PeerStreamer

/*

 * QPEG codec

 * Copyright (c) 2004 Konstantin Shishkov

 *

 * 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 qpeg.c

 * QPEG codec.

 */

#include "avcodec.h"

#include "mpegvideo.h"

typedef struct QpegContext{

    AVCodecContext *avctx;

    AVFrame pic;

    uint8_t *refdata;

} QpegContext;

static void qpeg_decode_intra(uint8_t *src, uint8_t *dst, int size,

                            int stride, int width, int height)

{

    int i;

    int code;

    int c0, c1;

    int run, copy;

    int filled = 0;

    int rows_to_go;

    rows_to_go = height;

    height--;

    dst = dst + height * stride;

    while((size > 0) && (rows_to_go > 0)) {

        code = *src++;

        size--;

        run = copy = 0;

        if(code == 0xFC) /* end-of-picture code */

            break;

        if(code >= 0xF8) { /* very long run */

            c0 = *src++;

            c1 = *src++;

            size -= 2;

            run = ((code & 0x7) << 16) + (c0 << 8) + c1 + 2;

        } else if (code >= 0xF0) { /* long run */

            c0 = *src++;

            size--;

            run = ((code & 0xF) << 8) + c0 + 2;

        } else if (code >= 0xE0) { /* short run */

            run = (code & 0x1F) + 2;

        } else if (code >= 0xC0) { /* very long copy */

            c0 = *src++;

            c1 = *src++;

            size -= 2;

            copy = ((code & 0x3F) << 16) + (c0 << 8) + c1 + 1;

        } else if (code >= 0x80) { /* long copy */

            c0 = *src++;

            size--;

            copy = ((code & 0x7F) << 8) + c0 + 1;

        } else { /* short copy */

            copy = code + 1;

        }

        /* perform actual run or copy */

        if(run) {

            int p;

            p = *src++;

            size--;

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

                dst[filled++] = p;

                if (filled >= width) {

                    filled = 0;

                    dst -= stride;

                    rows_to_go--;

                    if(rows_to_go <= 0)

                        break;

                }

            }

        } else {

            size -= copy;

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

                dst[filled++] = *src++;

                if (filled >= width) {

                    filled = 0;

                    dst -= stride;

                    rows_to_go--;

                    if(rows_to_go <= 0)

                        break;

                }

            }

        }

    }

}

static int qpeg_table_h[16] =

 { 0x00, 0x20, 0x20, 0x20, 0x18, 0x10, 0x10, 0x20, 0x10, 0x08, 0x18, 0x08, 0x08, 0x18, 0x10, 0x04};

static int qpeg_table_w[16] =

 { 0x00, 0x20, 0x18, 0x08, 0x18, 0x10, 0x20, 0x10, 0x08, 0x10, 0x20, 0x20, 0x08, 0x10, 0x18, 0x04};

/* Decodes delta frames */

static void qpeg_decode_inter(uint8_t *src, uint8_t *dst, int size,

                            int stride, int width, int height,

                            int delta, uint8_t *ctable, uint8_t *refdata)

{

    int i, j;

    int code;

    int filled = 0;

    int orig_height;

    uint8_t *blkdata;

    /* copy prev frame */

    for(i = 0; i < height; i++)

        memcpy(refdata + (i * width), dst + (i * stride), width);

    orig_height = height;

    blkdata = src - 0x86;

    height--;

    dst = dst + height * stride;

    while((size > 0) && (height >= 0)) {

        code = *src++;

        size--;

        if(delta) {

            /* motion compensation */

            while((code & 0xF0) == 0xF0) {

                if(delta == 1) {

                    int me_idx;

                    int me_w, me_h, me_x, me_y;

                    uint8_t *me_plane;

                    int corr, val;

                    /* get block size by index */

                    me_idx = code & 0xF;

                    me_w = qpeg_table_w[me_idx];

                    me_h = qpeg_table_h[me_idx];

                    /* extract motion vector */

                    corr = *src++;

                    size--;

                    val = corr >> 4;

                    if(val > 7)

                        val -= 16;

                    me_x = val;

                    val = corr & 0xF;

                    if(val > 7)

                        val -= 16;

                    me_y = val;

