Function decode_ppc

libavcodec/twinvq.c:467–490

}

static void decode_ppc(TwinContext *tctx, int period_coef, const float *shape,
                       float ppc_gain, float *speech)
{
    const ModeTab *mtab = tctx->mtab;
    int isampf = tctx->avctx->sample_rate/1000;
    int ibps = tctx->avctx->bit_rate/(1000 * tctx->avctx->channels);
    int min_period = ROUNDED_DIV(  40*2*mtab->size, isampf);
    int max_period = ROUNDED_DIV(6*40*2*mtab->size, isampf);
    int period_range = max_period - min_period;

    // This is actually the period multiplied by 400. It is just linearly coded
    // between its maximum and minimum value.
    int period = min_period +
        ROUNDED_DIV(period_coef*period_range, (1 << mtab->ppc_period_bit) - 1);
    int width;

    if (isampf == 22 && ibps == 32) {
        // For some unknown reason, NTT decided to code this case differently...
        width = ROUNDED_DIV((period + 800)* mtab->peak_per2wid, 400*mtab->size);
    } else
        width =             (period      )* mtab->peak_per2wid/(400*mtab->size);

    add_peak(period, width, shape, ppc_gain, speech, mtab->ppc_shape_len);
}

static void dec_gain(TwinContext *tctx, GetBitContext *gb, enum FrameType ftype,
                     float *out)