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ffmpeg / libavcodec / aac_ac3_parser.c @ be1e2a2b

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/*
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 * Common AAC and AC3 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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    AACAC3FrameFlag frame_flag;
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    const uint8_t *buf_ptr;
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    int len;
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    *poutbuf = NULL;
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    *poutbuf_size = 0;
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    buf_ptr = buf;
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    while (buf_size > 0) {
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        int size_needed= s->frame_size ? s->frame_size : s->header_size;
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        len = s->inbuf_ptr - s->inbuf;
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        if(len<size_needed){
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            len = FFMIN(size_needed - len, buf_size);
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            memcpy(s->inbuf_ptr, buf_ptr, len);
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            buf_ptr      += len;
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            s->inbuf_ptr += len;
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            buf_size     -= len;
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        }
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        if (s->frame_size == 0) {
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            if ((s->inbuf_ptr - s->inbuf) == s->header_size) {
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                len = s->sync(s, &frame_flag);
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                if (len == 0) {
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                    /* no sync found : move by one byte (inefficient, but simple!) */
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                    memmove(s->inbuf, s->inbuf + 1, s->header_size - 1);
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                    s->inbuf_ptr--;
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                } else {
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                    s->frame_size = len;
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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 AC3) */
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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->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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                }
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            }
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        } else {
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            if(s->inbuf_ptr - s->inbuf == s->frame_size){
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                *poutbuf = s->inbuf;
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                *poutbuf_size = s->frame_size;
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                s->inbuf_ptr = s->inbuf;
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                s->frame_size = 0;
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                break;
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            }
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        }
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    }
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    return buf_ptr - buf;
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}