                    /* check motion vector */

                    if ((me_x + filled < 0) || (me_x + me_w + filled > width) ||

                       (height - me_y - me_h < 0) || (height - me_y > orig_height) ||

                       (filled + me_w > width) || (height - me_h < 0))

                        av_log(NULL, AV_LOG_ERROR, "Bogus motion vector (%i,%i), block size %ix%i at %i,%i\n",

                               me_x, me_y, me_w, me_h, filled, height);

                    else {

                        /* do motion compensation */

                        me_plane = refdata + (filled + me_x) + (height - me_y) * width;

                        for(j = 0; j < me_h; j++) {

                            for(i = 0; i < me_w; i++)

                                dst[filled + i - (j * stride)] = me_plane[i - (j * width)];

                        }

                    }

                }

                code = *src++;

                size--;

            }

        }

        if(code == 0xE0) /* end-of-picture code */

            break;

        if(code > 0xE0) { /* run code: 0xE1..0xFF */

            int p;

            code &= 0x1F;

            p = *src++;

            size--;

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

                dst[filled++] = p;

                if(filled >= width) {

                    filled = 0;

                    dst -= stride;

                    height--;

                }

            }

        } else if(code >= 0xC0) { /* copy code: 0xC0..0xDF */

            code &= 0x1F;

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

                dst[filled++] = *src++;

                if(filled >= width) {

                    filled = 0;

                    dst -= stride;

                    height--;

                }

            }

            size -= code + 1;

        } else if(code >= 0x80) { /* skip code: 0x80..0xBF */

            int skip;

            code &= 0x3F;

            /* codes 0x80 and 0x81 are actually escape codes,

               skip value minus constant is in the next byte */

            if(!code)

                skip = (*src++) + 64;

            else if(code == 1)

                skip = (*src++) + 320;

            else

                skip = code;

            filled += skip;

            while( filled >= width) {

                filled -= width;

                dst -= stride;

                height--;

                if(height < 0)

                    break;

            }

        } else {

            /* zero code treated as one-pixel skip */

            if(code)

                dst[filled++] = ctable[code & 0x7F];

            else

                filled++;

            if(filled >= width) {

                filled = 0;

                dst -= stride;

                height--;

            }

        }

    }

}

static int decode_frame(AVCodecContext *avctx,

                        void *data, int *data_size,

                        uint8_t *buf, int buf_size)

{

    QpegContext * const a = avctx->priv_data;

    AVFrame * const p= (AVFrame*)&a->pic;

    uint8_t* outdata;

    int delta;

    if(p->data[0])

        avctx->release_buffer(avctx, p);

    p->reference= 0;

    if(avctx->get_buffer(avctx, p) < 0){

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

        return -1;

    }

    outdata = a->pic.data[0];

    if(buf[0x85] == 0x10) {

        qpeg_decode_intra(buf+0x86, outdata, buf_size - 0x86, a->pic.linesize[0], avctx->width, avctx->height);

    } else {

        delta = buf[0x85];

        qpeg_decode_inter(buf+0x86, outdata, buf_size - 0x86, a->pic.linesize[0], avctx->width, avctx->height, delta, buf + 4, a->refdata);

    }

    /* make the palette available on the way out */

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

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

        a->pic.palette_has_changed = 1;

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

    }

    *data_size = sizeof(AVFrame);

    *(AVFrame*)data = a->pic;

    return buf_size;

}

static int decode_init(AVCodecContext *avctx){

    QpegContext * const a = avctx->priv_data;

    a->avctx = avctx;

    avctx->pix_fmt= PIX_FMT_PAL8;

    avctx->has_b_frames = 0;

    a->pic.data[0] = NULL;

    a->refdata = av_malloc(avctx->width * avctx->height);

    return 0;

}

static int decode_end(AVCodecContext *avctx){

    QpegContext * const a = avctx->priv_data;

    AVFrame * const p= (AVFrame*)&a->pic;

    if(p->data[0])

        avctx->release_buffer(avctx, p);

    av_free(a->refdata);

    return 0;

}

AVCodec qpeg_decoder = {

    "qpeg",

    CODEC_TYPE_VIDEO,

    CODEC_ID_QPEG,

    sizeof(QpegContext),

    decode_init,

    NULL,

    decode_end,

    decode_frame,

    CODEC_CAP_DR1,

};