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( ͡° ͜ʖ ͡°){ʇlnɐɟ ƃǝs}Týr
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Join Date: Jun 2012
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Next up. something cool.
Okay, enough initialising. Let's hear something.
First off TURN YOUR VOLUME DOWN.
This demo is LOUD. I hope I SHOUTED that enough. I warned you.
Next up is the built version of the demo at
http://www.alsa-project.org/alsa-doc...c-example.html
It plays a simple sine wave to our speaker - pretty dull huh?
But it paves the wave for all kind of coolness so here's the blurb
Spoiler:
Code:
/*
* This small demo sends a simple sinusoidal wave to your speakers.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sched.h>
#include <errno.h>
#include <getopt.h>
#include <asoundlib.h>
#include <sys/time.h>
#include <math.h>
static char *device = "hw:0,0"; /* playback device */
static snd_pcm_format_t format = SND_PCM_FORMAT_S16; /* sample format */
static unsigned int rate = 44100; /* stream rate */
static unsigned int channels = 2; /* count of channels */
static unsigned int buffer_time = 500000; /* ring buffer length in us */
static unsigned int period_time = 100000; /* period time in us */
static double freq = 440; /* sinusoidal wave frequency in Hz */
static int verbose = 0; /* verbose flag */
static int resample = 1; /* enable alsa-lib resampling */
static int period_event = 0; /* produce poll event after each period */
static snd_pcm_sframes_t buffer_size;
static snd_pcm_sframes_t period_size;
static snd_output_t *output = NULL;
static void generate_sine(const snd_pcm_channel_area_t *areas,
snd_pcm_uframes_t offset,
int count, double *_phase)
{
static double max_phase = 2. * M_PI;
double phase = *_phase;
double step = max_phase*freq/(double)rate;
unsigned char *samples[channels];
int steps[channels];
unsigned int chn;
int format_bits = snd_pcm_format_width(format);
unsigned int maxval = (1 << (format_bits - 1)) - 1;
int bps = format_bits / 8; /* bytes per sample */
int phys_bps = snd_pcm_format_physical_width(format) / 8;
int big_endian = snd_pcm_format_big_endian(format) == 1;
int to_unsigned = snd_pcm_format_unsigned(format) == 1;
int is_float = (format == SND_PCM_FORMAT_FLOAT_LE ||
format == SND_PCM_FORMAT_FLOAT_BE);
/* verify and prepare the contents of areas */
for (chn = 0; chn < channels; chn++) {
if ((areas[chn].first % 8) != 0) {
printf("areas[%i].first == %i, aborting...\n", chn, areas[chn].first);
exit(EXIT_FAILURE);
}
samples[chn] = /*(signed short *)*/(((unsigned char *)areas[chn].addr) + (areas[chn].first / 8));
if ((areas[chn].step % 16) != 0) {
printf("areas[%i].step == %i, aborting...\n", chn, areas[chn].step);
exit(EXIT_FAILURE);
}
steps[chn] = areas[chn].step / 8;
samples[chn] += offset * steps[chn];
}
/* fill the channel areas */
while (count-- > 0) {
union {
float f;
int i;
} fval;
int res, i;
if (is_float) {
fval.f = sin(phase) * maxval;
res = fval.i;
} else
res = sin(phase) * maxval;
if (to_unsigned)
res ^= 1U << (format_bits - 1);
for (chn = 0; chn < channels; chn++) {
/* Generate data in native endian format */
if (big_endian) {
for (i = 0; i < bps; i++)
*(samples[chn] + phys_bps - 1 - i) = (res >> i * 8) & 0xff;
} else {
for (i = 0; i < bps; i++)
*(samples[chn] + i) = (res >> i * 8) & 0xff;
}
samples[chn] += steps[chn];
}
phase += step;
if (phase >= max_phase)
phase -= max_phase;
}
*_phase = phase;
}
static int set_hwparams(snd_pcm_t *handle,
snd_pcm_hw_params_t *params,
snd_pcm_access_t access)
{
unsigned int rrate;
snd_pcm_uframes_t size;
int err, dir;
/* choose all parameters */
err = snd_pcm_hw_params_any(handle, params);
if (err < 0) {
