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Diffstat (limited to 'share/examples/sound/oss')
| -rw-r--r-- | share/examples/sound/oss/README | 66 | ||||
| -rw-r--r-- | share/examples/sound/oss/audio.c | 310 |
2 files changed, 0 insertions, 376 deletions
diff --git a/share/examples/sound/oss/README b/share/examples/sound/oss/README deleted file mode 100644 index 0188a26348c8..000000000000 --- a/share/examples/sound/oss/README +++ /dev/null @@ -1,66 +0,0 @@ -Briefly summarised, a general audio application will: -- open(2) -- ioctl(2) -- read(2) -- write(2) -- close(2) - -In this example, read/write will be called in a loop for a duration of -record/playback. Usually, /dev/dsp is the device you want to open, but it can -be any OSS compatible device, even user space one created with virtual_oss. For -configuring sample rate, bit depth and all other configuring of the device -ioctl is used. As devices can support multiple sample rates and formats, what -specific application should do in case there's an error issuing ioctl, as not -all errors are fatal, is upon the developer to decide. As a general guideline -Official OSS development howto should be used. FreeBSD OSS and virtual_oss are -different to a small degree. - -For more advanced OSS and real-time applications, developers need to handle -buffers more carefully. The size of the buffer in OSS is selected using fragment -size size_selector and the buffer size is 2^size_selector for values between 4 -and 16. The formula on the official site is: - -int frag = (max_fragments << 16) | (size_selector); -ioctl(fd, SNDCTL_DSP_SETFRAGMENT, &frag); - -The max_fragments determines in how many fragments the buffer will be, hence if -the size_selector is 4, the requested size is 2^4 = 16 and for the -max_fragments of 2, the total buffer size will be - -(2 ^ size_selector) * max_fragments - -or in this case 32 bytes. Please note that size of buffer is in bytes not -samples. For example, 24bit sample will be represented with 3 bytes. If you're -porting audio app from Linux, you should be aware that 24 bit samples are -represented with 4 bytes (usually int). - -FreeBSD kernel will round up max_fragments and size of fragment/buffer, so the -last thing any OSS code should do is get info about buffer with audio_buf_info -and SNDCTL_DSP_GETOSPACE. That also means that not all values of max_fragments -are permitted. - -From kernel perspective, there are few points OSS developers should be aware of: -- There is a software facing buffer (bs) and a hardware driver buffer (b) -- The sizes can be seen with cat /dev/sndstat as [b:_/_/_] [bs:_/_/_] (needed: - sysctl hw.snd.verbose=2) -- OSS ioctl only concern software buffer fragments, not hardware - -For USB the block size is according to hw.usb.uaudio.buffer_ms sysctl, meaning -2ms at 48kHz gives 0.002 * 48000 = 96 samples per block, all multiples of this -work well. Block size for virtual_oss, if used, should be set accordingly. - -OSS driver insists on reading / writing a certain number of samples at a time, -one fragment full of samples. It is bound to do so in a fixed time frame, to -avoid under- and overruns in communication with the hardware. - -The idea of a total buffer size that holds max_fragments fragments is to give -some slack and allow application to be about max_fragments - 1 fragments late. -Let's call this the jitter tolerance. The jitter tolerance may be much less if -there is a slight mismatch between the period and the samples per fragment. - -Jitter tolerance gets better if we can make either the period or the samples -per fragment considerably smaller than the other. In our case that means we -divide the total buffer size into smaller fragments, keeping overall latency at -the same level. - -Official OSS development howto: http://manuals.opensound.com/developer/DSP.html diff --git a/share/examples/sound/oss/audio.c b/share/examples/sound/oss/audio.c deleted file mode 100644 index 4dd3c8b82575..000000000000 --- a/share/examples/sound/oss/audio.c +++ /dev/null @@ -1,310 +0,0 @@ -/* - * SPDX-License-Identifier: BSD-2-Clause - * - * Copyright (c) 2021 Goran Mekić - * Copyright (c) 2024 The FreeBSD Foundation - * - * Portions of this software were developed by Christos Margiolis - * <christos@FreeBSD.org> under sponsorship from the FreeBSD Foundation. - * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions - * are met: - * 1. Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. - * 2. Redistributions in binary form must reproduce the above copyright - * notice, this list of conditions and the following disclaimer in the - * documentation and/or other materials provided with the distribution. - * - * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND - * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE - * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE - * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE - * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL - * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS - * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) - * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT - * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY - * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF - * SUCH DAMAGE. - */ - -#include <sys/soundcard.h> - -#include <err.h> -#include <errno.h> -#include <fcntl.h> -#include <stdio.h> -#include <stdlib.h> -#include <string.h> -#include <unistd.h> - -#ifndef SAMPLE_SIZE -#define SAMPLE_SIZE 16 -#endif - -/* Format can be unsigned, in which case replace S with U */ -#if SAMPLE_SIZE == 32 -typedef int32_t sample_t; -int format = AFMT_S32_NE; /* Signed 32bit native endian format */ -#elif SAMPLE_SIZE == 16 -typedef int16_t sample_t; -int format = AFMT_S16_NE; /* Signed 16bit native endian format */ -#elif SAMPLE_SIZE == 8 -typedef int8_t sample_t; -int format = AFMT_S8_NE; /* Signed 8bit native endian format */ -#else -#error Unsupported sample format! -typedef int32_t sample_t; -int format = AFMT_S32_NE; /* Not a real value, just silencing - * compiler errors */ -#endif - -/* - * Minimal configuration for OSS - * For real world applications, this structure will probably contain many - * more fields - */ -typedef struct config { - char *device; - int channels; - int fd; - int format; - int frag; - int sample_count; - int sample_rate; - int sample_size; - int chsamples; - int mmap; - oss_audioinfo audio_info; - audio_buf_info buffer_info; -} config_t; - -/* - * Error state is indicated by value=-1 in which case application exits with - * error - */ -static inline void -check_error(const int value, const char *message) -{ - if (value == -1) - err(1, "OSS error: %s\n", message); -} - - -/* Calculate frag by giving it minimal size of buffer */ -static inline int -size2frag(int x) -{ - int frag = 0; - - while ((1 << frag) < x) - ++frag; - - return (frag); -} - -/* - * Split input buffer into channels. Input buffer is in interleaved format - * which means if we have 2 channels (L and R), this is what the buffer of 8 - * samples would contain: L,R,L,R,L,R,L,R. The result are two channels - * containing: L,L,L,L and R,R,R,R. - */ -static void -oss_split(config_t *config, sample_t *input, sample_t *output) -{ - int channel, index, i; - - for (i = 0; i < config->sample_count; ++i) { - channel = i % config->channels; - index = i / config->channels; - output[channel * index] = input[i]; - } -} - -/* - * Convert channels into interleaved format and place it in output - * buffer - */ -static void -oss_merge(config_t *config, sample_t *input, sample_t *output) -{ - int channel, index; - - for (channel = 0; channel < config->channels; ++channel) { - for (index = 0; index < config->chsamples; ++index) { - output[index * config->channels + channel] = - input[channel * index]; - } - } -} - -static void -oss_init(config_t *config) -{ - int error, tmp, min_frag; - - /* Open the device for read and write */ - config->fd = open(config->device, O_RDWR); - check_error(config->fd, "open"); - - /* Get device information */ - config->audio_info.dev = -1; - error = ioctl(config->fd, SNDCTL_ENGINEINFO, &(config->audio_info)); - check_error(error, "SNDCTL_ENGINEINFO"); - printf("min_channels: %d\n", config->audio_info.min_channels); - printf("max_channels: %d\n", config->audio_info.max_channels); - printf("latency: %d\n", config->audio_info.latency); - printf("handle: %s\n", config->audio_info.handle); - if (config->audio_info.min_rate > config->sample_rate || - config->sample_rate > config->audio_info.max_rate) { - errx(1, "%s doesn't support chosen samplerate of %dHz!