www.pudn.com > ffmpeg_src2007.rar > 4xm.c


/* 
 * 4XM codec 
 * Copyright (c) 2003 Michael Niedermayer 
 * 
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 
 */ 
 
/** 
 * @file 4xm.c 
 * 4XM codec. 
 */ 
 
#include "avcodec.h" 
#include "dsputil.h" 
#include "mpegvideo.h" 
 
//#undef NDEBUG 
//#include  
 
#define BLOCK_TYPE_VLC_BITS 5 
#define ACDC_VLC_BITS 9 
 
#define CFRAME_BUFFER_COUNT 100 
 
static const uint8_t block_type_tab[4][8][2]={ 
  {   //{8,4,2}x{8,4,2} 
    { 0,1}, { 2,2}, { 6,3}, {14,4}, {30,5}, {31,5}, { 0,0} 
  },{ //{8,4}x1 
    { 0,1}, { 0,0}, { 2,2}, { 6,3}, {14,4}, {15,4}, { 0,0} 
  },{ //1x{8,4} 
    { 0,1}, { 2,2}, { 0,0}, { 6,3}, {14,4}, {15,4}, { 0,0} 
  },{ //1x2, 2x1 
    { 0,1}, { 0,0}, { 0,0}, { 2,2}, { 6,3}, {14,4}, {15,4} 
  } 
}; 
 
static const uint8_t size2index[4][4]={ 
  {-1, 3, 1, 1}, 
  { 3, 0, 0, 0}, 
  { 2, 0, 0, 0}, 
  { 2, 0, 0, 0}, 
}; 
 
static const int8_t mv[256][2]={ 
{  0,  0},{  0, -1},{ -1,  0},{  1,  0},{  0,  1},{ -1, -1},{  1, -1},{ -1,  1}, 
{  1,  1},{  0, -2},{ -2,  0},{  2,  0},{  0,  2},{ -1, -2},{  1, -2},{ -2, -1}, 
{  2, -1},{ -2,  1},{  2,  1},{ -1,  2},{  1,  2},{ -2, -2},{  2, -2},{ -2,  2}, 
{  2,  2},{  0, -3},{ -3,  0},{  3,  0},{  0,  3},{ -1, -3},{  1, -3},{ -3, -1}, 
{  3, -1},{ -3,  1},{  3,  1},{ -1,  3},{  1,  3},{ -2, -3},{  2, -3},{ -3, -2}, 
{  3, -2},{ -3,  2},{  3,  2},{ -2,  3},{  2,  3},{  0, -4},{ -4,  0},{  4,  0}, 
{  0,  4},{ -1, -4},{  1, -4},{ -4, -1},{  4, -1},{  4,  1},{ -1,  4},{  1,  4}, 
{ -3, -3},{ -3,  3},{  3,  3},{ -2, -4},{ -4, -2},{  4, -2},{ -4,  2},{ -2,  4}, 
{  2,  4},{ -3, -4},{  3, -4},{  4, -3},{ -5,  0},{ -4,  3},{ -3,  4},{  3,  4}, 
{ -1, -5},{ -5, -1},{ -5,  1},{ -1,  5},{ -2, -5},{  2, -5},{  5, -2},{  5,  2}, 
{ -4, -4},{ -4,  4},{ -3, -5},{ -5, -3},{ -5,  3},{  3,  5},{ -6,  0},{  0,  6}, 
{ -6, -1},{ -6,  1},{  1,  6},{  2, -6},{ -6,  2},{  2,  6},{ -5, -4},{  5,  4}, 
{  4,  5},{ -6, -3},{  6,  3},{ -7,  0},{ -1, -7},{  5, -5},{ -7,  1},{ -1,  7}, 
{  4, -6},{  6,  4},{ -2, -7},{ -7,  2},{ -3, -7},{  7, -3},{  3,  7},{  6, -5}, 
{  0, -8},{ -1, -8},{ -7, -4},{ -8,  1},{  4,  7},{  2, -8},{ -2,  8},{  6,  6}, 
{ -8,  3},{  5, -7},{ -5,  7},{  8, -4},{  0, -9},{ -9, -1},{  1,  9},{  7, -6}, 
{ -7,  6},{ -5, -8},{ -5,  8},{ -9,  3},{  9, -4},{  7, -7},{  8, -6},{  6,  8}, 
{ 10,  1},{-10,  2},{  9, -5},{ 10, -3},{ -8, -7},{-10, -4},{  6, -9},{-11,  0}, 
{ 11,  1},{-11, -2},{ -2, 11},{  7, -9},{ -7,  9},{ 10,  6},{ -4, 11},{  8, -9}, 
{  8,  9},{  5, 11},{  7,-10},{ 12, -3},{ 11,  6},{ -9, -9},{  8, 10},{  5, 12}, 
{-11,  7},{ 13,  2},{  6,-12},{ 10,  9},{-11,  8},{ -7, 12},{  0, 14},{ 14, -2}, 
{ -9, 11},{ -6, 13},{-14, -4},{ -5,-14},{  5, 14},{-15, -1},{-14, -6},{  3,-15}, 
{ 11,-11},{ -7, 14},{ -5, 15},{  8,-14},{ 15,  6},{  3, 16},{  7,-15},{-16,  5}, 
{  0, 17},{-16, -6},{-10, 14},{-16,  7},{ 12, 13},{-16,  8},{-17,  6},{-18,  3}, 
{ -7, 17},{ 15, 11},{ 16, 10},{  2,-19},{  3,-19},{-11,-16},{-18,  8},{-19, -6}, 
{  2,-20},{-17,-11},{-10,-18},{  8, 19},{-21, -1},{-20,  7},{ -4, 21},{ 21,  5}, 
{ 15, 16},{  2,-22},{-10,-20},{-22,  5},{ 20,-11},{ -7,-22},{-12, 20},{ 23, -5}, 
{ 13,-20},{ 24, -2},{-15, 19},{-11, 22},{ 16, 19},{ 23,-10},{-18,-18},{ -9,-24}, 
{ 24,-10},{ -3, 26},{-23, 13},{-18,-20},{ 17, 21},{ -4, 27},{ 27,  6},{  1,-28}, 
{-11, 26},{-17,-23},{  7, 28},{ 11,-27},{ 29,  5},{-23,-19},{-28,-11},{-21, 22}, 
{-30,  7},{-17, 26},{-27, 16},{ 13, 29},{ 19,-26},{ 10,-31},{-14,-30},{ 20,-27}, 
{-29, 18},{-16,-31},{-28,-22},{ 21,-30},{-25, 28},{ 26,-29},{ 25,-32},{-32,-32} 
}; 
 
