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FFmpeg/libavformat/mp3.c

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/*
* MP3 muxer and demuxer
* 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 <strings.h>
#include "libavutil/avstring.h"
#include "libavutil/intreadwrite.h"
#include "avformat.h"
#include "id3v2.h"
#include "id3v1.h"
#if CONFIG_MP3_DEMUXER
#include "libavcodec/mpegaudio.h"
#include "libavcodec/mpegaudiodecheader.h"
/* mp3 read */
static int mp3_read_probe(AVProbeData *p)
{
int max_frames, first_frames = 0;
int fsize, frames, sample_rate;
uint32_t header;
uint8_t *buf, *buf0, *buf2, *end;
AVCodecContext avctx;
buf0 = p->buf;
if(ff_id3v2_match(buf0)) {
buf0 += ff_id3v2_tag_len(buf0);
}
end = p->buf + p->buf_size - sizeof(uint32_t);
while(buf0 < end && !*buf0)
buf0++;
max_frames = 0;
buf = buf0;
for(; buf < end; buf= buf2+1) {
buf2 = buf;
for(frames = 0; buf2 < end; frames++) {
header = AV_RB32(buf2);
fsize = ff_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
if(fsize < 0)
break;
buf2 += fsize;
}
max_frames = FFMAX(max_frames, frames);
if(buf == buf0)
first_frames= frames;
}
// keep this in sync with ac3 probe, both need to avoid
// issues with MPEG-files!
if (first_frames>=4) return AVPROBE_SCORE_MAX/2+1;
else if(max_frames>500)return AVPROBE_SCORE_MAX/2;
else if(max_frames>=4) return AVPROBE_SCORE_MAX/4;
else if(buf0!=p->buf) return AVPROBE_SCORE_MAX/4-1;
else if(max_frames>=1) return 1;
else return 0;
//mpegps_mp3_unrecognized_format.mpg has max_frames=3
}
/**
* Try to find Xing/Info/VBRI tags and compute duration from info therein
*/
static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
{
uint32_t v, spf;
int frames = -1; /* Total number of frames in file */
const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
MPADecodeHeader c;
int vbrtag_size = 0;
v = get_be32(s->pb);
if(ff_mpa_check_header(v) < 0)
return -1;
if (ff_mpegaudio_decode_header(&c, v) == 0)
vbrtag_size = c.frame_size;
if(c.layer != 3)
return -1;
/* Check for Xing / Info tag */
url_fseek(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1], SEEK_CUR);
v = get_be32(s->pb);
if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) {
v = get_be32(s->pb);
if(v & 0x1)
frames = get_be32(s->pb);
}
/* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
url_fseek(s->pb, base + 4 + 32, SEEK_SET);
v = get_be32(s->pb);
if(v == MKBETAG('V', 'B', 'R', 'I')) {
/* Check tag version */
if(get_be16(s->pb) == 1) {
/* skip delay, quality and total bytes */
url_fseek(s->pb, 8, SEEK_CUR);
frames = get_be32(s->pb);
}
}
if(frames < 0)
return -1;
/* Skip the vbr tag frame */
url_fseek(s->pb, base + vbrtag_size, SEEK_SET);
spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
st->time_base);
return 0;
}
static int mp3_read_header(AVFormatContext *s,
AVFormatParameters *ap)
{
AVStream *st;
int64_t off;
st = av_new_stream(s, 0);
if (!st)
return AVERROR(ENOMEM);
st->codec->codec_type = CODEC_TYPE_AUDIO;
st->codec->codec_id = CODEC_ID_MP3;
st->need_parsing = AVSTREAM_PARSE_FULL;
st->start_time = 0;
// lcm of all mp3 sample rates
av_set_pts_info(st, 64, 1, 14112000);
ff_id3v2_read(s);
off = url_ftell(s->pb);
if (!av_metadata_get(s->metadata, "", NULL, AV_METADATA_IGNORE_SUFFIX))
ff_id3v1_read(s);
if (mp3_parse_vbr_tags(s, st, off) < 0)
url_fseek(s->pb, off, SEEK_SET);
/* the parameters will be extracted from the compressed bitstream */
return 0;
}
#define MP3_PACKET_SIZE 1024
static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
{
int ret, size;
// AVStream *st = s->streams[0];
size= MP3_PACKET_SIZE;
ret= av_get_packet(s->pb, pkt, size);
pkt->stream_index = 0;
if (ret <= 0) {
return AVERROR(EIO);
}
/* note: we need to modify the packet size here to handle the last
packet */
pkt->size = ret;
return ret;
}
AVInputFormat mp3_demuxer = {
"mp3",
NULL_IF_CONFIG_SMALL("MPEG audio layer 2/3"),
0,
mp3_read_probe,
