mirror of
https://github.com/alsa-project/alsa-lib.git
synced 2025-10-29 05:40:25 -04:00
Added latency example...
This commit is contained in:
Jaroslav Kysela
parent
ebfe8d8a24
commit
3bb1db2e17
2 changed files with 244 additions and 1 deletions
242
test/latency.c
Normal file
242
test/latency.c
Normal file
|
|
@ -0,0 +1,242 @@
|
|||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
#include <string.h>
|
||||
#include <sched.h>
|
||||
#include "../include/asoundlib.h"
|
||||
|
||||
static char *xitoa(int aaa)
|
||||
{
|
||||
static char str[12];
|
||||
|
||||
sprintf(str, "%i", aaa);
|
||||
return str;
|
||||
}
|
||||
|
||||
/*
|
||||
* This small demo program can be used for measuring latency between
|
||||
* record and playback. This latency is measured from driver (diff when
|
||||
* playback and record was started). Scheduler is set to SCHED_RR.
|
||||
*
|
||||
* Used format is 44100Hz, Signed Little Endian 16-bit, Stereo.
|
||||
*
|
||||
* Program begins with 128-byte fragment (about 726us) and step is 32-byte
|
||||
* until playback without underruns is reached. This program starts playback
|
||||
* after two fragments are recorded (teoretical latency is 1452us by 128-byte
|
||||
* fragment).
|
||||
*/
|
||||
|
||||
void setformat(void *phandle, void *rhandle)
|
||||
{
|
||||
int err;
|
||||
snd_pcm_format_t format;
|
||||
|
||||
bzero(&format, sizeof(format));
|
||||
format.format = SND_PCM_SFMT_S16_LE;
|
||||
format.channels = 2;
|
||||
format.rate = 44100;
|
||||
if ((err = snd_pcm_playback_format(phandle, &format)) < 0) {
|
||||
printf("Playback format error: %s\n", snd_strerror(err));
|
||||
exit(0);
|
||||
}
|
||||
if ((err = snd_pcm_record_format(rhandle, &format)) < 0) {
|
||||
printf("Record format error: %s\n", snd_strerror(err));
|
||||
exit(0);
|
||||
}
|
||||
if ((err = snd_pcm_playback_time(phandle, 1)) < 0) {
|
||||
printf("Playback time error: %s\n", snd_strerror(err));
|
||||
exit(0);
|
||||
}
|
||||
if ((err = snd_pcm_record_time(rhandle, 1)) < 0) {
|
||||
printf("Record time error: %s\n", snd_strerror(err));
|
||||
exit(0);
|
||||
}
|
||||
}
|
||||
|
||||
int setparams(void *phandle, void *rhandle, int *fragmentsize)
|
||||
{
|
||||
int err, step = 4;
|
||||
snd_pcm_playback_info_t pinfo;
|
||||
snd_pcm_record_info_t rinfo;
|
||||
snd_pcm_playback_params_t pparams;
|
||||
snd_pcm_record_params_t rparams;
|
||||
|
||||
if ((err = snd_pcm_playback_info(phandle, &pinfo)) < 0) {
|
||||
printf("Playback info error: %s\n", snd_strerror(err));
|
||||
exit(0);
|
||||
}
|
||||
if ((err = snd_pcm_record_info(rhandle, &rinfo)) < 0) {
|
||||
printf("Record info error: %s\n", snd_strerror(err));
|
||||
exit(0);
|
||||
}
|
||||
if (step < pinfo.min_fragment_size)
|
||||
step = pinfo.min_fragment_size;
|
||||
if (step < rinfo.min_fragment_size)
|
||||
step = rinfo.min_fragment_size;
|
||||
while (step < 4096 &&
|
||||
(step & pinfo.fragment_align) != 0 &&
|
||||
(step & rinfo.fragment_align) != 0) step++;
|
||||
if (*fragmentsize) {
|
||||
*fragmentsize += step;
|
||||
} else {
|
||||
if (step < 128)
|
||||
*fragmentsize = 128;
|
||||
else
|
||||
*fragmentsize = step;
|
||||
}
|
||||
while (*fragmentsize < 4096) {
|
||||
bzero(&pparams, sizeof(pparams));
|
||||
pparams.fragment_size = *fragmentsize;
|
||||
pparams.fragments_max = -1; /* maximum */
|
||||
pparams.fragments_room = 1;
|
||||
if ((err = snd_pcm_playback_params(phandle, &pparams)) < 0) {
|
||||
*fragmentsize += step;
|
||||
continue;
|
||||
}
|
||||
bzero(&rparams, sizeof(rparams));
|
||||
rparams.fragment_size = *fragmentsize;
|
||||
rparams.fragments_min = 1; /* wakeup if at least one fragment is ready */
|
||||
if ((err = snd_pcm_record_params(rhandle, &rparams)) < 0) {
|
||||
*fragmentsize += step;
|
||||
continue;
|
||||
}
|
||||
break;
|
||||
}
|
||||
if (*fragmentsize < 4096) {
|
||||
printf("Trying fragment size %i...\n", *fragmentsize);
|
||||
fflush(stdout);
|
||||
return 0;
|
||||
}
|
||||
return -1;
|
||||
}
|
||||
|
||||
int playbackunderrun(void *phandle)
|
||||
{
|
||||
int err;
|
||||
snd_pcm_playback_status_t pstatus;
|
||||
|
||||
if ((err = snd_pcm_playback_status(phandle, &pstatus)) < 0) {