// this is simply the scaled down elementwise product of the standard jpeg quantizer table and the AAN premul table 
static const uint8_t dequant_table[64]={ 
 16, 15, 13, 19, 24, 31, 28, 17, 
 17, 23, 25, 31, 36, 63, 45, 21, 
 18, 24, 27, 37, 52, 59, 49, 20, 
 16, 28, 34, 40, 60, 80, 51, 20, 
 18, 31, 48, 66, 68, 86, 56, 21, 
 19, 38, 56, 59, 64, 64, 48, 20, 
 27, 48, 55, 55, 56, 51, 35, 15, 
 20, 35, 34, 32, 31, 22, 15,  8, 
}; 
 
static VLC block_type_vlc[4]; 
 
 
typedef struct CFrameBuffer{ 
    int allocated_size; 
    int size; 
    int id; 
    uint8_t *data; 
}CFrameBuffer; 
 
typedef struct FourXContext{ 
    AVCodecContext *avctx; 
    DSPContext dsp; 
    AVFrame current_picture, last_picture; 
    GetBitContext pre_gb;          ///< ac/dc prefix 
    GetBitContext gb; 
    uint8_t *bytestream; 
    uint16_t *wordstream; 
    int mv[256]; 
    VLC pre_vlc; 
    int last_dc; 
    DECLARE_ALIGNED_8(DCTELEM, block[6][64]); 
    uint8_t *bitstream_buffer; 
    unsigned int bitstream_buffer_size; 
    CFrameBuffer cfrm[CFRAME_BUFFER_COUNT]; 
} FourXContext; 
 
 
#define FIX_1_082392200  70936 
#define FIX_1_414213562  92682 
#define FIX_1_847759065 121095 
#define FIX_2_613125930 171254 
 
