PeerStreamer

/*

 * Electronic Arts Madcow Video Decoder

 * Copyright (c) 2007-2009 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 Madcow Video Decoder

 * by Peter Ross <pross@xvid.org>

 *

 * Technical details here:

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

 */

#include "avcodec.h"

#include "get_bits.h"

#include "dsputil.h"

#include "aandcttab.h"

#include "mpeg12.h"

#include "mpeg12data.h"

#include "libavcore/imgutils.h"

#define EA_PREAMBLE_SIZE    8

#define MADk_TAG MKTAG('M', 'A', 'D', 'k')    /* MAD i-frame */

#define MADm_TAG MKTAG('M', 'A', 'D', 'm')    /* MAD p-frame */

#define MADe_TAG MKTAG('M', 'A', 'D', 'e')    /* MAD lqp-frame */

typedef struct MadContext {

    MpegEncContext s;

    AVFrame frame;

    AVFrame last_frame;

    void *bitstream_buf;

    unsigned int bitstream_buf_size;

    DECLARE_ALIGNED(16, DCTELEM, block)[64];

} MadContext;

static void bswap16_buf(uint16_t *dst, const uint16_t *src, int count)

{

    int i;

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

        dst[i] = av_bswap16(src[i]);

}

static av_cold int decode_init(AVCodecContext *avctx)

{

    MadContext *t = avctx->priv_data;

    MpegEncContext *s = &t->s;

    s->avctx = avctx;

    avctx->pix_fmt = PIX_FMT_YUV420P;

    if (avctx->idct_algo == FF_IDCT_AUTO)

        avctx->idct_algo = FF_IDCT_EA;

    dsputil_init(&s->dsp, avctx);

    ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable, ff_zigzag_direct);

    ff_mpeg12_init_vlcs();

    return 0;

}

static inline void comp(unsigned char *dst, int dst_stride,

                        unsigned char *src, int src_stride, int add)

{

    int j, i;

    for (j=0; j<8; j++)

        for (i=0; i<8; i++)

            dst[j*dst_stride + i] = av_clip_uint8(src[j*src_stride + i] + add);

}

static inline void comp_block(MadContext *t, int mb_x, int mb_y,

                              int j, int mv_x, int mv_y, int add)

{

    MpegEncContext *s = &t->s;

    if (j < 4) {

        comp(t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),

             t->frame.linesize[0],

             t->last_frame.data[0] + (mb_y*16 + ((j&2)<<2) + mv_y)*t->last_frame.linesize[0] + mb_x*16 + ((j&1)<<3) + mv_x,

             t->last_frame.linesize[0], add);

    } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {

        int index = j - 3;

        comp(t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x * 8,

             t->frame.linesize[index],

             t->last_frame.data[index] + (mb_y * 8 + (mv_y/2))*t->last_frame.linesize[index] + mb_x * 8 + (mv_x/2),

             t->last_frame.linesize[index], add);

    }

}

static inline void idct_put(MadContext *t, DCTELEM *block, int mb_x, int mb_y, int j)

{

    MpegEncContext *s = &t->s;

    if (j < 4) {

        s->dsp.idct_put(

            t->frame.data[0] + (mb_y*16 + ((j&2)<<2))*t->frame.linesize[0] + mb_x*16 + ((j&1)<<3),

            t->frame.linesize[0], block);

    } else if (!(s->avctx->flags & CODEC_FLAG_GRAY)) {

        int index = j - 3;

        s->dsp.idct_put(

            t->frame.data[index] + (mb_y*8)*t->frame.linesize[index] + mb_x*8,

            t->frame.linesize[index], block);

    }

}

static inline void decode_block_intra(MadContext * t, DCTELEM * block)

{

    MpegEncContext *s = &t->s;

    int level, i, j, run;

    RLTable *rl = &ff_rl_mpeg1;

    const uint8_t *scantable = s->intra_scantable.permutated;

    int16_t *quant_matrix = s->intra_matrix;

    block[0] = (128 + get_sbits(&s->gb, 8)) * quant_matrix[0];

    /* The RL decoder is derived from mpeg1_decode_block_intra;

       Escaped level and run values a decoded differently */

    i = 0;

    {

        OPEN_READER(re, &s->gb);

        /* now quantify & encode AC coefficients */

        for (;;) {

            UPDATE_CACHE(re, &s->gb);

            GET_RL_VLC(level, run, re, &s->gb, rl->rl_vlc[0], TEX_VLC_BITS, 2, 0);

            if (level == 127) {

                break;

            } else if (level != 0) {

                i += run;

                j = scantable[i];

                level = (level*quant_matrix[j]) >> 4;

                level = (level-1)|1;

                level = (level ^ SHOW_SBITS(re, &s->gb, 1)) - SHOW_SBITS(re, &s->gb, 1);

                LAST_SKIP_BITS(re, &s->gb, 1);

            } else {

                /* escape */

                UPDATE_CACHE(re, &s->gb);

                level = SHOW_SBITS(re, &s->gb, 10); SKIP_BITS(re, &s->gb, 10);

