Add a tone generator test program

Currently used to test the general output, particularly the resampler, by
checking the results with a spectrum analyzer and/or oscilloscope (for example
using PulseAudio's "Monitor of ..." devices feeding an external app).

1 files changed, 250 insertions, 0 deletions

diff --git a/examples/altonegen.c b/examples/altonegen.c
new file mode 100644
index 00000000..d8601f7e
--- /dev/null
+++ b/examples/altonegen.c
@@ -0,0 +1,250 @@
+/*
+ * OpenAL Tone Generator Test
+ *
+ * Copyright (c) 2015 by Chris Robinson <[email protected]>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+/* This file contains a test for generating waveforms and plays them for a
+ * given length of time. Intended to inspect the behavior of the mixer by
+ * checking the output with a spectrum analyzer and oscilloscope.
+ *
+ * TODO: This would actually be nicer as a GUI app with buttons to start and
+ * stop individual waveforms, include additional whitenoise and pinknoise
+ * generators, and have the ability to hook up EFX filters and effects.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <math.h>
+
+#include "AL/al.h"
+#include "AL/alc.h"
+#include "AL/alext.h"
+
+#include "common/alhelpers.h"
+
+#ifndef M_PI
+#define M_PI    (3.14159265358979323846)
+#endif
+
+enum WaveType {
+    WT_Sine,
+    WT_Square,
+    WT_Sawtooth,
+    WT_Triangle,
+};
+
+static void ApplySin(ALfloat *data, ALdouble g, ALuint srate, ALuint freq)
+{
+    ALdouble smps_per_cycle = (ALdouble)srate / freq;
+    ALuint i;
+    for(i = 0;i < srate;i++)
+        data[i] += sin(i/smps_per_cycle * 2.0*M_PI) * g;
+}
+
+/* Generates waveforms using additive synthesis. Each waveform is constructed
+ * by summing one or more sine waves, up to (and excluding) nyquist.
+ */
+static ALuint CreateWave(enum WaveType type, ALuint freq, ALuint srate)
+{
+    ALint data_size;
+    ALfloat *data;
+    ALuint buffer;
+    ALenum err;
+    ALuint i;
+
+    data_size = srate * sizeof(ALfloat);
+    data = calloc(1, data_size);
+    if(type == WT_Sine)
+        ApplySin(data, 1.0, srate, freq);
+    else if(type == WT_Square)
+        for(i = 1;freq*i < srate/2;i+=2)
+            ApplySin(data, 4.0/M_PI * 1.0/i, srate, freq*i);
+    else if(type == WT_Sawtooth)
+        for(i = 1;freq*i < srate/2;i++)
+            ApplySin(data, 2.0/M_PI * ((i&1)*2 - 1.0) / i, srate, freq*i);
+    else if(type == WT_Triangle)
+        for(i = 1;freq*i < srate/2;i+=2)
+            ApplySin(data, 8.0/(M_PI*M_PI) * (1.0 - (i&2)) / (i*i), srate, freq*i);
+
+    /* Buffer the audio data into a new buffer object. */
+    buffer = 0;
+    alGenBuffers(1, &buffer);
+    alBufferData(buffer, AL_FORMAT_MONO_FLOAT32, data, data_size, srate);
+    free(data);
+
+    /* Check if an error occured, and clean up if so. */
+    err = alGetError();
+    if(err != AL_NO_ERROR)
+    {
+        fprintf(stderr, "OpenAL Error: %s\n", alGetString(err));
+        if(alIsBuffer(buffer))
+            alDeleteBuffers(1, &buffer);
+        return 0;
+    }
+
+    return buffer;
+}
+
+
+int main(int argc, char *argv[])
+{
+    enum WaveType wavetype = WT_Sine;
+    ALuint source, buffer;
+    ALint last_pos, num_loops;
+    ALint max_loops = 4;
+    ALint srate = 44100;
+    ALint tone_freq = 1000;
+    ALenum state;
+    int i;
+
+    for(i = 1;i < argc;i++)
+    {
+        if(strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0)
+        {
+            fprintf(stderr, "OpenAL Tone Generator\n"
+"\n"
+"Usage: %s <options>\n"
+"\n"
+"Available options:\n"
+"  --help/-h                 This help text\n"
+"  -t <seconds>              Time to play a tone (default 5 seconds)\n"
+"  --waveform/-w <type>      Waveform type: sine (default), square, sawtooth,\n"
+"                                triangle\n"
