mp3dec: use named constants for Xing header flags
[libav.git] / libavformat / mp3dec.c
CommitLineData
115329f1 1/*
d08928bb 2 * MP3 demuxer
406792e7 3 * Copyright (c) 2003 Fabrice Bellard
6a58e151 4 *
2912e87a 5 * This file is part of Libav.
b78e7197 6 *
2912e87a 7 * Libav is free software; you can redistribute it and/or
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8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
b78e7197 10 * version 2.1 of the License, or (at your option) any later version.
6a58e151 11 *
2912e87a 12 * Libav is distributed in the hope that it will be useful,
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13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
2912e87a 18 * License along with Libav; if not, write to the Free Software
5509bffa 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
6a58e151 20 */
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21
22#include "libavutil/avstring.h"
ff06d76a 23#include "libavutil/intreadwrite.h"
d2d67e42 24#include "libavutil/dict.h"
0ebcdf5c 25#include "libavutil/mathematics.h"
6a58e151 26#include "avformat.h"
c3f9ebf7 27#include "internal.h"
2ea512a6 28#include "id3v2.h"
75411182 29#include "id3v1.h"
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30#include "libavcodec/mpegaudiodecheader.h"
31
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32#define XING_FLAG_FRAMES 0x01
33#define XING_FLAG_SIZE 0x02
34
6a58e151 35/* mp3 read */
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36
37static int mp3_read_probe(AVProbeData *p)
38{
ea7599ba 39 int max_frames, first_frames = 0;
498c544a 40 int fsize, frames, sample_rate;
abade142 41 uint32_t header;
ac3ef4a4 42 uint8_t *buf, *buf0, *buf2, *end;
abade142 43 AVCodecContext avctx;
dc4ed3b1 44
ac3ef4a4 45 buf0 = p->buf;
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46 end = p->buf + p->buf_size - sizeof(uint32_t);
47 while(buf0 < end && !*buf0)
48 buf0++;
dc4ed3b1 49
abade142 50 max_frames = 0;
ac3ef4a4 51 buf = buf0;
dc4ed3b1 52
5ef5501b 53 for(; buf < end; buf= buf2+1) {
abade142 54 buf2 = buf;
dc4ed3b1 55
d0702de9 56 for(frames = 0; buf2 < end; frames++) {
80fb8234 57 header = AV_RB32(buf2);
82ab61f9 58 fsize = avpriv_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
abade142
59 if(fsize < 0)
60 break;
61 buf2 += fsize;
62 }
63 max_frames = FFMAX(max_frames, frames);
ac3ef4a4 64 if(buf == buf0)
22668218 65 first_frames= frames;
abade142 66 }
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67 // keep this in sync with ac3 probe, both need to avoid
68 // issues with MPEG-files!
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69 if (first_frames >= 4) return AVPROBE_SCORE_MAX / 2 + 1;
70
71 if (max_frames) {
72 int pes = 0, i;
73 unsigned int code = -1;
74
75#define VIDEO_ID 0x000001e0
76#define AUDIO_ID 0x000001c0
77 /* do a search for mpegps headers to be able to properly bias
78 * towards mpegps if we detect this stream as both. */
79 for (i = 0; i<p->buf_size; i++) {
80 code = (code << 8) + p->buf[i];
81 if ((code & 0xffffff00) == 0x100) {
82 if ((code & 0x1f0) == VIDEO_ID) pes++;
83 else if((code & 0x1e0) == AUDIO_ID) pes++;
84 }
85 }
86
87 if (pes)
88 max_frames = (max_frames + pes - 1) / pes;
89 }
90 if (max_frames > 500) return AVPROBE_SCORE_MAX / 2;
91 else if (max_frames >= 4) return AVPROBE_SCORE_MAX / 4;
92 else if (max_frames >= 1) return 1;
93 else return 0;
f9f2ab82 94//mpegps_mp3_unrecognized_format.mpg has max_frames=3
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95}
96
ca851a3a 97/**
8862fb41 98 * Try to find Xing/Info/VBRI tags and compute duration from info therein
ca851a3a 99 */
853a9753 100static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
ca851a3a 101{
db233e83 102 uint32_t v, spf;
2a758efe 103 unsigned frames = 0; /* Total number of frames in file */
49d7ef28 104 unsigned size = 0; /* Total number of bytes in the stream */
bc5c918e 105 const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
cf92cec7 106 MPADecodeHeader c;
853a9753 107 int vbrtag_size = 0;
ca851a3a 108
b7effd4e 109 v = avio_rb32(s->pb);
5b5bd7c9 110 if(ff_mpa_check_header(v) < 0)