printf("Broken configuration for playback: no configurations available: %s\n", snd_strerror(err));
return err;
}
/* set hardware resampling */
err = snd_pcm_hw_params_set_rate_resample(handle, params, resample);
if (err < 0) {
printf("Resampling setup failed for playback: %s\n", snd_strerror(err));
return err;
}
/* set the interleaved read/write format */
err = snd_pcm_hw_params_set_access(handle, params, access);
if (err < 0) {
printf("Access type not available for playback: %s\n", snd_strerror(err));
return err;
}
/* set the sample format */
err = snd_pcm_hw_params_set_format(handle, params, format);
if (err < 0) {
printf("Sample format not available for playback: %s\n", snd_strerror(err));
return err;
}
/* set the count of channels */
err = snd_pcm_hw_params_set_channels(handle, params, channels);
if (err < 0) {
printf("Channels count (%i) not available for playbacks: %s\n", channels, snd_strerror(err));
return err;
}
/* set the stream rate */
rrate = rate;
err = snd_pcm_hw_params_set_rate_near(handle, params, &rrate, 0);
if (err < 0) {
printf("Rate %iHz not available for playback: %s\n", rate, snd_strerror(err));
return err;
}
if (rrate != rate) {
printf("Rate doesn't match (requested %iHz, get %iHz)\n", rate, err);
return -EINVAL;
}
/* set the buffer time */
err = snd_pcm_hw_params_set_buffer_time_near(handle, params, &buffer_time, &dir);
if (err < 0) {
printf("Unable to set buffer time %i for playback: %s\n", buffer_time, snd_strerror(err));
return err;
}
err = snd_pcm_hw_params_get_buffer_size(params, &size);
if (err < 0) {
printf("Unable to get buffer size for playback: %s\n", snd_strerror(err));
return err;
}
buffer_size = size;
/* set the period time */
err = snd_pcm_hw_params_set_period_time_near(handle, params, &period_time, &dir);
if (err < 0) {
printf("Unable to set period time %i for playback: %s\n", period_time, snd_strerror(err));
return err;
}
err = snd_pcm_hw_params_get_period_size(params, &size, &dir);
if (err < 0) {
printf("Unable to get period size for playback: %s\n", snd_strerror(err));
return err;
}
period_size = size;
/* write the parameters to device */
err = snd_pcm_hw_params(handle, params);
if (err < 0) {
printf("Unable to set hw params for playback: %s\n", snd_strerror(err));
return err;
}
return 0;
}
static int set_swparams(snd_pcm_t *handle, snd_pcm_sw_params_t *swparams)
{
int err;
/* get the current swparams */
err = snd_pcm_sw_params_current(handle, swparams);
if (err < 0) {
printf("Unable to determine current swparams for playback: %s\n", snd_strerror(err));
return err;
}
/* start the transfer when the buffer is almost full: */
/* (buffer_size / avail_min) * avail_min */
err = snd_pcm_sw_params_set_start_threshold(handle, swparams, (buffer_size / period_size) * period_size);
if (err < 0) {
printf("Unable to set start threshold mode for playback: %s\n", snd_strerror(err));
return err;
}
/* allow the transfer when at least period_size samples can be processed */
/* or disable this mechanism when period event is enabled (aka interrupt like style processing) */
err = snd_pcm_sw_params_set_avail_min(handle, swparams, period_event ? buffer_size : period_size);
if (err < 0) {
printf("Unable to set avail min for playback: %s\n", snd_strerror(err));
return err;
}
/* enable period events when requested */
if (period_event) {
// err = snd_pcm_sw_params_set_period_event(handle, swparams, 1);
// if (err < 0) {
// printf("Unable to set period event: %s\n", snd_strerror(err));
// return err;
// }
}
/* write the parameters to the playback device */
err = snd_pcm_sw_params(handle, swparams);
if (err < 0) {
printf("Unable to set sw params for playback: %s\n", snd_strerror(err));
return err;
}
return 0;
}
/*
