org.xiph.speex
Class Vbr
public class Vbr
extends java.lang.Object
This class analyses the signal to help determine what bitrate to use when
the Varible BitRate option has been selected.
- Marc Gimpel, Wimba S.A. (mgimpel@horizonwimba.com)
float | analysis(float[] sig, int len, int pitch, float pitch_coef) - This function should analyse the signal and decide how critical the
coding error will be perceptually.
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MIN_ENERGY
public static final int MIN_ENERGY
NOISE_POW
public static final float NOISE_POW
VBR_MEMORY_SIZE
public static final int VBR_MEMORY_SIZE
accum_sum
private float accum_sum
average_energy
private float average_energy
consec_noise
private int consec_noise
energy_alpha
private float energy_alpha
hb_thresh
public static final float[][] hb_thresh
Wideband threshhold table.
last_energy
private float last_energy
last_log_energy
private float[] last_log_energy
last_pitch_coef
private float last_pitch_coef
last_quality
private float last_quality
nb_thresh
public static final float[][] nb_thresh
Narrowband threshhold table.
noise_accum
private float noise_accum
noise_accum_count
private float noise_accum_count
noise_level
private float noise_level
soft_pitch
private float soft_pitch
uhb_thresh
public static final float[][] uhb_thresh
Ultra-wideband threshhold table.
Vbr
public Vbr()
Constructor
analysis
public float analysis(float[] sig,
int len,
int pitch,
float pitch_coef)
This function should analyse the signal and decide how critical the
coding error will be perceptually. The following factors should be
taken into account:
- Attacks (positive energy derivative) should be coded with more bits
- Stationary voiced segments should receive more bits
- Segments with (very) low absolute energy should receive less bits
(maybe only shaped noise?)
- DTX for near-zero energy?
- Stationary fricative segments should have less bits
- Temporal masking: when energy slope is decreasing, decrease the bit-rate
- Decrease bit-rate for males (low pitch)?
- (wideband only) less bits in the high-band when signal is very
non-stationary (harder to notice high-frequency noise)???
sig
- - signal.len
- - signal length.pitch
- - signal pitch.pitch_coef
- - pitch coefficient.
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