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Miscellaneous Tips

Tips for Zero Latency mode

Zero Latency mode's speed depends on the size of period time. The period time should not be too small since fixed length of DFT calculations will be repeated. 8192 is the default frame size for K7/PentiumIII/Pentium4 machines.

XMMS/Audacious Realtime Effect Tips for Very Slow Machines

The period time should be small since it takes long time to process one large fragment of PCM data. The buffer time or buffer size should be large since the Audio Stream often stalls. 16384 is the default frame size for normal K7/PentiumIII/Pentium4 machines

Audacious ALSA Audacious OSS

Waves IR1 .wir file format

// 32bit LE
typedef struct{
  char magic[4]; // "wvIR"
  int fileSizeLE; // filesize-8
  char version[8]; // version "ver1fmt "
  int headerSizeLE;
  short int i3; // 0x3
  short int channels;
  int fs; // impulse Fs
  int fs2;
  short int i4; // MONO 0x4 STEREO 0x8 4CH 0x10
  short int i5; // 0x17
  char data[4]; // "data"
} WirHeader;
// rest of the data is FLOAT_LE (32bit float)

Adobe Audition .imp file format

//32bit LE
typedef struct{
  char magic[4]; // "impf"
  int size; //
  int i1; //
  int i2; //
} ImpHeader;
// rest of the data is FLOAT64_LE (64bit float)

Limiter/Compressor curve sample

Limiter Curve Compressor Curve

Tested Environments, Speeds and Accuracy (1.x non SIMD version)

Athlon 800MHz (PC133 SDRAM) - CentOS 4 (GCC 3.4.6 FPU)
fragmentSize 16384 impulseSize 1323000x2 (30[s]@44.1kHz)
impulse load time 1.72[s] (x17.44@44.1kHz)
s2s,filter 7.77[s] (x1.29@44.1kHz)
Pentium4 2.40BGHz Northwood (DDR 333 single channel) - Slackware 11.0 (ICC Version 9.0 SSE)
fragmentSize 16384 impulseSize 7938000x2 (180[s]@44.1kHz)
impulse load time 3.84[s] (x46.88@44.1kHz)
s2s,filter 7.87[s] (x1.27@44.1kHz)
8[s] sweep * 4[s] inverse sweep created by rec_imp
S/N ratio: 100.96 dB
(IR2-Reference): Signal Max : 4.58956e-06 (-106.76 dB)
Reference time domain: Signal Max : 0.51309 (-5.80 dB)
Freeverb3 IR2: Signal Max : 0.513095 (-5.80 dB)
rec_imp rec.pcm 44100 10 21000 4 0:0 0:0 1:0 1:0 0.1

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