+"  --freq/-f <hz>            Tone frequency (default 1000 hz)\n"
+"  --srate/-s <sample rate>  Sampling rate (default 44100 hz)\n",
+                argv[0]
+            );
+            return 1;
+        }
+        else if(i+1 < argc && strcmp(argv[i], "-t") == 0)
+        {
+            i++;
+            max_loops = atoi(argv[i]) - 1;
+        }
+        else if(i+1 < argc && (strcmp(argv[i], "--waveform") == 0 || strcmp(argv[i], "-w") == 0))
+        {
+            i++;
+            if(strcmp(argv[i], "sine") == 0)
+                wavetype = WT_Sine;
+            else if(strcmp(argv[i], "square") == 0)
+                wavetype = WT_Square;
+            else if(strcmp(argv[i], "sawtooth") == 0)
+                wavetype = WT_Sawtooth;
+            else if(strcmp(argv[i], "triangle") == 0)
+                wavetype = WT_Triangle;
+            else
+                fprintf(stderr, "Unhandled waveform: %s\n", argv[i]);
+        }
+        else if(i+1 < argc && (strcmp(argv[i], "--freq") == 0 || strcmp(argv[i], "-f") == 0))
+        {
+            i++;
+            tone_freq = atoi(argv[i]);
+            if(tone_freq < 20)
+            {
+                fprintf(stderr, "Invalid tone frequency: %s (min: 20hz)\n", argv[i]);
+                tone_freq = 20;
+            }
+        }
+        else if(i+1 < argc && (strcmp(argv[i], "--srate") == 0 || strcmp(argv[i], "-s") == 0))
+        {
+            i++;
+            srate = atoi(argv[i]);
+            if(srate < 40)
+            {
+                fprintf(stderr, "Invalid sample rate: %s (min: 40hz)\n", argv[i]);
+                srate = 40;
+            }
+        }
+    }
+
+    InitAL();
+
+    if(!alIsExtensionPresent("AL_EXT_FLOAT32"))
+    {
+        fprintf(stderr, "Required AL_EXT_FLOAT32 extension not supported on this device!\n");
+        CloseAL();
+        return 1;
+    }
+
+    /* Load the sound into a buffer. */
+    buffer = CreateWave(wavetype, tone_freq, srate);
+    if(!buffer)
+    {
+        CloseAL();
+        return 1;
+    }
+
+    {
+        ALCdevice *device;
+        ALCint dev_rate;
+        ALint buf_rate;
+
+        device = alcGetContextsDevice(alcGetCurrentContext());
+        alcGetIntegerv(device, ALC_FREQUENCY, 1, &dev_rate);
+        assert(alcGetError(device)==ALC_NO_ERROR && "Failed to get device sample rate");
+
+        alGetBufferi(buffer, AL_FREQUENCY, &buf_rate);
+        assert(alGetError()==AL_NO_ERROR && "Failed to get buffer sample rate");
+
+        printf("Playing %dhz tone with %dhz sample rate and %dhz output, for %d second%s...\n",
+               tone_freq, buf_rate, dev_rate, max_loops+1, max_loops?"s":"");
+        fflush(stdout);
+    }
+
+    /* Create the source to play the sound with. */
+    source = 0;
+    alGenSources(1, &source);
+    alSourcei(source, AL_BUFFER, buffer);
+    assert(alGetError()==AL_NO_ERROR && "Failed to setup sound source");
+
+    /* Play the sound for a while. */
+    num_loops = 0;
+    last_pos = 0;
+    alSourcei(source, AL_LOOPING, (max_loops > 0) ? AL_TRUE : AL_FALSE);
+    alSourcePlay(source);
+    do {
+        ALint pos;
+        Sleep(10);
+        alGetSourcei(source, AL_SAMPLE_OFFSET, &pos);
+        alGetSourcei(source, AL_SOURCE_STATE, &state);
+        if(pos < last_pos && state == AL_PLAYING)
+        {
+            ++num_loops;
+            if(num_loops >= max_loops)
+                alSourcei(source, AL_LOOPING, AL_FALSE);
+            printf("%d...\n", max_loops - num_loops + 1);
+            fflush(stdout);
+        }
+        last_pos = pos;
+    } while(alGetError() == AL_NO_ERROR && state == AL_PLAYING);
+
+    /* All done. Delete resources, and close OpenAL. */
+    alDeleteSources(1, &source);
+    alDeleteBuffers(1, &buffer);
+
+    /* Close up OpenAL. */
+    CloseAL();
+
+    return 0;
+}