Mercurial > hg > audiostuff
comparison intercom/oss.cpp @ 2:13be24d74cd2
import intercom-0.4.1
| author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
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| date | Fri, 25 Jun 2010 09:57:52 +0200 |
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| 1:9cadc470e3da | 2:13be24d74cd2 |
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| 1 /* oss.cpp | |
| 2 * | |
| 3 * Copyright (C) DFS Deutsche Flugsicherung (2004, 2005). | |
| 4 * All Rights Reserved. | |
| 5 * | |
| 6 * Open Sound System functions | |
| 7 * | |
| 8 * Version 0.3 | |
| 9 */ | |
| 10 | |
| 11 #include <stdio.h> | |
| 12 #include <stdlib.h> | |
| 13 #include <string.h> | |
| 14 #include <math.h> | |
| 15 | |
| 16 /* Error handling */ | |
| 17 #include <assert.h> | |
| 18 #include <errno.h> | |
| 19 extern int errno; | |
| 20 | |
| 21 /* low level io */ | |
| 22 #include <sys/types.h> | |
| 23 #include <sys/stat.h> | |
| 24 #include <fcntl.h> | |
| 25 #include <sys/ioctl.h> | |
| 26 | |
| 27 /* OSS, see www.4front-tech.com/pguide/index.html */ | |
| 28 #include <sys/soundcard.h> | |
| 29 | |
| 30 #include "oss.h" | |
| 31 #include "intercomd.h" | |
| 32 | |
| 33 int audio_init(char *pathname, int channels_, int mode) | |
| 34 { | |
| 35 /* Using OSS is simple in theory. The application just: | |
| 36 * Opens the device. | |
| 37 * Optional turns on full duplex | |
| 38 * Sets fragment size if necessary | |
| 39 * Sets number of channels, sample format and sampling rate | |
| 40 * Starts reading and/or writing the device | |
| 41 * | |
| 42 * Linux ALSA dmix note: To allow dmix simultaneous playback of | |
| 43 * different PCM-out, do not open OSS in full duplex mode. Open two file | |
| 44 * descriptors instead. | |
| 45 */ | |
| 46 // fprintf(stderr, "OSS Header SOUND_VERSION = %x\n", SOUND_VERSION); | |
| 47 | |
| 48 int audio_fd = open(pathname, mode); | |
| 49 return_if(audio_fd < 0, -1); | |
| 50 | |
| 51 fprintf(stderr, "audio_init() mode = %d\n", mode); | |
| 52 | |
| 53 int sound_version = 0; | |
| 54 ioctl(audio_fd, OSS_GETVERSION, &sound_version); | |
| 55 // fprintf(stderr, "OSS Driver SOUND_VERSION = %x\n", SOUND_VERSION); | |
| 56 | |
| 57 ioctl(audio_fd, SNDCTL_DSP_SETDUPLEX, 0); | |
| 58 | |
| 59 /* The 16 most significant bits (MMMM) determine maximum number of | |
| 60 * fragments. By default the driver computes this based on available | |
| 61 * buffer space. | |
| 62 * The minimum value is 2 and the maximum depends on the situation. | |
| 63 * Set MMMM=0x7fff if you don't want to limit the number of fragments | |
| 64 */ | |
| 65 int frag = AUDIOBUFS << 16 | FRAGSIZELD; | |
| 66 if (2 == channels_) { | |
| 67 ++frag; // double FRAGSIZE in stereo mode | |
| 68 } | |
| 69 int frag_ = frag; | |
| 70 ioctl(audio_fd, SNDCTL_DSP_SETFRAGMENT, &frag); | |
| 71 // fprintf(stderr, "SETFRAGMENT=0x%x\n", frag); | |
| 72 assert_errno(frag_ == frag); | |
| 73 | |
| 74 int format = FORMAT_OSS; | |
| 75 ioctl(audio_fd, SNDCTL_DSP_SETFMT, &format); | |
| 76 assert_errno(format == FORMAT_OSS); | |
| 77 | |
| 78 int channels = channels_; | |
| 79 ioctl(audio_fd, SNDCTL_DSP_CHANNELS, &channels); | |
| 80 assert_errno(channels_ == channels); | |
| 81 // fprintf(stderr, "SNDCTL_DSP_CHANNELS=%d\n", channels); | |
| 82 | |
| 83 int rate = RATE; | |
| 84 ioctl(audio_fd, SNDCTL_DSP_SPEED, &rate); | |
| 85 assert_errno(RATE == rate); | |
| 86 // fprintf(stderr, "mode=%d SNDCTL_DSP_SPEED=%d\n", mode, rate); | |
| 87 | |
| 88 fprintf(stderr, "\n"); | |
| 89 return audio_fd; | |
| 90 } |