* Underrun and suspend recovery
*/
static int xrun_recovery(snd_pcm_t *handle, int err)
{
if (verbose)
printf("stream recovery\n");
if (err == -EPIPE) { /* under-run */
err = snd_pcm_prepare(handle);
if (err < 0)
printf("Can't recovery from underrun, prepare failed: %s\n", snd_strerror(err));
return 0;
} else if (err == -ESTRPIPE) {
while ((err = snd_pcm_resume(handle)) == -EAGAIN)
sleep(1); /* wait until the suspend flag is released */
if (err < 0) {
err = snd_pcm_prepare(handle);
if (err < 0)
printf("Can't recovery from suspend, prepare failed: %s\n", snd_strerror(err));
}
return 0;
}
return err;
}
/*
* Transfer method - write only
*/
static int write_loop(snd_pcm_t *handle,
signed short *samples,
snd_pcm_channel_area_t *areas)
{
double phase = 0;
signed short *ptr;
int err, cptr;
while (1) {
generate_sine(areas, 0, period_size, &phase);
ptr = samples;
cptr = period_size;
while (cptr > 0) {
err = snd_pcm_writei(handle, ptr, cptr);
if (err == -EAGAIN)
continue;
if (err < 0) {
if (xrun_recovery(handle, err) < 0) {
printf("Write error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
break; /* skip one period */
}
ptr += err * channels;
cptr -= err;
}
}
}
/*
* Transfer method - write and wait for room in buffer using poll
*/
static int wait_for_poll(snd_pcm_t *handle, struct pollfd *ufds, unsigned int count)
{
unsigned short revents;
while (1) {
poll(ufds, count, -1);
snd_pcm_poll_descriptors_revents(handle, ufds, count, &revents);
if (revents & POLLERR)
return -EIO;
if (revents & POLLOUT)
return 0;
}
}
static int write_and_poll_loop(snd_pcm_t *handle,
signed short *samples,
snd_pcm_channel_area_t *areas)
{
struct pollfd *ufds;
double phase = 0;
signed short *ptr;
int err, count, cptr, init;
count = snd_pcm_poll_descriptors_count (handle);
if (count <= 0) {
printf("Invalid poll descriptors count\n");
return count;
}
ufds = malloc(sizeof(struct pollfd) * count);
if (ufds == NULL) {
printf("No enough memory\n");
return -ENOMEM;
}
if ((err = snd_pcm_poll_descriptors(handle, ufds, count)) < 0) {
printf("Unable to obtain poll descriptors for playback: %s\n", snd_strerror(err));
return err;
}
init = 1;
while (1) {
if (!init) {
err = wait_for_poll(handle, ufds, count);
if (err < 0) {
if (snd_pcm_state(handle) == SND_PCM_STATE_XRUN ||
snd_pcm_state(handle) == SND_PCM_STATE_SUSPENDED) {
err = snd_pcm_state(handle) == SND_PCM_STATE_XRUN ? -EPIPE : -ESTRPIPE;
if (xrun_recovery(handle, err) < 0) {
printf("Write error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
init = 1;
} else {
printf("Wait for poll failed\n");
return err;
}
}
}
generate_sine(areas, 0, period_size, &phase);
ptr = samples;
cptr = period_size;
while (cptr > 0) {
err = snd_pcm_writei(handle, ptr, cptr);
if (err < 0) {
if (xrun_recovery(handle, err) < 0) {
printf("Write error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
init = 1;
break; /* skip one period */
}
if (snd_pcm_state(handle) == SND_PCM_STATE_RUNNING)
init = 0;
ptr += err * channels;
cptr -= err;
if (cptr == 0)
break;
/* it is possible, that the initial buffer cannot store */
/* all data from the last period, so wait awhile */
err = wait_for_poll(handle, ufds, count);
if (err < 0) {
if (snd_pcm_state(handle) == SND_PCM_STATE_XRUN ||
snd_pcm_state(handle) == SND_PCM_STATE_SUSPENDED) {
err = snd_pcm_state(handle) == SND_PCM_STATE_XRUN ? -EPIPE : -ESTRPIPE;
if (xrun_recovery(handle, err) < 0) {
printf("Write error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
init = 1;
} else {
printf("Wait for poll failed\n");
return err;
}
}
}
}
}
/*
* Transfer method - asynchronous notification
*/
struct async_private_data {
signed short *samples;
snd_pcm_channel_area_t *areas;
double phase;