|
||||
printf("Playback status error: %s\n", snd_strerror(err));
|
||||
exit(0);
|
||||
}
|
||||
return pstatus.underrun;
|
||||
}
|
||||
|
||||
void recordfragment(void *rhandle, char *buffer, int index, int fragmentsize)
|
||||
{
|
||||
int err;
|
||||
|
||||
buffer += index * fragmentsize;
|
||||
if ((err = snd_pcm_read(rhandle, buffer, fragmentsize)) != fragmentsize) {
|
||||
printf("Read error: %s\n", err < 0 ? snd_strerror(err) : xitoa(err));
|
||||
exit(0);
|
||||
}
|
||||
}
|
||||
|
||||
void playfragment(void *phandle, char *buffer, int index, int fragmentsize)
|
||||
{
|
||||
int err;
|
||||
|
||||
buffer += index * fragmentsize;
|
||||
if ((err = snd_pcm_write(phandle, buffer, fragmentsize)) != fragmentsize) {
|
||||
printf("Write error: %s\n", err < 0 ? snd_strerror(err) : xitoa(err));
|
||||
exit(0);
|
||||
}
|
||||
}
|
||||
|
||||
void setscheduler(void)
|
||||
{
|
||||
struct sched_param sched_param;
|
||||
|
||||
if (sched_getparam(0, &sched_param)<0) {
|
||||
printf("Scheduler getparam failed...\n");
|
||||
return;
|
||||
}
|
||||
sched_param.sched_priority = sched_get_priority_max(SCHED_RR);
|
||||
if (!sched_setscheduler(0, SCHED_RR, &sched_param)) {
|
||||
printf("Scheduler set to Round Robin with priority %i...\n", sched_param.sched_priority);
|
||||
fflush(stdout);
|
||||
return;
|
||||
}
|
||||
printf("!!!Scheduler set to Round Robin with priority %i FAILED!!!\n", sched_param.sched_priority);
|
||||
}
|
||||
|
||||
long timediff(struct timeval t1, struct timeval t2)
|
||||
{
|
||||
signed long l;
|
||||
|
||||
t1.tv_sec -= t2.tv_sec;
|
||||
l = (signed long)t1.tv_usec - (signed long)t2.tv_usec;
|
||||
if (l < 0) {
|
||||
t1.tv_sec--;
|
||||
l = -l;
|
||||
l %= 1000000;
|
||||
}
|
||||
return (t1.tv_sec * 1000000) + l;
|
||||
}
|
||||
|
||||
void main(void)
|
||||
{
|
||||
void *phandle, *rhandle;
|
||||
char buffer[4096 * 2]; /* max two fragments by 4096 bytes */
|
||||
int pcard = 0, pdevice = 0;
|
||||
int rcard = 0, rdevice = 0;
|
||||
int err, fragmentsize = 0;
|
||||
int ridx, pidx, size, ok;
|
||||
snd_pcm_playback_status_t pstatus;
|
||||
snd_pcm_record_status_t rstatus;
|
||||
|
||||
setscheduler();
|
||||
if ((err = snd_pcm_open(&phandle, pcard, pdevice, SND_PCM_OPEN_PLAYBACK)) < 0) {
|
||||
printf("Playback open error: %s\n", snd_strerror(err));
|
||||
return;
|
||||
}
|
||||
if ((err = snd_pcm_open(&rhandle, rcard, rdevice, SND_PCM_OPEN_RECORD)) < 0) {
|
||||
printf( "Record open error: %s\n", snd_strerror(err));
|
||||
return;
|
||||
}
|
||||
setformat(phandle, rhandle);
|
||||
while (1) {
|
||||
if (setparams(phandle, rhandle, &fragmentsize)<0)
|
||||
break;
|
||||
ok = 1;
|
||||
ridx = pidx = size = 0;
|
||||
recordfragment(rhandle, buffer, ridx++, fragmentsize);
|
||||
recordfragment(rhandle, buffer, ridx++, fragmentsize);
|
||||
if ((err = snd_pcm_record_status(rhandle, &rstatus)) < 0) {
|
||||
printf("Record status error: %s\n", snd_strerror(err));
|
||||
exit(0);
|
||||
}
|
||||
ridx %= 2;
|
||||
playfragment(phandle, buffer, 0, 2 * fragmentsize);
|
||||
size += 2 * fragmentsize;
|
||||
pidx += 2;
|
||||
pidx %= 2;
|
||||
while (ok && size < 3 * 176400) { /* 30 seconds */
|
||||
recordfragment(rhandle, buffer, ridx++, fragmentsize);
|
||||
ridx %= 2;
|
||||
playfragment(phandle, buffer, pidx++, fragmentsize);
|
||||
size += fragmentsize;
|
||||
pidx %= 2;
|
||||
if (playbackunderrun(phandle)>0)
|
||||
ok = 0;
|
||||
}
|
||||
if ((err = snd_pcm_playback_status(phandle, &pstatus)) < 0) {
|
||||
printf("Playback status error: %s\n", snd_strerror(err));
|
||||
exit(0);
|
||||
}
|
||||
snd_pcm_flush_record(rhandle);
|
||||
snd_pcm_flush_playback(phandle);
|
||||
if (ok && !playbackunderrun(phandle)>0) {
|
||||
printf("Playback OK!!!\n");
|
||||
printf("Playback time = %li.%i, Record time = %li.%i, diff = %li\n",
|
||||
pstatus.stime.tv_sec,
|
||||
pstatus.stime.tv_usec,
|
||||
rstatus.stime.tv_sec,
|
||||
rstatus.stime.tv_usec,
|
||||
timediff(pstatus.stime, rstatus.stime));
|
||||
break;
|
||||
}
|
||||
}
|
||||
snd_pcm_close(phandle);
|
||||
snd_pcm_close(rhandle);
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue