static int mpc7_decode_frame(AVCodecContext * avctx,
                            void *data, int *data_size,
                            AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    MPCContext *c = avctx->priv_data;
    GetBitContext gb;
    uint8_t *bits;
    int i, ch, t;
    int mb = -1;
    Band *bands = c->bands;
    int off;
    int bits_used, bits_avail;

    memset(bands, 0, sizeof(bands));
    if(buf_size <= 4){
        av_log(avctx, AV_LOG_ERROR, "Too small buffer passed (%i bytes)\n", buf_size);
    }

    bits = av_malloc(((buf_size - 1) & ~3) + FF_INPUT_BUFFER_PADDING_SIZE);
    c->dsp.bswap_buf((uint32_t*)bits, (const uint32_t*)(buf + 4), (buf_size - 4) >> 2);
    init_get_bits(&gb, bits, (buf_size - 4)* 8);
    skip_bits(&gb, buf[0]);

    /* read subband indexes */
    for(i = 0; i <= c->maxbands; i++){
        for(ch = 0; ch < 2; ch++){
            if(i) t = get_vlc2(&gb, hdr_vlc.table, MPC7_HDR_BITS, 1) - 5;
            if(!i || (t == 4)) bands[i].res[ch] = get_bits(&gb, 4);
            else bands[i].res[ch] = bands[i-1].res[ch] + t;
        }

        if(bands[i].res[0] || bands[i].res[1]){
            mb = i;
            if(c->MSS) bands[i].msf = get_bits1(&gb);
        }
    }
    /* get scale indexes coding method */
    for(i = 0; i <= mb; i++)
        for(ch = 0; ch < 2; ch++)
            if(bands[i].res[ch]) bands[i].scfi[ch] = get_vlc2(&gb, scfi_vlc.table, MPC7_SCFI_BITS, 1);
    /* get scale indexes */
    for(i = 0; i <= mb; i++){
        for(ch = 0; ch < 2; ch++){
            if(bands[i].res[ch]){
                bands[i].scf_idx[ch][2] = c->oldDSCF[ch][i];
                bands[i].scf_idx[ch][0] = get_scale_idx(&gb, bands[i].scf_idx[ch][2]);
                switch(bands[i].scfi[ch]){
                case 0:
                    bands[i].scf_idx[ch][1] = get_scale_idx(&gb, bands[i].scf_idx[ch][0]);
                    bands[i].scf_idx[ch][2] = get_scale_idx(&gb, bands[i].scf_idx[ch][1]);
                    break;
                case 1:
                    bands[i].scf_idx[ch][1] = get_scale_idx(&gb, bands[i].scf_idx[ch][0]);
                    bands[i].scf_idx[ch][2] = bands[i].scf_idx[ch][1];
                    break;
                case 2:
                    bands[i].scf_idx[ch][1] = bands[i].scf_idx[ch][0];
                    bands[i].scf_idx[ch][2] = get_scale_idx(&gb, bands[i].scf_idx[ch][1]);
                    break;
                case 3:
                    bands[i].scf_idx[ch][2] = bands[i].scf_idx[ch][1] = bands[i].scf_idx[ch][0];
                    break;
                }
                c->oldDSCF[ch][i] = bands[i].scf_idx[ch][2];
            }
        }
    }
    /* get quantizers */
    memset(c->Q, 0, sizeof(c->Q));
    off = 0;
    for(i = 0; i < BANDS; i++, off += SAMPLES_PER_BAND)
        for(ch = 0; ch < 2; ch++)
            idx_to_quant(c, &gb, bands[i].res[ch], c->Q[ch] + off);

    ff_mpc_dequantize_and_synth(c, mb, data);

    av_free(bits);

    bits_used = get_bits_count(&gb);
    bits_avail = (buf_size - 4) * 8;
    if(!buf[1] && ((bits_avail < bits_used) || (bits_used + 32 <= bits_avail))){
        av_log(NULL,0, "Error decoding frame: used %i of %i bits\n", bits_used, bits_avail);
        return -1;
    }
    if(c->frames_to_skip){
        c->frames_to_skip--;
        *data_size = 0;
        return buf_size;
    }
    *data_size = (buf[1] ? c->lastframelen : MPC_FRAME_SIZE) * 4;

    return buf_size;
}