cyuv.c 5.86 KB
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/*
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 * Creative YUV (CYUV) Video Decoder
 *   by Mike Melanson (melanson@pcisys.net)
 * based on "Creative YUV (CYUV) stream format for AVI":
 *   http://www.csse.monash.edu.au/~timf/videocodec/cyuv.txt
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 *
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 * Copyright (C) 2003 The FFmpeg project
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 *
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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
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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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 * 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
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 */

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/**
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 * @file
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 * Creative YUV (CYUV) Video Decoder.
 */
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#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "avcodec.h"
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#include "internal.h"
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#include "libavutil/internal.h"
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typedef struct CyuvDecodeContext {
    AVCodecContext *avctx;
    int width, height;
} CyuvDecodeContext;

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static av_cold int cyuv_decode_init(AVCodecContext *avctx)
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{
    CyuvDecodeContext *s = avctx->priv_data;

    s->avctx = avctx;
    s->width = avctx->width;
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    /* width needs to be divisible by 4 for this codec to work */
    if (s->width & 0x3)
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        return AVERROR_INVALIDDATA;
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    s->height = avctx->height;
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    avctx->pix_fmt = AV_PIX_FMT_YUV411P;
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    return 0;
}

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static int cyuv_decode_frame(AVCodecContext *avctx,
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                             void *data, int *got_frame,
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                             AVPacket *avpkt)
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{
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    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
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    CyuvDecodeContext *s=avctx->priv_data;
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    AVFrame *frame = data;
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    unsigned char *y_plane;
    unsigned char *u_plane;
    unsigned char *v_plane;
    int y_ptr;
    int u_ptr;
    int v_ptr;

    /* prediction error tables (make it clear that they are signed values) */
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    const signed char *y_table = (const signed char*)buf +  0;
    const signed char *u_table = (const signed char*)buf + 16;
    const signed char *v_table = (const signed char*)buf + 32;
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    unsigned char y_pred, u_pred, v_pred;
    int stream_ptr;
    unsigned char cur_byte;
    int pixel_groups;
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    int ret;
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    if (avctx->codec_id == AV_CODEC_ID_AURA) {
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        y_table = u_table;
        u_table = v_table;
    }
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    /* sanity check the buffer size: A buffer has 3x16-bytes tables
     * followed by (height) lines each with 3 bytes to represent groups
     * of 4 pixels. Thus, the total size of the buffer ought to be:
     *    (3 * 16) + height * (width * 3 / 4) */
    if (buf_size != 48 + s->height * (s->width * 3 / 4)) {
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        av_log(avctx, AV_LOG_ERROR, "got a buffer with %d bytes when %d were expected\n",
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               buf_size, 48 + s->height * (s->width * 3 / 4));
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        return AVERROR_INVALIDDATA;
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    }

    /* pixel data starts 48 bytes in, after 3x16-byte tables */
    stream_ptr = 48;

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    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) {
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        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
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        return ret;
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    }

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    y_plane = frame->data[0];
    u_plane = frame->data[1];
    v_plane = frame->data[2];
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    /* iterate through each line in the height */
    for (y_ptr = 0, u_ptr = 0, v_ptr = 0;
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         y_ptr < (s->height * frame->linesize[0]);
         y_ptr += frame->linesize[0] - s->width,
         u_ptr += frame->linesize[1] - s->width / 4,
         v_ptr += frame->linesize[2] - s->width / 4) {
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        /* reset predictors */
        cur_byte = buf[stream_ptr++];
        u_plane[u_ptr++] = u_pred = cur_byte & 0xF0;
        y_plane[y_ptr++] = y_pred = (cur_byte & 0x0F) << 4;

        cur_byte = buf[stream_ptr++];
        v_plane[v_ptr++] = v_pred = cur_byte & 0xF0;
        y_pred += y_table[cur_byte & 0x0F];
        y_plane[y_ptr++] = y_pred;

        cur_byte = buf[stream_ptr++];
        y_pred += y_table[cur_byte & 0x0F];
        y_plane[y_ptr++] = y_pred;
        y_pred += y_table[(cur_byte & 0xF0) >> 4];
        y_plane[y_ptr++] = y_pred;

        /* iterate through the remaining pixel groups (4 pixels/group) */
        pixel_groups = s->width / 4 - 1;
        while (pixel_groups--) {

            cur_byte = buf[stream_ptr++];
            u_pred += u_table[(cur_byte & 0xF0) >> 4];
            u_plane[u_ptr++] = u_pred;
            y_pred += y_table[cur_byte & 0x0F];
            y_plane[y_ptr++] = y_pred;

            cur_byte = buf[stream_ptr++];
            v_pred += v_table[(cur_byte & 0xF0) >> 4];
            v_plane[v_ptr++] = v_pred;
            y_pred += y_table[cur_byte & 0x0F];
            y_plane[y_ptr++] = y_pred;

            cur_byte = buf[stream_ptr++];
            y_pred += y_table[cur_byte & 0x0F];
            y_plane[y_ptr++] = y_pred;
            y_pred += y_table[(cur_byte & 0xF0) >> 4];
            y_plane[y_ptr++] = y_pred;

        }
    }

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    *got_frame = 1;
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    return buf_size;
}

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#if CONFIG_AURA_DECODER
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AVCodec ff_aura_decoder = {
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    .name           = "aura",
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    .long_name      = NULL_IF_CONFIG_SMALL("Auravision AURA"),
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    .type           = AVMEDIA_TYPE_VIDEO,
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    .id             = AV_CODEC_ID_AURA,
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    .priv_data_size = sizeof(CyuvDecodeContext),
    .init           = cyuv_decode_init,
    .decode         = cyuv_decode_frame,
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    .capabilities   = AV_CODEC_CAP_DR1,
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};
#endif

#if CONFIG_CYUV_DECODER
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AVCodec ff_cyuv_decoder = {
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    .name           = "cyuv",
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    .long_name      = NULL_IF_CONFIG_SMALL("Creative YUV (CYUV)"),
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    .type           = AVMEDIA_TYPE_VIDEO,
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    .id             = AV_CODEC_ID_CYUV,
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    .priv_data_size = sizeof(CyuvDecodeContext),
    .init           = cyuv_decode_init,
    .decode         = cyuv_decode_frame,
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    .capabilities   = AV_CODEC_CAP_DR1,
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};
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#endif