smacker.c

ffmpeg源码分析

    }

    /* make the palette available on the way out */
    out = buf + 1;
    pal = (uint32_t*)smk->pic.data[1];
    smk->pic.palette_has_changed = buf[0] & 1;
    smk->pic.key_frame = !!(buf[0] & 2);
    if(smk->pic.key_frame)
        smk->pic.pict_type = FF_I_TYPE;
    else
        smk->pic.pict_type = FF_P_TYPE;

    for(i = 0; i < 256; i++) {
        int r, g, b;
        r = *out++;
        g = *out++;
        b = *out++;
        *pal++ = (r << 16) | (g << 8) | b;
    }

    last_reset(smk->mmap_tbl, smk->mmap_last);
    last_reset(smk->mclr_tbl, smk->mclr_last);
    last_reset(smk->full_tbl, smk->full_last);
    last_reset(smk->type_tbl, smk->type_last);
    init_get_bits(&gb, buf + 769, (buf_size - 769) * 8);

    blk = 0;
    bw = avctx->width >> 2;
    bh = avctx->height >> 2;
    blocks = bw * bh;
    out = smk->pic.data[0];
    stride = smk->pic.linesize[0];
    while(blk < blocks) {
        int type, run, mode;
        uint16_t pix;

        type = smk_get_code(&gb, smk->type_tbl, smk->type_last);
        run = block_runs[(type >> 2) & 0x3F];
        switch(type & 3){
        case SMK_BLK_MONO:
            while(run-- && blk < blocks){
                int clr, map;
                int hi, lo;
                clr = smk_get_code(&gb, smk->mclr_tbl, smk->mclr_last);
                map = smk_get_code(&gb, smk->mmap_tbl, smk->mmap_last);
                out = smk->pic.data[0] + (blk / bw) * (stride * 4) + (blk % bw) * 4;
                hi = clr >> 8;
                lo = clr & 0xFF;
                for(i = 0; i < 4; i++) {
                    if(map & 1) out[0] = hi; else out[0] = lo;
                    if(map & 2) out[1] = hi; else out[1] = lo;
                    if(map & 4) out[2] = hi; else out[2] = lo;
                    if(map & 8) out[3] = hi; else out[3] = lo;
                    map >>= 4;
                    out += stride;
                }
                blk++;
            }
            break;
        case SMK_BLK_FULL:
            mode = 0;
            if(avctx->codec_tag != 0) { // In case of Smacker v4 we have three modes
                if(get_bits1(&gb)) mode = 1;
                else if(get_bits1(&gb)) mode = 2;
            }
            while(run-- && blk < blocks){
                out = smk->pic.data[0] + (blk / bw) * (stride * 4) + (blk % bw) * 4;
                switch(mode){
                case 0:
                    for(i = 0; i < 4; i++) {
                        pix = smk_get_code(&gb, smk->full_tbl, smk->full_last);
                        out[2] = pix & 0xFF;
                        out[3] = pix >> 8;
                        pix = smk_get_code(&gb, smk->full_tbl, smk->full_last);
                        out[0] = pix & 0xFF;
                        out[1] = pix >> 8;
                        out += stride;
                    }
                    break;
                case 1:
                    pix = smk_get_code(&gb, smk->full_tbl, smk->full_last);
                    out[0] = out[1] = pix & 0xFF;
                    out[2] = out[3] = pix >> 8;
                    out += stride;
                    out[0] = out[1] = pix & 0xFF;
                    out[2] = out[3] = pix >> 8;
                    out += stride;
                    pix = smk_get_code(&gb, smk->full_tbl, smk->full_last);
                    out[0] = out[1] = pix & 0xFF;
                    out[2] = out[3] = pix >> 8;
                    out += stride;
                    out[0] = out[1] = pix & 0xFF;
                    out[2] = out[3] = pix >> 8;
                    out += stride;
                    break;
                case 2:
                    for(i = 0; i < 2; i++) {
                        uint16_t pix1, pix2;
                        pix1 = smk_get_code(&gb, smk->full_tbl, smk->full_last);
                        pix2 = smk_get_code(&gb, smk->full_tbl, smk->full_last);
                        out[0] = pix1 & 0xFF; out[1] = pix1 >> 8;
                        out[2] = pix2 & 0xFF; out[3] = pix2 >> 8;
                        out += stride;
                        out[0] = pix1 & 0xFF; out[1] = pix1 >> 8;
                        out[2] = pix2 & 0xFF; out[3] = pix2 >> 8;
                        out += stride;
                    }
                    break;
                }
                blk++;
            }
            break;
        case SMK_BLK_SKIP:
            while(run-- && blk < blocks)
                blk++;
            break;
        case SMK_BLK_FILL:
            mode = type >> 8;
            while(run-- && blk < blocks){
                uint32_t col;
                out = smk->pic.data[0] + (blk / bw) * (stride * 4) + (blk % bw) * 4;
                col = mode * 0x01010101;
                for(i = 0; i < 4; i++) {
                    *((uint32_t*)out) = col;
                    out += stride;
                }
                blk++;
            }
            break;
        }

