Alsa playback example. wav # Playback through 3. This...
Alsa playback example. wav # Playback through 3. This article is to tell how to configure alsa-lib by configuration file. The focus is on programming the PCM interfaces of ALSA, including programming examples with which you can experiment. The configuration takes place in /etc/asound. The ALSA Audio Playback block sends audio data to the audio output devices, such as speakers or headphones, connected to the hardware. The reason no sound is played when it finishes reading early is because we return as well after finish reading, which destroys everything. , it has to finish playback first, then start to record, which records nothing meaningful but just clicks. There are quite a few options for dealing with audio Mar 14, 2025 · ALSA : A Complete Guide (Advanced Linux Sound Architecture 2026) covers ALSA basics, architecture, drivers, mixer, playback, recording & embedded Linux audio. Contribute to tdebrouw/alsa-examples development by creating an account on GitHub. Both utilities are implemented in the same source file and share much of their codebase, differing primarily in their operational direction (playback vs. * This small demo sends a simple sinusoidal wave to your speakers. Check out the accompanying blog post for a more in-depth explanation. Programming ⇝ Tutorial: ALSA Tutorial 1 - Initialization This tutorial assumes that you are familiar with the C++ programming language and the Linux operating system. Using the ALSA JACK PCM plugin The simpler approach has its drawbacks: if an application stops playing audio, it will disappear from the JACK world, which can be quite inconvenient. wav By default this captures audio in 8-bit, 8KHz M2496 coming from the CARD=M2496 associated to my preferred hardware device for sound playback (you should adapt according to your output of aplay -L) nonblock true because you don't want Alsa to lock the character special file (/dev/snd/pcmwhatever) associated to the device driver of your sound card. capture) and some default behaviors. The buffer size for each data URB is maxpacksize * packets, which in this example is 40 * 6 = 240; When the user performs a write operation to send audio data into the ALSA PCM playback stream, the calculated number of frames is packsize [0] * packets = 264, which exceeds the allocated URB buffer size, triggering the out-of-bounds (OOB) issue is there an example of a full-duplex ALSA connection in C? I've read that it is supported, but all the introductory examples I saw did either record or play a sound sample, but I'd like to have one handler that can do both for my VoIP-app. 04. Note Most things discussed here are much easier to accomplish using ALSA plugins like upmix which are explained in the main article. ogg -f alsa hw:2,1,0 Instruction On Linux OS, we have two major audio system API to play/record audio pcm, alsa-lib and pulseaudio. Topic I would like to make the minimal working code to generate any kind of PCM sound using ALSA in C++ for a Linux computer. None of the following configurations are guaranteed to work. playback_pcm "bluealsa" in the ~/. I start with aplay. Jan 29, 2026 · Download ZIP Simple sound playback using ALSA API and libasound Raw sound_playback. Pulseaudio is in Freescale Ubuntu root fs release, while alsa-lib is used by default in LTIB release. With this method data is written to an ALSA output buffer and ALSA is instructed to send an asynchronous notification to the application when it is ready for more data. On some platforms, this can lead to the last audio samples in the stream being lost and not played out. c The ALSA Audio Playback block sends audio data to the audio output devices, such as speakers or headphones, connected to the hardware. The ALSA API is rather big, so everything is not covered yet, but expect the following to work: Audio Playback (example in pcm module docs) Audio Recording Mixer controls HCtl API (jack detection example in hctl module docs) Raw midi Midi sequencer (most Using an ALSA Loopback device and JACK alsa_in/alsa_out clients This more complex but probably more robust approach is well-documented in this document. In addition, I cannot use sound in more than one application concurrently, I get errors like "sound device in use", etc. An introduction to sound playback programming using ALSA. This article is just to demonstrate basic playback using the memory-mapped (mmap) functionality. It represents about the simplest possible use of the ALSA Audio API, and isn't meant to be a real program. wav into hw:2,0,4: $ aplay -D hw:2,0,4 audio. wav * generic alsa samples. To complete the list, we should note that snd_pcm_wait () function contains embedded poll waiting implementation. h. Examples Record audio from your microphone When doing screencast recordings, you usually want to record your voice too: ffmpeg -f alsa -channels 1 -sample_rate 44100 -i hw:0 -t 30 out. e. Some possible workarounds: Add silence padding to the end of the tone Pulse Audio (linux command pavucontrol) is definitely one of the best ways to handle sound settings under linux. c /* * Simple sound playback using ALSA API and libasound. This is usually most noticeable when playing short tones using the tone player. The Advanced Linux Sound Architecture (ALSA) is the standard audio API of Linux as of kernel version 2. Writing a Linux ALSA device driver from scratch. It is responsible for May 7, 2023 · Lately I’ve been tinkering with DSP and playing audio using ALSA. I'd like to load several wav files and play them depending on some test conditions. aplay is a small command-line player built for ALSA (Advanced Linux Sound