3 * Copyright (c) 2003 Fabrice Bellard
4 * Copyright (c) 2003 Michael Niedermayer
6 * This file is part of FFmpeg.
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 #include "mpegaudio.h"
25 #include "mpegaudiodecheader.h"
28 typedef struct MpegAudioParseContext {
33 } MpegAudioParseContext;
35 #define MPA_HEADER_SIZE 4
37 /* header + layer + bitrate + freq + lsf/mpeg25 */
38 #undef SAME_HEADER_MASK /* mpegaudio.h defines different version */
39 #define SAME_HEADER_MASK \
40 (0xffe00000 | (3 << 17) | (3 << 10) | (3 << 19))
42 /* useful helper to get mpeg audio stream infos. Return -1 if error in
43 header, otherwise the coded frame size in bytes */
44 int ff_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bit_rate)
46 MPADecodeHeader s1, *s = &s1;
48 if (ff_mpa_check_header(head) != 0)
51 if (ff_mpegaudio_decode_header(s, head) != 0) {
57 avctx->codec_id = CODEC_ID_MP1;
61 avctx->codec_id = CODEC_ID_MP2;
66 avctx->codec_id = CODEC_ID_MP3;
74 *sample_rate = s->sample_rate;
75 *channels = s->nb_channels;
76 *bit_rate = s->bit_rate;
77 avctx->sub_id = s->layer;
81 static int mpegaudio_parse(AVCodecParserContext *s1,
82 AVCodecContext *avctx,
83 const uint8_t **poutbuf, int *poutbuf_size,
84 const uint8_t *buf, int buf_size)
86 MpegAudioParseContext *s = s1->priv_data;
87 ParseContext *pc = &s->pc;
88 uint32_t state= pc->state;
90 int next= END_NOT_FOUND;
92 for(i=0; i<buf_size; ){
94 int inc= FFMIN(buf_size - i, s->frame_size);
104 int ret, sr, channels, bit_rate, frame_size;
106 state= (state<<8) + buf[i++];
108 ret = ff_mpa_decode_header(avctx, state, &sr, &channels, &frame_size, &bit_rate);
112 if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
116 s->frame_size = ret-4;
118 if(s->header_count > 1){
119 avctx->sample_rate= sr;
120 avctx->channels = channels;
121 avctx->frame_size = frame_size;
122 avctx->bit_rate = bit_rate;
131 if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
138 *poutbuf_size = buf_size;
143 AVCodecParser ff_mpegaudio_parser = {
144 { CODEC_ID_MP1, CODEC_ID_MP2, CODEC_ID_MP3 },
145 sizeof(MpegAudioParseContext),