root/libavcodec/kmvc.c

DEFINITIONS

1. kmvc_decode_intra_8x8
2. kmvc_decode_inter_8x8
3. decode_frame
4. decode_init

/*
 * KMVC decoder
 * Copyright (c) 2006 Konstantin Shishkov
 *
 * 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
 * Karl Morton's Video Codec decoder
 */

#include <stdio.h>
#include <stdlib.h>

#include "avcodec.h"
#include "bytestream.h"
#include "internal.h"
#include "libavutil/common.h"

#define KMVC_KEYFRAME 0x80
#define KMVC_PALETTE  0x40
#define KMVC_METHOD   0x0F
#define MAX_PALSIZE   256

/*
 * Decoder context
 */
typedef struct KmvcContext {
    AVCodecContext *avctx;

    int setpal;
    int palsize;
    uint32_t pal[MAX_PALSIZE];
    uint8_t *cur, *prev;
    uint8_t frm0[320 * 200], frm1[320 * 200];
    GetByteContext g;
} KmvcContext;

typedef struct BitBuf {
    int bits;
    int bitbuf;
} BitBuf;

#define BLK(data, x, y)  data[av_clip((x) + (y) * 320, 0, 320 * 200 -1)]

#define kmvc_init_getbits(bb, g)  bb.bits = 7; bb.bitbuf = bytestream2_get_byte(g);

#define kmvc_getbit(bb, g, res) {\
    res = 0; \
    if (bb.bitbuf & (1 << bb.bits)) res = 1; \
    bb.bits--; \
    if(bb.bits == -1) { \
        bb.bitbuf = bytestream2_get_byte(g); \
        bb.bits = 7; \
    } \
}

static int kmvc_decode_intra_8x8(KmvcContext * ctx, int w, int h)
{
    BitBuf bb;
    int res, val;
    int i, j;
    int bx, by;
    int l0x, l1x, l0y, l1y;
    int mx, my;

    kmvc_init_getbits(bb, &ctx->g);

    for (by = 0; by < h; by += 8)
        for (bx = 0; bx < w; bx += 8) {
            if (!bytestream2_get_bytes_left(&ctx->g)) {
                av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
                return AVERROR_INVALIDDATA;
            }
            kmvc_getbit(bb, &ctx->g, res);
            if (!res) {         // fill whole 8x8 block
                val = bytestream2_get_byte(&ctx->g);
                for (i = 0; i < 64; i++)
                    BLK(ctx->cur, bx + (i & 0x7), by + (i >> 3)) = val;
            } else {            // handle four 4x4 subblocks
                for (i = 0; i < 4; i++) {
                    l0x = bx + (i & 1) * 4;
                    l0y = by + (i & 2) * 2;
                    kmvc_getbit(bb, &ctx->g, res);
                    if (!res) {
                        kmvc_getbit(bb, &ctx->g, res);
                        if (!res) {     // fill whole 4x4 block
                            val = bytestream2_get_byte(&ctx->g);
                            for (j = 0; j < 16; j++)
                                BLK(ctx->cur, l0x + (j & 3), l0y + (j >> 2)) = val;
                        } else {        // copy block from already decoded place
                            val = bytestream2_get_byte(&ctx->g);
                            mx = val & 0xF;
                            my = val >> 4;
                            if ((l0x-mx) + 320*(l0y-my) < 0 || (l0x-mx) + 320*(l0y-my) > 320*197 - 4) {
                                av_log(ctx->avctx, AV_LOG_ERROR, "Invalid MV\n");
                                return AVERROR_INVALIDDATA;
                            }
                            for (j = 0; j < 16; j++)
                                BLK(ctx->cur, l0x + (j & 3), l0y + (j >> 2)) =
                                    BLK(ctx->cur, l0x + (j & 3) - mx, l0y + (j >> 2) - my);
                        }
                    } else {    // descend to 2x2 sub-sub-blocks
                        for (j = 0; j < 4; j++) {
                            l1x = l0x + (j & 1) * 2;
                            l1y = l0y + (j & 2);
                            kmvc_getbit(bb, &ctx->g, res);
                            if (!res) {
                                kmvc_getbit(bb, &ctx->g, res);
                                if (!res) {     // fill whole 2x2 block
                                    val = bytestream2_get_byte(&ctx->g);
                                    BLK(ctx->cur, l1x, l1y) = val;
                                    BLK(ctx->cur, l1x + 1, l1y) = val;
                                    BLK(ctx->cur, l1x, l1y + 1) = val;
                                    BLK(ctx->cur, l1x + 1, l1y + 1) = val;
                                } else {        // copy block from already decoded place
                                    val = bytestream2_get_byte(&ctx->g);
                                    mx = val & 0xF;
                                    my = val >> 4;
                                    if ((l1x-mx) + 320*(l1y-my) < 0 || (l1x-mx) + 320*(l1y-my) > 320*199 - 2) {
                                        av_log(ctx->avctx, AV_LOG_ERROR, "Invalid MV\n");
                                        return AVERROR_INVALIDDATA;
                                    }
                                    BLK(ctx->cur, l1x, l1y) = BLK(ctx->cur, l1x - mx, l1y - my);
                                    BLK(ctx->cur, l1x + 1, l1y) =
                                        BLK(ctx->cur, l1x + 1 - mx, l1y - my);
                                    BLK(ctx->cur, l1x, l1y + 1) =
                                        BLK(ctx->cur, l1x - mx, l1y + 1 - my);
                                    BLK(ctx->cur, l1x + 1, l1y + 1) =
                                        BLK(ctx->cur, l1x + 1 - mx, l1y + 1 - my);
                                }
                            } else {    // read values for block
                                BLK(ctx->cur, l1x, l1y) = bytestream2_get_byte(&ctx->g);
                                BLK(ctx->cur, l1x + 1, l1y) = bytestream2_get_byte(&ctx->g);
                                BLK(ctx->cur, l1x, l1y + 1) = bytestream2_get_byte(&ctx->g);
                                BLK(ctx->cur, l1x + 1, l1y + 1) = bytestream2_get_byte(&ctx->g);
                            }
                        }
                    }
                }
            }
        }

