AVResampleContext *swr_resample_init(AVResampleContext *c, int out_rate, int in_rate, int filter_size, int phase_shift, int linear, double cutoff){
    double factor= FFMIN(out_rate * cutoff / in_rate, 1.0);
    int phase_count= 1<<phase_shift;

    if (!c || c->phase_shift != phase_shift || c->linear!=linear || c->factor != factor
           || c->filter_length != FFMAX((int)ceil(filter_size/factor), 1)) {
        c = av_mallocz(sizeof(AVResampleContext));
        if (!c)
            return NULL;

        c->phase_shift   = phase_shift;
        c->phase_mask    = phase_count - 1;
        c->linear        = linear;
        c->factor        = factor;
        c->filter_length = FFMAX((int)ceil(filter_size/factor), 1);
        c->filter_bank   = av_mallocz(c->filter_length*(phase_count+1)*sizeof(FELEM));
        if (!c->filter_bank)
            goto error;
        if (build_filter(c->filter_bank, factor, c->filter_length, phase_count, 1<<FILTER_SHIFT, WINDOW_TYPE))
            goto error;
        memcpy(&c->filter_bank[c->filter_length*phase_count+1], c->filter_bank, (c->filter_length-1)*sizeof(FELEM));
        c->filter_bank[c->filter_length*phase_count]= c->filter_bank[c->filter_length - 1];
    }

    c->compensation_distance= 0;
    if(!av_reduce(&c->src_incr, &c->dst_incr, out_rate, in_rate * (int64_t)phase_count, INT32_MAX/2))
        goto error;
    c->ideal_dst_incr= c->dst_incr;

    c->index= -phase_count*((c->filter_length-1)/2);
    c->frac= 0;

    return c;
error:
    av_free(c->filter_bank);
    av_free(c);
    return NULL;
}