gsmdec.c 4.11 KB
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/*
 * gsm 06.10 decoder
 * Copyright (c) 2010 Reimar Döffinger <Reimar.Doeffinger@gmx.de>
 *
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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
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
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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
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * 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
 */

/**
 * @file
 * GSM decoder
 */

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#include "libavutil/channel_layout.h"
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#include "avcodec.h"
#include "get_bits.h"
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#include "internal.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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    avctx->channels       = 1;
    avctx->channel_layout = AV_CH_LAYOUT_MONO;
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    if (!avctx->sample_rate)
        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 AV_CODEC_ID_GSM:
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        avctx->frame_size  = GSM_FRAME_SIZE;
        avctx->block_align = GSM_BLOCK_SIZE;
        break;
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    case AV_CODEC_ID_GSM_MS:
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        avctx->frame_size  = 2 * GSM_FRAME_SIZE;
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        if (!avctx->block_align)
            avctx->block_align = GSM_MS_BLOCK_SIZE;
        else
            if (avctx->block_align < MSN_MIN_BLOCK_SIZE ||
                avctx->block_align > GSM_MS_BLOCK_SIZE  ||
                (avctx->block_align - MSN_MIN_BLOCK_SIZE) % 3) {
                av_log(avctx, AV_LOG_ERROR, "Invalid block alignment %d\n",
                       avctx->block_align);
                return AVERROR_INVALIDDATA;
            }
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    }

    return 0;
}

static int gsm_decode_frame(AVCodecContext *avctx, void *data,
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                            int *got_frame_ptr, AVPacket *avpkt)
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{
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    AVFrame *frame = data;
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    int res;
    GetBitContext gb;
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
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    int16_t *samples;
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    if (buf_size < avctx->block_align) {
        av_log(avctx, AV_LOG_ERROR, "Packet is too small\n");
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        return AVERROR_INVALIDDATA;
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    }
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    /* get output buffer */
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    frame->nb_samples = avctx->frame_size;
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    if ((res = ff_get_buffer(avctx, frame, 0)) < 0) {
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        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
        return res;
    }
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    samples = (int16_t *)frame->data[0];
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    switch (avctx->codec_id) {
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    case AV_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)
            av_log(avctx, AV_LOG_WARNING, "Missing GSM magic!\n");
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        res = gsm_decode_block(avctx, samples, &gb, GSM_13000);
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        if (res < 0)
            return res;
        break;
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    case AV_CODEC_ID_GSM_MS:
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        res = ff_msgsm_decode_block(avctx, samples, buf,
                                    (GSM_MS_BLOCK_SIZE - avctx->block_align) / 3);
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        if (res < 0)
            return res;
    }
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    *got_frame_ptr = 1;
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    return avctx->block_align;
}

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static void gsm_flush(AVCodecContext *avctx)
{
    GSMContext *s = avctx->priv_data;
    memset(s, 0, sizeof(*s));
}

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AVCodec ff_gsm_decoder = {
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    .name           = "gsm",
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    .long_name      = NULL_IF_CONFIG_SMALL("GSM"),
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    .type           = AVMEDIA_TYPE_AUDIO,
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    .id             = AV_CODEC_ID_GSM,
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    .priv_data_size = sizeof(GSMContext),
    .init           = gsm_init,
    .decode         = gsm_decode_frame,
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    .flush          = gsm_flush,
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    .capabilities   = AV_CODEC_CAP_DR1,
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};

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AVCodec ff_gsm_ms_decoder = {
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    .name           = "gsm_ms",
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    .long_name      = NULL_IF_CONFIG_SMALL("GSM Microsoft variant"),
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    .type           = AVMEDIA_TYPE_AUDIO,
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    .id             = AV_CODEC_ID_GSM_MS,
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    .priv_data_size = sizeof(GSMContext),
    .init           = gsm_init,
    .decode         = gsm_decode_frame,
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    .flush          = gsm_flush,
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    .capabilities   = AV_CODEC_CAP_DR1,
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};