interplayvideo.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

/*
 * Interplay MVE Video Decoder
 * Copyright (C) 2003 the ffmpeg project
 *
 * 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 interplayvideo.c
 * Interplay MVE Video Decoder by Mike Melanson ([e-mail])
 * For more information about the Interplay MVE format, visit:
 *   http://www.pcisys.net/~melanson/codecs/interplay-mve.txt
 * This code is written in such a way that the identifiers match up
 * with the encoding descriptions in the document.
 *
 * This decoder presently only supports a PAL8 output colorspace.
 *
 * An Interplay video frame consists of 2 parts: The decoding map and
 * the video data. A demuxer must load these 2 parts together in a single
 * buffer before sending it through the stream to this decoder.
 */

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

#include "avcodec.h"
#include "bytestream.h"
#include "dsputil.h"

#define PALETTE_COUNT 256

/* debugging support */
#define DEBUG_INTERPLAY 0
#if DEBUG_INTERPLAY
#define debug_interplay(x,...) av_log(NULL, AV_LOG_DEBUG, x, __VA_ARGS__)
#else
static inline void debug_interplay(const char *format, ...) { }
#endif

typedef struct IpvideoContext {

    AVCodecContext *avctx;
    DSPContext dsp;
    AVFrame second_last_frame;
    AVFrame last_frame;
    AVFrame current_frame;
    unsigned char *decoding_map;
    int decoding_map_size;

    unsigned char *buf;
    int size;

    unsigned char *stream_ptr;
    unsigned char *stream_end;
    unsigned char *pixel_ptr;
    int line_inc;
    int stride;
    int upper_motion_limit_offset;

} IpvideoContext;

#define CHECK_STREAM_PTR(n) \
  if ((s->stream_ptr + n) > s->stream_end) { \
    av_log(s->avctx, AV_LOG_ERROR, "Interplay video warning: stream_ptr out of bounds (%p >= %p)\n", \
      s->stream_ptr + n, s->stream_end); \
    return -1; \
  }

#define COPY_FROM_CURRENT() \
    motion_offset = current_offset; \
    motion_offset += y * s->stride; \
    motion_offset += x; \
    if (motion_offset < 0) { \
        av_log(s->avctx, AV_LOG_ERROR, " Interplay video: motion offset < 0 (%d)\n", motion_offset); \
        return -1; \
    } else if (motion_offset > s->upper_motion_limit_offset) { \
        av_log(s->avctx, AV_LOG_ERROR, " Interplay video: motion offset above limit (%d >= %d)\n", \
            motion_offset, s->upper_motion_limit_offset); \
        return -1; \
    } \
    s->dsp.put_pixels_tab[0][0](s->pixel_ptr, \
        s->current_frame.data[0] + motion_offset, s->stride, 8);

#define COPY_FROM_PREVIOUS() \
    motion_offset = current_offset; \
    motion_offset += y * s->stride; \
    motion_offset += x; \
    if (motion_offset < 0) { \
        av_log(s->avctx, AV_LOG_ERROR, " Interplay video: motion offset < 0 (%d)\n", motion_offset); \
        return -1; \
    } else if (motion_offset > s->upper_motion_limit_offset) { \
        av_log(s->avctx, AV_LOG_ERROR, " Interplay video: motion offset above limit (%d >= %d)\n", \
            motion_offset, s->upper_motion_limit_offset); \
        return -1; \
    } \
    s->dsp.put_pixels_tab[0][0](s->pixel_ptr, \
        s->last_frame.data[0] + motion_offset, s->stride, 8);