853a9753 111 return -1;
5b5bd7c9 112
82ab61f9 113 if (avpriv_mpegaudio_decode_header(&c, v) == 0)
853a9753 114 vbrtag_size = c.frame_size;
db233e83 115 if(c.layer != 3)
853a9753 116 return -1;
ca851a3a 117
db233e83 118 /* Check for Xing / Info tag */
e42500cb 119 avio_skip(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1]);
b7effd4e 120 v = avio_rb32(s->pb);
db233e83 121 if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) {
b7effd4e 122 v = avio_rb32(s->pb);
2d1a1a7f 123 if(v & XING_FLAG_FRAMES)
b7effd4e 124 frames = avio_rb32(s->pb);
2d1a1a7f 125 if(v & XING_FLAG_SIZE)
b7effd4e 126 size = avio_rb32(s->pb);
ca851a3a 127 }
db233e83 128
8862fb41 129 /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
6b4aa5da 130 avio_seek(s->pb, base + 4 + 32, SEEK_SET);
b7effd4e 131 v = avio_rb32(s->pb);
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132 if(v == MKBETAG('V', 'B', 'R', 'I')) {
133 /* Check tag version */
b7effd4e 134 if(avio_rb16(s->pb) == 1) {
49d7ef28 135 /* skip delay and quality */
45a8a02a 136 avio_skip(s->pb, 4);
b7effd4e 137 size = avio_rb32(s->pb);
c05e2be9 138 frames = avio_rb32(s->pb);
8862fb41
139 }
140 }
141
2a758efe 142 if(!frames && !size)
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143 return -1;
144
145 /* Skip the vbr tag frame */
6b4aa5da 146 avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
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147
148 spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
2a758efe 149 if(frames)
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150 st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
151 st->time_base);
7cf0472e 152 if(size && frames)
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153 st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf);
154
853a9753 155 return 0;
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156}
157
6e9651d1 158static int mp3_read_header(AVFormatContext *s)
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159{
160 AVStream *st;
bc5c918e 161 int64_t off;
6a58e151 162
3b3bbdd3 163 st = avformat_new_stream(s, NULL);
6a58e151 164 if (!st)
769e10f0 165 return AVERROR(ENOMEM);
6a58e151 166
72415b2a 167 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
36ef5369 168 st->codec->codec_id = AV_CODEC_ID_MP3;
57004ff1 169 st->need_parsing = AVSTREAM_PARSE_FULL;
f97931c1 170 st->start_time = 0;
115329f1 171
9c5a9e6b 172 // lcm of all mp3 sample rates
c3f9ebf7 173 avpriv_set_pts_info(st, 64, 1, 14112000);
9c5a9e6b 174
a2704c97 175 off = avio_tell(s->pb);
80242f9b 176
d2d67e42 177 if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
7fd5aeb3 178 ff_id3v1_read(s);
6a58e151 179
853a9753 180 if (mp3_parse_vbr_tags(s, st, off) < 0)
6b4aa5da 181 avio_seek(s->pb, off, SEEK_SET);
ca851a3a 182
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183 /* the parameters will be extracted from the compressed bitstream */
184 return 0;
185}
186
187#define MP3_PACKET_SIZE 1024
188
189static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
190{
67b1156f 191 int ret;
115329f1 192
67b1156f 193 ret = av_get_packet(s->pb, pkt, MP3_PACKET_SIZE);
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194 if (ret < 0)
195 return ret;
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196
197 pkt->stream_index = 0;
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198
199 if (ret > ID3v1_TAG_SIZE &&
200 memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0)
201 ret -= ID3v1_TAG_SIZE;
202
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203 /* note: we need to modify the packet size here to handle the last
204 packet */
205 pkt->size = ret;
206 return ret;
207}
208
c6610a21 209AVInputFormat ff_mp3_demuxer = {
dfc2c4d9 210 .name = "mp3",
0177b7d2 211 .long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
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212 .read_probe = mp3_read_probe,
213 .read_header = mp3_read_header,
214 .read_packet = mp3_read_packet,
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215 .flags = AVFMT_GENERIC_INDEX,
216 .extensions = "mp2,mp3,m2a", /* XXX: use probe */
de653ba3 217};