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Diffstat (limited to 'tutorials/sndkit/samples/mixer_applet.c')
| -rw-r--r-- | tutorials/sndkit/samples/mixer_applet.c | 404 |
1 files changed, 404 insertions, 0 deletions
diff --git a/tutorials/sndkit/samples/mixer_applet.c b/tutorials/sndkit/samples/mixer_applet.c new file mode 100644 index 0000000..e443d13 --- /dev/null +++ b/tutorials/sndkit/samples/mixer_applet.c @@ -0,0 +1,404 @@ +/* + * Purpose: A sample program for developing a simple mixer applet. + * Copyright (C) 4Front Technologies, 2007. Released under GPLv2/CDDL. + * + * This program is not usefull by itself. It just demonstrates techniques that + * can be used when developing very simple mixer applets that control just + * the key volumes in the system. + * + * The full OSS 4.0 mixer API is rather complex and designed for allmighty + * master mixer applications. However there is a subset of the API that can be + * used rather easily. This subset is limited to control of the main output volume, + * audio/wave/pcm playback volume and/or recording input level. It cannot be + * used for anything else. + * + * This program demonstrates three main techniques to be used by mixer applets: + * + * 1) How to find the default mixer device that controls the primary + * sound card/device in the system. This device is connected to the + * primary (desktop) speakers and the default system sounds/beep are + * directed to it. Normally this device is the audio chip installed on + * the motherboard of the computer. + * + * 2) How to find out the main, pcm and recording volume controls for + * the given device. + * + * 3) How to read the current volume and how to change it. + * + */ + +#include <stdio.h> +#include <unistd.h> +#include <stdlib.h> +#include <fcntl.h> +#include <soundcard.h> +#include <time.h> +#include <errno.h> + +oss_sysinfo sysinfo; + +#define MAX_CTL 50 + +static int mixer_dev = -1; /* Use the default mixer */ + +int +find_default_mixer (int mixer_fd) +{ + int default_mix = -1; + int best_pri = -2; + + oss_mixerinfo mi; + + int i; + +/* + * The default mixer device in the system can be found by checking the + * priority parameter of all mixer devices in the system. The device with the + * highest priority value is the winner. If there are multiple devices with the + * same priority then the first one should be selected. + * + * Note that there should be some method for selecting the mixer device number. + * In many cases the user actually wants to use some other mixer than the + * motherboard one. + */ + + for (i = 0; i < sysinfo.nummixers; i++) + { + mi.dev = i; + + if (ioctl (mixer_fd, SNDCTL_MIXERINFO, &mi) == -1) + { + perror ("SNDCTL_MIXERINFO"); + continue; + } + + if (mi.priority < -1) /* Not suitable default mixer */ + continue; + + if (mi.priority > best_pri) + { + default_mix = i; + best_pri = mi.priority; + } + } + + printf("Mixer device %d seems to be the most probable motherboard device\n", + default_mix); + + return default_mix; +} + +void +show_controls (int mixer_fd, char *heading, int mixer_dev, int ctls[], int count) +{ + oss_mixext ext; + oss_mixer_value val; + int ctl, i; + + printf("\n***** %s *****\n", heading); + + for (i=0;i<count;i++) + { + ctl = ctls[i]; +/* + * Obtain the mixer extension definition. It might be a good idea to cache + * this info in global variables so that doesn't need to be reloaded + * every time. + * + * Reloading this info every time may cause serious troubles because in that + * way the application cannot be noticed after the mixer interface has changed. + */ + + ext.dev = mixer_dev; + ext.ctrl = ctl; + + if (ioctl (mixer_fd, SNDCTL_MIX_EXTINFO, &ext) == -1) + { + perror ("SNDCTL_MIX_EXTINFO"); + exit (-1); + } + +/* + * Have to initialize the dev, ctl and timestamp fields before reading the + * actual value. + */ + + val.dev = mixer_dev; + val.ctrl = ctl; + val.timestamp = ext.timestamp; + + if (ioctl (mixer_fd, SNDCTL_MIX_READ, &val) == -1) + { + if (errno == EIDRM) + { +/* + * Getting errno=EIDRM tells that the mixer struicture has been changed. This + * may happen for example if new firmware gets loaded to the device. In such + * case the application should start from the beginning and to load all + * the information again. + * + */ + fprintf (stderr, "Mixer structure changed. Please try again\n"); + exit (-1); + } + + perror ("SNDCTL_MIX_READ"); + exit (-1); + } + + printf ("\t%3d: %s\t ", ctl, ext.extname); + + switch (ext.type) + { + case MIXT_MONOSLIDER: + printf ("monoslider %d ", val.value & 0xff); + break; + + case MIXT_STEREOSLIDER: + printf ("stereoslider %d:%d ", val.value & 0xff, + (val.value >> 8) & 0xff); + break; + + case MIXT_SLIDER: + printf ("slider %d ", val.value); + break; + + case MIXT_MONOSLIDER16: + printf ("monoslider %d ", val.value & 0xffff); + break; + + case MIXT_STEREOSLIDER16: + printf ("stereoslider %d:%d ", val.value & 0xffff, + (val.value >> 16) & 0xffff); + break; + +/* + * Sometimes there may be just a MUTE control instead of a slider. However + * it's also possible that there is both mute and a slider. + */ + case MIXT_ONOFF: + printf ("ONOFF %d ", val.value); + break; + + case MIXT_MUTE: + printf ("mute %d ", val.value); + break; + +/* + * Enumerated controls may be used for example for recording