mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
286 lines
8.2 KiB
286 lines
8.2 KiB
/* |
|
* MP3 demuxer |
|
* Copyright (c) 2003 Fabrice Bellard |
|
* |
|
* This file is part of Libav. |
|
* |
|
* Libav 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. |
|
* |
|
* Libav 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 Libav; if not, write to the Free Software |
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
|
*/ |
|
|
|
#include "libavutil/avstring.h" |
|
#include "libavutil/intreadwrite.h" |
|
#include "libavutil/dict.h" |
|
#include "libavutil/mathematics.h" |
|
#include "avformat.h" |
|
#include "internal.h" |
|
#include "id3v2.h" |
|
#include "id3v1.h" |
|
#include "libavcodec/mpegaudiodecheader.h" |
|
|
|
#define XING_FLAG_FRAMES 0x01 |
|
#define XING_FLAG_SIZE 0x02 |
|
#define XING_FLAG_TOC 0x04 |
|
|
|
#define XING_TOC_COUNT 100 |
|
|
|
typedef struct MP3DecContext { |
|
int xing_toc; |
|
} MP3DecContext; |
|
|
|
/* 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; |
|
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 = avpriv_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; |
|
|
|
if (max_frames) { |
|
int pes = 0, i; |
|
unsigned int code = -1; |
|
|
|
#define VIDEO_ID 0x000001e0 |
|
#define AUDIO_ID 0x000001c0 |
|
/* do a search for mpegps headers to be able to properly bias |
|
* towards mpegps if we detect this stream as both. */ |
|
for (i = 0; i<p->buf_size; i++) { |
|
code = (code << 8) + p->buf[i]; |
|
if ((code & 0xffffff00) == 0x100) { |
|
if ((code & 0x1f0) == VIDEO_ID) pes++; |
|
else if((code & 0x1e0) == AUDIO_ID) pes++; |
|
} |
|
} |
|
|
|
if (pes) |
|
max_frames = (max_frames + pes - 1) / pes; |
|
} |
|
if (max_frames > 500) return AVPROBE_SCORE_MAX / 2; |
|
else if (max_frames >= 4) return AVPROBE_SCORE_MAX / 4; |
|
else if (max_frames >= 1) return 1; |
|
else return 0; |
|
//mpegps_mp3_unrecognized_format.mpg has max_frames=3 |
|
} |
|
|
|
static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration) |
|
{ |
|
int i; |
|
MP3DecContext *mp3 = s->priv_data; |
|
|
|
if (!filesize && |
|
!(filesize = avio_size(s->pb))) { |
|
av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n"); |
|
return; |
|
} |
|
|
|
for (i = 0; i < XING_TOC_COUNT; i++) { |
|
uint8_t b = avio_r8(s->pb); |
|
|
|
av_add_index_entry(s->streams[0], |
|
av_rescale(b, filesize, 256), |
|
av_rescale(i, duration, XING_TOC_COUNT), |
|
0, 0, AVINDEX_KEYFRAME); |
|
} |
|
mp3->xing_toc = 1; |
|
} |
|
|
|
/** |
|
* 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; |
|
unsigned frames = 0; /* Total number of frames in file */ |
|
unsigned size = 0; /* Total number of bytes in the stream */ |
|
const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}}; |
|
MPADecodeHeader c; |
|
int vbrtag_size = 0; |
|
int is_cbr; |
|
|
|
v = avio_rb32(s->pb); |
|
if(ff_mpa_check_header(v) < 0) |
|
return -1; |
|
|
|
if (avpriv_mpegaudio_decode_header(&c, v) == 0) |
|
vbrtag_size = c.frame_size; |
|
if(c.layer != 3) |
|
return -1; |
|
|
|
spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */ |
|
|
|
/* Check for Xing / Info tag */ |
|
avio_skip(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1]); |
|
v = avio_rb32(s->pb); |
|
is_cbr = v == MKBETAG('I', 'n', 'f', 'o'); |
|