                UPDATE_CACHE(re, &s->gb);

                run = SHOW_UBITS(re, &s->gb, 6)+1; LAST_SKIP_BITS(re, &s->gb, 6);

                i += run;

                j = scantable[i];

                if (level < 0) {

                    level = -level;

                    level = (level*quant_matrix[j]) >> 4;

                    level = (level-1)|1;

                    level = -level;

                } else {

                    level = (level*quant_matrix[j]) >> 4;

                    level = (level-1)|1;

                }

            }

            if (i > 63) {

                av_log(s->avctx, AV_LOG_ERROR, "ac-tex damaged at %d %d\n", s->mb_x, s->mb_y);

                return;

            }

            block[j] = level;

        }

        CLOSE_READER(re, &s->gb);

    }

}

static int decode_motion(GetBitContext *gb)

{

    int value = 0;

    if (get_bits1(gb)) {

        if (get_bits1(gb))

            value = -17;

        value += get_bits(gb, 4) + 1;

    }

    return value;

}

static void decode_mb(MadContext *t, int inter)

{

    MpegEncContext *s = &t->s;

    int mv_map = 0;

    int mv_x, mv_y;

    int j;

    if (inter) {

        int v = decode210(&s->gb);

        if (v < 2) {

            mv_map = v ? get_bits(&s->gb, 6) : 63;

            mv_x = decode_motion(&s->gb);

            mv_y = decode_motion(&s->gb);

        } else {

            mv_map = 0;

        }

    }

    for (j=0; j<6; j++) {

        if (mv_map & (1<<j)) {  // mv_x and mv_y are guarded by mv_map

            int add = 2*decode_motion(&s->gb);

            comp_block(t, s->mb_x, s->mb_y, j, mv_x, mv_y, add);

        } else {

            s->dsp.clear_block(t->block);

            decode_block_intra(t, t->block);

            idct_put(t, t->block, s->mb_x, s->mb_y, j);

        }

    }

}

static void calc_intra_matrix(MadContext *t, int qscale)

{

    MpegEncContext *s = &t->s;

    int i;

    if (s->avctx->idct_algo == FF_IDCT_EA) {

        s->intra_matrix[0] = (ff_inv_aanscales[0]*ff_mpeg1_default_intra_matrix[0]) >> 11;

        for (i=1; i<64; i++)

            s->intra_matrix[i] = (ff_inv_aanscales[i]*ff_mpeg1_default_intra_matrix[i]*qscale + 32) >> 10;

    } else {

        s->intra_matrix[0] = ff_mpeg1_default_intra_matrix[0];

        for (i=1; i<64; i++)

            s->intra_matrix[i] = (ff_mpeg1_default_intra_matrix[i]*qscale) << 1;

    }

}

static int decode_frame(AVCodecContext *avctx,

                        void *data, int *data_size,

                        AVPacket *avpkt)

{

    const uint8_t *buf = avpkt->data;

    int buf_size       = avpkt->size;

    const uint8_t *buf_end = buf+buf_size;

    MadContext *t     = avctx->priv_data;

    MpegEncContext *s = &t->s;

    int chunk_type;

    int inter;

    if (buf_size < 17) {

        av_log(avctx, AV_LOG_ERROR, "Input buffer too small\n");

        *data_size = 0;

        return -1;

    }

    chunk_type = AV_RL32(&buf[0]);

    inter = (chunk_type == MADm_TAG || chunk_type == MADe_TAG);

    buf += 8;

    av_reduce(&avctx->time_base.num, &avctx->time_base.den,

              AV_RL16(&buf[6]), 1000, 1<<30);

    s->width  = AV_RL16(&buf[8]);

    s->height = AV_RL16(&buf[10]);

    calc_intra_matrix(t, buf[13]);

    buf += 16;

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

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

            return -1;

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

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

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

    }

    t->frame.reference = 1;

    if (!t->frame.data[0]) {

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

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

            return -1;

        }

    }

    av_fast_malloc(&t->bitstream_buf, &t->bitstream_buf_size, (buf_end-buf) + FF_INPUT_BUFFER_PADDING_SIZE);

    if (!t->bitstream_buf)

        return AVERROR(ENOMEM);

    bswap16_buf(t->bitstream_buf, (const uint16_t*)buf, (buf_end-buf)/2);

    init_get_bits(&s->gb, t->bitstream_buf, 8*(buf_end-buf));

    for (s->mb_y=0; s->mb_y < (avctx->height+15)/16; s->mb_y++)

        for (s->mb_x=0; s->mb_x < (avctx->width +15)/16; s->mb_x++)

            decode_mb(t, inter);

    *data_size = sizeof(AVFrame);

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

    if (chunk_type != MADe_TAG)

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

    return buf_size;

}

static av_cold int decode_end(AVCodecContext *avctx)

{

    MadContext *t = avctx->priv_data;

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

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

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

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

    av_free(t->bitstream_buf);

    return 0;

}

AVCodec ff_eamad_decoder = {

    "eamad",

    AVMEDIA_TYPE_VIDEO,

    CODEC_ID_MAD,

    sizeof(MadContext),

    decode_init,

    NULL,

    decode_end,

    decode_frame,

    CODEC_CAP_DR1,

    .long_name = NULL_IF_CONFIG_SMALL("Electronic Arts Madcow Video")

};