#define COPY_FROM_SECOND_LAST() \
    motion_offset = current_offset; \
    motion_offset += y * s->stride; \
    motion_offset += x; \
    if (motion_offset < 0) { \
        av_log(s->avctx, AV_LOG_ERROR, " Interplay video: motion offset < 0 (%d)\n", motion_offset); \
        return -1; \
    } else if (motion_offset > s->upper_motion_limit_offset) { \
        av_log(s->avctx, AV_LOG_ERROR, " Interplay video: motion offset above limit (%d >= %d)\n", \
            motion_offset, s->upper_motion_limit_offset); \
        return -1; \
    } \
    s->dsp.put_pixels_tab[0][0](s->pixel_ptr, \
        s->second_last_frame.data[0] + motion_offset, s->stride, 8);

static int ipvideo_decode_block_opcode_0x0(IpvideoContext *s)
{
    int x, y;
    int motion_offset;
    int current_offset = s->pixel_ptr - s->current_frame.data[0];

    /* copy a block from the previous frame */
    x = y = 0;
    COPY_FROM_PREVIOUS();

    /* report success */
    return 0;
}

static int ipvideo_decode_block_opcode_0x1(IpvideoContext *s)
{
    int x, y;
    int motion_offset;
    int current_offset = s->pixel_ptr - s->current_frame.data[0];

    /* copy block from 2 frames ago */
    x = y = 0;
    COPY_FROM_SECOND_LAST();

    /* report success */
    return 0;
}

static int ipvideo_decode_block_opcode_0x2(IpvideoContext *s)
{
    unsigned char B;
    int x, y;
    int motion_offset;
    int current_offset = s->pixel_ptr - s->current_frame.data[0];

    /* copy block from 2 frames ago using a motion vector; need 1 more byte */
    CHECK_STREAM_PTR(1);
    B = *s->stream_ptr++;

    if (B < 56) {
        x = 8 + (B % 7);
        y = B / 7;
    } else {
        x = -14 + ((B - 56) % 29);
        y =   8 + ((B - 56) / 29);
    }

    debug_interplay ("    motion byte = %d, (x, y) = (%d, %d)\n", B, x, y);
    COPY_FROM_SECOND_LAST();

    /* report success */
    return 0;
}

static int ipvideo_decode_block_opcode_0x3(IpvideoContext *s)
{
    unsigned char B;
    int x, y;
    int motion_offset;
    int current_offset = s->pixel_ptr - s->current_frame.data[0];

    /* copy 8x8 block from current frame from an up/left block */

    /* need 1 more byte for motion */
    CHECK_STREAM_PTR(1);
    B = *s->stream_ptr++;

    if (B < 56) {
        x = -(8 + (B % 7));
        y = -(B / 7);
    } else {
        x = -(-14 + ((B - 56) % 29));
        y = -(  8 + ((B - 56) / 29));
    }

    debug_interplay ("    motion byte = %d, (x, y) = (%d, %d)\n", B, x, y);
    COPY_FROM_CURRENT();

    /* report success */
    return 0;
}

static int ipvideo_decode_block_opcode_0x4(IpvideoContext *s)
{
    int x, y;
    unsigned char B, BL, BH;
    int motion_offset;
    int current_offset = s->pixel_ptr - s->current_frame.data[0];

    /* copy a block from the previous frame; need 1 more byte */
    CHECK_STREAM_PTR(1);

    B = *s->stream_ptr++;
    BL = B & 0x0F;
    BH = (B >> 4) & 0x0F;
    x = -8 + BL;
    y = -8 + BH;

    debug_interplay ("    motion byte = %d, (x, y) = (%d, %d)\n", B, x, y);
    COPY_FROM_PREVIOUS();

    /* report success */
    return 0;
}

static int ipvideo_decode_block_opcode_0x5(IpvideoContext *s)
{
    signed char x, y;
    int motion_offset;
    int current_offset = s->pixel_ptr - s->current_frame.data[0];

    /* copy a block from the previous frame using an expanded range;
     * need 2 more bytes */
    CHECK_STREAM_PTR(2);

    x = *s->stream_ptr++;
    y = *s->stream_ptr++;

    debug_interplay ("    motion bytes = %d, %d\n", x, y);
    COPY_FROM_PREVIOUS();

