mjpeg.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。

    /* Y component */
    put_bits(&s->pb, 8, 1); /* component number */
    put_bits(&s->pb, 4, s->mjpeg_hsample[0]); /* H factor */
    put_bits(&s->pb, 4, s->mjpeg_vsample[0]); /* V factor */
    put_bits(&s->pb, 8, 0); /* select matrix */
    
    /* Cb component */
    put_bits(&s->pb, 8, 2); /* component number */
    put_bits(&s->pb, 4, s->mjpeg_hsample[1]); /* H factor */
    put_bits(&s->pb, 4, s->mjpeg_vsample[1]); /* V factor */
#ifdef TWOMATRIXES
    put_bits(&s->pb, 8, 1); /* select matrix */
#else
    put_bits(&s->pb, 8, 0); /* select matrix */
#endif

    /* Cr component */
    put_bits(&s->pb, 8, 3); /* component number */
    put_bits(&s->pb, 4, s->mjpeg_hsample[2]); /* H factor */
    put_bits(&s->pb, 4, s->mjpeg_vsample[2]); /* V factor */
#ifdef TWOMATRIXES
    put_bits(&s->pb, 8, 1); /* select matrix */
#else
    put_bits(&s->pb, 8, 0); /* select matrix */
#endif
    }

    /* scan header */
    put_marker(&s->pb, SOS);
    put_bits(&s->pb, 16, 12); /* length */
    put_bits(&s->pb, 8, 3); /* 3 components */
    
    /* Y component */
    put_bits(&s->pb, 8, 1); /* index */
    put_bits(&s->pb, 4, 0); /* DC huffman table index */
    put_bits(&s->pb, 4, 0); /* AC huffman table index */
    
    /* Cb component */
    put_bits(&s->pb, 8, 2); /* index */
    put_bits(&s->pb, 4, 1); /* DC huffman table index */
    put_bits(&s->pb, 4, 1); /* AC huffman table index */
    
    /* Cr component */
    put_bits(&s->pb, 8, 3); /* index */
    put_bits(&s->pb, 4, 1); /* DC huffman table index */
    put_bits(&s->pb, 4, 1); /* AC huffman table index */

    put_bits(&s->pb, 8, 0); /* Ss (not used) */
    put_bits(&s->pb, 8, 63); /* Se (not used) */
    put_bits(&s->pb, 8, 0); /* Ah/Al (not used) */
}

static void escape_FF(MpegEncContext *s, int start)
{
    int size= get_bit_count(&s->pb) - start*8;
    int i, ff_count;
    uint8_t *buf= s->pb.buf + start;
    int align= (-(int)(buf))&3;
    
    assert((size&7) == 0);
    size >>= 3;
    
    ff_count=0;
    for(i=0; i<size && i<align; i++){
        if(buf[i]==0xFF) ff_count++;
    }
    for(; i<size-15; i+=16){
        int acc, v;

        v= *(uint32_t*)(&buf[i]);
        acc= (((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;
        v= *(uint32_t*)(&buf[i+4]);
        acc+=(((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;
        v= *(uint32_t*)(&buf[i+8]);
        acc+=(((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;
        v= *(uint32_t*)(&buf[i+12]);
        acc+=(((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;

        acc>>=4;
        acc+= (acc>>16);
        acc+= (acc>>8);
        ff_count+= acc&0xFF;
    }
    for(; i<size; i++){
        if(buf[i]==0xFF) ff_count++;
    }

    if(ff_count==0) return;
    
    /* skip put bits */
    for(i=0; i<ff_count-3; i+=4)
        put_bits(&s->pb, 32, 0);
    put_bits(&s->pb, (ff_count-i)*8, 0);
    flush_put_bits(&s->pb); 

    for(i=size-1; ff_count; i--){
        int v= buf[i];

        if(v==0xFF){
//printf("%d %d\n", i, ff_count);
            buf[i+ff_count]= 0;
            ff_count--;
        }

        buf[i+ff_count]= v;
    }
}

void mjpeg_picture_trailer(MpegEncContext *s)
{
    int pad= (-get_bit_count(&s->pb))&7;
    
    put_bits(&s->pb, pad,0xFF>>(8-pad));
    flush_put_bits(&s->pb);

    assert((s->header_bits&7)==0);
    
    escape_FF(s, s->header_bits>>3);

    put_marker(&s->pb, EOI);
}

static inline void mjpeg_encode_dc(MpegEncContext *s, int val,
				   UINT8 *huff_size, UINT16 *huff_code)
{
    int mant, nbits;

    if (val == 0) {
        put_bits(&s->pb, huff_size[0], huff_code[0]);
    } else {
        mant = val;
        if (val < 0) {
            val = -val;
            mant--;
        }
        