#define MULTIPLY(var,const)  (((var)*(const)) >> 16) 
 
static void idct(DCTELEM block[64]){ 
    int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; 
    int tmp10, tmp11, tmp12, tmp13; 
    int z5, z10, z11, z12, z13; 
    int i; 
    int temp[64]; 
 
    for(i=0; i<8; i++){ 
        tmp10 = block[8*0 + i] + block[8*4 + i]; 
        tmp11 = block[8*0 + i] - block[8*4 + i]; 
 
        tmp13 =          block[8*2 + i] + block[8*6 + i]; 
        tmp12 = MULTIPLY(block[8*2 + i] - block[8*6 + i], FIX_1_414213562) - tmp13; 
 
        tmp0 = tmp10 + tmp13; 
        tmp3 = tmp10 - tmp13; 
        tmp1 = tmp11 + tmp12; 
        tmp2 = tmp11 - tmp12; 
 
        z13 = block[8*5 + i] + block[8*3 + i]; 
        z10 = block[8*5 + i] - block[8*3 + i]; 
        z11 = block[8*1 + i] + block[8*7 + i]; 
        z12 = block[8*1 + i] - block[8*7 + i]; 
 
        tmp7  =          z11 + z13; 
        tmp11 = MULTIPLY(z11 - z13, FIX_1_414213562); 
 
        z5    = MULTIPLY(z10 + z12, FIX_1_847759065); 
        tmp10 = MULTIPLY(z12, FIX_1_082392200) - z5; 
        tmp12 = MULTIPLY(z10, - FIX_2_613125930) + z5; 
 
        tmp6 = tmp12 - tmp7; 
        tmp5 = tmp11 - tmp6; 
        tmp4 = tmp10 + tmp5; 
 
        temp[8*0 + i] = tmp0 + tmp7; 
        temp[8*7 + i] = tmp0 - tmp7; 
        temp[8*1 + i] = tmp1 + tmp6; 
        temp[8*6 + i] = tmp1 - tmp6; 
        temp[8*2 + i] = tmp2 + tmp5; 
        temp[8*5 + i] = tmp2 - tmp5; 
        temp[8*4 + i] = tmp3 + tmp4; 
        temp[8*3 + i] = tmp3 - tmp4; 
    } 
 
    for(i=0; i<8*8; i+=8){ 
        tmp10 = temp[0 + i] + temp[4 + i]; 
        tmp11 = temp[0 + i] - temp[4 + i]; 
 
        tmp13 = temp[2 + i] + temp[6 + i]; 
        tmp12 = MULTIPLY(temp[2 + i] - temp[6 + i], FIX_1_414213562) - tmp13; 
 
        tmp0 = tmp10 + tmp13; 
        tmp3 = tmp10 - tmp13; 
        tmp1 = tmp11 + tmp12; 
        tmp2 = tmp11 - tmp12; 
 
        z13 = temp[5 + i] + temp[3 + i]; 
        z10 = temp[5 + i] - temp[3 + i]; 
        z11 = temp[1 + i] + temp[7 + i]; 
        z12 = temp[1 + i] - temp[7 + i]; 
 
        tmp7 = z11 + z13; 
        tmp11 = MULTIPLY(z11 - z13, FIX_1_414213562); 
 
        z5 = MULTIPLY(z10 + z12, FIX_1_847759065); 
        tmp10 = MULTIPLY(z12, FIX_1_082392200) - z5; 
        tmp12 = MULTIPLY(z10, - FIX_2_613125930) + z5; 
 
        tmp6 = tmp12 - tmp7; 
        tmp5 = tmp11 - tmp6; 
        tmp4 = tmp10 + tmp5; 
 
        block[0 + i] = (tmp0 + tmp7)>>6; 
        block[7 + i] = (tmp0 - tmp7)>>6; 
        block[1 + i] = (tmp1 + tmp6)>>6; 
        block[6 + i] = (tmp1 - tmp6)>>6; 
        block[2 + i] = (tmp2 + tmp5)>>6; 
        block[5 + i] = (tmp2 - tmp5)>>6; 
        block[4 + i] = (tmp3 + tmp4)>>6; 
        block[3 + i] = (tmp3 - tmp4)>>6; 
    } 
} 
 