    return 0;
}

static int kmvc_decode_inter_8x8(KmvcContext * ctx, int w, int h)
{
    BitBuf bb;
    int res, val;
    int i, j;
    int bx, by;
    int l0x, l1x, l0y, l1y;
    int mx, my;

    kmvc_init_getbits(bb, &ctx->g);

    for (by = 0; by < h; by += 8)
        for (bx = 0; bx < w; bx += 8) {
            kmvc_getbit(bb, &ctx->g, res);
            if (!res) {
                kmvc_getbit(bb, &ctx->g, res);
                if (!res) {     // fill whole 8x8 block
                    if (!bytestream2_get_bytes_left(&ctx->g)) {
                        av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
                        return AVERROR_INVALIDDATA;
                    }
                    val = bytestream2_get_byte(&ctx->g);
                    for (i = 0; i < 64; i++)
                        BLK(ctx->cur, bx + (i & 0x7), by + (i >> 3)) = val;
                } else {        // copy block from previous frame
                    for (i = 0; i < 64; i++)
                        BLK(ctx->cur, bx + (i & 0x7), by + (i >> 3)) =
                            BLK(ctx->prev, bx + (i & 0x7), by + (i >> 3));
                }
            } else {            // handle four 4x4 subblocks
                if (!bytestream2_get_bytes_left(&ctx->g)) {
                    av_log(ctx->avctx, AV_LOG_ERROR, "Data overrun\n");
                    return AVERROR_INVALIDDATA;
                }
                for (i = 0; i < 4; i++) {
                    l0x = bx + (i & 1) * 4;
                    l0y = by + (i & 2) * 2;
                    kmvc_getbit(bb, &ctx->g, res);
                    if (!res) {
                        kmvc_getbit(bb, &ctx->g, res);
                        if (!res) {     // fill whole 4x4 block
                            val = bytestream2_get_byte(&ctx->g);
                            for (j = 0; j < 16; j++)
                                BLK(ctx->cur, l0x + (j & 3), l0y + (j >> 2)) = val;
                        } else {        // copy block
                            val = bytestream2_get_byte(&ctx->g);
                            mx = (val & 0xF) - 8;
                            my = (val >> 4) - 8;
                            if ((l0x+mx) + 320*(l0y+my) < 0 || (l0x+mx) + 320*(l0y+my) > 320*197 - 4) {
                                av_log(ctx->avctx, AV_LOG_ERROR, "Invalid MV\n");
                                return AVERROR_INVALIDDATA;
                            }
                            for (j = 0; j < 16; j++)
                                BLK(ctx->cur, l0x + (j & 3), l0y + (j >> 2)) =
                                    BLK(ctx->prev, l0x + (j & 3) + mx, l0y + (j >> 2) + my);
                        }
                    } else {    // descend to 2x2 sub-sub-blocks
                        for (j = 0; j < 4; j++) {
                            l1x = l0x + (j & 1) * 2;
                            l1y = l0y + (j & 2);
                            kmvc_getbit(bb, &ctx->g, res);
                            if (!res) {
                                kmvc_getbit(bb, &ctx->g, res);
                                if (!res) {     // fill whole 2x2 block