    /* report success */
    return 0;
}

static int ipvideo_decode_block_opcode_0x6(IpvideoContext *s)
{
    /* mystery opcode? skip multiple blocks? */
    av_log(s->avctx, AV_LOG_ERROR, "  Interplay video: Help! Mystery opcode 0x6 seen\n");

    /* report success */
    return 0;
}

static int ipvideo_decode_block_opcode_0x7(IpvideoContext *s)
{
    int x, y;
    unsigned char P0, P1;
    unsigned char B[8];
    unsigned int flags;
    int bitmask;

    /* 2-color encoding */
    CHECK_STREAM_PTR(2);

    P0 = *s->stream_ptr++;
    P1 = *s->stream_ptr++;

    if (P0 <= P1) {

        /* need 8 more bytes from the stream */
        CHECK_STREAM_PTR(8);
        for (y = 0; y < 8; y++)
            B[y] = *s->stream_ptr++;

        for (y = 0; y < 8; y++) {
            flags = B[y];
            for (x = 0x01; x <= 0x80; x <<= 1) {
                if (flags & x)
                    *s->pixel_ptr++ = P1;
                else
                    *s->pixel_ptr++ = P0;
            }
            s->pixel_ptr += s->line_inc;
        }

    } else {

        /* need 2 more bytes from the stream */
        CHECK_STREAM_PTR(2);

        flags = bytestream_get_le16(&s->stream_ptr);
        bitmask = 0x0001;
        for (y = 0; y < 8; y += 2) {
            for (x = 0; x < 8; x += 2, bitmask <<= 1) {
                if (flags & bitmask) {
                    *(s->pixel_ptr + x) = P1;
                    *(s->pixel_ptr + x + 1) = P1;
                    *(s->pixel_ptr + s->stride + x) = P1;
                    *(s->pixel_ptr + s->stride + x + 1) = P1;
                } else {
                    *(s->pixel_ptr + x) = P0;
                    *(s->pixel_ptr + x + 1) = P0;
                    *(s->pixel_ptr + s->stride + x) = P0;
                    *(s->pixel_ptr + s->stride + x + 1) = P0;
                }
            }
            s->pixel_ptr += s->stride * 2;
        }
    }

    /* report success */
    return 0;
}

static int ipvideo_decode_block_opcode_0x8(IpvideoContext *s)
{
    int x, y;
    unsigned char P[8];
    unsigned char B[8];
    unsigned int flags = 0;
    unsigned int bitmask = 0;
    unsigned char P0 = 0, P1 = 0;
    int lower_half = 0;

    /* 2-color encoding for each 4x4 quadrant, or 2-color encoding on
     * either top and bottom or left and right halves */
    CHECK_STREAM_PTR(2);

    P[0] = *s->stream_ptr++;
    P[1] = *s->stream_ptr++;

    if (P[0] <= P[1]) {

        /* need 12 more bytes */
        CHECK_STREAM_PTR(12);
        B[0] = *s->stream_ptr++;  B[1] = *s->stream_ptr++;
        P[2] = *s->stream_ptr++;  P[3] = *s->stream_ptr++;
        B[2] = *s->stream_ptr++;  B[3] = *s->stream_ptr++;
        P[4] = *s->stream_ptr++;  P[5] = *s->stream_ptr++;
        B[4] = *s->stream_ptr++;  B[5] = *s->stream_ptr++;
        P[6] = *s->stream_ptr++;  P[7] = *s->stream_ptr++;
        B[6] = *s->stream_ptr++;  B[7] = *s->stream_ptr++;

