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1fea432b7a
ffmpeg/libavformat/mp3enc.c
Michael Niedermayer 1fea432b7a mp3enc: simplify mp3_write_xing() 
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
2011-11-14 20:52:42 +01:00

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/*
* MP3 muxer
* Copyright (c) 2003 Fabrice Bellard
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#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 "libavcodec/mpegaudio.h"
#include "libavcodec/mpegaudiodata.h"
#include "libavcodec/mpegaudiodecheader.h"
#include "libavformat/avio_internal.h"
#include "libavutil/dict.h"
static int id3v1_set_string(AVFormatContext *s, const char *key,
uint8_t *buf, int buf_size)
{
AVDictionaryEntry *tag;
if ((tag = av_dict_get(s->metadata, key, NULL, 0)))
av_strlcpy(buf, tag->value, buf_size);
return !!tag;
}
static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf)
{
AVDictionaryEntry *tag;
int i, count = 0;
memset(buf, 0, ID3v1_TAG_SIZE); /* fail safe */
buf[0] = 'T';
buf[1] = 'A';
buf[2] = 'G';
/* we knowingly overspecify each tag length by one byte to compensate for the mandatory null byte added by av_strlcpy */
count += id3v1_set_string(s, "TIT2", buf + 3, 30 + 1); //title
count += id3v1_set_string(s, "TPE1", buf + 33, 30 + 1); //author|artist
count += id3v1_set_string(s, "TALB", buf + 63, 30 + 1); //album
count += id3v1_set_string(s, "TDRL", buf + 93, 4 + 1); //date
count += id3v1_set_string(s, "comment", buf + 97, 30 + 1);
if ((tag = av_dict_get(s->metadata, "TRCK", NULL, 0))) { //track
buf[125] = 0;
buf[126] = atoi(tag->value);
count++;
}
buf[127] = 0xFF; /* default to unknown genre */
if ((tag = av_dict_get(s->metadata, "TCON", NULL, 0))) { //genre
for(i = 0; i <= ID3v1_GENRE_MAX; i++) {
if (!av_strcasecmp(tag->value, ff_id3v1_genre_str[i])) {
buf[127] = i;
count++;
break;
}
}
}
return count;
}
#define VBR_NUM_BAGS 400
#define VBR_TOC_SIZE 100
typedef struct MP3Context {
const AVClass *class;
int id3v2_version;
int write_id3v1;
int64_t frames_offset;
int32_t frames;
int32_t size;
uint32_t want;
uint32_t seen;
uint32_t pos;
uint64_t bag[VBR_NUM_BAGS];
} MP3Context;
static int mp2_write_trailer(struct AVFormatContext *s)
{
uint8_t buf[ID3v1_TAG_SIZE];
MP3Context *mp3 = s->priv_data;
/* write the id3v1 tag */
if (mp3 && mp3->write_id3v1 && id3v1_create_tag(s, buf) > 0) {
avio_write(s->pb, buf, ID3v1_TAG_SIZE);
}
/* write number of frames */
if (mp3 && mp3->frames_offset) {
avio_seek(s->pb, mp3->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;
}
#if CONFIG_MP2_MUXER
AVOutputFormat ff_mp2_muxer = {
.name = "mp2",
.long_name = NULL_IF_CONFIG_SMALL("MPEG audio layer 2"),
.mime_type = "audio/x-mpeg",
.extensions = "mp2,m2a",
.audio_codec = CODEC_ID_MP2,
.video_codec = CODEC_ID_NONE,
.write_packet = ff_raw_write_packet,
.write_trailer = mp2_write_trailer,
.flags = AVFMT_NOTIMESTAMPS,
};
#endif
#if CONFIG_MP3_MUXER
static const AVOption options[] = {
{ "id3v2_version", "Select ID3v2 version to write. Currently 3 and 4 are supported.",
offsetof(MP3Context, id3v2_version), AV_OPT_TYPE_INT, {.dbl = 4}, 3, 4, AV_OPT_FLAG_ENCODING_PARAM},
{ "write_id3v1", "Enable ID3v1 writing. ID3v1 tags are written in UTF-8 which may not be supported by most software.",
offsetof(MP3Context, write_id3v1), AV_OPT_TYPE_INT, {.dbl = 0}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM},
{ NULL },
};
static const AVClass mp3_muxer_class = {
.class_name = "MP3 muxer",
.item_name = av_default_item_name,
.option = options,
.version = LIBAVUTIL_VERSION_INT,
};
static const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
/*
* Write an empty XING header and initialize respective data.