    }

    *data_size = sizeof(AVFrame);
    *(AVFrame*)data = smk->pic;

    /* always report that the buffer was completely consumed */
    return buf_size;
}



/*
 *
 * Init smacker decoder
 *
 */
static int decode_init(AVCodecContext *avctx)
{
    SmackVContext * const c = (SmackVContext *)avctx->priv_data;

    c->avctx = avctx;
    avctx->has_b_frames = 0;

    c->pic.data[0] = NULL;

    if (avcodec_check_dimensions(avctx, avctx->height, avctx->width) < 0) {
        return 1;
    }

    avctx->pix_fmt = PIX_FMT_PAL8;


    /* decode huffman trees from extradata */
    if(avctx->extradata_size < 16){
        av_log(avctx, AV_LOG_ERROR, "Extradata missing!\n");
        return -1;
    }

    decode_header_trees(c);


    return 0;
}



/*
 *
 * Uninit smacker decoder
 *
 */
static int decode_end(AVCodecContext *avctx)
{
    SmackVContext * const smk = (SmackVContext *)avctx->priv_data;

    if(smk->mmap_tbl)
        av_free(smk->mmap_tbl);
    if(smk->mclr_tbl)
        av_free(smk->mclr_tbl);
    if(smk->full_tbl)
        av_free(smk->full_tbl);
    if(smk->type_tbl)
        av_free(smk->type_tbl);

    if (smk->pic.data[0])
        avctx->release_buffer(avctx, &smk->pic);

    return 0;
}


static int smka_decode_init(AVCodecContext *avctx)
{
    return 0;
}

/**
 * Decode Smacker audio data
 */
static int smka_decode_frame(AVCodecContext *avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
{
    GetBitContext gb;
    HuffContext h[4];
    VLC vlc[4];
    int16_t *samples = data;
    int val;
    int i, res;
    int unp_size;
    int bits, stereo;
    int pred[2] = {0, 0};

    unp_size = LE_32(buf);

    init_get_bits(&gb, buf + 4, (buf_size - 4) * 8);

    if(!get_bits1(&gb)){
        av_log(avctx, AV_LOG_INFO, "Sound: no data\n");
        *data_size = 0;
        return 1;
    }
    stereo = get_bits1(&gb);
    bits = get_bits1(&gb);

