xan.c

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

/*
 * Wing Commander/Xan Video Decoder
 * Copyright (C) 2003 the ffmpeg project
 *
 * This library 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 of the License, or (at your option) any later version.
 *
 * This library 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 this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

/**
 * @file xan.c
 * Xan video decoder for Wing Commander III & IV computer games
 * by Mario Brito ([e-mail])
 * and Mike Melanson ([e-mail])
 *
 * The xan_wc3 decoder outputs the following colorspaces natively:
 *   PAL8 (default), RGB555, RGB565, RGB24, BGR24, RGBA32, YUV444P
 */

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

#include "common.h"
#include "avcodec.h"
#include "dsputil.h"

#define PALETTE_COUNT 256
#define PALETTE_CONTROL_SIZE ((256 * 3) + 1)

typedef struct XanContext {

    AVCodecContext *avctx;
    DSPContext dsp;
    AVFrame last_frame;
    AVFrame current_frame;

    unsigned char *buf;
    int size;

    unsigned char palette[PALETTE_COUNT * 4];

    /* scratch space */
    unsigned char *buffer1;
    unsigned char *buffer2;

} XanContext;

#define BE_16(x)  ((((uint8_t*)(x))[0] << 8) | ((uint8_t*)(x))[1])
#define LE_16(x)  ((((uint8_t*)(x))[1] << 8) | ((uint8_t*)(x))[0])
#define LE_32(x)  ((((uint8_t*)(x))[3] << 24) | \
                   (((uint8_t*)(x))[2] << 16) | \
                   (((uint8_t*)(x))[1] << 8) | \
                    ((uint8_t*)(x))[0])

/* RGB -> YUV conversion stuff */
#define SCALEFACTOR 65536
#define CENTERSAMPLE 128

#define COMPUTE_Y(r, g, b) \
  (unsigned char) \
  ((y_r_table[r] + y_g_table[g] + y_b_table[b]) / SCALEFACTOR)
#define COMPUTE_U(r, g, b) \
  (unsigned char) \
  ((u_r_table[r] + u_g_table[g] + u_b_table[b]) / SCALEFACTOR + CENTERSAMPLE)
#define COMPUTE_V(r, g, b) \
  (unsigned char) \
  ((v_r_table[r] + v_g_table[g] + v_b_table[b]) / SCALEFACTOR + CENTERSAMPLE)

#define Y_R (SCALEFACTOR *  0.29900)
#define Y_G (SCALEFACTOR *  0.58700)
#define Y_B (SCALEFACTOR *  0.11400)

#define U_R (SCALEFACTOR * -0.16874)
#define U_G (SCALEFACTOR * -0.33126)
#define U_B (SCALEFACTOR *  0.50000)

#define V_R (SCALEFACTOR *  0.50000)
#define V_G (SCALEFACTOR * -0.41869)
#define V_B (SCALEFACTOR * -0.08131)

/*
 * Precalculate all of the YUV tables since it requires fewer than
 * 10 kilobytes to store them.
 */
static int y_r_table[256];
static int y_g_table[256];
static int y_b_table[256];

static int u_r_table[256];
static int u_g_table[256];
static int u_b_table[256];

static int v_r_table[256];
static int v_g_table[256];
static int v_b_table[256];

static int xan_decode_init(AVCodecContext *avctx)
{
    XanContext *s = avctx->priv_data;
    int i;

    s->avctx = avctx;

    if ((avctx->codec->id == CODEC_ID_XAN_WC3) && 
        (s->avctx->palctrl == NULL)) {
        av_log(avctx, AV_LOG_ERROR, " WC3 Xan video: palette expected.\n");
        return -1;
    }

    avctx->pix_fmt = PIX_FMT_PAL8;
    avctx->has_b_frames = 0;
    dsputil_init(&s->dsp, avctx);