\n", - config->device, config->sample_rate); - } - if (config->channels < 1) - config->channels = config->audio_info.max_channels; - - /* - * If device is going to be used in mmap mode, disable all format - * conversions. Official OSS documentation states error code should not - * be checked. - * http://manuals.opensound.com/developer/mmap_test.c.html#LOC10 - */ - if (config->mmap) { - tmp = 0; - ioctl(config->fd, SNDCTL_DSP_COOKEDMODE, &tmp); - } - - /* - * Set number of channels. If number of channels is chosen to the value - * near the one wanted, save it in config - */ - tmp = config->channels; - error = ioctl(config->fd, SNDCTL_DSP_CHANNELS, &tmp); - check_error(error, "SNDCTL_DSP_CHANNELS"); - /* Or check if tmp is close enough? */ - if (tmp != config->channels) { - errx(1, "%s doesn't support chosen channel count of %d set " - "to %d!\n", config->device, config->channels, tmp); - } - config->channels = tmp; - - /* Set format, or bit size: 8, 16, 24 or 32 bit sample */ - tmp = config->format; - error = ioctl(config->fd, SNDCTL_DSP_SETFMT, &tmp); - check_error(error, "SNDCTL_DSP_SETFMT"); - if (tmp != config->format) { - errx(1, "%s doesn't support chosen sample format!\n", - config->device); - } - - /* Most common values for samplerate (in kHz): 44.1, 48, 88.2, 96 */ - tmp = config->sample_rate; - error = ioctl(config->fd, SNDCTL_DSP_SPEED, &tmp); - check_error(error, "SNDCTL_DSP_SPEED"); - - /* Get and check device capabilities */ - error = ioctl(config->fd, SNDCTL_DSP_GETCAPS, &(config->audio_info.caps)); - check_error(error, "SNDCTL_DSP_GETCAPS"); - if (!(config->audio_info.caps & PCM_CAP_DUPLEX)) - errx(1, "Device doesn't support full duplex!\n"); - - if (config->mmap) { - if (!(config->audio_info.caps & PCM_CAP_TRIGGER)) - errx(1, "Device doesn't support triggering!\n"); - if (!(config->audio_info.caps & PCM_CAP_MMAP)) - errx(1, "Device doesn't support mmap mode!\n"); - } - - /* - * If desired frag is smaller than minimum, based on number of channels - * and format (size in bits: 8, 16, 24, 32), set that as frag. Buffer - * size is 2^frag, but the real size of the buffer will be read when - * the configuration of the device is successful - */ - min_frag = size2frag(config->sample_size * config->channels); - - if (config->frag < min_frag) - config->frag = min_frag; - - /* - * Allocate buffer in fragments. Total buffer will be split in number - * of fragments (2 by default) - */ - if (config->buffer_info.fragments < 0) - config->buffer_info.fragments = 2; - tmp = ((config->buffer_info.fragments) << 16) | config->frag; - error = ioctl(config->fd, SNDCTL_DSP_SETFRAGMENT, &tmp); - check_error(error, "SNDCTL_DSP_SETFRAGMENT"); - - /* When all is set and ready to go, get the size of buffer */ - error = ioctl(config->fd, SNDCTL_DSP_GETOSPACE, &(config->buffer_info)); - check_error(error, "SNDCTL_DSP_GETOSPACE"); - if (config->buffer_info.bytes < 1) { - errx(1, "OSS buffer error: buffer size can not be %d\n", - config->buffer_info.bytes); - } - config->sample_count = config->buffer_info.bytes / config->sample_size; - config->chsamples = config->sample_count / config->channels; -} - -int -main(int argc, char *argv[]) -{ - int ret, bytes; - int8_t *ibuf, *obuf; - config_t config = { - .device = "/dev/dsp", - .channels = -1, - .format = format, - .frag = -1, - .sample_rate = 48000, - .sample_size = sizeof(sample_t), - .buffer_info.fragments = -1, - .mmap = 0, - }; - - /* Initialize device */ - oss_init(&config); - - /* - * Allocate input and output buffers so that their size match frag_size - */ - bytes = config.buffer_info.bytes; - ibuf = malloc(bytes); - obuf = malloc(bytes); - sample_t *channels = malloc(bytes); - - printf("bytes: %d, fragments: %d, fragsize: %d, fragstotal: %d, " - "samples: %d\n", - bytes, config.buffer_info.fragments, - config.buffer_info.fragsize, config.buffer_info.fragstotal, - config.sample_count); - - /* Minimal engine: read input and copy it to the output */ - for (;;) { - ret = read(config.fd, ibuf, bytes); - if (ret < bytes) { - fprintf(stderr, "Requested %d bytes, but read %d!\n", - bytes, ret); - break; - } - oss_split(&config, (sample_t *)ibuf, channels); - /* All processing will happen here */ - oss_merge(&config, channels, (sample_t *)obuf); - ret = write(config.fd, obuf, bytes); - if (ret < bytes) { - fprintf(stderr, "Requested %d bytes, but wrote %d!\n", - bytes, ret); - break; - } - } - - /* Cleanup */ - free(channels); - free(obuf); - free(ibuf); - close(config.fd); - - return (0); -} |