        /* compute the log (XXX: optimize) */
        nbits = 0;
        while (val != 0) {
            val = val >> 1;
            nbits++;
        }
            
        put_bits(&s->pb, huff_size[nbits], huff_code[nbits]);
        
        put_bits(&s->pb, nbits, mant & ((1 << nbits) - 1));
    }
}

static void encode_block(MpegEncContext *s, DCTELEM *block, int n)
{
    int mant, nbits, code, i, j;
    int component, dc, run, last_index, val;
    MJpegContext *m = s->mjpeg_ctx;
    UINT8 *huff_size_ac;
    UINT16 *huff_code_ac;
    
    /* DC coef */
    component = (n <= 3 ? 0 : n - 4 + 1);
    dc = block[0]; /* overflow is impossible */
    val = dc - s->last_dc[component];
    if (n < 4) {
        mjpeg_encode_dc(s, val, m->huff_size_dc_luminance, m->huff_code_dc_luminance);
        huff_size_ac = m->huff_size_ac_luminance;
        huff_code_ac = m->huff_code_ac_luminance;
    } else {
        mjpeg_encode_dc(s, val, m->huff_size_dc_chrominance, m->huff_code_dc_chrominance);
        huff_size_ac = m->huff_size_ac_chrominance;
        huff_code_ac = m->huff_code_ac_chrominance;
    }
    s->last_dc[component] = dc;
    
    /* AC coefs */
    
    run = 0;
    last_index = s->block_last_index[n];
    for(i=1;i<=last_index;i++) {
        j = s->intra_scantable.permutated[i];
        val = block[j];
        if (val == 0) {
            run++;
        } else {
            while (run >= 16) {
                put_bits(&s->pb, huff_size_ac[0xf0], huff_code_ac[0xf0]);
                run -= 16;
            }
            mant = val;
            if (val < 0) {
                val = -val;
                mant--;
            }
            
            /* compute the log (XXX: optimize) */
            nbits = 0;
            while (val != 0) {
                val = val >> 1;
                nbits++;
            }
            code = (run << 4) | nbits;

            put_bits(&s->pb, huff_size_ac[code], huff_code_ac[code]);
        
            put_bits(&s->pb, nbits, mant & ((1 << nbits) - 1));
            run = 0;
        }
    }

    /* output EOB only if not already 64 values */
    if (last_index < 63 || run != 0)
        put_bits(&s->pb, huff_size_ac[0], huff_code_ac[0]);
}

void mjpeg_encode_mb(MpegEncContext *s, 
                     DCTELEM block[6][64])
{
    int i;
    for(i=0;i<6;i++) {
        encode_block(s, block[i], i);
    }
}

/******************************************/
/* decoding */

#define MAX_COMPONENTS 4

typedef struct MJpegDecodeContext {
    AVCodecContext *avctx;
    GetBitContext gb;
    int mpeg_enc_ctx_allocated; /* true if decoding context allocated */

    int start_code; /* current start code */
    int buffer_size;
    UINT8 *buffer;

    INT16 quant_matrixes[4][64];
    VLC vlcs[2][4];

    int org_width, org_height;  /* size given at codec init */
    int first_picture;    /* true if decoding first picture */
    int interlaced;     /* true if interlaced */
    int bottom_field;   /* true if bottom field */

    int width, height;
    int nb_components;
    int component_id[MAX_COMPONENTS];
    int h_count[MAX_COMPONENTS]; /* horizontal and vertical count for each component */
    int v_count[MAX_COMPONENTS];
    int h_max, v_max; /* maximum h and v counts */
    int quant_index[4];   /* quant table index for each component */
    int last_dc[MAX_COMPONENTS]; /* last DEQUANTIZED dc (XXX: am I right to do that ?) */
    UINT8 *current_picture[MAX_COMPONENTS]; /* picture structure */
    int linesize[MAX_COMPONENTS];
    DCTELEM block[64] __align8;
    ScanTable scantable;
    void (*idct_put)(UINT8 *dest/*align 8*/, int line_size, DCTELEM *block/*align 16*/);

    int restart_interval;
    int restart_count;

    int buggy_avid;
    int interlace_polarity;
} MJpegDecodeContext;

static int mjpeg_decode_dht(MJpegDecodeContext *s);

static void build_vlc(VLC *vlc, const UINT8 *bits_table, const UINT8 *val_table, 
                      int nb_codes)
{
    UINT8 huff_size[256];
    UINT16 huff_code[256];

    memset(huff_size, 0, sizeof(huff_size));
    build_huffman_codes(huff_size, huff_code, bits_table, val_table);
    
    init_vlc(vlc, 9, nb_codes, huff_size, 1, 1, huff_code, 2, 2);
}

static int mjpeg_decode_init(AVCodecContext *avctx)
{
    MJpegDecodeContext *s = avctx->priv_data;
    MpegEncContext s2;

    s->avctx = avctx;

