414c7e9174c80a8b4d7024cc0be7cafdc8cb30e7
[libav.git] / libavformat / mp3dec.c
1 /*
2 * MP3 demuxer
3 * Copyright (c) 2003 Fabrice Bellard
4 *
5 * This file is part of Libav.
6 *
7 * Libav is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * Libav is distributed in the hope that it will be useful,
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
18 * License along with Libav; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "libavutil/avstring.h"
23 #include "libavutil/intreadwrite.h"
24 #include "libavutil/dict.h"
25 #include "libavutil/mathematics.h"
26 #include "avformat.h"
27 #include "internal.h"
28 #include "id3v2.h"
29 #include "id3v1.h"
30 #include "replaygain.h"
31
32 #include "libavcodec/mpegaudiodecheader.h"
33
34 #define XING_FLAG_FRAMES 0x01
35 #define XING_FLAG_SIZE 0x02
36 #define XING_FLAG_TOC 0x04
37
38 #define XING_TOC_COUNT 100
39
40 typedef struct MP3DecContext {
41 int xing_toc;
42 } MP3DecContext;
43
44 /* mp3 read */
45
46 static int mp3_read_probe(AVProbeData *p)
47 {
48 int max_frames, first_frames = 0;
49 int fsize, frames, sample_rate;
50 uint32_t header;
51 uint8_t *buf, *buf0, *buf2, *end;
52 AVCodecContext avctx;
53
54 buf0 = p->buf;
55 end = p->buf + p->buf_size - sizeof(uint32_t);
56 while(buf0 < end && !*buf0)
57 buf0++;
58
59 max_frames = 0;
60 buf = buf0;
61
62 for(; buf < end; buf= buf2+1) {
63 buf2 = buf;
64
65 for(frames = 0; buf2 < end; frames++) {
66 header = AV_RB32(buf2);
67 fsize = avpriv_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
68 if(fsize < 0)
69 break;
70 buf2 += fsize;
71 }
72 max_frames = FFMAX(max_frames, frames);
73 if(buf == buf0)
74 first_frames= frames;
75 }
76 // keep this in sync with ac3 probe, both need to avoid
77 // issues with MPEG-files!
78 if (first_frames >= 4) return AVPROBE_SCORE_EXTENSION + 1;
79
80 if (max_frames) {
81 int pes = 0, i;
82 unsigned int code = -1;
83
84 #define VIDEO_ID 0x000001e0
85 #define AUDIO_ID 0x000001c0
86 /* do a search for mpegps headers to be able to properly bias
87 * towards mpegps if we detect this stream as both. */
88 for (i = 0; i<p->buf_size; i++) {
89 code = (code << 8) + p->buf[i];
90 if ((code & 0xffffff00) == 0x100) {
91 if ((code & 0x1f0) == VIDEO_ID) pes++;
92 else if((code & 0x1e0) == AUDIO_ID) pes++;
93 }
94 }
95
96 if (pes)
97 max_frames = (max_frames + pes - 1) / pes;
98 }
99 if (max_frames > 500) return AVPROBE_SCORE_EXTENSION;
100 else if (max_frames >= 4) return AVPROBE_SCORE_EXTENSION / 2;
101 else if (max_frames >= 1) return 1;
102 else return 0;
103 //mpegps_mp3_unrecognized_format.mpg has max_frames=3
104 }
105
106 static void read_xing_toc(AVFormatContext *s, int64_t filesize, int64_t duration)
107 {
108 int i;
109 MP3DecContext *mp3 = s->priv_data;
110
111 if (!filesize &&
112 !(filesize = avio_size(s->pb))) {
113 av_log(s, AV_LOG_WARNING, "Cannot determine file size, skipping TOC table.\n");
114 return;
115 }
116
117 for (i = 0; i < XING_TOC_COUNT; i++) {
118 uint8_t b = avio_r8(s->pb);
119
120 av_add_index_entry(s->streams[0],
121 av_rescale(b, filesize, 256),
122 av_rescale(i, duration, XING_TOC_COUNT),
123 0, 0, AVINDEX_KEYFRAME);
124 }
125 mp3->xing_toc = 1;
126 }
127
128 /**
129 * Try to find Xing/Info/VBRI tags and compute duration from info therein
130 */
131 static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
132 {
133 uint32_t v, spf;
134 unsigned frames = 0; /* Total number of frames in file */
135 unsigned size = 0; /* Total number of bytes in the stream */
136 const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
137 MPADecodeHeader c;
138 int vbrtag_size = 0;
139 int is_cbr;
140
141 v = avio_rb32(s->pb);
142 if(ff_mpa_check_header(v) < 0)
143 return -1;
144
145 if (avpriv_mpegaudio_decode_header(&c, v) == 0)
146 vbrtag_size = c.frame_size;
147 if(c.layer != 3)
148 return -1;
149