source + * selection. + */ + case MIXT_ENUM: + printf ("Selection %d ", val.value); + break; + + + default: + printf ("Unknown control type (%d), value=0x%08x ", ext.type, + val.value); + } + + printf ("\n"); + } + +} + +int +main (int argc, char *argv[]) +{ + int mixer_fd = -1; + int i, n; + + /* + * Bins for the mixer controls. + */ +#define ADD_TO_BIN(bin, ctl) \ + if (n_##bin >= MAX_CTL) \ + { \ + fprintf(stderr, #bin " table is full\n"); exit(-1); \ + } \ + bin##_ctls[n_##bin++] = ctl + + int mainvol_ctls[MAX_CTL]; + int pcmvol_ctls[MAX_CTL]; + int recvol_ctls[MAX_CTL]; + int monvol_ctls[MAX_CTL]; + int n_mainvol=0, n_pcmvol=0, n_recvol=0, n_monvol=0; + char *devmixer; + + if ((devmixer=getenv("OSS_MIXERDEV"))==NULL) + devmixer = "/dev/mixer"; + +/* + * Get the mixer device number from command line. + */ + if (argc > 1) + mixer_dev = atoi (argv[1]); + +/* + * Open /dev/mixer. This device file can be used regardless of the actual + * mixer device number. + */ + + if ((mixer_fd = open (devmixer, O_RDWR, 0)) == -1) + { + perror (devmixer); + exit (-1); + } + +/* + * Get OSS system info to a global buffer. + */ + + if (ioctl (mixer_fd, SNDCTL_SYSINFO, &sysinfo) == -1) + { + perror ("SNDCTL_SYSINFO"); + exit (-1); + } + +/* + * Check the mixer device number. + */ + + if (mixer_dev == -1) + mixer_dev = find_default_mixer (mixer_fd); + + if (mixer_dev < 0 || mixer_dev >= sysinfo.nummixers) + { + fprintf (stderr, "Nonexistent mixer device %d\n", mixer_dev); + exit (-1); + } + + printf ("Using OSS mixer device %d\n", mixer_dev); + +/* + * The second step is to find the main volume, audio/pcm playback volume and + * recording level controls. + * + * It's important to understand that many mixer devices don't have such + * controls. This is perfectly normal and the mixer applet must be able to + * handle this. Aborting or displaying loud error message should be avoided. + * + * It's also possible that some mixers have multiple main volume, pcm or + * record level controls. In such case the application can support all of + * of them or select just the first one. Having multiple controls means that + * the device hase multiple sets of speakers or audio devices and each of + * them has separate volume controls. + */ + + n = mixer_dev; + if (ioctl (mixer_fd, SNDCTL_MIX_NREXT, &n) == -1) + { + perror ("SNDCTL_MIX_NREXT"); + exit (-1); + } + + for (i = 0; i < n; i++) + { + oss_mixext ext; + + ext.dev = mixer_dev; + ext.ctrl = i; + + if (ioctl (mixer_fd, SNDCTL_MIX_EXTINFO, &ext) == -1) + { + perror ("SNDCTL_MIX_EXTINFO"); + exit (-1); + } + +/* + * The MIXF_MAINVOL, MIXF_PCMVOL, MIXF_MONVOL and MIXF_RECVOL flags are used to mark + * potential main volume, pcm and recording level controls. This makes it + * possible to implement support for these common types of controls without + * having to implement fully featured mixer program. + * + * Mixer applets using this simplified interface should ignore all mixer + * controls that don't have any of these three flags. However + * + * Note that while mixer controls should have at most one of thse flags defined + * it may happen that some devices violate this rule. It's up to + * application what it does with such controls. Preferably it gets added + * to all of the bins. + */ + + if (ext. + flags & (MIXF_MAINVOL | MIXF_PCMVOL | MIXF_RECVOL | MIXF_MONVOL)) + { + printf ("Mixer control %d is ", i); + + if (ext.flags & MIXF_MAINVOL) + { + printf ("Mainvol "); + + ADD_TO_BIN(mainvol, i); + } + + if (ext.flags & MIXF_PCMVOL) + { + printf ("PCMvol "); + + ADD_TO_BIN(pcmvol, i); + } + + if (ext.flags & MIXF_RECVOL) + { + printf ("Recvol "); + + ADD_TO_BIN(recvol, i); + } + + if (ext.flags & MIXF_MONVOL) + { + printf ("Monvol "); + + ADD_TO_BIN(monvol, i); + } +/* + * It is possible that many/most/all mixer controls don't have any of the above + * flags set. This means that such controls are for expert use only. It is + * recommended that mixer applets have an [Advanced options] button that is + * enabled if such controls are found. This button can launch ossxmix (or + * some configurable program). + */ + + printf ("%s\n", ext.extname); + } + } + +/* + * Now we have selected the mixer controls. Next show their values. + * Since setting the value is pretty much identical to reading them we don't + * demonstrate it in this program. + */ + printf ("\n"); + + if (n_mainvol > 0) + show_controls (mixer_fd, "Main volume controls", mixer_dev, mainvol_ctls, n_mainvol); + else + printf ("No main volume control available\n"); + + if (n_pcmvol > 0) + show_controls (mixer_fd, "Pcm volume controls", mixer_dev, pcmvol_ctls, n_pcmvol); + else + printf ("No pcm volume control available\n"); + + if (n_recvol > 0) + show_controls (mixer_fd, "Rec volume controls", mixer_dev, recvol_ctls, n_recvol); + else + printf ("No rec volume control available\n"); + + if (n_monvol > 0) + show_controls (mixer_fd, "Monitor volume controls", mixer_dev, monvol_ctls, n_monvol); + else + printf ("No monitor volume control available\n"); + + close (mixer_fd); + + if (n_mainvol + n_pcmvol + n_recvol + n_monvol == 0) + { + printf("\nNo 'simple' mixer controls available for this device\n"); + printf("It may be a good idea to start 'ossxmix -d %d' which can access advanced options.\n", mixer_dev); + } + + exit (0); +} |