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ffmpeg / libavcodec / aac_ac3_parser.c @ bf2cdefc

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/*
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 * Common AAC and AC-3 parser
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 * Copyright (c) 2003 Fabrice Bellard.
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 * Copyright (c) 2003 Michael Niedermayer.
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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#include "parser.h"
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#include "aac_ac3_parser.h"
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int ff_aac_ac3_parse(AVCodecParserContext *s1,
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                     AVCodecContext *avctx,
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                     const uint8_t **poutbuf, int *poutbuf_size,
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                     const uint8_t *buf, int buf_size)
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{
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    AACAC3ParseContext *s = s1->priv_data;
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    ParseContext *pc = &s->pc;
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    int len, i;
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    int new_frame_start;
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get_next:
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    i=END_NOT_FOUND;
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    if(s->remaining_size <= buf_size){
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        if(s->remaining_size && !s->need_next_header){
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            i= s->remaining_size;
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            s->remaining_size = 0;
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        }else{ //we need a header first
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            len=0;
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            for(i=s->remaining_size; i<buf_size; i++){
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                s->state = (s->state<<8) + buf[i];
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                if((len=s->sync(s->state, s, &s->need_next_header, &new_frame_start)))
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                    break;
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            }
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            if(len<=0){
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                i=END_NOT_FOUND;
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            }else{
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                s->state=0;
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                i-= s->header_size -1;
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                s->remaining_size = len;
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                if(!new_frame_start || pc->index+i<=0){
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                    s->remaining_size += i;
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                    goto get_next;
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                }
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            }
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        }
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    }
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    if(ff_combine_frame(pc, i, &buf, &buf_size)<0){
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        s->remaining_size -= FFMIN(s->remaining_size, buf_size);
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        *poutbuf = NULL;
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        *poutbuf_size = 0;
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        return buf_size;
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    }
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    *poutbuf = buf;
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    *poutbuf_size = buf_size;
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    /* update codec info */
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    avctx->sample_rate = s->sample_rate;
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    /* allow downmixing to stereo (or mono for AC-3) */
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    if(avctx->request_channels > 0 &&
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            avctx->request_channels < s->channels &&
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            (avctx->request_channels <= 2 ||
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            (avctx->request_channels == 1 &&
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            (avctx->codec_id == CODEC_ID_AC3 ||
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             avctx->codec_id == CODEC_ID_EAC3)))) {
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        avctx->channels = avctx->request_channels;
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    } else {
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        avctx->channels = s->channels;
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    }
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    avctx->bit_rate = s->bit_rate;
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    avctx->frame_size = s->samples;
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    return i;
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}