mp3_read_header,
mp3_read_packet,
.flags= AVFMT_GENERIC_INDEX,
.extensions = "mp2,mp3,m2a", /* XXX: use probe */
.metadata_conv = ff_id3v2_metadata_conv,
};
#endif
#if CONFIG_MP2_MUXER || CONFIG_MP3_MUXER
static int id3v1_set_string(AVFormatContext *s, const char *key,
uint8_t *buf, int buf_size)
{
AVMetadataTag *tag;
if ((tag = av_metadata_get(s->metadata, key, NULL, 0)))
strncpy(buf, tag->value, buf_size);
return !!tag;
}
static int id3v1_create_tag(AVFormatContext *s, uint8_t *buf)
{
AVMetadataTag *tag;
int i, count = 0;
memset(buf, 0, ID3v1_TAG_SIZE); /* fail safe */
buf[0] = 'T';
buf[1] = 'A';
buf[2] = 'G';
count += id3v1_set_string(s, "title", buf + 3, 30);
count += id3v1_set_string(s, "author", buf + 33, 30);
count += id3v1_set_string(s, "album", buf + 63, 30);
count += id3v1_set_string(s, "date", buf + 93, 4);
count += id3v1_set_string(s, "comment", buf + 97, 30);
if ((tag = av_metadata_get(s->metadata, "track", NULL, 0))) {
buf[125] = 0;
buf[126] = atoi(tag->value);
count++;
}
buf[127] = 0xFF; /* default to unknown genre */
if ((tag = av_metadata_get(s->metadata, "genre", NULL, 0))) {
for(i = 0; i <= ID3v1_GENRE_MAX; i++) {
if (!strcasecmp(tag->value, ff_id3v1_genre_str[i])) {
buf[127] = i;
count++;
break;
}
}
}
return count;
}
/* simple formats */
static void id3v2_put_size(AVFormatContext *s, int size)
{
put_byte(s->pb, size >> 21 & 0x7f);
put_byte(s->pb, size >> 14 & 0x7f);
put_byte(s->pb, size >> 7 & 0x7f);
put_byte(s->pb, size & 0x7f);
}
static void id3v2_put_ttag(AVFormatContext *s, const char *buf, int len,
uint32_t tag)
{
put_be32(s->pb, tag);
id3v2_put_size(s, len + 1);
put_be16(s->pb, 0);
put_byte(s->pb, 3); /* UTF-8 */
put_buffer(s->pb, buf, len);
}
static int mp3_write_packet(struct AVFormatContext *s, AVPacket *pkt)
{
put_buffer(s->pb, pkt->data, pkt->size);
put_flush_packet(s->pb);
return 0;
}
static int mp3_write_trailer(struct AVFormatContext *s)
{
uint8_t buf[ID3v1_TAG_SIZE];
/* write the id3v1 tag */
if (id3v1_create_tag(s, buf) > 0) {
put_buffer(s->pb, buf, ID3v1_TAG_SIZE);
put_flush_packet(s->pb);
}
return 0;
}
#endif /* CONFIG_MP2_MUXER || CONFIG_MP3_MUXER */
#if CONFIG_MP2_MUXER
AVOutputFormat mp2_muxer = {
"mp2",
NULL_IF_CONFIG_SMALL("MPEG audio layer 2"),
"audio/x-mpeg",
"mp2,m2a",
0,
CODEC_ID_MP2,
CODEC_ID_NONE,
NULL,
mp3_write_packet,
mp3_write_trailer,
};
#endif
#if CONFIG_MP3_MUXER
/**
* Write an ID3v2.4 header at beginning of stream
*/
static int mp3_write_header(struct AVFormatContext *s)
{
AVMetadataTag *t = NULL;
int totlen = 0;
int64_t size_pos, cur_pos;
put_be32(s->pb, MKBETAG('I', 'D', '3', 0x04)); /* ID3v2.4 */
put_byte(s->pb, 0);
put_byte(s->pb, 0); /* flags */
/* reserve space for size */
size_pos = url_ftell(s->pb);
put_be32(s->pb, 0);
while ((t = av_metadata_get(s->metadata, "", t, AV_METADATA_IGNORE_SUFFIX))) {
uint32_t tag = 0;
if (t->key[0] == 'T' && strlen(t->key) == 4) {
int i;
for (i = 0; *ff_id3v2_tags[i]; i++)
if (AV_RB32(t->key) == AV_RB32(ff_id3v2_tags[i])) {
int len = strlen(t->value);
tag = AV_RB32(t->key);
totlen += len + ID3v2_HEADER_SIZE + 2;
id3v2_put_ttag(s, t->value, len + 1, tag);
break;
}
}
if (!tag) { /* unknown tag, write as TXXX frame */
int len = strlen(t->key), len1 = strlen(t->value);
char *buf = av_malloc(len + len1 + 2);
if (!buf)
return AVERROR(ENOMEM);
tag = MKBETAG('T', 'X', 'X', 'X');
strcpy(buf, t->key);
strcpy(buf + len + 1, t->value);
id3v2_put_ttag(s, buf, len + len1 + 2, tag);
totlen += len + len1 + ID3v2_HEADER_SIZE + 3;
av_free(buf);
}
}
cur_pos = url_ftell(s->pb);
url_fseek(s->pb, size_pos, SEEK_SET);
id3v2_put_size(s, totlen);
url_fseek(s->pb, cur_pos, SEEK_SET);
return 0;
}
AVOutputFormat mp3_muxer = {
"mp3",
NULL_IF_CONFIG_SMALL("MPEG audio layer 3"),
"audio/x-mpeg",
"mp3",
0,
CODEC_ID_MP3,
CODEC_ID_NONE,
mp3_write_header,
mp3_write_packet,
mp3_write_trailer,
.metadata_conv = ff_id3v2_metadata_conv,
};
#endif