annotate ffmpeg/libavcodec/yuv4dec.c @ 13:844d341cf643 tip

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/*
 * libquicktime yuv4 decoder
 *
 * Copyright (c) 2011 Carl Eugen Hoyos
 *
 * 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 "avcodec.h"
#include "internal.h"

static av_cold int yuv4_decode_init(AVCodecContext *avctx)
{
    avctx->pix_fmt = AV_PIX_FMT_YUV420P;

    return 0;
}

static int yuv4_decode_frame(AVCodecContext *avctx, void *data,
                             int *got_frame, AVPacket *avpkt)
{
    AVFrame *pic = data;
    const uint8_t *src = avpkt->data;
    uint8_t *y, *u, *v;
    int i, j, ret;

    if (avpkt->size < 6 * (avctx->width + 1 >> 1) * (avctx->height + 1 >> 1)) {
        av_log(avctx, AV_LOG_ERROR, "Insufficient input data.\n");
        return AVERROR(EINVAL);
    }

    if ((ret = ff_get_buffer(avctx, pic, 0)) < 0)
        return ret;

    pic->key_frame = 1;
    pic->pict_type = AV_PICTURE_TYPE_I;

    y = pic->data[0];
    u = pic->data[1];
    v = pic->data[2];

    for (i = 0; i < (avctx->height + 1) >> 1; i++) {
        for (j = 0; j < (avctx->width + 1) >> 1; j++) {
            u[j] = *src++ ^ 0x80;
            v[j] = *src++ ^ 0x80;
            y[                   2 * j    ] = *src++;
            y[                   2 * j + 1] = *src++;
            y[pic->linesize[0] + 2 * j    ] = *src++;
            y[pic->linesize[0] + 2 * j + 1] = *src++;
        }

        y += 2 * pic->linesize[0];
        u +=     pic->linesize[1];
        v +=     pic->linesize[2];
    }

    *got_frame = 1;

    return avpkt->size;
}

AVCodec ff_yuv4_decoder = {
    .name         = "yuv4",
    .type         = AVMEDIA_TYPE_VIDEO,
    .id           = AV_CODEC_ID_YUV4,
    .init         = yuv4_decode_init,
    .decode       = yuv4_decode_frame,
    .capabilities = CODEC_CAP_DR1,
    .long_name    = NULL_IF_CONFIG_SMALL("Uncompressed packed 4:2:0"),
};