Improve descriptiveness of a number of codec and container long names
[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 "libavcodec/mpegaudiodecheader.h"
31
32 /* mp3 read */
33
34 static int mp3_read_probe(AVProbeData *p)
35 {
36 int max_frames, first_frames = 0;
37 int fsize, frames, sample_rate;
38 uint32_t header;
39 uint8_t *buf, *buf0, *buf2, *end;
40 AVCodecContext avctx;
41
42 buf0 = p->buf;
43 end = p->buf + p->buf_size - sizeof(uint32_t);
44 while(buf0 < end && !*buf0)
45 buf0++;
46
47 max_frames = 0;
48 buf = buf0;
49
50 for(; buf < end; buf= buf2+1) {
51 buf2 = buf;
52
53 for(frames = 0; buf2 < end; frames++) {
54 header = AV_RB32(buf2);
55 fsize = avpriv_mpa_decode_header(&avctx, header, &sample_rate, &sample_rate, &sample_rate, &sample_rate);
56 if(fsize < 0)
57 break;
58 buf2 += fsize;
59 }
60 max_frames = FFMAX(max_frames, frames);
61 if(buf == buf0)
62 first_frames= frames;
63 }
64 // keep this in sync with ac3 probe, both need to avoid
65 // issues with MPEG-files!
66 if (first_frames >= 4) return AVPROBE_SCORE_MAX / 2 + 1;
67
68 if (max_frames) {
69 int pes = 0, i;
70 unsigned int code = -1;
71
72 #define VIDEO_ID 0x000001e0
73 #define AUDIO_ID 0x000001c0
74 /* do a search for mpegps headers to be able to properly bias
75 * towards mpegps if we detect this stream as both. */
76 for (i = 0; i<p->buf_size; i++) {
77 code = (code << 8) + p->buf[i];
78 if ((code & 0xffffff00) == 0x100) {
79 if ((code & 0x1f0) == VIDEO_ID) pes++;
80 else if((code & 0x1e0) == AUDIO_ID) pes++;
81 }
82 }
83
84 if (pes)
85 max_frames = (max_frames + pes - 1) / pes;
86 }
87 if (max_frames > 500) return AVPROBE_SCORE_MAX / 2;
88 else if (max_frames >= 4) return AVPROBE_SCORE_MAX / 4;
89 else if (max_frames >= 1) return 1;
90 else return 0;
91 //mpegps_mp3_unrecognized_format.mpg has max_frames=3
92 }
93
94 /**
95 * Try to find Xing/Info/VBRI tags and compute duration from info therein
96 */
97 static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
98 {
99 uint32_t v, spf;
100 unsigned frames = 0; /* Total number of frames in file */
101 unsigned size = 0; /* Total number of bytes in the stream */
102 const int64_t xing_offtbl[2][2] = {{32, 17}, {17,9}};
103 MPADecodeHeader c;
104 int vbrtag_size = 0;
105
106 v = avio_rb32(s->pb);
107 if(ff_mpa_check_header(v) < 0)
108 return -1;
109
110 if (avpriv_mpegaudio_decode_header(&c, v) == 0)
111 vbrtag_size = c.frame_size;
112 if(c.layer != 3)
113 return -1;
114
115 /* Check for Xing / Info tag */
116 avio_skip(s->pb, xing_offtbl[c.lsf == 1][c.nb_channels == 1]);
117 v = avio_rb32(s->pb);
118 if(v == MKBETAG('X', 'i', 'n', 'g') || v == MKBETAG('I', 'n', 'f', 'o')) {
119 v = avio_rb32(s->pb);
120 if(v & 0x1)
121 frames = avio_rb32(s->pb);
122 if(v & 0x2)
123 size = avio_rb32(s->pb);
124 }
125
126 /* Check for VBRI tag (always 32 bytes after end of mpegaudio header) */
127 avio_seek(s->pb, base + 4 + 32, SEEK_SET);
128 v = avio_rb32(s->pb);
129 if(v == MKBETAG('V', 'B', 'R', 'I')) {
130 /* Check tag version */
131 if(avio_rb16(s->pb) == 1) {
132 /* skip delay and quality */
133 avio_skip(s->pb, 4);
134 size = avio_rb32(s->pb);
135 frames = avio_rb32(s->pb);
136 }
137 }
138
139 if(!frames && !size)
140 return -1;
141
142 /* Skip the vbr tag frame */
143 avio_seek(s->pb, base + vbrtag_size, SEEK_SET);
144
145 spf = c.lsf ? 576 : 1152; /* Samples per frame, layer 3 */
146 if(frames)
147 st->duration = av_rescale_q(frames, (AVRational){spf, c.sample_rate},
148 st->time_base);
149 if(size && frames)
150 st->codec->bit_rate = av_rescale(size, 8 * c.sample_rate, frames * (int64_t)spf);
151
152 return 0;
153 }
154
155 static int mp3_read_header(AVFormatContext *s)
156 {
157 AVStream *st;
158 int64_t off;
159
160 st = avformat_new_stream(s, NULL);
161 if (!st)
162 return AVERROR(ENOMEM);
163
164 st->codec->codec_type = AVMEDIA_TYPE_AUDIO;
165 st->codec->codec_id = CODEC_ID_MP3;
166 st->need_parsing = AVSTREAM_PARSE_FULL;
167 st->start_time = 0;
168
169 // lcm of all mp3 sample rates
170 avpriv_set_pts_info(st, 64, 1, 14112000);
171
172 off = avio_tell(s->pb);
173
174 if (!av_dict_get(s->metadata, "", NULL, AV_DICT_IGNORE_SUFFIX))
175 ff_id3v1_read(s);
176
177 if (mp3_parse_vbr_tags(s, st, off) < 0)
178 avio_seek(s->pb, off, SEEK_SET);
179
180 /* the parameters will be extracted from the compressed bitstream */
181 return 0;
182 }
183
184 #define MP3_PACKET_SIZE 1024
185
186 static int mp3_read_packet(AVFormatContext *s, AVPacket *pkt)
187 {
188 int ret;
189
190 ret = av_get_packet(s->pb, pkt, MP3_PACKET_SIZE);
191 if (ret < 0)
192 return ret;
193
194 pkt->stream_index = 0;
195
196 if (ret > ID3v1_TAG_SIZE &&
197 memcmp(&pkt->data[ret - ID3v1_TAG_SIZE], "TAG", 3) == 0)
198 ret -= ID3v1_TAG_SIZE;
199
200 /* note: we need to modify the packet size here to handle the last
201 packet */
202 pkt->size = ret;
203 return ret;
204 }
205
206 AVInputFormat ff_mp3_demuxer = {
207 .name = "mp3",
208 .long_name = NULL_IF_CONFIG_SMALL("MP2/3 (MPEG audio layer 2/3)"),
209 .read_probe = mp3_read_probe,
210 .read_header = mp3_read_header,
211 .read_packet = mp3_read_packet,
212 .flags = AVFMT_GENERIC_INDEX,
213 .extensions = "mp2,mp3,m2a", /* XXX: use probe */
214 };