yading@10: /*
yading@10:  * MPEG Audio parser
yading@10:  * Copyright (c) 2003 Fabrice Bellard
yading@10:  * Copyright (c) 2003 Michael Niedermayer
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: #include "parser.h"
yading@10: #include "mpegaudiodecheader.h"
yading@10: #include "libavutil/common.h"
yading@10: 
yading@10: 
yading@10: typedef struct MpegAudioParseContext {
yading@10:     ParseContext pc;
yading@10:     int frame_size;
yading@10:     uint32_t header;
yading@10:     int header_count;
yading@10:     int no_bitrate;
yading@10: } MpegAudioParseContext;
yading@10: 
yading@10: #define MPA_HEADER_SIZE 4
yading@10: 
yading@10: /* header + layer + bitrate + freq + lsf/mpeg25 */
yading@10: #define SAME_HEADER_MASK \
yading@10:    (0xffe00000 | (3 << 17) | (3 << 10) | (3 << 19))
yading@10: 
yading@10: static int mpegaudio_parse(AVCodecParserContext *s1,
yading@10:                            AVCodecContext *avctx,
yading@10:                            const uint8_t **poutbuf, int *poutbuf_size,
yading@10:                            const uint8_t *buf, int buf_size)
yading@10: {
yading@10:     MpegAudioParseContext *s = s1->priv_data;
yading@10:     ParseContext *pc = &s->pc;
yading@10:     uint32_t state= pc->state;
yading@10:     int i;
yading@10:     int next= END_NOT_FOUND;
yading@10: 
yading@10:     for(i=0; i<buf_size; ){
yading@10:         if(s->frame_size){
yading@10:             int inc= FFMIN(buf_size - i, s->frame_size);
yading@10:             i += inc;
yading@10:             s->frame_size -= inc;
yading@10:             state = 0;
yading@10: 
yading@10:             if(!s->frame_size){
yading@10:                 next= i;
yading@10:                 break;
yading@10:             }
yading@10:         }else{
yading@10:             while(i<buf_size){
yading@10:                 int ret, sr, channels, bit_rate, frame_size;
yading@10: 
yading@10:                 state= (state<<8) + buf[i++];
yading@10: 
yading@10:                 ret = avpriv_mpa_decode_header(avctx, state, &sr, &channels, &frame_size, &bit_rate);
yading@10:                 if (ret < 4) {
yading@10:                     if (i > 4)
yading@10:                         s->header_count = -2;
yading@10:                 } else {
yading@10:                     if((state&SAME_HEADER_MASK) != (s->header&SAME_HEADER_MASK) && s->header)
yading@10:                         s->header_count= -3;
yading@10:                     s->header= state;
yading@10:                     s->header_count++;
yading@10:                     s->frame_size = ret-4;
yading@10: 
yading@10:                     if (s->header_count > 0) {
yading@10:                         avctx->sample_rate= sr;
yading@10:                         avctx->channels   = channels;
yading@10:                         s1->duration      = frame_size;
yading@10:                         if (s->no_bitrate || !avctx->bit_rate) {
yading@10:                             s->no_bitrate = 1;
yading@10:                             avctx->bit_rate += (bit_rate - avctx->bit_rate) / s->header_count;
yading@10:                         }
yading@10:                     }
yading@10:                     break;
yading@10:                 }
yading@10:             }
yading@10:         }
yading@10:     }
yading@10: 
yading@10:     pc->state= state;
yading@10:     if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {
yading@10:         *poutbuf = NULL;
yading@10:         *poutbuf_size = 0;
yading@10:         return buf_size;
yading@10:     }
yading@10: 
yading@10:     *poutbuf = buf;
yading@10:     *poutbuf_size = buf_size;
yading@10:     return next;
yading@10: }
yading@10: 
yading@10: 
yading@10: AVCodecParser ff_mpegaudio_parser = {
yading@10:     .codec_ids      = { AV_CODEC_ID_MP1, AV_CODEC_ID_MP2, AV_CODEC_ID_MP3 },
yading@10:     .priv_data_size = sizeof(MpegAudioParseContext),
yading@10:     .parser_parse   = mpegaudio_parse,
yading@10:     .parser_close   = ff_parse_close,
yading@10: };