        for (y = 0; y < 8; y++) {

            /* time to reload flags? */
            if (y == 0) {
                flags =
                    ((B[0] & 0xF0) <<  4) | ((B[4] & 0xF0) <<  8) |
                    ((B[0] & 0x0F)      ) | ((B[4] & 0x0F) <<  4) |
                    ((B[1] & 0xF0) << 20) | ((B[5] & 0xF0) << 24) |
                    ((B[1] & 0x0F) << 16) | ((B[5] & 0x0F) << 20);
                bitmask = 0x00000001;
                lower_half = 0;  /* still on top half */
            } else if (y == 4) {
                flags =
                    ((B[2] & 0xF0) <<  4) | ((B[6] & 0xF0) <<  8) |
                    ((B[2] & 0x0F)      ) | ((B[6] & 0x0F) <<  4) |
                    ((B[3] & 0xF0) << 20) | ((B[7] & 0xF0) << 24) |
                    ((B[3] & 0x0F) << 16) | ((B[7] & 0x0F) << 20);
                bitmask = 0x00000001;
                lower_half = 2;
            }

            for (x = 0; x < 8; x++, bitmask <<= 1) {
                /* get the pixel values ready for this quadrant */
                if (x == 0) {
                    P0 = P[lower_half + 0];
                    P1 = P[lower_half + 1];
                } else if (x == 4) {
                    P0 = P[lower_half + 4];
                    P1 = P[lower_half + 5];
                }

                if (flags & bitmask)
                    *s->pixel_ptr++ = P1;
                else
                    *s->pixel_ptr++ = P0;
            }
            s->pixel_ptr += s->line_inc;
        }

    } else {

        /* need 10 more bytes */
        CHECK_STREAM_PTR(10);
        B[0] = *s->stream_ptr++;  B[1] = *s->stream_ptr++;
        B[2] = *s->stream_ptr++;  B[3] = *s->stream_ptr++;
        P[2] = *s->stream_ptr++;  P[3] = *s->stream_ptr++;
        B[4] = *s->stream_ptr++;  B[5] = *s->stream_ptr++;
        B[6] = *s->stream_ptr++;  B[7] = *s->stream_ptr++;

        if (P[2] <= P[3]) {

            /* vertical split; left & right halves are 2-color encoded */

            for (y = 0; y < 8; y++) {

                /* time to reload flags? */
                if (y == 0) {
                    flags =
                        ((B[0] & 0xF0) <<  4) | ((B[4] & 0xF0) <<  8) |
                        ((B[0] & 0x0F)      ) | ((B[4] & 0x0F) <<  4) |
                        ((B[1] & 0xF0) << 20) | ((B[5] & 0xF0) << 24) |
                        ((B[1] & 0x0F) << 16) | ((B[5] & 0x0F) << 20);
                    bitmask = 0x00000001;
                } else if (y == 4) {
                    flags =
                        ((B[2] & 0xF0) <<  4) | ((B[6] & 0xF0) <<  8) |
                        ((B[2] & 0x0F)      ) | ((B[6] & 0x0F) <<  4) |
                        ((B[3] & 0xF0) << 20) | ((B[7] & 0xF0) << 24) |
                        ((B[3] & 0x0F) << 16) | ((B[7] & 0x0F) << 20);
                    bitmask = 0x00000001;
                }

                for (x = 0; x < 8; x++, bitmask <<= 1) {
                    /* get the pixel values ready for this half */
                    if (x == 0) {
                        P0 = P[0];
                        P1 = P[1];
                    } else if (x == 4) {
                        P0 = P[2];
                        P1 = P[3];
                    }

                    if (flags & bitmask)
                        *s->pixel_ptr++ = P1;
                    else
                        *s->pixel_ptr++ = P0;
                }
                s->pixel_ptr += s->line_inc;
            }

        } else {

            /* horizontal split; top & bottom halves are 2-color encoded */

            for (y = 0; y < 8; y++) {

                flags = B[y];
                if (y == 0) {
                    P0 = P[0];
                    P1 = P[1];
                } else if (y == 4) {
                    P0 = P[2];
                    P1 = P[3];
                }

                for (bitmask = 0x01; bitmask <= 0x80; bitmask <<= 1) {

                    if (flags & bitmask)
                        *s->pixel_ptr++ = P1;
                    else
                        *s->pixel_ptr++ = P0;
                }
                s->pixel_ptr += s->line_inc;
            }
        }
    }

    /* report success */
    return 0;
}