    /* initialize the RGB -> YUV tables */
    for (i = 0; i < 256; i++) {
        y_r_table[i] = Y_R * i;
        y_g_table[i] = Y_G * i;
        y_b_table[i] = Y_B * i;

        u_r_table[i] = U_R * i;
        u_g_table[i] = U_G * i;
        u_b_table[i] = U_B * i;

        v_r_table[i] = V_R * i;
        v_g_table[i] = V_G * i;
        v_b_table[i] = V_B * i;
    }

    s->buffer1 = av_malloc(avctx->width * avctx->height);
    s->buffer2 = av_malloc(avctx->width * avctx->height);
    if (!s->buffer1 || !s->buffer2)
        return -1;

    return 0;
}

/* This function is used in lieu of memcpy(). This decoder can not use 
 * memcpy because the memory locations often overlap and
 * memcpy doesn't like that; it's not uncommon, for example, for
 * dest = src+1, to turn byte A into  pattern AAAAAAAA.
 * This was originally repz movsb in Intel x86 ASM. */
static inline void bytecopy(unsigned char *dest, unsigned char *src, int count)
{
    int i;

    for (i = 0; i < count; i++)
        dest[i] = src[i];
}

static int xan_huffman_decode(unsigned char *dest, unsigned char *src)
{
    unsigned char byte = *src++;
    unsigned char ival = byte + 0x16;
    unsigned char * ptr = src + byte*2;
    unsigned char val = ival;
    int counter = 0;

    unsigned char bits = *ptr++;

    while ( val != 0x16 ) {
        if ( (1 << counter) & bits )
            val = src[byte + val - 0x17];
        else
            val = src[val - 0x17];

        if ( val < 0x16 ) {
            *dest++ = val;
            val = ival;
        }

        if (counter++ == 7) {
            counter = 0;
            bits = *ptr++;
        }
    }

    return 0;
}

static void xan_unpack(unsigned char *dest, unsigned char *src)
{
    unsigned char opcode;
    int size;
    int offset;
    int byte1, byte2, byte3;

    for (;;) {
        opcode = *src++;

        if ( (opcode & 0x80) == 0 ) {

            offset = *src++;

            size = opcode & 3;
            bytecopy(dest, src, size);  dest += size;  src += size;

            size = ((opcode & 0x1c) >> 2) + 3;
            bytecopy (dest, dest - (((opcode & 0x60) << 3) + offset + 1), size);
            dest += size;

        } else if ( (opcode & 0x40) == 0 ) {

            byte1 = *src++;
            byte2 = *src++;

            size = byte1 >> 6;
            bytecopy (dest, src, size);  dest += size;  src += size;

            size = (opcode & 0x3f) + 4;
            bytecopy (dest, dest - (((byte1 & 0x3f) << 8) + byte2 + 1), size);
            dest += size;

        } else if ( (opcode & 0x20) == 0 ) {

            byte1 = *src++;
            byte2 = *src++;
            byte3 = *src++;

            size = opcode & 3;
            bytecopy (dest, src, size);  dest += size;  src += size;

            size = byte3 + 5 + ((opcode & 0xc) << 6);
            bytecopy (dest,
                dest - ((((opcode & 0x10) >> 4) << 0x10) + 1 + (byte1 << 8) + byte2),
                size);
            dest += size;
        } else {
            size = ((opcode & 0x1f) << 2) + 4;

            if (size > 0x70)
                break;

            bytecopy (dest, src, size);  dest += size;  src += size;
        }
    }

    size = opcode & 3;
    bytecopy(dest, src, size);  dest += size;  src += size;
}

static void inline xan_wc3_build_palette(XanContext *s, 
    unsigned int *palette_data)
{
    int i;
    unsigned char r, g, b;
    unsigned short *palette16;
    unsigned int *palette32;
    unsigned int pal_elem;

    /* transform the palette passed through the palette control structure
     * into the necessary internal format depending on colorspace */

    switch (s->avctx->pix_fmt) {

    case PIX_FMT_RGB555:
        palette16 = (unsigned short *)s->palette;
        for (i = 0; i < PALETTE_COUNT; i++) {
            pal_elem = palette_data[i];
            r = (pal_elem >> 16) & 0xff;
            g = (pal_elem >> 8) & 0xff;
            b = pal_elem & 0xff;
            palette16[i] = 
                ((r >> 3) << 10) |
                ((g >> 3) <<  5) |
                ((b >> 3) <<  0);
        }
        break;

    case PIX_FMT_RGB565:
        palette16 = (unsigned short *)s->palette;
        for (i = 0; i < PALETTE_COUNT; i++) {
            pal_elem = palette_data[i];
            r = (pal_elem >> 16) & 0xff;
            g = (pal_elem >> 8) & 0xff;
            b = pal_elem & 0xff;
            palette16[i] = 
                ((r >> 3) << 11) |
                ((g >> 2) <<  5) |
                ((b >> 3) <<  0);
        }
        break;

