dv.c

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.7平台上编译为嵌入式图形界面操作系统。

/*
 * DV decoder
 * Copyright (c) 2002 Fabrice Bellard.
 *
 * 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
 */
#include "avcodec.h"
#include "dsputil.h"
#include "mpegvideo.h"
#include "simple_idct.h"

#define NTSC_FRAME_SIZE 120000
#define PAL_FRAME_SIZE  144000

#define TEX_VLC_BITS 9

typedef struct DVVideoDecodeContext {
    AVCodecContext *avctx;
    GetBitContext gb;
    VLC *vlc;
    int sampling_411; /* 0 = 420, 1 = 411 */
    int width, height;
    UINT8 *current_picture[3]; /* picture structure */
    int linesize[3];
    DCTELEM block[5*6][64] __align8;
    UINT8 dv_zigzag[2][64];
    UINT8 idct_permutation[64];
    /* XXX: move it to static storage ? */
    UINT8 dv_shift[2][22][64];
    void (*idct_put[2])(UINT8 *dest, int line_size, DCTELEM *block);
} DVVideoDecodeContext;

#include "dvdata.h"

static VLC dv_vlc;
/* XXX: also include quantization */
static RL_VLC_ELEM *dv_rl_vlc[1];

static void dv_build_unquantize_tables(DVVideoDecodeContext *s)
{
    int i, q, j;

    /* NOTE: max left shift is 6 */
    for(q = 0; q < 22; q++) {
        /* 88 unquant */
        for(i = 1; i < 64; i++) {
            /* 88 table */
            j = s->idct_permutation[i];
            s->dv_shift[0][q][j] =
                dv_quant_shifts[q][dv_88_areas[i]] + 1;
        }
        
        /* 248 unquant */
        for(i = 1; i < 64; i++) {
            /* 248 table */
            s->dv_shift[1][q][i] =  
                    dv_quant_shifts[q][dv_248_areas[i]] + 1;
        }
    }
}

static int dvvideo_decode_init(AVCodecContext *avctx)
{
    DVVideoDecodeContext *s = avctx->priv_data;
    MpegEncContext s2;
    static int done;

    if (!done) {
        int i;

        done = 1;

        /* NOTE: as a trick, we use the fact the no codes are unused
           to accelerate the parsing of partial codes */
        init_vlc(&dv_vlc, TEX_VLC_BITS, NB_DV_VLC, 
                 dv_vlc_len, 1, 1, dv_vlc_bits, 2, 2);

        dv_rl_vlc[0] = av_malloc(dv_vlc.table_size * sizeof(RL_VLC_ELEM));
        for(i = 0; i < dv_vlc.table_size; i++){
            int code= dv_vlc.table[i][0];
            int len = dv_vlc.table[i][1];
            int level, run;
        
            if(len<0){ //more bits needed
                run= 0;
                level= code;
            } else if (code == (NB_DV_VLC - 1)) {
                /* EOB */
                run = 0;
                level = 256;
            } else {
                run=   dv_vlc_run[code] + 1;
                level= dv_vlc_level[code];
            }
            dv_rl_vlc[0][i].len = len;
            dv_rl_vlc[0][i].level = level;
            dv_rl_vlc[0][i].run = run;
        }
    }

    /* ugly way to get the idct & scantable */
    /* XXX: fix it */
    memset(&s2, 0, sizeof(MpegEncContext));
    s2.avctx = avctx;
    dsputil_init(&s2.dsp, avctx->dsp_mask);
    if (DCT_common_init(&s2) < 0)
       return -1;

    s->idct_put[0] = s2.idct_put;
    memcpy(s->idct_permutation, s2.idct_permutation, 64);
    memcpy(s->dv_zigzag[0], s2.intra_scantable.permutated, 64);

    /* XXX: use MMX also for idct248 */
    s->idct_put[1] = simple_idct248_put;
    memcpy(s->dv_zigzag[1], dv_248_zigzag, 64);

