/// <summary>
/// Create a new resampler with fractional input/output rates. The sampling
/// rate ratio is an arbitrary rational number with both the numerator and
/// denominator being 32-bit integers.
/// </summary>
/// <param name="nb_channels">The number of channels to be processed</param>
/// <param name="ratio_num">Numerator of sampling rate ratio</param>
/// <param name="ratio_den">Denominator of sampling rate ratio</param>
/// <param name="in_rate">Input sample rate rounded to the nearest integer (in hz)</param>
/// <param name="out_rate">Output sample rate rounded to the nearest integer (in hz)</param>
/// <param name="quality">Resampling quality, from 0 to 10</param>
/// <returns>A newly created restampler</returns>
public SpeexResampler(int nb_channels, int ratio_num, int ratio_den, int in_rate, int out_rate, int quality)
{
int i;
if (quality > 10 || quality < 0)
{
throw new ArgumentException("Quality must be between 0 and 10");
}
this.initialised = 0;
this.started = 0;
this.in_rate = 0;
this.out_rate = 0;
this.num_rate = 0;
this.den_rate = 0;
this.quality = -1;
this.sinc_table_length = 0;
this.mem_alloc_size = 0;
this.filt_len = 0;
this.mem = null;
this.resampler_ptr = null;
this.cutoff = 1.0f;
this.nb_channels = nb_channels;
this.in_stride = 1;
this.out_stride = 1;
this.buffer_size = 160;
/* Per channel data */
this.last_sample = new int[nb_channels];
this.magic_samples = new int[nb_channels];
this.samp_frac_num = new int[nb_channels];
for (i = 0; i < nb_channels; i++)
{
this.last_sample[i] = 0;
this.magic_samples[i] = 0;
this.samp_frac_num[i] = 0;
}
this.Quality = quality;
this.SetRateFraction(ratio_num, ratio_den, in_rate, out_rate);
this.update_filter();
this.initialised = 1;
}
private void update_filter()
{
int old_length;
old_length = this.filt_len;
this.oversample = QualityMapping.quality_map[this.quality].oversample;
this.filt_len = QualityMapping.quality_map[this.quality].base_length;
if (this.num_rate > this.den_rate)
{
/* down-sampling */
this.cutoff = QualityMapping.quality_map[this.quality].downsample_bandwidth * this.den_rate / this.num_rate;
/* FIXME: divide the numerator and denominator by a certain amount if they're too large */
this.filt_len = this.filt_len * this.num_rate / this.den_rate;
/* Round up to make sure we have a multiple of 8 */
this.filt_len = ((this.filt_len - 1) & (~0x7)) + 8;
if (2 * this.den_rate < this.num_rate)
{
this.oversample >>= 1;
}
if (4 * this.den_rate < this.num_rate)
{
this.oversample >>= 1;
}
if (8 * this.den_rate < this.num_rate)
{
this.oversample >>= 1;
}
if (16 * this.den_rate < this.num_rate)
{
this.oversample >>= 1;
}
if (this.oversample < 1)
{
this.oversample = 1;
}
}
else
{
/* up-sampling */
this.cutoff = QualityMapping.quality_map[this.quality].upsample_bandwidth;
}
if (this.den_rate <= 16 * (this.oversample + 8))
{
int i;
if (this.sinc_table == null)
{
this.sinc_table = new short[this.filt_len * this.den_rate];
}
else if (this.sinc_table_length < this.filt_len * this.den_rate)
{
this.sinc_table = new short[this.filt_len * this.den_rate];
this.sinc_table_length = this.filt_len * this.den_rate;
}
for (i = 0; i < this.den_rate; i++)
{
int j;
for (j = 0; j < this.filt_len; j++)
{
this.sinc_table[i * this.filt_len + j] = sinc(this.cutoff, ((j - (int)this.filt_len / 2 + 1) - ((float)i) / this.den_rate), this.filt_len, QualityMapping.quality_map[this.quality].window_func);
}
}
this.resampler_ptr = resampler_basic_direct_single;
/*fprintf (stderr, "resampler uses direct sinc table and normalised cutoff %f\n", cutoff);*/
}
else
{
int i;
if (this.sinc_table == null)
{
this.sinc_table = new short[this.filt_len * this.oversample + 8];
}
else if (this.sinc_table_length < this.filt_len * this.oversample + 8)
{
