PeerStreamer

/*

 * Electronic Arts CMV Video Decoder

 * Copyright (c) 2007-2008 Peter Ross

 *

 * 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 St, Fifth Floor, Boston, MA  02110-1301  USA

 */

/**

 * @file

 * Electronic Arts CMV Video Decoder

 * by Peter Ross (pross@xvid.org)

 *

 * Technical details here:

 * http://wiki.multimedia.cx/index.php?title=Electronic_Arts_CMV

 */

#include "libavutil/intreadwrite.h"

#include "libavcore/imgutils.h"

#include "avcodec.h"

typedef struct CmvContext {

    AVCodecContext *avctx;

    AVFrame frame;        ///< current

    AVFrame last_frame;   ///< last

    AVFrame last2_frame;  ///< second-last

    int width, height;

    unsigned int palette[AVPALETTE_COUNT];

} CmvContext;

static av_cold int cmv_decode_init(AVCodecContext *avctx){

    CmvContext *s = avctx->priv_data;

    s->avctx = avctx;

    avctx->pix_fmt = PIX_FMT_PAL8;

    return 0;

}

static void cmv_decode_intra(CmvContext * s, const uint8_t *buf, const uint8_t *buf_end){

    unsigned char *dst = s->frame.data[0];

    int i;

    for (i=0; i < s->avctx->height && buf+s->avctx->width<=buf_end; i++) {

        memcpy(dst, buf, s->avctx->width);

        dst += s->frame.linesize[0];

        buf += s->avctx->width;

    }

}

static void cmv_motcomp(unsigned char *dst, int dst_stride,

                        const unsigned char *src, int src_stride,

                        int x, int y,

                        int xoffset, int yoffset,

                        int width, int height){

    int i,j;

    for(j=y;j<y+4;j++)

    for(i=x;i<x+4;i++)

    {

        if (i+xoffset>=0 && i+xoffset<width &&

            j+yoffset>=0 && j+yoffset<height) {

            dst[j*dst_stride + i] = src[(j+yoffset)*src_stride + i+xoffset];

        }else{

            dst[j*dst_stride + i] = 0;

        }

    }

}

static void cmv_decode_inter(CmvContext * s, const uint8_t *buf, const uint8_t *buf_end){

    const uint8_t *raw = buf + (s->avctx->width*s->avctx->height/16);

    int x,y,i;

    i = 0;

    for(y=0; y<s->avctx->height/4; y++)

    for(x=0; x<s->avctx->width/4 && buf+i<buf_end; x++) {

        if (buf[i]==0xFF) {

            unsigned char *dst = s->frame.data[0] + (y*4)*s->frame.linesize[0] + x*4;

            if (raw+16<buf_end && *raw==0xFF) { /* intra */

                raw++;

                memcpy(dst, raw, 4);

                memcpy(dst+s->frame.linesize[0], raw+4, 4);

                memcpy(dst+2*s->frame.linesize[0], raw+8, 4);

                memcpy(dst+3*s->frame.linesize[0], raw+12, 4);

                raw+=16;

            }else if(raw<buf_end) {  /* inter using second-last frame as reference */

                int xoffset = (*raw & 0xF) - 7;

                int yoffset = ((*raw >> 4)) - 7;

                if (s->last2_frame.data[0])

                    cmv_motcomp(s->frame.data[0], s->frame.linesize[0],

                                s->last2_frame.data[0], s->last2_frame.linesize[0],

                                x*4, y*4, xoffset, yoffset, s->avctx->width, s->avctx->height);

                raw++;

            }

        }else{  /* inter using last frame as reference */

            int xoffset = (buf[i] & 0xF) - 7;

            int yoffset = ((buf[i] >> 4)) - 7;

            cmv_motcomp(s->frame.data[0], s->frame.linesize[0],

                      s->last_frame.data[0], s->last_frame.linesize[0],

                      x*4, y*4, xoffset, yoffset, s->avctx->width, s->avctx->height);

        }

        i++;

    }

}

static void cmv_process_header(CmvContext *s, const uint8_t *buf, const uint8_t *buf_end)

{

    int pal_start, pal_count, i;

    if(buf+16>=buf_end) {

        av_log(s->avctx, AV_LOG_WARNING, "truncated header\n");

        return;

    }

    s->width  = AV_RL16(&buf[4]);

    s->height = AV_RL16(&buf[6]);

    if (s->avctx->width!=s->width || s->avctx->height!=s->height)

        avcodec_set_dimensions(s->avctx, s->width, s->height);

    s->avctx->time_base.num = 1;

    s->avctx->time_base.den = AV_RL16(&buf[10]);

    pal_start = AV_RL16(&buf[12]);

    pal_count = AV_RL16(&buf[14]);

    buf += 16;

    for (i=pal_start; i<pal_start+pal_count && i<AVPALETTE_COUNT && buf+2<buf_end; i++) {

        s->palette[i] = AV_RB24(buf);

        buf += 3;

    }

}

#define EA_PREAMBLE_SIZE 8

#define MVIh_TAG MKTAG('M', 'V', 'I', 'h')

static int cmv_decode_frame(AVCodecContext *avctx,

                            void *data, int *data_size,

                            AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size = avpkt->size;

    CmvContext *s = avctx->priv_data;

    const uint8_t *buf_end = buf + buf_size;

    if (AV_RL32(buf)==MVIh_TAG||AV_RB32(buf)==MVIh_TAG) {

        cmv_process_header(s, buf+EA_PREAMBLE_SIZE, buf_end);

        return buf_size;

    }

    if (av_image_check_size(s->width, s->height, 0, s->avctx))

        return -1;

    /* shuffle */

    if (s->last2_frame.data[0])

        avctx->release_buffer(avctx, &s->last2_frame);

    FFSWAP(AVFrame, s->last_frame, s->last2_frame);

    FFSWAP(AVFrame, s->frame, s->last_frame);

    s->frame.reference = 1;

    s->frame.buffer_hints = FF_BUFFER_HINTS_VALID;

    if (avctx->get_buffer(avctx, &s->frame)<0) {

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

        return -1;

    }

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

    buf += EA_PREAMBLE_SIZE;

    if ((buf[0]&1)) {  // subtype

        cmv_decode_inter(s, buf+2, buf_end);

        s->frame.key_frame = 0;

        s->frame.pict_type = FF_P_TYPE;

    }else{

        s->frame.key_frame = 1;

        s->frame.pict_type = FF_I_TYPE;

        cmv_decode_intra(s, buf+2, buf_end);

    }

    *data_size = sizeof(AVFrame);

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

    return buf_size;

}

static av_cold int cmv_decode_end(AVCodecContext *avctx){

    CmvContext *s = avctx->priv_data;

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

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

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

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

    if (s->last2_frame.data[0])

        s->avctx->release_buffer(avctx, &s->last2_frame);

    return 0;

}

AVCodec ff_eacmv_decoder = {

    "eacmv",

    AVMEDIA_TYPE_VIDEO,

    CODEC_ID_CMV,

    sizeof(CmvContext),

    cmv_decode_init,

    NULL,

    cmv_decode_end,

    cmv_decode_frame,

    CODEC_CAP_DR1,

    .long_name = NULL_IF_CONFIG_SMALL("Electronic Arts CMV video"),

};