};
static void async_callback(snd_async_handler_t *ahandler)
{
snd_pcm_t *handle = snd_async_handler_get_pcm(ahandler);
struct async_private_data *data = snd_async_handler_get_callback_private(ahandler);
signed short *samples = data->samples;
snd_pcm_channel_area_t *areas = data->areas;
snd_pcm_sframes_t avail;
int err;
avail = snd_pcm_avail_update(handle);
while (avail >= period_size) {
generate_sine(areas, 0, period_size, &data->phase);
err = snd_pcm_writei(handle, samples, period_size);
if (err < 0) {
printf("Write error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
if (err != period_size) {
printf("Write error: written %i expected %li\n", err, period_size);
exit(EXIT_FAILURE);
}
avail = snd_pcm_avail_update(handle);
}
}
static int async_loop(snd_pcm_t *handle,
signed short *samples,
snd_pcm_channel_area_t *areas)
{
struct async_private_data data;
snd_async_handler_t *ahandler;
int err, count;
data.samples = samples;
data.areas = areas;
data.phase = 0;
err = snd_async_add_pcm_handler(&ahandler, handle, async_callback, &data);
if (err < 0) {
printf("Unable to register async handler\n");
exit(EXIT_FAILURE);
}
for (count = 0; count < 2; count++) {
generate_sine(areas, 0, period_size, &data.phase);
err = snd_pcm_writei(handle, samples, period_size);
if (err < 0) {
printf("Initial write error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
if (err != period_size) {
printf("Initial write error: written %i expected %li\n", err, period_size);
exit(EXIT_FAILURE);
}
}
if (snd_pcm_state(handle) == SND_PCM_STATE_PREPARED) {
err = snd_pcm_start(handle);
if (err < 0) {
printf("Start error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
}
/* because all other work is done in the signal handler,
suspend the process */
while (1) {
sleep(1);
}
}
/*
* Transfer method - asynchronous notification + direct write
*/
static void async_direct_callback(snd_async_handler_t *ahandler)
{
snd_pcm_t *handle = snd_async_handler_get_pcm(ahandler);
struct async_private_data *data = snd_async_handler_get_callback_private(ahandler);
const snd_pcm_channel_area_t *my_areas;
snd_pcm_uframes_t offset, frames, size;
snd_pcm_sframes_t avail, commitres;
snd_pcm_state_t state;
int first = 0, err;
while (1) {
state = snd_pcm_state(handle);
if (state == SND_PCM_STATE_XRUN) {
err = xrun_recovery(handle, -EPIPE);
if (err < 0) {
printf("XRUN recovery failed: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
first = 1;
} else if (state == SND_PCM_STATE_SUSPENDED) {
err = xrun_recovery(handle, -ESTRPIPE);
if (err < 0) {
printf("SUSPEND recovery failed: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
}
avail = snd_pcm_avail_update(handle);
if (avail < 0) {
err = xrun_recovery(handle, avail);
if (err < 0) {
printf("avail update failed: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
first = 1;
continue;
}
if (avail < period_size) {
if (first) {
first = 0;
err = snd_pcm_start(handle);
if (err < 0) {
printf("Start error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
} else {
break;
}
continue;
}
size = period_size;
while (size > 0) {
frames = size;
err = snd_pcm_mmap_begin(handle, &my_areas, &offset, &frames);
if (err < 0) {
if ((err = xrun_recovery(handle, err)) < 0) {
printf("MMAP begin avail error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
first = 1;
}
generate_sine(my_areas, offset, frames, &data->phase);
commitres = snd_pcm_mmap_commit(handle, offset, frames);
if (commitres < 0 || (snd_pcm_uframes_t)commitres != frames) {
if ((err = xrun_recovery(handle, commitres >= 0 ? -EPIPE : commitres)) < 0) {
printf("MMAP commit error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
first = 1;
}
size -= frames;
}
}
}