this.sinc_table = new short[this.filt_len * this.oversample + 8];
this.sinc_table_length = this.filt_len * this.oversample + 8;
}
for (i = -4; i < (int)(this.oversample * this.filt_len + 4); i++)
{
this.sinc_table[i + 4] = sinc(this.cutoff, (i / (float)this.oversample - this.filt_len / 2), this.filt_len, QualityMapping.quality_map[this.quality].window_func);
}
this.resampler_ptr = resampler_basic_interpolate_single;
/*fprintf (stderr, "resampler uses interpolated sinc table and normalised cutoff %f\n", cutoff);*/
}
this.int_advance = this.num_rate / this.den_rate;
this.frac_advance = this.num_rate % this.den_rate;
/* Here's the place where we update the filter memory to take into account
* the change in filter length. It's probably the messiest part of the code
* due to handling of lots of corner cases. */
if (this.mem == null)
{
int i;
this.mem_alloc_size = this.filt_len - 1 + this.buffer_size;
this.mem = new short[this.nb_channels * this.mem_alloc_size];
for (i = 0; i < this.nb_channels * this.mem_alloc_size; i++)
{
this.mem[i] = 0;
}
/*speex_warning("init filter");*/
}
else if (this.started == 0)
{
int i;
this.mem_alloc_size = this.filt_len - 1 + this.buffer_size;
this.mem = new short[this.nb_channels * this.mem_alloc_size];
for (i = 0; i < this.nb_channels * this.mem_alloc_size; i++)
{
this.mem[i] = 0;
}
/*speex_warning("reinit filter");*/
}
else if (this.filt_len > old_length)
{
int i;
/* Increase the filter length */
/*speex_warning("increase filter size");*/
int old_alloc_size = this.mem_alloc_size;
if ((this.filt_len - 1 + this.buffer_size) > this.mem_alloc_size)
{
this.mem_alloc_size = this.filt_len - 1 + this.buffer_size;
this.mem = new short[this.nb_channels * this.mem_alloc_size];
}
for (i = this.nb_channels - 1; i >= 0; i--)
{
int j;
int olen = old_length;
/*if (st.magic_samples[i])*/
{
/* Try and remove the magic samples as if nothing had happened */
/* FIXME: This is wrong but for now we need it to avoid going over the array bounds */
olen = old_length + 2 * this.magic_samples[i];
for (j = old_length - 2 + this.magic_samples[i]; j >= 0; j--)
{
this.mem[i * this.mem_alloc_size + j + this.magic_samples[i]] = this.mem[i * old_alloc_size + j];
}
for (j = 0; j < this.magic_samples[i]; j++)
{
this.mem[i * this.mem_alloc_size + j] = 0;
}
this.magic_samples[i] = 0;
}
if (this.filt_len > olen)
{
/* If the new filter length is still bigger than the "augmented" length */
/* Copy data going backward */
for (j = 0; j < olen - 1; j++)
{
this.mem[i * this.mem_alloc_size + (this.filt_len - 2 - j)] = this.mem[i * this.mem_alloc_size + (olen - 2 - j)];
}
/* Then put zeros for lack of anything better */
for (; j < this.filt_len - 1; j++)
{
this.mem[i * this.mem_alloc_size + (this.filt_len - 2 - j)] = 0;
}
/* Adjust last_sample */
this.last_sample[i] += (this.filt_len - olen) / 2;
}
else
{
/* Put back some of the magic! */
this.magic_samples[i] = (olen - this.filt_len) / 2;
for (j = 0; j < this.filt_len - 1 + this.magic_samples[i]; j++)
{
this.mem[i * this.mem_alloc_size + j] = this.mem[i * this.mem_alloc_size + j + this.magic_samples[i]];
}
}
}
}
else if (this.filt_len < old_length)
{
int i;
/* Reduce filter length, this a bit tricky. We need to store some of the memory as "magic"
* samples so they can be used directly as input the next time(s) */
for (i = 0; i < this.nb_channels; i++)
{
int j;
int old_magic = this.magic_samples[i];
this.magic_samples[i] = (old_length - this.filt_len) / 2;
/* We must copy some of the memory that's no longer used */
/* Copy data going backward */
for (j = 0; j < this.filt_len - 1 + this.magic_samples[i] + old_magic; j++)
{
this.mem[i * this.mem_alloc_size + j] = this.mem[i * this.mem_alloc_size + j + this.magic_samples[i]];
}
this.magic_samples[i] += old_magic;
}
}
}