static void init_vlcs(FourXContext *f){ 
    int i; 
 
    for(i=0; i<4; i++){ 
        init_vlc(&block_type_vlc[i], BLOCK_TYPE_VLC_BITS, 7, 
                 &block_type_tab[i][0][1], 2, 1, 
                 &block_type_tab[i][0][0], 2, 1, 1); 
    } 
} 
 
static void init_mv(FourXContext *f){ 
    int i; 
 
    for(i=0; i<256; i++){ 
        f->mv[i] = mv[i][0] + mv[i][1]*f->current_picture.linesize[0]/2; 
    } 
} 
 
static inline void mcdc(uint16_t *dst, uint16_t *src, int log2w, int h, int stride, int scale, int dc){ 
   int i; 
   dc*= 0x10001; 
 
   switch(log2w){ 
   case 0: 
        for(i=0; igb, block_type_vlc[index].table, BLOCK_TYPE_VLC_BITS, 1); 
 
    assert(code>=0 && code<=6); 
 
    if(code == 0){ 
        src += f->mv[ *f->bytestream++ ]; 
        mcdc(dst, src, log2w, h, stride, 1, 0); 
    }else if(code == 1){ 
        log2h--; 
        decode_p_block(f, dst                  , src                  , log2w, log2h, stride); 
        decode_p_block(f, dst + (stride<mv[ *f->bytestream++ ]; 
        mcdc(dst, src, log2w, h, stride, 1, le2me_16(*f->wordstream++)); 
    }else if(code == 5){ 
        mcdc(dst, src, log2w, h, stride, 0, le2me_16(*f->wordstream++)); 
    }else if(code == 6){ 
        if(log2w){ 
            dst[0] = le2me_16(*f->wordstream++); 
            dst[1] = le2me_16(*f->wordstream++); 
        }else{ 
            dst[0     ] = le2me_16(*f->wordstream++); 
            dst[stride] = le2me_16(*f->wordstream++); 
        } 
    } 
} 
 
static int get32(void *p){ 
    return le2me_32(*(uint32_t*)p); 
} 
 
static int decode_p_frame(FourXContext *f, uint8_t *buf, int length){ 
    int x, y; 
    const int width= f->avctx->width; 
    const int height= f->avctx->height; 
    uint16_t *src= (uint16_t*)f->last_picture.data[0]; 
    uint16_t *dst= (uint16_t*)f->current_picture.data[0]; 
    const int stride= f->current_picture.linesize[0]>>1; 
    const unsigned int bitstream_size= get32(buf+8); 
    const unsigned int bytestream_size= get32(buf+16); 
    const unsigned int wordstream_size= get32(buf+12); 
 
    if(bitstream_size+ bytestream_size+ wordstream_size + 20 != length 
       || bitstream_size  > (1<<26) 
       || bytestream_size > (1<<26) 
       || wordstream_size > (1<<26) 
       ){ 
        av_log(f->avctx, AV_LOG_ERROR, "lengths %d %d %d %d\n", bitstream_size, bytestream_size, wordstream_size, 
        bitstream_size+ bytestream_size+ wordstream_size - length); 
        return -1; 
    } 
 
    f->bitstream_buffer= av_fast_realloc(f->bitstream_buffer, &f->bitstream_buffer_size, bitstream_size + FF_INPUT_BUFFER_PADDING_SIZE); 
    f->dsp.bswap_buf((uint32_t*)f->bitstream_buffer, (uint32_t*)(buf + 20), bitstream_size/4); 
    init_get_bits(&f->gb, f->bitstream_buffer, 8*bitstream_size); 
 
    f->wordstream= (uint16_t*)(buf + 20 + bitstream_size); 
    f->bytestream= buf + 20 + bitstream_size + wordstream_size; 
 
    init_mv(f); 
 
    for(y=0; ygb)+31)/32*4) 
        av_log(f->avctx, AV_LOG_ERROR, " %d %td %td bytes left\n", 
            bitstream_size - (get_bits_count(&f->gb)+31)/32*4, 
            bytestream_size - (f->bytestream - (buf + 20 + bitstream_size + wordstream_size)), 
            wordstream_size - (((uint8_t*)f->wordstream) - (buf + 20 + bitstream_size)) 
        ); 
 
    return 0; 
} 
 
/** 
 * decode block and dequantize. 
 * Note this is allmost identical to mjpeg 
 */ 
static int decode_i_block(FourXContext *f, DCTELEM *block){ 
    int code, i, j, level, val; 
 