    case PIX_FMT_RGB24:
        for (i = 0; i < PALETTE_COUNT; i++) {
            pal_elem = palette_data[i];
            r = (pal_elem >> 16) & 0xff;
            g = (pal_elem >> 8) & 0xff;
            b = pal_elem & 0xff;
            s->palette[i * 4 + 0] = r;
            s->palette[i * 4 + 1] = g;
            s->palette[i * 4 + 2] = b;
        }
        break;

    case PIX_FMT_BGR24:
        for (i = 0; i < PALETTE_COUNT; i++) {
            pal_elem = palette_data[i];
            r = (pal_elem >> 16) & 0xff;
            g = (pal_elem >> 8) & 0xff;
            b = pal_elem & 0xff;
            s->palette[i * 4 + 0] = b;
            s->palette[i * 4 + 1] = g;
            s->palette[i * 4 + 2] = r;
        }
        break;

    case PIX_FMT_PAL8:
    case PIX_FMT_RGBA32:
        palette32 = (unsigned int *)s->palette;
        memcpy (palette32, palette_data, PALETTE_COUNT * sizeof(unsigned int));
        break;

    case PIX_FMT_YUV444P:
        for (i = 0; i < PALETTE_COUNT; i++) {
            pal_elem = palette_data[i];
            r = (pal_elem >> 16) & 0xff;
            g = (pal_elem >> 8) & 0xff;
            b = pal_elem & 0xff;
            s->palette[i * 4 + 0] = COMPUTE_Y(r, g, b);
            s->palette[i * 4 + 1] = COMPUTE_U(r, g, b);
            s->palette[i * 4 + 2] = COMPUTE_V(r, g, b);
        }
        break;

    default:
        av_log(s->avctx, AV_LOG_ERROR, " Xan WC3: Unhandled colorspace\n");
        break;
    }
}

/* advance current_x variable; reset accounting variables if current_x
 * moves beyond width */
#define ADVANCE_CURRENT_X() \
    current_x++; \
    if (current_x >= width) { \
        index += line_inc; \
        current_x = 0; \
    }

static void inline xan_wc3_output_pixel_run(XanContext *s, 
    unsigned char *pixel_buffer, int x, int y, int pixel_count)
{
    int stride;
    int line_inc;
    int index;
    int current_x;
    int width = s->avctx->width;
    unsigned char pix;
    unsigned char *palette_plane;
    unsigned char *y_plane;
    unsigned char *u_plane;
    unsigned char *v_plane;
    unsigned char *rgb_plane;
    unsigned short *rgb16_plane;
    unsigned short *palette16;
    unsigned int *rgb32_plane;
    unsigned int *palette32;

    switch (s->avctx->pix_fmt) {

    case PIX_FMT_PAL8:
        palette_plane = s->current_frame.data[0];
        stride = s->current_frame.linesize[0];
        line_inc = stride - width;
        index = y * stride + x;
        current_x = x;
        while(pixel_count--) {

            /* don't do a memcpy() here; keyframes generally copy an entire
             * frame of data and the stride needs to be accounted for */
            palette_plane[index++] = *pixel_buffer++;

            ADVANCE_CURRENT_X();
        }
        break;

    case PIX_FMT_RGB555:
    case PIX_FMT_RGB565:
        rgb16_plane = (unsigned short *)s->current_frame.data[0];
        palette16 = (unsigned short *)s->palette;
        stride = s->current_frame.linesize[0] / 2;
        line_inc = stride - width;
        index = y * stride + x;
        current_x = x;
        while(pixel_count--) {

            rgb16_plane[index++] = palette16[*pixel_buffer++];

            ADVANCE_CURRENT_X();
        }
        break;

    case PIX_FMT_RGB24:
    case PIX_FMT_BGR24:
        rgb_plane = s->current_frame.data[0];
        stride = s->current_frame.linesize[0];
        line_inc = stride - width * 3;
        index = y * stride + x * 3;
        current_x = x;
        while(pixel_count--) {
            pix = *pixel_buffer++;