PeerStreamer

/*

 * Micrsoft RLE Video Decoder

 * Copyright (C) 2003 the ffmpeg project

 *

 * 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

 */

/**

 * @file msrle.c

 * MS RLE Video Decoder by Mike Melanson (melanson@pcisys.net)

 * For more information about the MS RLE format, visit:

 *   http://www.pcisys.net/~melanson/codecs/

 *

 * The MS RLE decoder outputs PAL8 colorspace data.

 *

 * Note that this decoder expects the palette colors from the end of the

 * BITMAPINFO header passed through palctrl.

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include "common.h"

#include "avcodec.h"

#include "dsputil.h"

typedef struct MsrleContext {

    AVCodecContext *avctx;

    AVFrame frame;

    unsigned char *buf;

    int size;

} MsrleContext;

#define FETCH_NEXT_STREAM_BYTE() \

    if (stream_ptr >= s->size) \

    { \

      av_log(s->avctx, AV_LOG_ERROR, " MS RLE: stream ptr just went out of bounds (1)\n"); \

      return; \

    } \

    stream_byte = s->buf[stream_ptr++];

static void msrle_decode_pal4(MsrleContext *s)

{

    int stream_ptr = 0;

    unsigned char rle_code;

    unsigned char extra_byte, odd_pixel;

    unsigned char stream_byte;

    int pixel_ptr = 0;

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

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

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

    int i;

    /* make the palette available */

    memcpy(s->frame.data[1], s->avctx->palctrl->palette, AVPALETTE_SIZE);

    if (s->avctx->palctrl->palette_changed) {

        s->frame.palette_has_changed = 1;

        s->avctx->palctrl->palette_changed = 0;

    }

    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 */

                return;

            } 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

            odd_pixel =  stream_byte & 1;

            rle_code = (stream_byte + 1) / 2;

            extra_byte = rle_code & 0x01;

            if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||

                (row_ptr < 0)) {

                av_log(s->avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");

                return;

            }

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

                if (pixel_ptr >= s->avctx->width)

                    break;

                FETCH_NEXT_STREAM_BYTE();

                s->frame.data[0][row_ptr + pixel_ptr] = stream_byte >> 4;

                pixel_ptr++;

                if (i + 1 == rle_code && odd_pixel)

                    break;

                if (pixel_ptr >= s->avctx->width)

                    break;

                s->frame.data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;

                pixel_ptr++;

            }

            // if the RLE code is odd, skip a byte in the stream

            if (extra_byte)

              stream_ptr++;

            }

        } else {

            // decode a run of data

            if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||

                (row_ptr < 0)) {

                av_log(s->avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");

                return;

            }

            FETCH_NEXT_STREAM_BYTE();

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

                if (pixel_ptr >= s->avctx->width)

                    break;

                if ((i & 1) == 0)

                    s->frame.data[0][row_ptr + pixel_ptr] = stream_byte >> 4;

                else

                    s->frame.data[0][row_ptr + pixel_ptr] = stream_byte & 0x0F;

                pixel_ptr++;

            }

        }

    }

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

    if (stream_ptr < s->size)

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

            stream_ptr, s->size);

}

static void msrle_decode_pal8(MsrleContext *s)

{

    int stream_ptr = 0;

    unsigned char rle_code;

    unsigned char extra_byte;

    unsigned char stream_byte;

    int pixel_ptr = 0;

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

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

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

    /* make the palette available */

    memcpy(s->frame.data[1], s->avctx->palctrl->palette, AVPALETTE_SIZE);

    if (s->avctx->palctrl->palette_changed) {

        s->frame.palette_has_changed = 1;

        s->avctx->palctrl->palette_changed = 0;

    }

    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 */

                return;

            } 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 ((row_ptr + pixel_ptr + stream_byte > frame_size) ||

                    (row_ptr < 0)) {

                    av_log(s->avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (1)\n");

                    return;

                }

                rle_code = stream_byte;

                extra_byte = stream_byte & 0x01;

                if (stream_ptr + rle_code + extra_byte > s->size) {

                    av_log(s->avctx, AV_LOG_ERROR, " MS RLE: stream ptr just went out of bounds (2)\n");

                    return;

                }

                while (rle_code--) {

                    FETCH_NEXT_STREAM_BYTE();

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

                    pixel_ptr++;

                }

                /* if the RLE code is odd, skip a byte in the stream */

                if (extra_byte)

                    stream_ptr++;

            }

        } else {

            /* decode a run of data */

            if ((row_ptr + pixel_ptr + stream_byte > frame_size) ||

                (row_ptr < 0)) {

                av_log(s->avctx, AV_LOG_ERROR, " MS RLE: frame ptr just went out of bounds (2)\n");

                return;

            }

            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 < s->size)

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

            stream_ptr, s->size);

}

static int msrle_decode_init(AVCodecContext *avctx)

{

    MsrleContext *s = avctx->priv_data;

    s->avctx = avctx;

    avctx->pix_fmt = PIX_FMT_PAL8;

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

    return 0;

}

static int msrle_decode_frame(AVCodecContext *avctx,

                              void *data, int *data_size,

                              uint8_t *buf, int buf_size)

{

    MsrleContext *s = avctx->priv_data;

    s->buf = buf;

    s->size = buf_size;

    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;

    }

    switch (avctx->bits_per_sample) {

        case 8:

            msrle_decode_pal8(s);

            break;

        case 4:

            msrle_decode_pal4(s);

            break;

        default:

            av_log(avctx, AV_LOG_ERROR, "Don't know how to decode depth %u.\n",

                   avctx->bits_per_sample);

    }

    *data_size = sizeof(AVFrame);

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

    /* report that the buffer was completely consumed */

    return buf_size;

}

static int msrle_decode_end(AVCodecContext *avctx)

{

    MsrleContext *s = avctx->priv_data;

    /* release the last frame */

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

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

    return 0;

}

AVCodec msrle_decoder = {

    "msrle",

    CODEC_TYPE_VIDEO,

    CODEC_ID_MSRLE,

    sizeof(MsrleContext),

    msrle_decode_init,

    NULL,

    msrle_decode_end,

    msrle_decode_frame,

    CODEC_CAP_DR1,

};