                                    val = bytestream2_get_byte(&ctx->g);
                                    BLK(ctx->cur, l1x, l1y) = val;
                                    BLK(ctx->cur, l1x + 1, l1y) = val;
                                    BLK(ctx->cur, l1x, l1y + 1) = val;
                                    BLK(ctx->cur, l1x + 1, l1y + 1) = val;
                                } else {        // copy block
                                    val = bytestream2_get_byte(&ctx->g);
                                    mx = (val & 0xF) - 8;
                                    my = (val >> 4) - 8;
                                    if ((l1x+mx) + 320*(l1y+my) < 0 || (l1x+mx) + 320*(l1y+my) > 320*199 - 2) {
                                        av_log(ctx->avctx, AV_LOG_ERROR, "Invalid MV\n");
                                        return AVERROR_INVALIDDATA;
                                    }
                                    BLK(ctx->cur, l1x, l1y) = BLK(ctx->prev, l1x + mx, l1y + my);
                                    BLK(ctx->cur, l1x + 1, l1y) =
                                        BLK(ctx->prev, l1x + 1 + mx, l1y + my);
                                    BLK(ctx->cur, l1x, l1y + 1) =
                                        BLK(ctx->prev, l1x + mx, l1y + 1 + my);
                                    BLK(ctx->cur, l1x + 1, l1y + 1) =
                                        BLK(ctx->prev, l1x + 1 + mx, l1y + 1 + my);
                                }
                            } else {    // read values for block
                                BLK(ctx->cur, l1x, l1y) = bytestream2_get_byte(&ctx->g);
                                BLK(ctx->cur, l1x + 1, l1y) = bytestream2_get_byte(&ctx->g);
                                BLK(ctx->cur, l1x, l1y + 1) = bytestream2_get_byte(&ctx->g);
                                BLK(ctx->cur, l1x + 1, l1y + 1) = bytestream2_get_byte(&ctx->g);
                            }
                        }
                    }
                }
            }
        }

    return 0;
}

static int decode_frame(AVCodecContext * avctx, void *data, int *got_frame,
                        AVPacket *avpkt)
{
    KmvcContext *const ctx = avctx->priv_data;
    AVFrame *frame = data;
    uint8_t *out, *src;
    int i, ret;
    int header;
    int blocksize;
    const uint8_t *pal = av_packet_get_side_data(avpkt, AV_PKT_DATA_PALETTE, NULL);

    bytestream2_init(&ctx->g, avpkt->data, avpkt->size);

    if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
        return ret;

    header = bytestream2_get_byte(&ctx->g);

    /* blocksize 127 is really palette change event */
    if (bytestream2_peek_byte(&ctx->g) == 127) {
        bytestream2_skip(&ctx->g, 3);
        for (i = 0; i < 127; i++) {
            ctx->pal[i + (header & 0x81)] = 0xFFU << 24 | bytestream2_get_be24(&ctx->g);
            bytestream2_skip(&ctx->g, 1);
        }
        bytestream2_seek(&ctx->g, -127 * 4 - 3, SEEK_CUR);
    }

    if (header & KMVC_KEYFRAME) {
        frame->key_frame = 1;
        frame->pict_type = AV_PICTURE_TYPE_I;
    } else {
        frame->key_frame = 0;
        frame->pict_type = AV_PICTURE_TYPE_P;
    }

