PeerStreamer

/*

 * Winnov WNV1 codec

 * Copyright (c) 2005 Konstantin Shishkov

 *

 * 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

 */

/**

 * @file

 * Winnov WNV1 codec.

 */

#include "avcodec.h"

#include "get_bits.h"

#include "libavutil/common.h"

typedef struct WNV1Context{

    AVCodecContext *avctx;

    AVFrame pic;

    int shift;

    GetBitContext gb;

} WNV1Context;

static const uint16_t code_tab[16][2]={

{0x1FD,9}, {0xFD,8}, {0x7D,7}, {0x3D,6}, {0x1D,5}, {0x0D,4}, {0x005,3},

{0x000,1},

{0x004,3}, {0x0C,4}, {0x1C,5}, {0x3C,6}, {0x7C,7}, {0xFC,8}, {0x1FC,9}, {0xFF,8}

};

#define CODE_VLC_BITS 9

static VLC code_vlc;

/* returns modified base_value */

static inline int wnv1_get_code(WNV1Context *w, int base_value)

{

    int v = get_vlc2(&w->gb, code_vlc.table, CODE_VLC_BITS, 1);

    if(v==15)

        return av_reverse[ get_bits(&w->gb, 8 - w->shift) ];

    else

        return base_value + ((v - 7)<<w->shift);

}

static int decode_frame(AVCodecContext *avctx,

                        void *data, int *data_size,

                        AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    WNV1Context * const l = avctx->priv_data;

    AVFrame * const p= (AVFrame*)&l->pic;

    unsigned char *Y,*U,*V;

    int i, j;

    int prev_y = 0, prev_u = 0, prev_v = 0;

    uint8_t *rbuf;

    rbuf = av_malloc(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);

    if(!rbuf){

        av_log(avctx, AV_LOG_ERROR, "Cannot allocate temporary buffer\n");

        return -1;

    }

    if(p->data[0])

        avctx->release_buffer(avctx, p);

    p->reference = 0;

    if(avctx->get_buffer(avctx, p) < 0){

        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

        av_free(rbuf);

        return -1;

    }

    p->key_frame = 1;

    for(i=8; i<buf_size; i++)

        rbuf[i]= av_reverse[ buf[i] ];

    init_get_bits(&l->gb, rbuf+8, (buf_size-8)*8);

    if (buf[2] >> 4 == 6)

        l->shift = 2;

    else {

        l->shift = 8 - (buf[2] >> 4);

        if (l->shift > 4) {

            av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4);

            l->shift = 4;

        }

        if (l->shift < 1) {

            av_log(avctx, AV_LOG_ERROR, "Unknown WNV1 frame header value %i, please upload file for study\n", buf[2] >> 4);

            l->shift = 1;

        }

    }

    Y = p->data[0];

    U = p->data[1];

    V = p->data[2];

    for (j = 0; j < avctx->height; j++) {

        for (i = 0; i < avctx->width / 2; i++) {

            Y[i * 2] = wnv1_get_code(l, prev_y);

            prev_u = U[i] = wnv1_get_code(l, prev_u);

            prev_y = Y[(i * 2) + 1] = wnv1_get_code(l, Y[i * 2]);

            prev_v = V[i] = wnv1_get_code(l, prev_v);

        }

        Y += p->linesize[0];

        U += p->linesize[1];

        V += p->linesize[2];

    }

    *data_size = sizeof(AVFrame);

    *(AVFrame*)data = l->pic;

    av_free(rbuf);

    return buf_size;

}

static av_cold int decode_init(AVCodecContext *avctx){

    WNV1Context * const l = avctx->priv_data;

    static VLC_TYPE code_table[1 << CODE_VLC_BITS][2];

    l->avctx = avctx;

    avctx->pix_fmt = PIX_FMT_YUV422P;

    code_vlc.table = code_table;

    code_vlc.table_allocated = 1 << CODE_VLC_BITS;

    init_vlc(&code_vlc, CODE_VLC_BITS, 16,

             &code_tab[0][1], 4, 2,

             &code_tab[0][0], 4, 2, INIT_VLC_USE_NEW_STATIC);

    return 0;

}

static av_cold int decode_end(AVCodecContext *avctx){

    WNV1Context * const l = avctx->priv_data;

    AVFrame *pic = &l->pic;

    if (pic->data[0])

        avctx->release_buffer(avctx, pic);

    return 0;

}

AVCodec ff_wnv1_decoder = {

    "wnv1",

    AVMEDIA_TYPE_VIDEO,

    CODEC_ID_WNV1,

    sizeof(WNV1Context),

    decode_init,

    NULL,

    decode_end,

    decode_frame,

    CODEC_CAP_DR1,

    .long_name = NULL_IF_CONFIG_SMALL("Winnov WNV1"),

};