Function tta_encode_frame

libavcodec/ttaenc.c:87–194

}

static int tta_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
                            const AVFrame *frame, int *got_packet_ptr)
{
    TTAEncContext *s = avctx->priv_data;
    PutBitContext pb;
    int ret, i, out_bytes, cur_chan, res, samples;
    int64_t pkt_size =  frame->nb_samples * 2LL * avctx->ch_layout.nb_channels * s->bps;

pkt_alloc:
    cur_chan = 0, res = 0, samples = 0;
    if ((ret = ff_alloc_packet(avctx, avpkt, pkt_size)) < 0)
        return ret;
    init_put_bits(&pb, avpkt->data, avpkt->size);

    // init per channel states
    for (i = 0; i < avctx->ch_layout.nb_channels; i++) {
        s->ch_ctx[i].predictor = 0;
        ff_tta_filter_init(&s->ch_ctx[i].filter, ff_tta_filter_configs[s->bps - 1]);
        ff_tta_rice_init(&s->ch_ctx[i].rice, 10, 10);
    }

    for (i = 0; i < frame->nb_samples * avctx->ch_layout.nb_channels; i++) {
        TTAChannel *c = &s->ch_ctx[cur_chan];
        TTAFilter *filter = &c->filter;
        TTARice *rice = &c->rice;
        uint32_t k, unary, outval;
        int32_t value, temp;

        value = get_sample(frame, samples++, avctx->sample_fmt);

        if (avctx->ch_layout.nb_channels > 1) {
            if (cur_chan < avctx->ch_layout.nb_channels - 1)
                value  = res = get_sample(frame, samples, avctx->sample_fmt) - value;
            else
                value -= res / 2;
        }

        temp = value;
#define PRED(x, k) (int32_t)((((uint64_t)(x) << (k)) - (x)) >> (k))
        switch (s->bps) {
        case 1: value -= PRED(c->predictor, 4); break;
        case 2:
        case 3: value -= PRED(c->predictor, 5); break;
        }
        c->predictor = temp;

        s->dsp.filter_process(filter->qm, filter->dx, filter->dl, &filter->error, &value,
                              filter->shift, filter->round);
        outval = (value > 0) ? (value << 1) - 1: -value << 1;

        k = rice->k0;

        rice->sum0 += outval - (rice->sum0 >> 4);
        if (rice->k0 > 0 && rice->sum0 < ff_tta_shift_16[rice->k0])
            rice->k0--;
        else if (rice->sum0 > ff_tta_shift_16[rice->k0 + 1])
            rice->k0++;