Architecture). PDF | This paper discusses the collaboration between the ALSA userspace library and ALSA kernel drivers to facilitate basic audio playback. External speaker in 3. I'm using alsa lib in c under linux. * * Compile: * $ cc -o play sound_playback. Architectur In this example I'm reading samples from file, to focus on the playback part. If you do not need very fast audios, use the code above with lib SFML, as it is very easy and quick to implement, otherwise use the SDL and you will be successful. If you're using GCC, then you can link with the ALSA library with -lasound. You may want to explore ALSA simply because it is new, but it is not the only sound API available. For example, the following works fine: # Capture from Webcam arecord test. And in parallel (from another shell) play an audio from audio. Please suggest me some tutorial for mixer settings as well as alsa programming . The following should serve as a guide for more advanced ALSA setups. The ALSA Audio Playback block sends audio data to the audio output devices, such as speakers or headphones, connected to the NVIDIA hardware. Background I You write those samples to the PCM device with snd_pcm_writei, for example. The definitions of the ALSA library are located in alsa/asoundlib. wav In the example above the ALSA code was simply part of another application, which could still function if ALSA for some reason broke during execution. In this article we will show you two ways to adjust the volume of that playback from the command line by using the Alsamixer and Amixer utilities. /play <sample_rate> <channels> <seconds> < <file> * * Examples: * $ . This is why I set pcm_handle to NULL, it is used throughout the application to indicate if ALSA is initialized. Here is the playback code I'm using: alsaloop (1) - Linux man page Name alsaloop - command-line PCM loopback Synopsis alsaloop [-option] [cmd] Description alsaloop allows create a PCM loopback between a PCM capture device and a PCM playback device. GitHub Gist: instantly share code, notes, and snippets. Whereas what we really want is just to break out of the for loop and stop reading and writing. /play 22050 1 8 < /path/to/file. wav This Howto describes setting up ALSA for playback of sound using the "asynchronous callback" method. A repo containing some recent generic ALSA examples. In this post, we will explore how the PCM Interface can be used for sound playback. 04, PulseAudio present, default device): In ALSA land a single audio device is identified by a device name that has the pattern 'hw:x,y,z' where 'x' is the card number, 'y' is the device number, and 'z' is the subdevice number. c -lasound * * Usage: * $ . To achieve this, all I had to do was to specify the format of the output "file" as alsa and set output to hw:[snd-aloop-card],1,0 Example: ffmpeg -i myfile. I'm using the following code, but it needs to be improved: // A simple C Other web sources include a LINUX Journal article about basic ALSA programming, which includes example programs, tutorials on the ALSA project web site, which also include code fragments, and one of the developers' home page, even though it is a bit old. Nov 19, 2021 · The Advanced Linux Sound Architecture (ALSA) project is used to implement sound card drivers in Linux. Master Playback switch), enum in mixer elements and what value should i set to those switchs . There’s a whole load of information Contents Playback: A generic simple playback of a WAV file Capture: Just capture the Microphone Utils: List-devices: Use ALSA to display the current PCM devices available Update-volume: Connect to the Master mixer and sweep the volume between 0 and 50% A repo containing some recent generic ALSA examples. wav Looking at our example device listing, this would be the same as this: ffmpeg -f alsa -channels 1 -sample_rate 44100 -i default:CARD=ICH5 -t 30 out. - OpenPixelSystems/c-alsa-examples In this article, I present a brief overview of the ALSA Project and its software components. Note that providing the sample format, channel count, frame rate in recording ensures that playback picks up the same settings – this is because there is no real hardware underneath it is just a virtual loopback connection. Audio Playback (example in pcm module docs) Audio Recording Mixer controls HCtl API (jack detection example in hctl module docs) Raw midi Midi sequencer (most of it) Ctl API Device name hints (example in device_name module docs) Enumerations of all of the above Poll and/or wait for all of the above ALSA project - the C library reference Main Page Related Pages Topics Data Structures Files Examples ALSA appears to be using the first one by default. The second method, uses the direct audio buffer to communicate with the device while ALSA library manages this space itself. It’s boring in the best way: it talks directly to ALSA devices, it’s scriptable, and it tells you quickly whether the kernel/ALSA layer can actually push samples to hardware (or to a virtual device). So far it has just been some basic tone generation to test the playback code so that I can reuse it for further projects. However, the ALSA library provides the interface through which applications can reach those functions, helping form a more homogeneous environment at the user level. The audio thread is pretty naive with it's behaviour, but there's so little useful information on ALSA, all of the playback examples only really show a naive playback example. Not all music players would use these low-level interactions. ALSA's user-space library provides programmers, and hence their programs, with easy access to ALSA's services, and its significance to the normal user may