PeerStreamer

/*

 * Westwood SNDx codecs

 * Copyright (c) 2005 Konstantin Shishkov

 *

 * This library 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 of the License, or (at your option) any later version.

 *

 * This library 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 this library; if not, write to the Free Software

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

 */

#include "avcodec.h"

/**

 * @file ws-snd.c

 * Westwood SNDx codecs.

 *

 * Reference documents about VQA format and its audio codecs

 * can be found here:

 * http://www.multimedia.cx

 */

typedef struct {

} WSSNDContext;

static const char ws_adpcm_2bit[] = { -2, -1, 0, 1};

static const char ws_adpcm_4bit[] = {

    -9, -8, -6, -5, -4, -3, -2, -1,

     0,  1,  2,  3,  4,  5,  6,  8 };

#define CLIP8(a) if(a>127)a=127;if(a<-128)a=-128;

static int ws_snd_decode_init(AVCodecContext * avctx)

{

//    WSSNDContext *c = avctx->priv_data;

    return 0;

}

static int ws_snd_decode_frame(AVCodecContext *avctx,

                void *data, int *data_size,

                uint8_t *buf, int buf_size)

{

//    WSSNDContext *c = avctx->priv_data;

    int in_size, out_size;

    int sample = 0;

    int i;

    short *samples = data;

    if (!buf_size)

        return 0;

    out_size = LE_16(&buf[0]);

    *data_size = out_size * 2;

    in_size = LE_16(&buf[2]);

    buf += 4;

    if (in_size == out_size) {

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

            *samples++ = (*buf++ - 0x80) << 8;

        return buf_size;

    }

    while (out_size > 0) {

        int code;

        uint8_t count;

        code = (*buf) >> 6;

        count = (*buf) & 0x3F;

        buf++;

        switch(code) {

        case 0: /* ADPCM 2-bit */

            for (count++; count > 0; count--) {

                code = *buf++;

                sample += ws_adpcm_2bit[code & 0x3];

                CLIP8(sample);

                *samples++ = sample << 8;

                sample += ws_adpcm_2bit[(code >> 2) & 0x3];

                CLIP8(sample);

                *samples++ = sample << 8;

                sample += ws_adpcm_2bit[(code >> 4) & 0x3];

                CLIP8(sample);

                *samples++ = sample << 8;

                sample += ws_adpcm_2bit[(code >> 6) & 0x3];

                CLIP8(sample);

                *samples++ = sample << 8;

                out_size -= 4;

            }

            break;

        case 1: /* ADPCM 4-bit */

            for (count++; count > 0; count--) {

                code = *buf++;

                sample += ws_adpcm_4bit[code & 0xF];

                CLIP8(sample);

                *samples++ = sample << 8;

                sample += ws_adpcm_4bit[code >> 4];

                CLIP8(sample);

                *samples++ = sample << 8;

                out_size -= 2;

            }

            break;

        case 2: /* no compression */

            if (count & 0x20) { /* big delta */

                char t;

                t = count;

                t <<= 3;

                sample += t >> 3;

                *samples++ = sample << 8;

                out_size--;

            } else { /* copy */

                for (count++; count > 0; count--) {

                    *samples++ = (*buf++ - 0x80) << 8;

                    out_size--;

                }

                sample = buf[-1] - 0x80;

            }

            break;

        default: /* run */

            for(count++; count > 0; count--) {

                *samples++ = sample << 8;

                out_size--;

            }

        }

    }

    return buf_size;

}

AVCodec ws_snd1_decoder = {

    "ws_snd1",

    CODEC_TYPE_AUDIO,

    CODEC_ID_WESTWOOD_SND1,

    sizeof(WSSNDContext),

    ws_snd_decode_init,

    NULL,

    NULL,

    ws_snd_decode_frame,

};