    if (header & KMVC_PALETTE) {
        frame->palette_has_changed = 1;
        // palette starts from index 1 and has 127 entries
        for (i = 1; i <= ctx->palsize; i++) {
            ctx->pal[i] = 0xFFU << 24 | bytestream2_get_be24(&ctx->g);
        }
    }

    if (pal) {
        frame->palette_has_changed = 1;
        memcpy(ctx->pal, pal, AVPALETTE_SIZE);
    }

    if (ctx->setpal) {
        ctx->setpal = 0;
        frame->palette_has_changed = 1;
    }

    /* make the palette available on the way out */
    memcpy(frame->data[1], ctx->pal, 1024);

    blocksize = bytestream2_get_byte(&ctx->g);

    if (blocksize != 8 && blocksize != 127) {
        av_log(avctx, AV_LOG_ERROR, "Block size = %i\n", blocksize);
        return AVERROR_INVALIDDATA;
    }
    memset(ctx->cur, 0, 320 * 200);
    switch (header & KMVC_METHOD) {
    case 0:
    case 1: // used in palette changed event
        memcpy(ctx->cur, ctx->prev, 320 * 200);
        break;
    case 3:
        kmvc_decode_intra_8x8(ctx, avctx->width, avctx->height);
        break;
    case 4:
        kmvc_decode_inter_8x8(ctx, avctx->width, avctx->height);
        break;
    default:
        av_log(avctx, AV_LOG_ERROR, "Unknown compression method %i\n", header & KMVC_METHOD);
        return AVERROR_INVALIDDATA;
    }

    out = frame->data[0];
    src = ctx->cur;
    for (i = 0; i < avctx->height; i++) {
        memcpy(out, src, avctx->width);
        src += 320;
        out += frame->linesize[0];
    }

    /* flip buffers */
    if (ctx->cur == ctx->frm0) {
        ctx->cur = ctx->frm1;
        ctx->prev = ctx->frm0;
    } else {
        ctx->cur = ctx->frm0;
        ctx->prev = ctx->frm1;
    }

    *got_frame = 1;

    /* always report that the buffer was completely consumed */
    return avpkt->size;
}



/*
 * Init kmvc decoder
 */
static av_cold int decode_init(AVCodecContext * avctx)
{
    KmvcContext *const c = avctx->priv_data;
    int i;

    c->avctx = avctx;

    if (avctx->width > 320 || avctx->height > 200) {
        av_log(avctx, AV_LOG_ERROR, "KMVC supports frames <= 320x200\n");
        return AVERROR(EINVAL);
    }

    c->cur = c->frm0;
    c->prev = c->frm1;

    for (i = 0; i < 256; i++) {
        c->pal[i] = 0xFFU << 24 | i * 0x10101;
    }

    if (avctx->extradata_size < 12) {
        av_log(avctx, AV_LOG_WARNING,
               "Extradata missing, decoding may not work properly...\n");
        c->palsize = 127;
    } else {
        c->palsize = AV_RL16(avctx->extradata + 10);
        if (c->palsize >= (unsigned)MAX_PALSIZE) {
            c->palsize = 127;
            av_log(avctx, AV_LOG_ERROR, "KMVC palette too large\n");
            return AVERROR_INVALIDDATA;
        }
    }

    if (avctx->extradata_size == 1036) {        // palette in extradata
        uint8_t *src = avctx->extradata + 12;
        for (i = 0; i < 256; i++) {
            c->pal[i] = AV_RL32(src);
            src += 4;
        }
        c->setpal = 1;
    }

    avctx->pix_fmt = AV_PIX_FMT_PAL8;

    return 0;
}

AVCodec ff_kmvc_decoder = {
    .name           = "kmvc",
    .long_name      = NULL_IF_CONFIG_SMALL("Karl Morton's video codec"),
    .type           = AVMEDIA_TYPE_VIDEO,
    .id             = AV_CODEC_ID_KMVC,
    .priv_data_size = sizeof(KmvcContext),
    .init           = decode_init,
    .decode         = decode_frame,
    .capabilities   = CODEC_CAP_DR1,
};