    /* DC coef */ 
    val = get_vlc2(&f->pre_gb, f->pre_vlc.table, ACDC_VLC_BITS, 3); 
    if (val>>4){ 
        av_log(f->avctx, AV_LOG_ERROR, "error dc run != 0\n"); 
    } 
 
    if(val) 
        val = get_xbits(&f->gb, val); 
 
    val = val * dequant_table[0] + f->last_dc; 
    f->last_dc = 
    block[0] = val; 
    /* AC coefs */ 
    i = 1; 
    for(;;) { 
        code = get_vlc2(&f->pre_gb, f->pre_vlc.table, ACDC_VLC_BITS, 3); 
 
        /* EOB */ 
        if (code == 0) 
            break; 
        if (code == 0xf0) { 
            i += 16; 
        } else { 
            level = get_xbits(&f->gb, code & 0xf); 
            i += code >> 4; 
            if (i >= 64) { 
                av_log(f->avctx, AV_LOG_ERROR, "run %d oveflow\n", i); 
                return 0; 
            } 
 
            j= ff_zigzag_direct[i]; 
            block[j] = level * dequant_table[j]; 
            i++; 
            if (i >= 64) 
                break; 
        } 
    } 
 
    return 0; 
} 
 
static inline void idct_put(FourXContext *f, int x, int y){ 
    DCTELEM (*block)[64]= f->block; 
    int stride= f->current_picture.linesize[0]>>1; 
    int i; 
    uint16_t *dst = ((uint16_t*)f->current_picture.data[0]) + y * stride + x; 
 
    for(i=0; i<4; i++){ 
        block[i][0] += 0x80*8*8; 
        idct(block[i]); 
    } 
 
    if(!(f->avctx->flags&CODEC_FLAG_GRAY)){ 
        for(i=4; i<6; i++) idct(block[i]); 
    } 
 
/* Note transform is: 
y= ( 1b + 4g + 2r)/14 
cb=( 3b - 2g - 1r)/14 
cr=(-1b - 4g + 5r)/14 
*/ 
    for(y=0; y<8; y++){ 
        for(x=0; x<8; x++){ 
            DCTELEM *temp= block[(x>>2) + 2*(y>>2)] + 2*(x&3) + 2*8*(y&3); //FIXME optimize 
            int cb= block[4][x + 8*y]; 
            int cr= block[5][x + 8*y]; 
            int cg= (cb + cr)>>1; 
            int y; 
 
            cb+=cb; 
 
            y = temp[0]; 
            dst[0       ]= ((y+cb)>>3) + (((y-cg)&0xFC)<<3) + (((y+cr)&0xF8)<<8); 
            y = temp[1]; 
            dst[1       ]= ((y+cb)>>3) + (((y-cg)&0xFC)<<3) + (((y+cr)&0xF8)<<8); 
            y = temp[8]; 
            dst[  stride]= ((y+cb)>>3) + (((y-cg)&0xFC)<<3) + (((y+cr)&0xF8)<<8); 
            y = temp[9]; 
            dst[1+stride]= ((y+cb)>>3) + (((y-cg)&0xFC)<<3) + (((y+cr)&0xF8)<<8); 
            dst += 2; 
        } 
        dst += 2*stride - 2*8; 
    } 
} 
 
static int decode_i_mb(FourXContext *f){ 
    int i; 
 
    f->dsp.clear_blocks(f->block[0]); 
 
    for(i=0; i<6; i++){ 
        if(decode_i_block(f, f->block[i]) < 0) 
            return -1; 
    } 
 
    return 0; 
} 
 
static uint8_t *read_huffman_tables(FourXContext *f, uint8_t * const buf){ 
    int frequency[512]; 
    uint8_t flag[512]; 
    int up[512]; 
    uint8_t len_tab[257]; 
    int bits_tab[257]; 
    int start, end; 
    uint8_t *ptr= buf; 
    int j; 
 