*/
static int mp3_write_xing(AVFormatContext *s)
{
AVCodecContext *codec = s->streams[0]->codec;
MP3Context *mp3 = s->priv_data;
int bitrate_idx = 3;
int64_t xing_offset;
int32_t mask, header;
MPADecodeHeader c;
int srate_idx, i, channels;
int needed;
for (i = 0; i < FF_ARRAY_ELEMS(avpriv_mpa_freq_tab); i++)
if (avpriv_mpa_freq_tab[i] == codec->sample_rate) {
srate_idx = i;
break;
}
if (i == FF_ARRAY_ELEMS(avpriv_mpa_freq_tab)) {
av_log(s, AV_LOG_ERROR, "Unsupported sample rate.\n");
return -1;
}
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 -1;
}
/* 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 |= (srate_idx << 2) << 8;
header |= channels << 6;
for (;; bitrate_idx++) {
if (15 == bitrate_idx)
return -1;
avpriv_mpegaudio_decode_header(&c, header | (bitrate_idx << (4+8)));
xing_offset=xing_offtbl[c.lsf == 1][c.nb_channels == 1];
needed = 4 // header
+ xing_offset
+ 4 // xing tag
+ 4 // frames/size/toc flags
+ 4 // frames
+ 4 // size
+ VBR_TOC_SIZE; // toc
if (needed <= c.frame_size)
break;
}
avio_wb32(s->pb, header);
ffio_fill(s->pb, 0, xing_offset);
avio_wb32(s->pb, MKBETAG('X', 'i', 'n', 'g'));
avio_wb32(s->pb, 0x01 | 0x02 | 0x04); // frames/size/toc
mp3->frames_offset = avio_tell(s->pb);
mp3->size = c.frame_size;
mp3->want=1;
mp3->seen=0;
mp3->pos=0;
avio_wb32(s->pb, 0); // frames
avio_wb32(s->pb, 0); // size
// toc
for (i = 0; i < VBR_TOC_SIZE; ++i)
avio_w8(s->pb, (uint8_t)(255 * i / VBR_TOC_SIZE));
ffio_fill(s->pb, 0, c.frame_size - needed);
avio_flush(s->pb);
return 0;
}
/*
* Add a frame to XING data.
* Following lame's "VbrTag.c".
*/
static void mp3_xing_add_frame(AVFormatContext *s, AVPacket *pkt)
{
MP3Context *mp3 = s->priv_data;
int i;
++mp3->frames;
mp3->size += pkt->size;
if (mp3->want == ++mp3->seen) {
mp3->bag[mp3->pos] = mp3->size;
if (VBR_NUM_BAGS == ++mp3->pos) {
/* shrink table to half size by throwing away each second bag. */
for (i = 1; i < VBR_NUM_BAGS; i += 2)
mp3->bag[i >> 1] = mp3->bag[i];
/* double wanted amount per bag. */
mp3->want <<= 1;
/* adjust current position to half of table size. */
mp3->pos >>= 1;
}
mp3->seen = 0;
}
}
static void mp3_fix_xing(AVFormatContext *s)
{
MP3Context *mp3 = s->priv_data;
int i;
avio_flush(s->pb);
avio_seek(s->pb, mp3->frames_offset, SEEK_SET);
avio_wb32(s->pb, mp3->frames);
avio_wb32(s->pb, mp3->size);
avio_w8(s->pb, 0); // first toc entry has to be zero.
for (i = 1; i < VBR_TOC_SIZE; ++i) {
int j = i * mp3->pos / VBR_TOC_SIZE;
int seek_point = 256LL * mp3->bag[j] / mp3->size;
avio_w8(s->pb, FFMIN(seek_point, 255));
}
avio_flush(s->pb);
avio_seek(s->pb, 0, SEEK_END);
}
/**
* Write an ID3v2 header at beginning of stream
*/
static int mp3_write_header(struct AVFormatContext *s)
{
MP3Context *mp3 = s->priv_data;
int ret;
ret = ff_id3v2_write(s, mp3->id3v2_version, ID3v2_DEFAULT_MAGIC);
if (ret < 0)
return ret;
if (s->pb->seekable)
mp3_write_xing(s);
return 0;
}
static int mp3_write_packet(AVFormatContext *s, AVPacket *pkt)
{
if (! pkt || ! pkt->data || pkt->size < 4)
return ff_raw_write_packet(s, pkt);
else {
MP3Context *mp3 = s->priv_data;
#ifdef FILTER_VBR_HEADERS
MPADecodeHeader c;
int base;
ff_mpegaudio_decode_header(&c, AV_RB32(pkt->data));
/* filter out XING and INFO headers. */
base = 4 + xing_offtbl[c.lsf == 1][c.nb_channels == 1];
if (base + 4 <= pkt->size) {
uint32_t v = AV_RB32(pkt->data + base);
if (MKBETAG('X','i','n','g') == v || MKBETAG('I','n','f','o') == v)
return 0;
}
/* filter out VBRI headers. */
base = 4 + 32;
if (base + 4 <= pkt->size && MKBETAG('V','B','R','I') == AV_RB32(pkt->data + base))
return 0;
#endif
if (mp3->frames_offset)
mp3_xing_add_frame(s, pkt);
return ff_raw_write_packet(s, pkt);
}
}
static int mp3_write_trailer(AVFormatContext *s)
{
MP3Context *mp3 = s->priv_data;
int ret=mp2_write_trailer(s);
if (ret < 0)
return ret;
if (mp3->frames_offset)
mp3_fix_xing(s);
return 0;
}
AVOutputFormat ff_mp3_muxer = {
.name = "mp3",
.long_name = NULL_IF_CONFIG_SMALL("MPEG audio layer 3"),
.mime_type = "audio/x-mpeg",
.extensions = "mp3",
.priv_data_size = sizeof(MP3Context),
.audio_codec = CODEC_ID_MP3,
.video_codec = CODEC_ID_NONE,
.write_header = mp3_write_header,
.write_packet = mp3_write_packet,
.write_trailer = mp3_write_trailer,
.flags = AVFMT_NOTIMESTAMPS,
.priv_class = &mp3_muxer_class,
};
#endif
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