150 spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
151
152 /* Check for Xing / Info tag */
153 avio_skip(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1]);
154 v = avio_rb32(s->pb);
155 is_cbr = v == MKBETAG('I', 'n', 'f', 'o');
156 if (v == MKBETAG('X', 'i', 'n', 'g') || is_cbr) {
157 v = avio_rb32(s->pb);
158 if(v & XING_FLAG_FRAMES)
159 frames = avio_rb32(s->pb);
160 if(v & XING_FLAG_SIZE)
161 size = avio_rb32(s->pb);
162 if (v & XING_FLAG_TOC && frames)
163 read_xing_toc(s, size, av_rescale_q(frames, (AVRational){spf, c.sample_rate},
164 st->time_base));
165 }
166
167 /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
168 avio_seek(s->pb, base + 4 + 32, SEEK_SET);
169 v = avio_rb32(s->pb);
170 if(v == MKBETAG('V', 'B', 'R', 'I')) {
171 /* Check tag version */
172 if(avio_rb16(s->pb) == 1) {
173 /* skip delay and quality */
174 avio_skip(s->pb, 4);
175 size = avio_rb32(s->pb);
176 frames = avio_rb32(s->pb);
177 }
178 }
179
180 if(!frames && !size)
181 return -1;
182
183 /* Skip the vbr tag frame */
184 avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
185
186 if(frames)
187 st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
188 st->time_base);
189 if (size && frames && !is_cbr)
190 st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf);
191
192 return 0;
193 }
194
195 static int mp3_read_header(AVFormatContext *s)
196 {
197 AVStream *st;
198 int64_t off;
199 int ret;
200
201 st = avformat_new_stream(s, NULL);
202 if (!st)
203 return AVERROR(ENOMEM);
204
205 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
206 st->codec->codec_id = AV_CODEC_ID_MP3;
207 st->need_parsing = AVSTREAM_PARSE_FULL;
208 st->start_time = 0;
209
210 // lcm of all mp3 sample rates
211 avpriv_set_pts_info(st, 64, 1, 14112000);
212
213 off = avio_tell(s->pb);
214
215 if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
216 ff_id3v1_read(s);
217
218 if (mp3_parse_vbr_tags(s, st, off) < 0)
219 avio_seek(s->pb, off, SEEK_SET);
220
221 ret = ff_replaygain_export(st, s->metadata);
222 if (ret < 0)
223 return ret;
224
225 /* the parameters will be extracted from the compressed bitstream */
226 return 0;
227 }
228
229 #define MP3_PACKET_SIZE 1024
230
231 static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
232 {
233 int ret;
234
235 ret = av_get_packet(s->pb, pkt, MP3_PACKET_SIZE);
236 if (ret < 0)
237 return ret;
238
239 pkt->stream_index = 0;
240
241 if (ret > ID3v1_TAG_SIZE &&
242 memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0)
243 ret -= ID3v1_TAG_SIZE;
244
245 /* note: we need to modify the packet size here to handle the last
246 packet */
247 pkt->size = ret;
248 return ret;
249 }
250
251 static int mp3_seek(AVFormatContext *s, int stream_index, int64_t timestamp,
252 int flags)
253 {
254 MP3DecContext *mp3 = s->priv_data;
255 AVIndexEntry *ie;
256 AVStream *st = s->streams[0];
257 int64_t ret = av_index_search_timestamp(st, timestamp, flags);
258 uint32_t header = 0;
259
260 if (!mp3->xing_toc)
261 return AVERROR(ENOSYS);
262
263 if (ret < 0)
264 return ret;
265
266 ie = &st->index_entries[ret];
267 ret = avio_seek(s->pb, ie->pos, SEEK_SET);
268 if (ret < 0)
269 return ret;
270
271 while (!s->pb->eof_reached) {
272 header = (header << 8) + avio_r8(s->pb);
273 if (ff_mpa_check_header(header) >= 0) {
274 ff_update_cur_dts(s, st, ie->timestamp);
275 ret = avio_seek(s->pb, -4, SEEK_CUR);
276 return (ret >= 0) ? 0 : ret;
277 }
278 }
279
280 return AVERROR_EOF;
281 }
282
283 AVInputFormat ff_mp3_demuxer = {
284 .name = "mp3",
285 .long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
286 .read_probe = mp3_read_probe,
287 .read_header = mp3_read_header,
288 .read_packet = mp3_read_packet,
289 .read_seek = mp3_seek,
290 .priv_data_size = sizeof(MP3DecContext),
291 .flags = AVFMT_GENERIC_INDEX,
292 .extensions = "mp2,mp3,m2a,mpa", /* XXX: use probe */
293 };