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mp3enc: write a xing frame containing number of frames in the file

This commit is contained in:
Anton Khirnov 2011-03-21 21:02:50 +01:00
parent 1c6d2b7df0
commit bda168d2b0
2 changed files with 71 additions and 5 deletions
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1
libavcodec/Makefile
View File

@ -536,6 +536,7 @@ OBJS-$(CONFIG_MATROSKA_DEMUXER) += mpeg4audio.o mpegaudiodata.o
OBJS-$(CONFIG_MATROSKA_MUXER) += xiph.o mpeg4audio.o \
flacdec.o flacdata.o flac.o \
mpegaudiodata.o
OBJS-$(CONFIG_MP3_MUXER) += mpegaudiodata.o mpegaudiodecheader.o
OBJS-$(CONFIG_MOV_DEMUXER) += mpeg4audio.o mpegaudiodata.o
OBJS-$(CONFIG_MOV_MUXER) += mpeg4audio.o mpegaudiodata.o
OBJS-$(CONFIG_MPEGTS_MUXER) += mpegvideo.o mpeg4audio.o

75
libavformat/mp3enc.c
View File

@ -21,10 +21,14 @@
#include <strings.h>
#include "avformat.h"
#include "avio_internal.h"
#include "id3v1.h"
#include "id3v2.h"
#include "rawenc.h"
#include "libavutil/avstring.h"
#include "libavcodec/mpegaudio.h"
#include "libavcodec/mpegaudiodata.h"
#include "libavcodec/mpegaudiodecheader.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/opt.h"
#include "libavutil/dict.h"
@ -128,15 +132,31 @@ static int id3v2_put_ttag(AVFormatContext *s, const char *str1, const char *str2
return len + ID3v2_HEADER_SIZE;
}
typedef struct MP3Context {
const AVClass *class;
int id3v2_version;
int64_t nb_frames_offset;
} MP3Context;
static int mp3_write_trailer(struct AVFormatContext *s)
{
uint8_t buf[ID3v1_TAG_SIZE];
MP3Context *mp3 = s->priv_data;
/* write the id3v1 tag */
if (id3v1_create_tag(s, buf) > 0) {
avio_write(s->pb, buf, ID3v1_TAG_SIZE);
avio_flush(s->pb);
}
/* write number of frames */
if (mp3 && mp3->nb_frames_offset) {
avio_seek(s->pb, mp3->nb_frames_offset, SEEK_SET);
avio_wb32(s->pb, s->streams[0]->nb_frames);
avio_seek(s->pb, 0, SEEK_END);
}
avio_flush(s->pb);
return 0;
}
@ -156,10 +176,6 @@ AVOutputFormat ff_mp2_muxer = {
#endif
#if CONFIG_MP3_MUXER
typedef struct MP3Context {
const AVClass *class;
int id3v2_version;
} MP3Context;
static const AVOption options[] = {
{ "id3v2_version", "Select ID3v2 version to write. Currently 3 and 4 are supported.",
@ -189,6 +205,52 @@ static int id3v2_check_write_tag(AVFormatContext *s, AVDictionaryEntry *t, const
return -1;
}
/* insert a dummy frame containing number of frames */
static void mp3_write_xing(AVFormatContext *s)
{
AVCodecContext *codec = s->streams[0]->codec;
MP3Context *mp3 = s->priv_data;
int bitrate_idx = 1; // 32 kbps
int64_t xing_offset = (codec->channels == 2) ? 32 : 17;
int32_t header;
MPADecodeHeader mpah;
int srate_idx, i, channels;
for (i = 0; i < FF_ARRAY_ELEMS(ff_mpa_freq_tab); i++)
if (ff_mpa_freq_tab[i] == codec->sample_rate) {
srate_idx = i;
break;
}
if (i == FF_ARRAY_ELEMS(ff_mpa_freq_tab)) {
av_log(s, AV_LOG_ERROR, "Unsupported sample rate.\n");
return;
}
switch (codec->channels) {
case 1: channels = MPA_MONO; break;
case 2: channels = MPA_STEREO; break;
default: av_log(s, AV_LOG_ERROR, "Unsupported number of channels.\n"); return;
}
/* dummy MPEG audio header */
header = 0xff << 24; // sync
header |= (0x7 << 5 | 0x3 << 3 | 0x1 << 1 | 0x1) << 16; // sync/mpeg-1/layer 3/no crc*/
header |= (bitrate_idx << 4 | srate_idx << 2) << 8;
header |= channels << 6;
avio_wb32(s->pb, header);
ff_mpegaudio_decode_header(&mpah, header);
ffio_fill(s->pb, 0, xing_offset);
ffio_wfourcc(s->pb, "Xing");
avio_wb32(s->pb, 0x1); // only number of frames
mp3->nb_frames_offset = avio_tell(s->pb);
avio_wb32(s->pb, 0);
mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4;
ffio_fill(s->pb, 0, mpah.frame_size);
}
/**
* Write an ID3v2 header at beginning of stream
*/
@ -237,6 +299,9 @@ static int mp3_write_header(struct AVFormatContext *s)
id3v2_put_size(s, totlen);
avio_seek(s->pb, cur_pos, SEEK_SET);
if (s->pb->seekable)
mp3_write_xing(s);
return 0;
}