Replace FFmpeg with Libav in licence headers
[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 "avformat.h"
25 #include "id3v2.h"
26 #include "id3v1.h"
27 #include "libavcodec/mpegaudiodecheader.h"
28
29 /* mp3 read */
30
31 static int mp3_read_probe(AVProbeData *p)
32 {
33 int max_frames, first_frames = 0;
34 int fsize, frames, sample_rate;
35 uint32_t header;
36 uint8_t *buf, *buf0, *buf2, *end;
37 AVCodecContext avctx;
38
39 buf0 = p->buf;
40 end = p->buf + p->buf_size - sizeof(uint32_t);
41 while(buf0 < end && !*buf0)
42 buf0++;
43
44 max_frames = 0;
45 buf = buf0;
46
47 for(; buf < end; buf= buf2+1) {
48 buf2 = buf;
49
50 for(frames = 0; buf2 < end; frames++) {
51 header = AV_RB32(buf2);
52 fsize = ff_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
53 if(fsize < 0)
54 break;
55 buf2 += fsize;
56 }
57 max_frames = FFMAX(max_frames, frames);
58 if(buf == buf0)
59 first_frames= frames;
60 }
61 // keep this in sync with ac3 probe, both need to avoid
62 // issues with MPEG-files!
63 if (first_frames>=4) return AVPROBE_SCORE_MAX/2+1;
64 else if(max_frames>500)return AVPROBE_SCORE_MAX/2;
65 else if(max_frames>=4) return AVPROBE_SCORE_MAX/4;
66 else if(max_frames>=1) return 1;
67 else return 0;
68 //mpegps_mp3_unrecognized_format.mpg has max_frames=3
69 }
70
71 /**
72 * Try to find Xing/Info/VBRI tags and compute duration from info therein
73 */
74 static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
75 {
76 uint32_t v, spf;
77 unsigned frames = 0; /* Total number of frames in file */
78 unsigned size = 0; /* Total number of bytes in the stream */
79 const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
80 MPADecodeHeader c;
81 int vbrtag_size = 0;
82
83 v = avio_rb32(s->pb);
84 if(ff_mpa_check_header(v) < 0)
85 return -1;
86
87 if (ff_mpegaudio_decode_header(&c, v) == 0)
88 vbrtag_size = c.frame_size;
89 if(c.layer != 3)
90 return -1;
91
92 /* Check for Xing / Info tag */
93 avio_seek(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1], SEEK_CUR);
94 v = avio_rb32(s->pb);
95 if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) {
96 v = avio_rb32(s->pb);
97 if(v & 0x1)
98 frames = avio_rb32(s->pb);
99 if(v & 0x2)
100 size = avio_rb32(s->pb);
101 }
102
103 /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
104 avio_seek(s->pb, base + 4 + 32, SEEK_SET);
105 v = avio_rb32(s->pb);
106 if(v == MKBETAG('V', 'B', 'R', 'I')) {
107 /* Check tag version */
108 if(avio_rb16(s->pb) == 1) {
109 /* skip delay and quality */
110 avio_skip(s->pb, 4);
111 frames = avio_rb32(s->pb);
112 size = avio_rb32(s->pb);
113 }
114 }
115
116 if(!frames && !size)
117 return -1;
118
119 /* Skip the vbr tag frame */
120 avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
121
122 spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
123 if(frames)
124 st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
125 st->time_base);
126 if(size && frames)
127 st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf);
128
129 return 0;
130 }
131
132 static int mp3_read_header(AVFormatContext *s,
133 AVFormatParameters *ap)
134 {
135 AVStream *st;
136 int64_t off;
137
138 st = av_new_stream(s, 0);
139 if (!st)
140 return AVERROR(ENOMEM);
141
142 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
143 st->codec->codec_id = CODEC_ID_MP3;
144 st->need_parsing = AVSTREAM_PARSE_FULL;
145 st->start_time = 0;
146
147 // lcm of all mp3 sample rates
148 av_set_pts_info(st, 64, 1, 14112000);
149
150 off = avio_tell(s->pb);
151
152 if (!av_metadata_get(s->metadata, "", NULL, AV_METADATA_IGNORE_SUFFIX))
153 ff_id3v1_read(s);
154
155 if (mp3_parse_vbr_tags(s, st, off) < 0)
156 avio_seek(s->pb, off, SEEK_SET);
157
158 /* the parameters will be extracted from the compressed bitstream */
159 return 0;
160 }
161
162 #define MP3_PACKET_SIZE 1024
163
164 static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
165 {
166 int ret, size;
167 // AVStream *st = s->streams[0];
168
169 size= MP3_PACKET_SIZE;
170
171 ret= av_get_packet(s->pb, pkt, size);
172
173 pkt->stream_index = 0;
174 if (ret <= 0) {
175 return AVERROR(EIO);
176 }
177
178 if (ret > ID3v1_TAG_SIZE &&
179 memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0)
180 ret -= ID3v1_TAG_SIZE;
181
182 /* note: we need to modify the packet size here to handle the last
183 packet */
184 pkt->size = ret;
185 return ret;
186 }
187
188 AVInputFormat ff_mp3_demuxer = {
189 "mp3",
190 NULL_IF_CONFIG_SMALL("MPEG audio layer 2/3"),
191 0,
192 mp3_read_probe,
193 mp3_read_header,
194 mp3_read_packet,
195 .flags= AVFMT_GENERIC_INDEX,
196 .extensions = "mp2,mp3,m2a", /* XXX: use probe */
197 };