    memset(frequency, 0, sizeof(frequency)); 
    memset(up, -1, sizeof(up)); 
 
    start= *ptr++; 
    end= *ptr++; 
    for(;;){ 
        int i; 
 
        for(i=start; i<=end; i++){ 
            frequency[i]= *ptr++; 
//            printf("%d %d %d\n", start, end, frequency[i]); 
        } 
        start= *ptr++; 
        if(start==0) break; 
 
        end= *ptr++; 
    } 
    frequency[256]=1; 
 
    while((ptr - buf)&3) ptr++; // 4byte align 
 
//    for(j=0; j<16; j++) 
//        printf("%2X", ptr[j]); 
 
    for(j=257; j<512; j++){ 
        int min_freq[2]= {256*256, 256*256}; 
        int smallest[2]= {0, 0}; 
        int i; 
        for(i=0; i 31) av_log(f->avctx, AV_LOG_ERROR, "vlc length overflow\n"); //can this happen at all ? 
        } 
 
        bits_tab[j]= bits; 
        len_tab[j]= len; 
    } 
 
    init_vlc(&f->pre_vlc, ACDC_VLC_BITS, 257, 
             len_tab , 1, 1, 
             bits_tab, 4, 4, 0); 
 
    return ptr; 
} 
 
static int decode_i_frame(FourXContext *f, uint8_t *buf, int length){ 
    int x, y; 
    const int width= f->avctx->width; 
    const int height= f->avctx->height; 
    uint16_t *dst= (uint16_t*)f->current_picture.data[0]; 
    const int stride= f->current_picture.linesize[0]>>1; 
    const unsigned int bitstream_size= get32(buf); 
    const int token_count __attribute__((unused)) = get32(buf + bitstream_size + 8); 
    unsigned int prestream_size= 4*get32(buf + bitstream_size + 4); 
    uint8_t *prestream= buf + bitstream_size + 12; 
 
    if(prestream_size + bitstream_size + 12 != length 
       || bitstream_size > (1<<26) 
       || prestream_size > (1<<26)){ 
        av_log(f->avctx, AV_LOG_ERROR, "size mismatch %d %d %d\n", prestream_size, bitstream_size, length); 
        return -1; 
    } 
 
    prestream= read_huffman_tables(f, prestream); 
 
    init_get_bits(&f->gb, buf + 4, 8*bitstream_size); 
 
    prestream_size= length + buf - prestream; 
 
    f->bitstream_buffer= av_fast_realloc(f->bitstream_buffer, &f->bitstream_buffer_size, prestream_size + FF_INPUT_BUFFER_PADDING_SIZE); 
    f->dsp.bswap_buf((uint32_t*)f->bitstream_buffer, (uint32_t*)prestream, prestream_size/4); 
    init_get_bits(&f->pre_gb, f->bitstream_buffer, 8*prestream_size); 
 
    f->last_dc= 0*128*8*8; 
 
    for(y=0; ypre_gb, f->pre_vlc.table, ACDC_VLC_BITS, 3) != 256) 
        av_log(f->avctx, AV_LOG_ERROR, "end mismatch\n"); 
 
    return 0; 
} 
 
static int decode_frame(AVCodecContext *avctx, 
                        void *data, int *data_size, 
                        uint8_t *buf, int buf_size) 
{ 
    FourXContext * const f = avctx->priv_data; 
    AVFrame *picture = data; 
    AVFrame *p, temp; 
    int i, frame_4cc, frame_size; 
 
    frame_4cc= get32(buf); 
    if(buf_size != get32(buf+4)+8){ 
        av_log(f->avctx, AV_LOG_ERROR, "size mismatch %d %d\n", buf_size, get32(buf+4)); 
    } 
 
    if(frame_4cc == ff_get_fourcc("cfrm")){ 
        int free_index=-1; 
        const int data_size= buf_size - 20; 
        const int id= get32(buf+12); 
        const int whole_size= get32(buf+16); 
        CFrameBuffer *cfrm; 
 
        for(i=0; icfrm[i].id && f->cfrm[i].id < avctx->frame_number) 
                av_log(f->avctx, AV_LOG_ERROR, "lost c frame %d\n", f->cfrm[i].id); 
        } 
 