    memset(vlc, 0, sizeof(VLC) * 4);
    memset(h, 0, sizeof(HuffContext) * 4);
    // Initialize
    for(i = 0; i < (1 << (bits + stereo)); i++) {
        h[i].length = 256;
        h[i].maxlength = 0;
        h[i].current = 0;
        h[i].bits = av_mallocz(256 * 4);
        h[i].lengths = av_mallocz(256 * sizeof(int));
        h[i].values = av_mallocz(256 * sizeof(int));
        get_bits1(&gb);
        smacker_decode_tree(&gb, &h[i], 0, 0);
        get_bits1(&gb);
        if(h[i].current > 1) {
            res = init_vlc(&vlc[i], SMKTREE_BITS, h[i].length,
                    h[i].lengths, sizeof(int), sizeof(int),
                    h[i].bits, sizeof(uint32_t), sizeof(uint32_t), INIT_VLC_LE);
            if(res < 0) {
                av_log(avctx, AV_LOG_ERROR, "Cannot build VLC table\n");
                return -1;
            }
        }
    }
    if(bits) { //decode 16-bit data
        pred[0]  = get_bits(&gb, 8);
        pred[0] |= get_bits(&gb, 8);
        *samples++ = pred[0];
        if(stereo) {
            pred[1]  = get_bits(&gb, 8);
            pred[1] |= get_bits(&gb, 8);
            *samples++ = pred[1];
        }
        for(i = 0; i < unp_size / 2; i++) {
            if(i & stereo) {
                if(vlc[2].table)
                    res = get_vlc2(&gb, vlc[2].table, SMKTREE_BITS, 3);
                else
                    res = 0;
                val  = h[2].values[res];
                if(vlc[3].table)
                    res = get_vlc2(&gb, vlc[3].table, SMKTREE_BITS, 3);
                else
                    res = 0;
                val |= h[3].values[res] << 8;
                pred[1] += (int16_t)val;
                *samples++ = pred[1];
            } else {
                if(vlc[0].table)
                    res = get_vlc2(&gb, vlc[0].table, SMKTREE_BITS, 3);
                else
                    res = 0;
                val  = h[0].values[res];
                if(vlc[1].table)
                    res = get_vlc2(&gb, vlc[1].table, SMKTREE_BITS, 3);
                else
                    res = 0;
                val |= h[1].values[res] << 8;
                pred[0] += val;
                *samples++ = pred[0];
            }
        }
    } else { //8-bit data
        pred[0] = get_bits(&gb, 8);
        *samples++ = (pred[0] - 0x80) << 8;
        if(stereo) {
            pred[1] = get_bits(&gb, 8);
            *samples++ = (pred[1] - 0x80) << 8;
        }
        for(i = 0; i < unp_size; i++) {
            if(i & stereo){
                if(vlc[1].table)
                    res = get_vlc2(&gb, vlc[1].table, SMKTREE_BITS, 3);
                else
                    res = 0;
                pred[1] += (int8_t)h[1].values[res];
                *samples++ = (pred[1] - 0x80) << 8;
            } else {
                if(vlc[0].table)
                    res = get_vlc2(&gb, vlc[0].table, SMKTREE_BITS, 3);
                else
                    res = 0;
                pred[0] += (int8_t)h[0].values[res];
                *samples++ = (pred[0] - 0x80) << 8;
            }
        }
        unp_size *= 2;
    }

    for(i = 0; i < 4; i++) {
        if(vlc[i].table)
            free_vlc(&vlc[i]);
        if(h[i].bits)
            av_free(h[i].bits);
        if(h[i].lengths)
            av_free(h[i].lengths);
        if(h[i].values)
            av_free(h[i].values);
    }

    *data_size = unp_size;
    return buf_size;
}

AVCodec smacker_decoder = {
    "smackvid",
    CODEC_TYPE_VIDEO,
    CODEC_ID_SMACKVIDEO,
    sizeof(SmackVContext),
    decode_init,
    NULL,
    decode_end,
    decode_frame
};

AVCodec smackaud_decoder = {
    "smackaud",
    CODEC_TYPE_AUDIO,
    CODEC_ID_SMACKAUDIO,
    0,
    smka_decode_init,
    NULL,
    NULL,
    smka_decode_frame
};