PeerStreamer

/*

 * Autodesc RLE Decoder

 * Copyright (C) 2005 the ffmpeg project

 *

 * This library 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 of the License, or (at your option) any later version.

 *

 * This library 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 this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file aasc.c

 * Autodesc RLE Video Decoder by Konstantin Shishkov

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "common.h"

#include "avcodec.h"

#include "dsputil.h"

typedef struct AascContext {

    AVCodecContext *avctx;

    AVFrame frame;

} AascContext;

#define FETCH_NEXT_STREAM_BYTE() \

    if (stream_ptr >= buf_size) \

    { \

      av_log(s->avctx, AV_LOG_ERROR, " AASC: stream ptr just went out of bounds (fetch)\n"); \

      break; \

    } \

    stream_byte = buf[stream_ptr++];

static int aasc_decode_init(AVCodecContext *avctx)

{

    AascContext *s = (AascContext *)avctx->priv_data;

    s->avctx = avctx;

    avctx->pix_fmt = PIX_FMT_BGR24;

    avctx->has_b_frames = 0;

    s->frame.data[0] = NULL;

    return 0;

}

static int aasc_decode_frame(AVCodecContext *avctx,

                              void *data, int *data_size,

                              uint8_t *buf, int buf_size)

{

    AascContext *s = (AascContext *)avctx->priv_data;

    int stream_ptr = 4;

    unsigned char rle_code;

    unsigned char stream_byte;

    int pixel_ptr = 0;

    int row_dec, row_ptr;

    int frame_size;

    int i;

    s->frame.reference = 1;

    s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;

    if (avctx->reget_buffer(avctx, &s->frame)) {

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

        return -1;

    }

    row_dec = s->frame.linesize[0];

    row_ptr = (s->avctx->height - 1) * row_dec;

    frame_size = row_dec * s->avctx->height;

    while (row_ptr >= 0) {

        FETCH_NEXT_STREAM_BYTE();

        rle_code = stream_byte;

        if (rle_code == 0) {

            /* fetch the next byte to see how to handle escape code */

            FETCH_NEXT_STREAM_BYTE();

            if (stream_byte == 0) {

                /* line is done, goto the next one */

                row_ptr -= row_dec;

                pixel_ptr = 0;

            } else if (stream_byte == 1) {

                /* decode is done */

                break;

            } else if (stream_byte == 2) {

                /* reposition frame decode coordinates */

                FETCH_NEXT_STREAM_BYTE();

                pixel_ptr += stream_byte;

                FETCH_NEXT_STREAM_BYTE();

                row_ptr -= stream_byte * row_dec;

            } else {

                /* copy pixels from encoded stream */

                if ((pixel_ptr + stream_byte > avctx->width * 3) ||

                    (row_ptr < 0)) {

                    av_log(s->avctx, AV_LOG_ERROR, " AASC: frame ptr just went out of bounds (copy1)\n");

                    break;

                }

                rle_code = stream_byte;

                if (stream_ptr + rle_code > buf_size) {

                    av_log(s->avctx, AV_LOG_ERROR, " AASC: stream ptr just went out of bounds (copy2)\n");

                    break;

                }

                for (i = 0; i < rle_code; i++) {

                    FETCH_NEXT_STREAM_BYTE();

                    s->frame.data[0][row_ptr + pixel_ptr] = stream_byte;

                    pixel_ptr++;

                }

                if (rle_code & 1)

                    stream_ptr++;

            }

        } else {

            /* decode a run of data */

            if ((pixel_ptr + rle_code > avctx->width * 3) ||

                (row_ptr < 0)) {

                av_log(s->avctx, AV_LOG_ERROR, " AASC: frame ptr just went out of bounds (run1)\n");

                break;

            }

            FETCH_NEXT_STREAM_BYTE();

            while(rle_code--) {

                s->frame.data[0][row_ptr + pixel_ptr] = stream_byte;

                pixel_ptr++;

            }

        }

    }

    /* one last sanity check on the way out */

    if (stream_ptr < buf_size)

        av_log(s->avctx, AV_LOG_ERROR, " AASC: ended frame decode with bytes left over (%d < %d)\n",

            stream_ptr, buf_size);

    *data_size = sizeof(AVFrame);

    *(AVFrame*)data = s->frame;

    /* report that the buffer was completely consumed */

    return buf_size;

}

static int aasc_decode_end(AVCodecContext *avctx)

{

    AascContext *s = (AascContext *)avctx->priv_data;

    /* release the last frame */

    if (s->frame.data[0])

        avctx->release_buffer(avctx, &s->frame);

    return 0;

}

AVCodec aasc_decoder = {

    "aasc",

    CODEC_TYPE_VIDEO,

    CODEC_ID_AASC,

    sizeof(AascContext),

    aasc_decode_init,

    NULL,

    aasc_decode_end,

    aasc_decode_frame,

    CODEC_CAP_DR1,

};