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/*

 * CPiA video decoder.

 * Copyright (c) 2010 Hans de Goede 

 *

 * This decoder is based on the LGPL code available at

 * https://v4l4j.googlecode.com/svn/v4l4j/trunk/libvideo/libv4lconvert/cpia1.c

 *

 * 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 "get_bits.h"

#include "internal.h"

#define FRAME_HEADER_SIZE 64

#define MAGIC_0         0x19    /**< First header byte */

#define MAGIC_1         0x68    /**< Second header byte */

#define SUBSAMPLE_420      0

#define SUBSAMPLE_422      1

#define YUVORDER_YUYV      0

#define YUVORDER_UYVY      1

#define NOT_COMPRESSED     0

#define COMPRESSED         1

#define NO_DECIMATION      0

#define DECIMATION_ENAB    1

#define EOL             0xfd    /**< End Of Line marker */

#define EOI             0xff    /**< End Of Image marker */

typedef struct {

    AVFrame *frame;

} CpiaContext;

static int cpia_decode_frame(AVCodecContext *avctx,

                             void *data, int *got_frame, AVPacket* avpkt)

{

    CpiaContext* const cpia = avctx->priv_data;

    int i,j,ret;

    uint8_t* const header = avpkt->data;

    uint8_t* src;

    int src_size;

    uint16_t linelength;

    uint8_t skip;

    AVFrame *frame = cpia->frame;

    uint8_t *y, *u, *v, *y_end, *u_end, *v_end;

    // Check header

    if ( avpkt->size < FRAME_HEADER_SIZE

      || header[0] != MAGIC_0 || header[1] != MAGIC_1

      || (header[17] != SUBSAMPLE_420 && header[17] != SUBSAMPLE_422)

      || (header[18] != YUVORDER_YUYV && header[18] != YUVORDER_UYVY)

      || (header[28] != NOT_COMPRESSED && header[28] != COMPRESSED)

      || (header[29] != NO_DECIMATION && header[29] != DECIMATION_ENAB)

    ) {

        av_log(avctx, AV_LOG_ERROR, "Invalid header!\n");

        return AVERROR_INVALIDDATA;

    }

    // currently unsupported properties

    if (header[17] == SUBSAMPLE_422) {

        av_log(avctx, AV_LOG_ERROR, "Unsupported subsample!\n");

        return AVERROR_PATCHWELCOME;

    }

    if (header[18] == YUVORDER_UYVY) {

        av_log(avctx, AV_LOG_ERROR, "Unsupported YUV byte order!\n");

        return AVERROR_PATCHWELCOME;

    }

    if (header[29] == DECIMATION_ENAB) {

        av_log(avctx, AV_LOG_ERROR, "Decimation unsupported!\n");

        return AVERROR_PATCHWELCOME;

    }

    src = header + FRAME_HEADER_SIZE;

    src_size = avpkt->size - FRAME_HEADER_SIZE;

    if (header[28] == NOT_COMPRESSED) {

        frame->pict_type = AV_PICTURE_TYPE_I;

        frame->key_frame = 1;

    } else {

        frame->pict_type = AV_PICTURE_TYPE_P;

        frame->key_frame = 0;

    }

    // Get buffer filled with previous frame

    if ((ret = ff_reget_buffer(avctx, frame)) < 0)

        return ret;

    for ( i = 0;

          i < frame->height;

          i++, src += linelength, src_size -= linelength

    ) {

        // Read line length, two byte little endian

        linelength = AV_RL16(src);

        src += 2;

        if (src_size < linelength) {

            av_frame_set_decode_error_flags(frame, FF_DECODE_ERROR_INVALID_BITSTREAM);

            av_log(avctx, AV_LOG_WARNING, "Frame ended enexpectedly!\n");

            break;

        }

        if (src[linelength - 1] != EOL) {

            av_frame_set_decode_error_flags(frame, FF_DECODE_ERROR_INVALID_BITSTREAM);

            av_log(avctx, AV_LOG_WARNING, "Wrong line length %d or line not terminated properly (found 0x%02x)!\n", linelength, src[linelength - 1]);

            break;

        }

        /* Update the data pointers. Y data is on every line.