        for(i=0; icfrm[i].id   == id) break; 
            if(f->cfrm[i].size == 0 ) free_index= i; 
        } 
 
        if(i>=CFRAME_BUFFER_COUNT){ 
            i= free_index; 
            f->cfrm[i].id= id; 
        } 
        cfrm= &f->cfrm[i]; 
 
        cfrm->data= av_fast_realloc(cfrm->data, &cfrm->allocated_size, cfrm->size + data_size + FF_INPUT_BUFFER_PADDING_SIZE); 
 
        memcpy(cfrm->data + cfrm->size, buf+20, data_size); 
        cfrm->size += data_size; 
 
        if(cfrm->size >= whole_size){ 
            buf= cfrm->data; 
            frame_size= cfrm->size; 
 
            if(id != avctx->frame_number){ 
                av_log(f->avctx, AV_LOG_ERROR, "cframe id mismatch %d %d\n", id, avctx->frame_number); 
            } 
 
            cfrm->size= cfrm->id= 0; 
            frame_4cc= ff_get_fourcc("pfrm"); 
        }else 
            return buf_size; 
    }else{ 
        buf= buf + 12; 
        frame_size= buf_size - 12; 
    } 
 
    temp= f->current_picture; 
    f->current_picture= f->last_picture; 
    f->last_picture= temp; 
 
    p= &f->current_picture; 
    avctx->coded_frame= p; 
 
    avctx->flags |= CODEC_FLAG_EMU_EDGE; // alternatively we would have to use our own buffer management 
 
    if(p->data[0]) 
        avctx->release_buffer(avctx, p); 
 
    p->reference= 1; 
    if(avctx->get_buffer(avctx, p) < 0){ 
        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n"); 
        return -1; 
    } 
 
    if(frame_4cc == ff_get_fourcc("ifrm")){ 
        p->pict_type= I_TYPE; 
        if(decode_i_frame(f, buf, frame_size) < 0) 
            return -1; 
    }else if(frame_4cc == ff_get_fourcc("pfrm")){ 
        p->pict_type= P_TYPE; 
        if(decode_p_frame(f, buf, frame_size) < 0) 
            return -1; 
    }else if(frame_4cc == ff_get_fourcc("snd_")){ 
        av_log(avctx, AV_LOG_ERROR, "ignoring snd_ chunk length:%d\n", buf_size); 
    }else{ 
        av_log(avctx, AV_LOG_ERROR, "ignoring unknown chunk length:%d\n", buf_size); 
    } 
 
#if 0 
for(i=0; i<20; i++){ 
    printf("%2X %c ", buf[i], clip(buf[i],16,126)); 
} 
#endif 
 
    p->key_frame= p->pict_type == I_TYPE; 
 
    *picture= *p; 
    *data_size = sizeof(AVPicture); 
 
    emms_c(); 
 
    return buf_size; 
} 
 
 
static void common_init(AVCodecContext *avctx){ 
    FourXContext * const f = avctx->priv_data; 
 
    dsputil_init(&f->dsp, avctx); 
 
    f->avctx= avctx; 
} 
 
static int decode_init(AVCodecContext *avctx){ 
    FourXContext * const f = avctx->priv_data; 
 
    common_init(avctx); 
    init_vlcs(f); 
 
    avctx->pix_fmt= PIX_FMT_RGB565; 
 
    return 0; 
} 
 
 
static int decode_end(AVCodecContext *avctx){ 
    FourXContext * const f = avctx->priv_data; 
    int i; 
 
    av_freep(&f->bitstream_buffer); 
    f->bitstream_buffer_size=0; 
    for(i=0; icfrm[i].data); 
        f->cfrm[i].allocated_size= 0; 
    } 
    free_vlc(&f->pre_vlc); 
 
    return 0; 
} 
 
AVCodec fourxm_decoder = { 
    "4xm", 
    CODEC_TYPE_VIDEO, 
    CODEC_ID_4XM, 
    sizeof(FourXContext), 
    decode_init, 
    NULL, 
    decode_end, 
    decode_frame, 
    /*CODEC_CAP_DR1,*/ 
};