if (v == MKBETAG('X', 'i', 'n', 'g') || is_cbr) { |
|
v = avio_rb32(s->pb); |
|
if(v & XING_FLAG_FRAMES) |
|
frames = avio_rb32(s->pb); |
|
if(v & XING_FLAG_SIZE) |
|
size = avio_rb32(s->pb); |
|
if (v & XING_FLAG_TOC && frames) |
|
read_xing_toc(s, size, av_rescale_q(frames, (AVRational){spf, c.sample_rate}, |
|
st->time_base)); |
|
} |
|
|
|
/* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */ |
|
avio_seek(s->pb, base + 4 + 32, SEEK_SET); |
|
v = avio_rb32(s->pb); |
|
if(v == MKBETAG('V', 'B', 'R', 'I')) { |
|
/* Check tag version */ |
|
if(avio_rb16(s->pb) == 1) { |
|
/* skip delay and quality */ |
|
avio_skip(s->pb, 4); |
|
size = avio_rb32(s->pb); |
|
frames = avio_rb32(s->pb); |
|
} |
|
} |
|
|
|
if(!frames && !size) |
|
return -1; |
|
|
|
/* Skip the vbr tag frame */ |
|
avio_seek(s->pb, base + vbrtag_size, SEEK_SET); |
|
|
|
if(frames) |
|
st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate}, |
|
st->time_base); |
|
if (size && frames && !is_cbr) |
|
st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf); |
|
|
|
return 0; |
|
} |
|
|
|
static int mp3_read_header(AVFormatContext *s) |
|
{ |
|
AVStream *st; |
|
int64_t off; |
|
|
|
st = avformat_new_stream(s, NULL); |
|
if (!st) |
|
return AVERROR(ENOMEM); |
|
|
|
st->codec->codec_type = AVMEDIA_TYPE_AUDIO; |
|
st->codec->codec_id = AV_CODEC_ID_MP3; |
|
st->need_parsing = AVSTREAM_PARSE_FULL; |
|
st->start_time = 0; |
|
|
|
// lcm of all mp3 sample rates |
|
avpriv_set_pts_info(st, 64, 1, 14112000); |
|
|
|
off = avio_tell(s->pb); |
|
|
|
if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX)) |
|
ff_id3v1_read(s); |
|
|
|
if (mp3_parse_vbr_tags(s, st, off) < 0) |
|
avio_seek(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; |
|
|
|
ret = av_get_packet(s->pb, pkt, MP3_PACKET_SIZE); |
|
if (ret < 0) |
|
return ret; |
|
|
|
pkt->stream_index = 0; |
|
|
|
if (ret > ID3v1_TAG_SIZE && |
|
memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0) |
|
ret -= ID3v1_TAG_SIZE; |
|
|
|
/* note: we need to modify the packet size here to handle the last |
|
packet */ |
|
pkt->size = ret; |
|
return ret; |
|
} |
|
|
|
static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp, |
|
int flags) |
|
{ |
|
MP3DecContext *mp3 = s->priv_data; |
|
AVIndexEntry *ie; |
|
AVStream *st = s->streams[0]; |
|
int64_t ret = av_index_search_timestamp(st, timestamp, flags); |
|
uint32_t header = 0; |
|
|
|
if (!mp3->xing_toc) |
|
return AVERROR(ENOSYS); |
|
|
|
if (ret < 0) |
|
return ret; |
|
|
|
ie = &st->index_entries[ret]; |
|
ret = avio_seek(s->pb, ie->pos, SEEK_SET); |
|
if (ret < 0) |
|
return ret; |
|
|
|
while (!s->pb->eof_reached) { |
|
header = (header << 8) + avio_r8(s->pb); |
|
if (ff_mpa_check_header(header) >= 0) { |
|
ff_update_cur_dts(s, st, ie->timestamp); |
|
ret = avio_seek(s->pb, -4, SEEK_CUR); |
|
return (ret >= 0) ? 0 : ret; |
|
} |
|
} |
|
|
|
return AVERROR_EOF; |
|
} |
|
|
|
AVInputFormat ff_mp3_demuxer = { |
|
.name = "mp3", |
|
.long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"), |
|
.read_probe = mp3_read_probe, |
|
.read_header = mp3_read_header, |
|
.read_packet = mp3_read_packet, |
|
.read_seek = mp3_seek, |
|
.priv_data_size = sizeof(MP3DecContext), |
|
.flags = AVFMT_GENERIC_INDEX, |
|
.extensions = "mp2,mp3,m2a", /* XXX: use probe */ |
|
};
|
|
|