch the info between the=0A=
+ tags */=0A=
+ mp3->trailing_metadata_offset =3D id3v1_offset;=0A=
+ goto done;=0A=
+ }=0A=
+ }=0A=
+=0A=
+ trailing_offset =3D ape_offset;=0A=
+ }=0A=
+=0A=
+ mp3->trailing_metadata_offset =3D trailing_offset;=0A=
+=0A=
+ done:=0A=
+ url_fseek(s->pb, 0, SEEK_SET);=0A=
+=0A=
+ return ret;=0A=
+}=0A=
+=0A=
static int mp3_read_probe(AVProbeData *p)=0A=
{=0A=
int max_frames, first_frames =3D 0;=0A=
@@ -143,6 +230,7 @@ static int mp3_read_header(AVFormatContext *s,=0A=
{=0A=
AVStream *st;=0A=
int64_t off;=0A=
+ int ret;=0A=
=0A=
st =3D av_new_stream(s, 0);=0A=
if (!st)=0A=
@@ -162,6 +250,18 @@ static int mp3_read_header(AVFormatContext *s,=0A=
if (!av_metadata_get(s->metadata, "", NULL, =
AV_METADATA_IGNORE_SUFFIX))=0A=
ff_id3v1_read(s);=0A=
=0A=
+ /* Eventually we may want to parse metadata from APE or=0A=
+ lyrics3 tags, but for now find the offset of trailing=0A=
+ metadata (i.e. lyrics3/APE/id3v1 tags with id3v1 at=0A=
+ the end (if present), but the other two in either=0A=
+ order before that. If we do decide to read all the=0A=
+ trailing metadata, perhaps this function becomes=0A=
+ ff_mp3_read_trailing_metadata and supercedes=0A=
+ ff_id3v1_read. */=0A=
+ ret =3D ff_mp3_find_trailing_metadata(s);=0A=
+ if (ret < 0)=0A=
+ return ret;=0A=
+=0A=
if (mp3_parse_vbr_tags(s, st, off) < 0)=0A=
url_fseek(s->pb, off, SEEK_SET);=0A=
=0A=
@@ -174,8 +274,28 @@ static int mp3_read_header(AVFormatContext *s,=0A=
static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)=0A=
{=0A=
int ret, size;=0A=
+ MP3Context *mp3 =3D s->priv_data;=0A=
+ int64_t pos;=0A=
+=0A=
// AVStream *st =3D s->streams[0];=0A=
=0A=
+ /* If we're into the trailing metadata, don't look for a packet */=0A=
+ if (mp3->trailing_metadata_offset !=3D -1) {=0A=
+ pos =3D url_ftell(s->pb);=0A=
+ av_log(s, AV_LOG_DEBUG, "%s: \"%s\": current offset: %" PRId64 =
", "=0A=
+ "trailing_metadata_offset: %" PRId64 "\n", __FUNCTION__,=0A=
+ s->filename, pos, mp3->trailing_metadata_offset);=0A=
+=0A=
+ if (pos < 0)=0A=
+ return pos;=0A=
+ if (pos >=3D mp3->trailing_metadata_offset) {=0A=
+ av_log(s, AV_LOG_DEBUG, "%s: \"%s\": giving up at offset: %"=0A=
+ PRId64 " due to trailing metadata\n", __FUNCTION__,=0A=
+ s->filename, pos);=0A=
+ return AVERROR_EOF;=0A=
+ }=0A=
+ }=0A=
+=0A=
size=3D MP3_PACKET_SIZE;=0A=
=0A=
ret=3D av_get_packet(s->pb, pkt, size);=0A=
@@ -193,7 +313,7 @@ static int mp3_read_packet(AVFormatContext *s, =
AVPacket *pkt)=0A=
AVInputFormat mp3_demuxer =3D {=0A=
"mp3",=0A=
NULL_IF_CONFIG_SMALL("MPEG audio layer 2/3"),=0A=
- 0,=0A=
+ sizeof(MP3Context),=0A=
mp3_read_probe,=0A=
mp3_read_header,=0A=
mp3_read_packet,=0A=
-- =0A=
1.6.0.4=0A=
=0A=
------=_NextPart_000_016F_01CB5E3E.615FC240
Content-Type: audio/mpeg;
name="ape_and_id3v1_with_audio_5.mp3"
Content-Transfer-Encoding: base64
Content-Disposition: attachment;
filename="ape_and_id3v1_with_audio_5.mp3"
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------=_NextPart_000_016F_01CB5E3E.615FC240
Content-Type: text/plain;
name="iterate_frames.c"
Content-Transfer-Encoding: quoted-printable
Content-Disposition: attachment;
filename="iterate_frames.c"
#include <assert.h>=0A=
#include <inttypes.h>=0A=
#include <libavcodec/avcodec.h>=0A=
#include <libavformat/avformat.h>=0A=
#include <libavformat/avio.h>=0A=
#include <stdio.h>=0A=
#include <stdint.h>=0A=
=0A=
int=0A=
main ( int argc,=0A=
char **argv )=0A=
{=0A=
AVFormatParameters ap;=0A=
static char errbuf[512];=0A=
const char *filename;=0A=
AVFormatContext *format_context;=0A=
unsigned long num_frames;=0A=
AVPacket packet;=0A=
int retval;=0A=
unsigned long total_bytes;=0A=
=0A=
if (argc < 2)=0A=
{=0A=
printf("usage: %s filename\n",argv[0]);=0A=
return 1;=0A=
}=0A=
filename =3D argv[1];=0A=
=0A=
av_log_set_level(AV_LOG_DEBUG);=0A=
=0A=
av_register_all();=0A=
=0A=
/*=0A=
** Tell the parser that we only want frame data. In=0A=
** other words, we don't care about metadata that comes=0A=
** before or after frames=0A=
*/=0A=
format_context =3D avformat_alloc_context();=0A=
if (!format_context)=0A=
{=0A=
printf("avformat_alloc_context failed\n");=0A=
return 1;=0A=
}=0A=
=0A=
// format_context->debug =3D FF_FDEBUG_TS;=0A=
=0A=
memset(&ap,0,sizeof(ap));=0A=
ap.prealloced_context =3D 1;=0A=
=0A=
retval =3D av_open_input_file(&format_context,filename,NULL,0,&ap);=0A=
if (retval !=3D 0)=0A=
{=0A=
av_strerror(retval,errbuf,sizeof(errbuf));=0A=
printf("av_open_input_file(%s) failed (%d) -- =
%s\n",filename,retval,=0A=
errbuf);=0A=
av_free(format_context);=0A=
format_context =3D NULL;=0A=
return 1;=0A=
}=0A=
assert(format_context);=0A=
=0A=
num_frames =3D 0;=0A=
total_bytes =3D 0;=0A=
=0A=
while (av_read_frame(format_context,&packet) =3D=3D 0)=0A=
{=0A=
if (packet.size > 0)=0A=
{=0A=
num_frames++;=0A=
total_bytes +=3D packet.size;=0A=
=0A=
printf("\"%s\": frame %ld: offset: %" PRId64 ", size %d "=0A=
"byte(s)\n",filename,num_frames,=0A=
url_ftell(format_context->pb),packet.size);=0A=
}=0A=
av_free_packet(&packet);=0A=
}=0A=
=0A=
av_close_input_file(format_context);=0A=
format_context =3D NULL;=0A=
=0A=
printf("\"%s\": %ld frame(s), %ld byte(s)\n",filename,num_frames,=0A=
total_bytes);=0A=
=0A=
return 0;=0A=
}=0A=
------=_NextPart_000_016F_01CB5E3E.615FC240--
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