FFmpeg/libavcodec/eacmv.c

/*
 * 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 libavcodec/eacmv.c
 * 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 "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;
                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 (avcodec_check_dimensions(s->avctx, s->width, s->height))
        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 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"),
};