    /* ugly way to get the idct & scantable */
    memset(&s2, 0, sizeof(MpegEncContext));
    s2.flags= avctx->flags;
    s2.avctx= avctx;
//    s2->out_format = FMT_MJPEG;
    s2.width = 8;
    s2.height = 8;
    if (MPV_common_init(&s2) < 0)
       return -1;
    s->scantable= s2.intra_scantable;
    s->idct_put= s2.idct_put;
    MPV_common_end(&s2);

    s->mpeg_enc_ctx_allocated = 0;
    s->buffer_size = 102400; /* smaller buffer should be enough,
				but photojpg files could ahive bigger sizes */
    s->buffer = av_malloc(s->buffer_size);
    s->start_code = -1;
    s->first_picture = 1;
    s->org_width = avctx->width;
    s->org_height = avctx->height;
    
    build_vlc(&s->vlcs[0][0], bits_dc_luminance, val_dc_luminance, 12);
    build_vlc(&s->vlcs[0][1], bits_dc_chrominance, val_dc_chrominance, 12);
    build_vlc(&s->vlcs[1][0], bits_ac_luminance, val_ac_luminance, 251);
    build_vlc(&s->vlcs[1][1], bits_ac_chrominance, val_ac_chrominance, 251);

    if (avctx->flags & CODEC_FLAG_EXTERN_HUFF)
    {
	printf("mjpeg: using external huffman table\n");
	init_get_bits(&s->gb, avctx->extradata, avctx->extradata_size);
	mjpeg_decode_dht(s);
	/* should check for error - but dunno */
    }

    return 0;
}

/* quantize tables */
static int mjpeg_decode_dqt(MJpegDecodeContext *s)
{
    int len, index, i, j;
    
    len = get_bits(&s->gb, 16) - 2;

    while (len >= 65) {
        /* only 8 bit precision handled */
        if (get_bits(&s->gb, 4) != 0)
	{
	    dprintf("dqt: 16bit precision\n");
            return -1;
	}
        index = get_bits(&s->gb, 4);
        if (index >= 4)
            return -1;
        dprintf("index=%d\n", index);
        /* read quant table */
        for(i=0;i<64;i++) {
            j = s->scantable.permutated[i];
	    s->quant_matrixes[index][j] = get_bits(&s->gb, 8);
        }
        len -= 65;
    }
    
    return 0;
}

/* decode huffman tables and build VLC decoders */
static int mjpeg_decode_dht(MJpegDecodeContext *s)
{
    int len, index, i, class, n, v, code_max;
    UINT8 bits_table[17];
    UINT8 val_table[256];
    
    len = get_bits(&s->gb, 16) - 2;

    while (len > 0) {
        if (len < 17)
            return -1;
        class = get_bits(&s->gb, 4);
        if (class >= 2)
            return -1;
        index = get_bits(&s->gb, 4);
        if (index >= 4)
            return -1;
        n = 0;
        for(i=1;i<=16;i++) {
            bits_table[i] = get_bits(&s->gb, 8);
            n += bits_table[i];
        }
        len -= 17;
        if (len < n || n > 256)
            return -1;

        code_max = 0;
        for(i=0;i<n;i++) {
            v = get_bits(&s->gb, 8);
            if (v > code_max)
                code_max = v;
            val_table[i] = v;
        }
        len -= n;

        /* build VLC and flush previous vlc if present */
        free_vlc(&s->vlcs[class][index]);
        dprintf("class=%d index=%d nb_codes=%d\n",
               class, index, code_max + 1);
        build_vlc(&s->vlcs[class][index], bits_table, val_table, code_max + 1);
    }
    return 0;
}

static int mjpeg_decode_sof0(MJpegDecodeContext *s)
{
    int len, nb_components, i, width, height;

    /* XXX: verify len field validity */
    len = get_bits(&s->gb, 16);
    /* only 8 bits/component accepted */
    if (get_bits(&s->gb, 8) != 8)
        return -1;
    height = get_bits(&s->gb, 16);
    width = get_bits(&s->gb, 16);
    dprintf("sof0: picture: %dx%d\n", width, height);

    nb_components = get_bits(&s->gb, 8);
    if (nb_components <= 0 ||
        nb_components > MAX_COMPONENTS)
        return -1;
    s->nb_components = nb_components;
    s->h_max = 1;
    s->v_max = 1;
    for(i=0;i<nb_components;i++) {
        /* component id */
        s->component_id[i] = get_bits(&s->gb, 8) - 1;