    /* XXX: do it only for constant case */
    dv_build_unquantize_tables(s);

    return 0;
}

//#define VLC_DEBUG

typedef struct BlockInfo {
    const UINT8 *shift_table;
    const UINT8 *scan_table;
    UINT8 pos; /* position in block */
    UINT8 eob_reached; /* true if EOB has been reached */
    UINT8 dct_mode;
    UINT8 partial_bit_count;
    UINT16 partial_bit_buffer;
    int shift_offset;
} BlockInfo;

/* block size in bits */
static const UINT16 block_sizes[6] = {
    112, 112, 112, 112, 80, 80
};

#ifndef ALT_BITSTREAM_READER
#error only works with ALT_BITSTREAM_READER
#endif

/* decode ac coefs */
static void dv_decode_ac(DVVideoDecodeContext *s, 
                         BlockInfo *mb, INT16 *block, int last_index)
{
    int last_re_index;
    int shift_offset = mb->shift_offset;
    const UINT8 *scan_table = mb->scan_table;
    const UINT8 *shift_table = mb->shift_table;
    int pos = mb->pos;
    int level, pos1, sign, run;
    int partial_bit_count;

    OPEN_READER(re, &s->gb);
    
#ifdef VLC_DEBUG
    printf("start\n");
#endif

    /* if we must parse a partial vlc, we do it here */
    partial_bit_count = mb->partial_bit_count;
    if (partial_bit_count > 0) {
        UINT8 buf[4];
        UINT32 v;
        int l, l1;
        GetBitContext gb1;

        /* build the dummy bit buffer */
        l = 16 - partial_bit_count;
        UPDATE_CACHE(re, &s->gb);
#ifdef VLC_DEBUG
        printf("show=%04x\n", SHOW_UBITS(re, &s->gb, 16));
#endif
        v = (mb->partial_bit_buffer << l) | SHOW_UBITS(re, &s->gb, l);
        buf[0] = v >> 8;
        buf[1] = v;
#ifdef VLC_DEBUG
        printf("v=%04x cnt=%d %04x\n", 
               v, partial_bit_count, (mb->partial_bit_buffer << l));
#endif
        /* try to read the codeword */
        init_get_bits(&gb1, buf, 4);
        {
            OPEN_READER(re1, &gb1);
            UPDATE_CACHE(re1, &gb1);
            GET_RL_VLC(level, run, re1, &gb1, dv_rl_vlc[0], 
                       TEX_VLC_BITS, 2);
            l = re1_index;
            CLOSE_READER(re1, &gb1);
        }
#ifdef VLC_DEBUG
        printf("****run=%d level=%d size=%d\n", run, level, l);
#endif
        /* compute codeword length */
        l1 = (level != 256 && level != 0);
        /* if too long, we cannot parse */
        l -= partial_bit_count;
        if ((re_index + l + l1) > last_index)
            return;
        /* skip read bits */
        last_re_index = 0; /* avoid warning */
        re_index += l;
        /* by definition, if we can read the vlc, all partial bits
           will be read (otherwise we could have read the vlc before) */
        mb->partial_bit_count = 0;
        UPDATE_CACHE(re, &s->gb);
        goto handle_vlc;
    }