static int async_direct_loop(snd_pcm_t *handle,
signed short *samples ATTRIBUTE_UNUSED,
snd_pcm_channel_area_t *areas ATTRIBUTE_UNUSED)
{
struct async_private_data data;
snd_async_handler_t *ahandler;
const snd_pcm_channel_area_t *my_areas;
snd_pcm_uframes_t offset, frames, size;
snd_pcm_sframes_t commitres;
int err, count;
data.samples = NULL; /* we do not require the global sample area for direct write */
data.areas = NULL; /* we do not require the global areas for direct write */
data.phase = 0;
err = snd_async_add_pcm_handler(&ahandler, handle, async_direct_callback, &data);
if (err < 0) {
printf("Unable to register async handler\n");
exit(EXIT_FAILURE);
}
for (count = 0; count < 2; count++) {
size = period_size;
while (size > 0) {
frames = size;
err = snd_pcm_mmap_begin(handle, &my_areas, &offset, &frames);
if (err < 0) {
if ((err = xrun_recovery(handle, err)) < 0) {
printf("MMAP begin avail error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
}
generate_sine(my_areas, offset, frames, &data.phase);
commitres = snd_pcm_mmap_commit(handle, offset, frames);
if (commitres < 0 || (snd_pcm_uframes_t)commitres != frames) {
if ((err = xrun_recovery(handle, commitres >= 0 ? -EPIPE : commitres)) < 0) {
printf("MMAP commit error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
}
size -= frames;
}
}
err = snd_pcm_start(handle);
if (err < 0) {
printf("Start error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
/* because all other work is done in the signal handler,
suspend the process */
while (1) {
sleep(1);
}
}
/*
* Transfer method - direct write only
*/
static int direct_loop(snd_pcm_t *handle,
signed short *samples ATTRIBUTE_UNUSED,
snd_pcm_channel_area_t *areas ATTRIBUTE_UNUSED)
{
double phase = 0;
const snd_pcm_channel_area_t *my_areas;
snd_pcm_uframes_t offset, frames, size;
snd_pcm_sframes_t avail, commitres;
snd_pcm_state_t state;
int err, first = 1;
while (1) {
state = snd_pcm_state(handle);
if (state == SND_PCM_STATE_XRUN) {
err = xrun_recovery(handle, -EPIPE);
if (err < 0) {
printf("XRUN recovery failed: %s\n", snd_strerror(err));
return err;
}
first = 1;
} else if (state == SND_PCM_STATE_SUSPENDED) {
err = xrun_recovery(handle, -ESTRPIPE);
if (err < 0) {
printf("SUSPEND recovery failed: %s\n", snd_strerror(err));
return err;
}
}
avail = snd_pcm_avail_update(handle);
if (avail < 0) {
err = xrun_recovery(handle, avail);
if (err < 0) {
printf("avail update failed: %s\n", snd_strerror(err));
return err;
}
first = 1;
continue;
}
if (avail < period_size) {
if (first) {
first = 0;
err = snd_pcm_start(handle);
if (err < 0) {
printf("Start error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
} else {
err = snd_pcm_wait(handle, -1);
if (err < 0) {
if ((err = xrun_recovery(handle, err)) < 0) {
printf("snd_pcm_wait error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
first = 1;
}
}
continue;
}
size = period_size;
while (size > 0) {
frames = size;
err = snd_pcm_mmap_begin(handle, &my_areas, &offset, &frames);
if (err < 0) {
if ((err = xrun_recovery(handle, err)) < 0) {
printf("MMAP begin avail error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
first = 1;
}
generate_sine(my_areas, offset, frames, &phase);
commitres = snd_pcm_mmap_commit(handle, offset, frames);
if (commitres < 0 || (snd_pcm_uframes_t)commitres != frames) {
if ((err = xrun_recovery(handle, commitres >= 0 ? -EPIPE : commitres)) < 0) {
printf("MMAP commit error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
first = 1;
}
size -= frames;
}
}
}
/*
* Transfer method - direct write only using mmap_write functions
*/
static int direct_write_loop(snd_pcm_t *handle,
signed short *samples,
snd_pcm_channel_area_t *areas)
