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ffmpeg / libavcodec / gsmdec.c @ 2912e87a

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/*
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 * gsm 06.10 decoder
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 * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
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 *
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 * This file is part of Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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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/**
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 * @file
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 * GSM decoder
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 */
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#include "avcodec.h"
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#include "get_bits.h"
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#include "msgsmdec.h"
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#include "gsmdec_template.c"
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static av_cold int gsm_init(AVCodecContext *avctx)
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{
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    avctx->channels = 1;
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    if (!avctx->sample_rate)
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        avctx->sample_rate = 8000;
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    avctx->sample_fmt = AV_SAMPLE_FMT_S16;
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    switch (avctx->codec_id) {
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    case CODEC_ID_GSM:
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        avctx->frame_size  = GSM_FRAME_SIZE;
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        avctx->block_align = GSM_BLOCK_SIZE;
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        break;
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    case CODEC_ID_GSM_MS:
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        avctx->frame_size  = 2 * GSM_FRAME_SIZE;
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        avctx->block_align = GSM_MS_BLOCK_SIZE;
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    }
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    return 0;
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}
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static int gsm_decode_frame(AVCodecContext *avctx, void *data,
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                            int *data_size, AVPacket *avpkt)
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{
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    int res;
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    GetBitContext gb;
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    const uint8_t *buf = avpkt->data;
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    int buf_size = avpkt->size;
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    int16_t *samples = data;
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    int frame_bytes = 2 * avctx->frame_size;
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    if (*data_size < frame_bytes)
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        return -1;
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    *data_size = 0;
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    if(buf_size < avctx->block_align)
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        return AVERROR_INVALIDDATA;
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    switch (avctx->codec_id) {
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    case CODEC_ID_GSM:
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        init_get_bits(&gb, buf, buf_size * 8);
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        if (get_bits(&gb, 4) != 0xd)
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            av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
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        res = gsm_decode_block(avctx, samples, &gb);
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        if (res < 0)
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            return res;
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        break;
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    case CODEC_ID_GSM_MS:
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        res = ff_msgsm_decode_block(avctx, samples, buf);
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        if (res < 0)
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            return res;
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    }
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    *data_size = frame_bytes;
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    return avctx->block_align;
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}
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AVCodec ff_gsm_decoder = {
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    "gsm",
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    AVMEDIA_TYPE_AUDIO,
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    CODEC_ID_GSM,
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    sizeof(GSMContext),
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    gsm_init,
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    NULL,
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    NULL,
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    gsm_decode_frame,
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    .long_name = NULL_IF_CONFIG_SMALL("GSM"),
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};
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AVCodec ff_gsm_ms_decoder = {
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    "gsm_ms",
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    AVMEDIA_TYPE_AUDIO,
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    CODEC_ID_GSM_MS,
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    sizeof(GSMContext),
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    gsm_init,
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    NULL,
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    NULL,
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    gsm_decode_frame,
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    .long_name = NULL_IF_CONFIG_SMALL("GSM Microsoft variant"),
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};