         * U and V data on every second line

         */

        y = &frame->data[0][i * frame->linesize[0]];

        u = &frame->data[1][(i >> 1) * frame->linesize[1]];

        v = &frame->data[2][(i >> 1) * frame->linesize[2]];

        y_end = y + frame->linesize[0] - 1;

        u_end = u + frame->linesize[1] - 1;

        v_end = v + frame->linesize[2] - 1;

        if ((i & 1) && header[17] == SUBSAMPLE_420) {

            /* We are on a odd line and 420 subsample is used.

             * On this line only Y values are specified, one per pixel.

             */

            for (j = 0; j < linelength - 1; j++) {

                if (y > y_end) {

                    av_frame_set_decode_error_flags(frame, FF_DECODE_ERROR_INVALID_BITSTREAM);

                    av_log(avctx, AV_LOG_WARNING, "Decoded data exceeded linesize!\n");

                    break;

                }

                if ((src[j] & 1) && header[28] == COMPRESSED) {

                    /* It seems that odd lines are always uncompressed, but

                     * we do it according to specification anyways.

                     */

                    skip = src[j] >> 1;

                    y += skip;

                } else {

                    *(y++) = src[j];

                }

            }

        } else if (header[17] == SUBSAMPLE_420) {

            /* We are on an even line and 420 subsample is used.

             * On this line each pair of pixels is described by four bytes.

             */

            for (j = 0; j < linelength - 4; ) {

                if (y + 1 > y_end || u > u_end || v > v_end) {

                    av_frame_set_decode_error_flags(frame, FF_DECODE_ERROR_INVALID_BITSTREAM);

                    av_log(avctx, AV_LOG_WARNING, "Decoded data exceeded linesize!\n");

                    break;

                }

                if ((src[j] & 1) && header[28] == COMPRESSED) {

                    // Skip amount of pixels and move forward one byte

                    skip = src[j] >> 1;

                    y += skip;

                    u += skip >> 1;

                    v += skip >> 1;

                    j++;

                } else {

                    // Set image data as specified and move forward 4 bytes

                    *(y++) = src[j];

                    *(u++) = src[j+1];

                    *(y++) = src[j+2];

                    *(v++) = src[j+3];

                    j += 4;

                }

            }

        }

    }

    *got_frame = 1;

    if ((ret = av_frame_ref(data, cpia->frame)) < 0)

        return ret;

    return avpkt->size;

}

static av_cold int cpia_decode_init(AVCodecContext *avctx)

{

    CpiaContext *s = avctx->priv_data;

    // output pixel format

    avctx->pix_fmt = AV_PIX_FMT_YUV420P;

    /* The default timebase set by the v4l2 demuxer leads to probing which is buggy.

     * Set some reasonable time_base to skip this.

     */

    if (avctx->time_base.num == 1 && avctx->time_base.den == 1000000) {

        avctx->time_base.num = 1;

        avctx->time_base.den = 60;

    }

    s->frame = av_frame_alloc();

    if (!s->frame)

        return AVERROR(ENOMEM);

    return 0;

}

static av_cold int cpia_decode_end(AVCodecContext *avctx)

{

    CpiaContext *s = avctx->priv_data;

    av_frame_free(&s->frame);

    return 0;

}

AVCodec ff_cpia_decoder = {

    .name           = "cpia",

    .long_name      = NULL_IF_CONFIG_SMALL("CPiA video format"),

    .type           = AVMEDIA_TYPE_VIDEO,

    .id             = AV_CODEC_ID_CPIA,

    .priv_data_size = sizeof(CpiaContext),

    .init           = cpia_decode_init,

    .close          = cpia_decode_end,

    .decode         = cpia_decode_frame,

    .capabilities   = CODEC_CAP_DR1,

};