cyanreg

ANSI Escape Sequences

Standard escape codes are prefixed with Escape:

• Ctrl-Key: ^[
• Octal: \033
• Unicode: \u001b
• Hexadecimal: \x1b
• Decimal: 27

cyanreg

/*
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of

cyanreg

;******************************************************************************
;* Copyright (c) Lynne
;*
;* This file is part of FFmpeg.
;*
;* FFmpeg is free software; you can redistribute it and/or
;* modify it under the terms of the GNU Lesser General Public
;* License as published by the Free Software Foundation; either
;* version 2.1 of the License, or (at your option) any later version.
;*

cyanreg

void forward_qmf(float *out_low, float *out_high, float *delay, const float *in,
                 int samples, int delay_samples)
{
    memcpy(delay, delay + samples, delay_samples * sizeof(float));
    memcpy(delay + delay_samples, in, samples * sizeof(float));

    for (int i = 0; i < samples; i += 2) {
        float low = 0.0f, high = 0.0f;

        /* Can be done via float_dsp */

cyanreg

#define BF(x, y, a, b)                           \
    do {                                         \
        x = (a) - (b);                           \
        y = (a) + (b);                           \
    } while (0)

#define BUTTERFLIES_MIX(a0,a1,a2,a3, P1, P2, P5, P6)      \
    do {                                       \
        r0=a0.re;                              \
        i0=a0.im;                              \

cyanreg

static void fft8(void *s, FFTComplex *z, FFTComplex *temp)
{
    FFTSample r1 = z[0].re - z[4].re;
    FFTSample r2 = z[0].im - z[4].im;
    FFTSample r3 = z[1].re - z[5].re;
    FFTSample r4 = z[1].im - z[5].im;

    FFTSample j1 = z[2].re - z[6].re;
    FFTSample j2 = z[2].im - z[6].im;
    FFTSample j3 = z[3].re - z[7].re;

cyanreg

// from https://gist.github.com/cyanreg/665b9c79cbe51df9296a969257f2a16c
static void fft4(FFTComplex *z)
{
    FFTSample r1 = z[0].re - z[4].re;
    FFTSample r2 = z[0].im - z[4].im;
    FFTSample r3 = z[1].re - z[5].re;
    FFTSample r4 = z[1].im - z[5].im;
    /* r5-r8 second transform */

    FFTSample t1 = z[0].re + z[4].re;

cyanreg

static void fft4(void *s, FFTComplex *z, FFTComplex *temp)
{
    FFTSample r1 = z[0].re - z[2].re;
    FFTSample r2 = z[0].im - z[2].im;
    FFTSample r3 = z[1].re - z[3].re;
    FFTSample r4 = z[1].im - z[3].im;
    /* r5-r8 second transform */

    FFTSample t1 = z[0].re + z[2].re;
    FFTSample t2 = z[0].im + z[2].im;

cyanreg

static void fft8(FFTComplex *z)
{
    FFTSample r1 = z[0].re - z[4].re;
    FFTSample r2 = z[0].im - z[4].im;
    FFTSample r3 = z[1].re - z[5].re;
    FFTSample r4 = z[1].im - z[5].im;

    FFTSample r5 = z[2].re - z[6].re;
    FFTSample r6 = z[2].im - z[6].im;
    FFTSample r7 = z[3].re - z[7].re;

cyanreg

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                             0.5 ns
Branch mispredict                              5   ns
L2 cache reference                             7   ns                         14x L1 cache
Mutex lock/unlock                             25   ns
Main memory reference                        100   ns                         20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy               3,000   ns        3 us
Send 1K bytes over 1 Gbps network         10,000   ns       10 us
Read 4K randomly from SSD*               150,000   ns      150 us             ~1GB/sec SSD