static int tta_decode_frame(AVCodecContext *avctx,
        void *data, int *data_size,
        AVPacket *avpkt)
{
    const uint8_t *buf = avpkt->data;
    int buf_size = avpkt->size;
    TTAContext *s = avctx->priv_data;
    int i;

    init_get_bits(&s->gb, buf, buf_size*8);
    {
        int32_t predictors[s->channels];
        TTAFilter filters[s->channels];
        TTARice rices[s->channels];
        int cur_chan = 0, framelen = s->frame_length;
        int32_t *p;

        // FIXME: seeking
        s->total_frames--;
        if (!s->total_frames && s->last_frame_length)
            framelen = s->last_frame_length;

        // init per channel states
        for (i = 0; i < s->channels; i++) {
            predictors[i] = 0;
            ttafilter_init(&(filters[i]), ttafilter_configs[s->bps-1][0], ttafilter_configs[s->bps-1][1]);
            rice_init(&(rices[i]), 10, 10);
        }

        for (p = s->decode_buffer; p < s->decode_buffer + (framelen * s->channels); p++) {
            int32_t *predictor = &(predictors[cur_chan]);
            TTAFilter *filter = &(filters[cur_chan]);
            TTARice *rice = &(rices[cur_chan]);
            uint32_t unary, depth, k;
            int32_t value;

            unary = tta_get_unary(&s->gb);

            if (unary == 0) {
                depth = 0;
                k = rice->k0;
            } else {
                depth = 1;
                k = rice->k1;
                unary--;
            }

            if (get_bits_left(&s->gb) < k)
                return -1;

            if (k) {
                if (k > MIN_CACHE_BITS)
                    return -1;
                value = (unary << k) + get_bits(&s->gb, k);
            } else
                value = unary;

            // FIXME: copy paste from original
            switch (depth) {
            case 1:
                rice->sum1 += value - (rice->sum1 >> 4);
                if (rice->k1 > 0 && rice->sum1 < shift_16[rice->k1])
                    rice->k1--;
                else if(rice->sum1 > shift_16[rice->k1 + 1])
                    rice->k1++;
                value += shift_1[rice->k0];
            default:
                rice->sum0 += value - (rice->sum0 >> 4);
                if (rice->k0 > 0 && rice->sum0 < shift_16[rice->k0])
                    rice->k0--;
                else if(rice->sum0 > shift_16[rice->k0 + 1])
                    rice->k0++;
            }

            // extract coded value
#define UNFOLD(x) (((x)&1) ? (++(x)>>1) : (-(x)>>1))
            *p = UNFOLD(value);

            // run hybrid filter
            ttafilter_process(filter, p, 0);

            // fixed order prediction
#define PRED(x, k) (int32_t)((((uint64_t)x << k) - x) >> k)
            switch (s->bps) {
                case 1: *p += PRED(*predictor, 4); break;
                case 2:
                case 3: *p += PRED(*predictor, 5); break;
                case 4: *p += *predictor; break;
            }
            *predictor = *p;

#if 0
            // extract 32bit float from last two int samples
            if (s->is_float && ((p - data) & 1)) {
                uint32_t neg = *p & 0x80000000;
                uint32_t hi = *(p - 1);
                uint32_t lo = abs(*p) - 1;

                hi += (hi || lo) ? 0x3f80 : 0;
                // SWAP16: swap all the 16 bits
                *(p - 1) = (hi << 16) | SWAP16(lo) | neg;
            }
#endif

            /*if ((get_bits_count(&s->gb)+7)/8 > buf_size)
            {
                av_log(NULL, AV_LOG_INFO, "overread!!\n");
                break;
            }*/

            // flip channels
            if (cur_chan < (s->channels-1))
                cur_chan++;
            else {
                // decorrelate in case of stereo integer
                if (!s->is_float && (s->channels > 1)) {
                    int32_t *r = p - 1;
                    for (*p += *r / 2; r > p - s->channels; r--)
                        *r = *(r + 1) - *r;
                }
                cur_chan = 0;
            }
        }

        if (get_bits_left(&s->gb) < 32)
            return -1;
        skip_bits(&s->gb, 32); // frame crc

        // convert to output buffer
        switch(s->bps) {
            case 2: {
                uint16_t *samples = data;
                for (p = s->decode_buffer; p < s->decode_buffer + (framelen * s->channels); p++) {
//                    *samples++ = (unsigned char)*p;
//                    *samples++ = (unsigned char)(*p >> 8);
                    *samples++ = *p;
                }
                *data_size = (uint8_t *)samples - (uint8_t *)data;
                break;
            }
            default:
                av_log(s->avctx, AV_LOG_ERROR, "Error, only 16bit samples supported!\n");
        }
    }

//    return get_bits_count(&s->gb)+7)/8;
    return buf_size;
}