{
double phase = 0;
signed short *ptr;
int err, cptr;
while (1) {
generate_sine(areas, 0, period_size, &phase);
ptr = samples;
cptr = period_size;
while (cptr > 0) {
err = snd_pcm_mmap_writei(handle, ptr, cptr);
if (err == -EAGAIN)
continue;
if (err < 0) {
if (xrun_recovery(handle, err) < 0) {
printf("Write error: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
break; /* skip one period */
}
ptr += err * channels;
cptr -= err;
}
}
}
/*
*
*/
struct transfer_method {
const char *name;
snd_pcm_access_t access;
int (*transfer_loop)(snd_pcm_t *handle,
signed short *samples,
snd_pcm_channel_area_t *areas);
};
static struct transfer_method transfer_methods[] = {
{ "write", SND_PCM_ACCESS_RW_INTERLEAVED, write_loop },
{ "write_and_poll", SND_PCM_ACCESS_RW_INTERLEAVED, write_and_poll_loop },
{ "async", SND_PCM_ACCESS_RW_INTERLEAVED, async_loop },
{ "async_direct", SND_PCM_ACCESS_MMAP_INTERLEAVED, async_direct_loop },
{ "direct_interleaved", SND_PCM_ACCESS_MMAP_INTERLEAVED, direct_loop },
{ "direct_noninterleaved", SND_PCM_ACCESS_MMAP_NONINTERLEAVED, direct_loop },
{ "direct_write", SND_PCM_ACCESS_MMAP_INTERLEAVED, direct_write_loop },
{ NULL, SND_PCM_ACCESS_RW_INTERLEAVED, NULL }
};
static void help(void)
{
int k;
printf(
"Usage: pcm [OPTION]... [FILE]...\n"
"-h,--help help\n"
"-D,--device playback device\n"
"-r,--rate stream rate in Hz\n"
"-c,--channels count of channels in stream\n"
"-f,--frequency sine wave frequency in Hz\n"
"-b,--buffer ring buffer size in us\n"
"-p,--period period size in us\n"
"-m,--method transfer method\n"
"-o,--format sample format\n"
"-v,--verbose show the PCM setup parameters\n"
"-n,--noresample do not resample\n"
"-e,--pevent enable poll event after each period\n"
"\n");
printf("Recognized sample formats are:");
for (k = 0; k < SND_PCM_FORMAT_LAST; ++k) {
const char *s = snd_pcm_format_name(k);
if (s)
printf(" %s", s);
}
printf("\n");
printf("Recognized transfer methods are:");
for (k = 0; transfer_methods[k].name; k++)
printf(" %s", transfer_methods[k].name);
printf("\n");
}
int main(int argc, char *argv[])
{
struct option long_option[] =
{
{"help", 0, NULL, 'h'},
{"device", 1, NULL, 'D'},
{"rate", 1, NULL, 'r'},
{"channels", 1, NULL, 'c'},
{"frequency", 1, NULL, 'f'},
{"buffer", 1, NULL, 'b'},
{"period", 1, NULL, 'p'},
{"method", 1, NULL, 'm'},
{"format", 1, NULL, 'o'},
{"verbose", 1, NULL, 'v'},
{"noresample", 1, NULL, 'n'},
{"pevent", 1, NULL, 'e'},
{NULL, 0, NULL, 0},
};
snd_pcm_t *handle;
int err, morehelp;
snd_pcm_hw_params_t *hwparams;
snd_pcm_sw_params_t *swparams;
int method = 0;
signed short *samples;
unsigned int chn;
snd_pcm_channel_area_t *areas;
snd_pcm_hw_params_alloca(&hwparams);
snd_pcm_sw_params_alloca(&swparams);
morehelp = 0;
while (1) {
int c;
if ((c = getopt_long(argc, argv, "hD:r:c:f:b:p:m:o:vne", long_option, NULL)) < 0)
break;
switch (c) {
case 'h':
morehelp++;
break;
case 'D':
device = strdup(optarg);
break;
case 'r':
rate = atoi(optarg);
rate = rate < 4000 ? 4000 : rate;
rate = rate > 196000 ? 196000 : rate;
break;
case 'c':
channels = atoi(optarg);
channels = channels < 1 ? 1 : channels;
channels = channels > 1024 ? 1024 : channels;
break;
case 'f':
freq = atoi(optarg);
freq = freq < 50 ? 50 : freq;
freq = freq > 5000 ? 5000 : freq;
break;
case 'b':
buffer_time = atoi(optarg);
buffer_time = buffer_time < 1000 ? 1000 : buffer_time;
buffer_time = buffer_time > 1000000 ? 1000000 : buffer_time;
break;
case 'p':
period_time = atoi(optarg);
period_time = period_time < 1000 ? 1000 : period_time;
period_time = period_time > 1000000 ? 1000000 : period_time;
break;
case 'm':
for (method = 0; transfer_methods[method].name; method++)
if (!strcasecmp(transfer_methods[method].name, optarg))