seem a rather slight matter. The block outputs data as a 3-by-2 matrix. Once in a while it might however be good to use the alsa sound commands directly since they offer some extra settings dependent on the sound cards capabilities. Playing a Sound with ALSA An introduction to sound playback programming using ALSA. c The Advanced Linux Sound Architecture (ALSA) provides Linux computers with audio support. Also, mixer controls can be It aims to offer capture and playback for both audio and video with minimal latency and support for PulseAudio, JACK, ALSA and GStreamer -based applications. This readme only covers some basics of ALSA. /play 22050 1 8 < /path/to The use of the ALSA lib is quite complicated because the level is very low. Contribute to jollen/linux-alsa-sample development by creating an account on GitHub. alsaloop allows create a PCM loopback between a PCM capture device and a PCM playback device. The author of PulseAudio, Lennart Poettering, alsa recommended a safe ALSA subset API to do basic PCM audio playback/capturing. You can find examples of all communication schemes for playback in Sine-wave generator example . asoundrc. Download ZIP Simple sound playback using ALSA API and libasound Raw sound_playback. This is my output device configuration, opened in blocking mode (Ubuntu 16. conf or $(HOME)/. 5mm jack. I am guessing that ALSA is not in a duplex mode, i. - OpenPixelSystems/c-alsa-examples Thin but safe wrappers for ALSA, the most common API for accessing audio devices on Linux. Overview aplay and arecord are core command-line utilities in the ALSA (Advanced Linux Sound Architecture) suite for playback and recording of audio data. Simple sound playback using ALSA API and libasound - sound_playback. Example use case: You want to be able to record your desktop but also whatever audio is playing. For this, alsa-lib, the userspace API interface to the ALSA drivers, provides PCM plugins. aec. Then its delivers a chunk of random data to it, and exits. alsaloop supports multiple soundcards, adaptive clock synchronization, adaptive rate resampling using the samplerate library (if available in the system). Those plugins are configured through configuration files that are usually known to be /etc/asound. The ALSA project also maintains various user-space tools and utilities that are installed by default in most Linux distributions. 6. aplay is a command-line audio player for ALSA (Advanced Linux Sound Architecture) sound card drivers. But with this config you just point whatever recording software to the loop record device. The daemon based on the framework can be configured to be both an audio server (with PulseAudio and JACK features) and a video capture server. Apart from the Kernel API, ALSA also provides a library API exposing the same functionality as the Kernel API but with a simpler and more usable interface. /play 44100 2 5 < /dev/urandom * $ . For more details, see for example the ALSA Documentation and A close look at ALSA Hardware devices In the ALSA scheme, a Simple sound playback using ALSA API and libasound Raw sound_playback. Usually, you would either need to use PulseAudio or ALSA+JACK. The playback module drops any samples still in the ALSA pipeline when closing the channel. 5mm audio jack which is used for playback So far I've managed to configure ALSA to, by default, capture via the USB Webcam and playback via the 3. So let’s start to use ALSA to record & play audio. aplay - command-line sound recorder and player for ALSA soundcard driver | linux commands examples - Thousands of examples to help you to the Force of the Command Line. Setup I'm coding in C++ on Code::Blocks with Ubuntu 20. For example, if you want to play on your bluetooth speaker via the bluealsa device (see the bluez-alsa project), you can play audio to the device aec:bluealsa, or you can set defaults. $ aplay -L null Discard all samples (playback) or generate zero samples (capture)pulse Playback/recording through the PulseAudio sound serversysdefault:CARD=ALSA bcm2835 ALSA, bcm2835 ALSA Default Audio Device Algorithm Consider a Simulink ® model that includes an ALSA Audio Capture block and an ALSA Audio Playback block. 1kHz, interleaved conventional read/write access. It supports several file formats and multiple soundcards with multiple devices. Can anyone provide me with some insight on the ALSA architecture, the tools I need to use in order to probe the system and advice on how to structure the configuration file. /play 22050 1 8 < /path/to A Minimal Playback Program This program opens an audio interface for playback, configures it for stereo, 16 bit, 44. ALSA C++ wrappers for working with playback and capture devices on linux. I want to know what is the purpose of switch (ex. conf as mentioned in the main article. At each sample time, the ALSA Audio Capture reads stereo audio data from the microphone connected to the audio input connector of the hardware. ALSA (Linux) Introduction ALSA is the low level audio API that is used in the Linux kernel. . 5mm jack aplay test. As a primarily embedded/firmware developer this is more my territory. What is ALSA (Advanced Linux Sound Architecture) ALSA : Advanced Linux Sound Architecture is a sound system framework and part of the Linux kernel that provides audio and MIDI functionality to Linux-based systems. Discover every day ! The most common use case would be separating a 4 or 8-channel sound card in multiple stereo PCM devices. pcm. The speaker still plays out the sound correctly. I made this because I have wasted so many hours in trying to figure out how things work. 00iio9, 9ke8, oghf, wx7d, hq9oih, 7ifa, mmbh, kh1z, 8aexuy, npu9f,