PeerStreamer

/*

 * Real Audio 1.0 (14.4K)

 *

 * Copyright (c) 2008 Vitor Sessak

 * Copyright (c) 2003 Nick Kurshev

 *     Based on public domain decoder at http://www.honeypot.net/audio

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * 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.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * 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

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

#include "libavutil/intmath.h"

#include "avcodec.h"

#include "get_bits.h"

#include "ra144.h"

static av_cold int ra144_decode_init(AVCodecContext * avctx)

{

    RA144Context *ractx = avctx->priv_data;

    ractx->avctx = avctx;

    ractx->lpc_coef[0] = ractx->lpc_tables[0];

    ractx->lpc_coef[1] = ractx->lpc_tables[1];

    avctx->sample_fmt = SAMPLE_FMT_S16;

    return 0;

}

static void do_output_subblock(RA144Context *ractx, const uint16_t  *lpc_coefs,

                               int gval, GetBitContext *gb)

{

    int cba_idx = get_bits(gb, 7); // index of the adaptive CB, 0 if none

    int gain    = get_bits(gb, 8);

    int cb1_idx = get_bits(gb, 7);

    int cb2_idx = get_bits(gb, 7);

    ff_subblock_synthesis(ractx, lpc_coefs, cba_idx, cb1_idx, cb2_idx, gval,

                          gain);

}

/** Uncompress one block (20 bytes -> 160*2 bytes). */

static int ra144_decode_frame(AVCodecContext * avctx, void *vdata,

                              int *data_size, AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    static const uint8_t sizes[10] = {6, 5, 5, 4, 4, 3, 3, 3, 3, 2};

    unsigned int refl_rms[4];    // RMS of the reflection coefficients

    uint16_t block_coefs[4][10]; // LPC coefficients of each sub-block

    unsigned int lpc_refl[10];   // LPC reflection coefficients of the frame

    int i, j;

    int16_t *data = vdata;

    unsigned int energy;

    RA144Context *ractx = avctx->priv_data;

    GetBitContext gb;

    if (*data_size < 2*160)

        return -1;

    if(buf_size < 20) {

        av_log(avctx, AV_LOG_ERROR,

               "Frame too small (%d bytes). Truncated file?\n", buf_size);

        *data_size = 0;

        return buf_size;

    }

    init_get_bits(&gb, buf, 20 * 8);

    for (i=0; i<10; i++)

        lpc_refl[i] = ff_lpc_refl_cb[i][get_bits(&gb, sizes[i])];

    ff_eval_coefs(ractx->lpc_coef[0], lpc_refl);

    ractx->lpc_refl_rms[0] = ff_rms(lpc_refl);

    energy = ff_energy_tab[get_bits(&gb, 5)];

    refl_rms[0] = ff_interp(ractx, block_coefs[0], 1, 1, ractx->old_energy);

    refl_rms[1] = ff_interp(ractx, block_coefs[1], 2,

                            energy <= ractx->old_energy,

                            ff_t_sqrt(energy*ractx->old_energy) >> 12);

    refl_rms[2] = ff_interp(ractx, block_coefs[2], 3, 0, energy);

    refl_rms[3] = ff_rescale_rms(ractx->lpc_refl_rms[0], energy);

    ff_int_to_int16(block_coefs[3], ractx->lpc_coef[0]);

    for (i=0; i < 4; i++) {

        do_output_subblock(ractx, block_coefs[i], refl_rms[i], &gb);

        for (j=0; j < BLOCKSIZE; j++)

            *data++ = av_clip_int16(ractx->curr_sblock[j + 10] << 2);

    }

    ractx->old_energy = energy;

    ractx->lpc_refl_rms[1] = ractx->lpc_refl_rms[0];

    FFSWAP(unsigned int *, ractx->lpc_coef[0], ractx->lpc_coef[1]);

    *data_size = 2*160;

    return 20;

}

AVCodec ra_144_decoder =

{

    "real_144",

    AVMEDIA_TYPE_AUDIO,

    CODEC_ID_RA_144,

    sizeof(RA144Context),

    ra144_decode_init,

    NULL,

    NULL,

    ra144_decode_frame,

    .long_name = NULL_IF_CONFIG_SMALL("RealAudio 1.0 (14.4K)"),

};