break;
if (transfer_methods[method].name == NULL)
method = 0;
break;
case 'o':
for (format = 0; format < SND_PCM_FORMAT_LAST; format++) {
const char *format_name = snd_pcm_format_name(format);
if (format_name)
if (!strcasecmp(format_name, optarg))
break;
}
if (format == SND_PCM_FORMAT_LAST)
format = SND_PCM_FORMAT_S16;
if (!snd_pcm_format_linear(format) &&
!(format == SND_PCM_FORMAT_FLOAT_LE ||
format == SND_PCM_FORMAT_FLOAT_BE)) {
printf("Invalid (non-linear/float) format %s\n",
optarg);
return 1;
}
break;
case 'v':
verbose = 1;
break;
case 'n':
resample = 0;
break;
case 'e':
period_event = 1;
break;
}
}
if (morehelp) {
help();
return 0;
}
err = snd_output_stdio_attach(&output, stdout, 0);
if (err < 0) {
printf("Output failed: %s\n", snd_strerror(err));
return 0;
}
printf("Playback device is %s\n", device);
printf("Stream parameters are %iHz, %s, %i channels\n", rate, snd_pcm_format_name(format), channels);
printf("Sine wave rate is %.4fHz\n", freq);
printf("Using transfer method: %s\n", transfer_methods[method].name);
if ((err = snd_pcm_open(&handle, device, SND_PCM_STREAM_PLAYBACK, 0)) < 0) {
printf("Playback open error: %s\n", snd_strerror(err));
return 0;
}
if ((err = set_hwparams(handle, hwparams, transfer_methods[method].access)) < 0) {
printf("Setting of hwparams failed: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
if ((err = set_swparams(handle, swparams)) < 0) {
printf("Setting of swparams failed: %s\n", snd_strerror(err));
exit(EXIT_FAILURE);
}
if (verbose > 0)
snd_pcm_dump(handle, output);
samples = malloc((period_size * channels * snd_pcm_format_physical_width(format)) / 8);
if (samples == NULL) {
printf("No enough memory\n");
exit(EXIT_FAILURE);
}
areas = calloc(channels, sizeof(snd_pcm_channel_area_t));
if (areas == NULL) {
printf("No enough memory\n");
exit(EXIT_FAILURE);
}
for (chn = 0; chn < channels; chn++) {
areas[chn].addr = samples;
areas[chn].first = chn * snd_pcm_format_physical_width(format);
areas[chn].step = channels * snd_pcm_format_physical_width(format);
}
err = transfer_methods[method].transfer_loop(handle, samples, areas);
if (err < 0)
printf("Transfer failed: %s\n", snd_strerror(err));
free(areas);
free(samples);
snd_pcm_close(handle);
return 0;
}
This was the first demo to work out-of-the-box on cross-compile. Happy days.
usage: ./sine
(it goes up to 5Khz), device hw ( hw:0 and synonyms ) is supported currently
install / uninstall: just copy / remove the file
Full listing of Usage: sine [OPTION]... [FILE]...
-h,--help help
-D,--device playback device
-r,--rate stream rate in Hz
-c,--channels count of channels in stream
-f,--frequency sine wave frequency in Hz
-b,--buffer ring buffer size in us
-p,--period period size in us
-m,--method transfer method
-o,--format sample format
-v,--verbose show the PCM setup parameters
-n,--noresample do not resample
-e,--pevent enable poll event after each period
Recognized sample formats are: S8 U8 S16_LE S16_BE U16_LE U16_BE S24_LE S24_BE U24_LE U24_BE S32_LE S32_BE U32_LE U32_BE FLOAT_LE FLOAT_BE FLOAT64_LE FLOAT64_BE IEC958_SUBFRAME_LE IEC958_SUBFRAME_BE MU_LAW A_LAW IMA_ADPCM MPEG GSM SPECIAL S24_3LE S24_3BE U24_3LE U24_3BE S20_3LE S20_3BE U20_3LE U20_3BE S18_3LE S18_3BE U18_3LE
Recognized transfer methods are: write write_and_poll async async_direct direct_interleaved direct_noninterleaved direct_write
WHAT IS ACTUALLY ATTACHED IS tones, THIS IS SIMPLY A MORE INTERESTING VARIATION OF THIS CODE. THANKS
TESTED ON ALL AUDIO CAPABLE KINDLES
Last edited by twobob; 07-12-2012 at 11:03 PM.
Reason: I updated the static Alsalib to stop to broken alsa.conf request
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