    /* get the AC coefficients until last_index is reached */
    for(;;) {
        UPDATE_CACHE(re, &s->gb);
#ifdef VLC_DEBUG
        printf("%2d: bits=%04x index=%d\n", 
               pos, SHOW_UBITS(re, &s->gb, 16), re_index);
#endif
        last_re_index = re_index;
        GET_RL_VLC(level, run, re, &s->gb, dv_rl_vlc[0], 
                   TEX_VLC_BITS, 2);
    handle_vlc:
#ifdef VLC_DEBUG
        printf("run=%d level=%d\n", run, level);
#endif
        if (level == 256) {
            if (re_index > last_index) {
            cannot_read:
                /* put position before read code */
                re_index = last_re_index;
                mb->eob_reached = 0;
                break;
            }
            /* EOB */
            mb->eob_reached = 1;
            break;
        } else if (level != 0) {
            if ((re_index + 1) > last_index)
                goto cannot_read;
            sign = SHOW_SBITS(re, &s->gb, 1);
            level = (level ^ sign) - sign;
            LAST_SKIP_BITS(re, &s->gb, 1);
            pos += run;
            /* error */
            if (pos >= 64) {
                goto read_error;
            }
            pos1 = scan_table[pos];
            level = level << (shift_table[pos1] + shift_offset);
            block[pos1] = level;
            //            printf("run=%d level=%d shift=%d\n", run, level, shift_table[pos1]);
        } else {
            if (re_index > last_index)
                goto cannot_read;
            /* level is zero: means run without coding. No
               sign is coded */
            pos += run;
            /* error */
            if (pos >= 64) {
            read_error:
#if defined(VLC_DEBUG) || 1
                printf("error pos=%d\n", pos);
#endif
                /* for errors, we consider the eob is reached */
                mb->eob_reached = 1;
                break;
            }
        }
    }
    CLOSE_READER(re, &s->gb);
    mb->pos = pos;
}

static inline void bit_copy(PutBitContext *pb, GetBitContext *gb, int bits_left)
{
    while (bits_left >= 16) {
        put_bits(pb, 16, get_bits(gb, 16));
        bits_left -= 16;
    }
    if (bits_left > 0) {
        put_bits(pb, bits_left, get_bits(gb, bits_left));
    }
}

/* mb_x and mb_y are in units of 8 pixels */
static inline void dv_decode_video_segment(DVVideoDecodeContext *s, 
                                           UINT8 *buf_ptr1, 
                                           const UINT16 *mb_pos_ptr)
{
    int quant, dc, dct_mode, class1, j;
    int mb_index, mb_x, mb_y, v, last_index;
    DCTELEM *block, *block1;
    int c_offset, bits_left;
    UINT8 *y_ptr;
    BlockInfo mb_data[5 * 6], *mb, *mb1;
    void (*idct_put)(UINT8 *dest, int line_size, DCTELEM *block);
    UINT8 *buf_ptr;
    PutBitContext pb, vs_pb;
    UINT8 mb_bit_buffer[80 + 4]; /* allow some slack */
    int mb_bit_count;
    UINT8 vs_bit_buffer[5 * 80 + 4]; /* allow some slack */
    int vs_bit_count;
    
    memset(s->block, 0, sizeof(s->block));

    /* pass 1 : read DC and AC coefficients in blocks */
    buf_ptr = buf_ptr1;
    block1 = &s->block[0][0];
    mb1 = mb_data;
    init_put_bits(&vs_pb, vs_bit_buffer, 5 * 80, NULL, NULL);
    vs_bit_count = 0;
    for(mb_index = 0; mb_index < 5; mb_index++) {
        /* skip header */
        quant = buf_ptr[3] & 0x0f;
        buf_ptr += 4;
        init_put_bits(&pb, mb_bit_buffer, 80, NULL, NULL);
        mb_bit_count = 0;
        mb = mb1;
        block = block1;
        for(j = 0;j < 6; j++) {
            /* NOTE: size is not important here */
            init_get_bits(&s->gb, buf_ptr, 14);
            
            /* get the dc */
            dc = get_bits(&s->gb, 9);
            dc = (dc << (32 - 9)) >> (32 - 9);
            dct_mode = get_bits1(&s->gb);
            mb->dct_mode = dct_mode;
            mb->scan_table = s->dv_zigzag[dct_mode];
            class1 = get_bits(&s->gb, 2);
            mb->shift_offset = (class1 == 3);
            mb->shift_table = s->dv_shift[dct_mode]
                [quant + dv_quant_offset[class1]];
            dc = dc << 2;
            /* convert to unsigned because 128 is not added in the