wnv1.c 4.93 KB
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/*
 * Winnov WNV1 codec
 * Copyright (c) 2005 Konstantin Shishkov
 *
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 * This file is part of FFmpeg.
 *
 * FFmpeg 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
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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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 * FFmpeg 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 FFmpeg; 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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 * Winnov WNV1 codec.
 */
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#include "avcodec.h"
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#include "get_bits.h"
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#include "internal.h"
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#include "mathops.h"
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typedef struct WNV1Context {
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    AVCodecContext *avctx;
    AVFrame pic;

    int shift;
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    GetBitContext gb;
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} WNV1Context;

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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 }
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};

#define CODE_VLC_BITS 9
static VLC code_vlc;

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/* returns modified base_value */
static inline int wnv1_get_code(WNV1Context *w, int base_value)
{
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    int v = get_vlc2(&w->gb, code_vlc.table, CODE_VLC_BITS, 1);
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    if (v == 15)
        return ff_reverse[get_bits(&w->gb, 8 - w->shift)];
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    else
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        return base_value + ((v - 7) << w->shift);
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}

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static int decode_frame(AVCodecContext *avctx,
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                        void *data, int *got_frame,
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                        AVPacket *avpkt)
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{
    WNV1Context * const l = avctx->priv_data;
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    const uint8_t *buf    = avpkt->data;
    int buf_size          = avpkt->size;
    AVFrame * const p     = &l->pic;
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    unsigned char *Y,*U,*V;
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    int i, j, ret;
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    int prev_y = 0, prev_u = 0, prev_v = 0;
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    uint8_t *rbuf;

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    if(buf_size<=8) {
        av_log(avctx, AV_LOG_ERROR, "buf_size %d is too small\n", buf_size);
        return AVERROR_INVALIDDATA;
    }

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    rbuf = av_malloc(buf_size + FF_INPUT_BUFFER_PADDING_SIZE);
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    if (!rbuf) {
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        av_log(avctx, AV_LOG_ERROR, "Cannot allocate temporary buffer\n");
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        return AVERROR(ENOMEM);
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    }
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    if (p->data[0])
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        avctx->release_buffer(avctx, p);

    p->reference = 0;
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    if ((ret = ff_get_buffer(avctx, p)) < 0) {
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        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
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        av_free(rbuf);
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        return ret;
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    }
    p->key_frame = 1;
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    for (i = 8; i < buf_size; i++)
        rbuf[i] = ff_reverse[buf[i]];
    init_get_bits(&l->gb, rbuf + 8, (buf_size - 8) * 8);
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    if (buf[2] >> 4 == 6)
        l->shift = 2;
    else {
        l->shift = 8 - (buf[2] >> 4);
        if (l->shift > 4) {
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            av_log_ask_for_sample(avctx, "Unknown WNV1 frame header value %i\n",
                                  buf[2] >> 4);
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            l->shift = 4;
        }
        if (l->shift < 1) {
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            av_log_ask_for_sample(avctx, "Unknown WNV1 frame header value %i\n",
                                  buf[2] >> 4);
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            l->shift = 1;
        }
    }
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    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];
    }

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    *got_frame      = 1;
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    *(AVFrame*)data = l->pic;
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    av_free(rbuf);
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    return buf_size;
}

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static av_cold int decode_init(AVCodecContext *avctx)
{
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    WNV1Context * const l = avctx->priv_data;
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    static VLC_TYPE code_table[1 << CODE_VLC_BITS][2];
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    l->avctx       = avctx;
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    avctx->pix_fmt = AV_PIX_FMT_YUV422P;
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    avcodec_get_frame_defaults(&l->pic);
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    code_vlc.table           = code_table;
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    code_vlc.table_allocated = 1 << CODE_VLC_BITS;
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    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);
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    return 0;
}

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static av_cold int decode_end(AVCodecContext *avctx)
{
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    WNV1Context * const l = avctx->priv_data;
    AVFrame *pic = &l->pic;

    if (pic->data[0])
        avctx->release_buffer(avctx, pic);

    return 0;
}

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AVCodec ff_wnv1_decoder = {
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    .name           = "wnv1",
    .type           = AVMEDIA_TYPE_VIDEO,
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    .id             = AV_CODEC_ID_WNV1,
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    .priv_data_size = sizeof(WNV1Context),
    .init           = decode_init,
    .close          = decode_end,
    .decode         = decode_frame,
    .capabilities   = CODEC_CAP_DR1,
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    .long_name      = NULL_IF_CONFIG_SMALL("Winnov WNV1"),
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};