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Snd_pcm_lib_read_transfer copy data to the user's buffer. The control interface primarily allows user-space Applications (ALSA-LIB) to access and manage the multi-channel switches, sliding controls, etc. in the audio codec chip. The control interface is particularly important for mixer (remix), starting with the Alsa 0.9.x version, where all mixer work is done through the API of the control interface. Def

Development Environment: ubuntu12.04 Development Board: ok6410, linux3.0 Alsamixer is one of the Alsa tools for Linux audio architecture. It is used to configure various audio parameters. Alsamixer is based on the graphic interface under the text. You can easily set the desired volume and switch a switch by using the upper and lower keys on the keyboard, left and right keys, and so on, on the ubuntu12.04 system configuration interface, the operation i

,Id.index);err =-ebusy;Goto error;} if (Snd_ctl_find_hole (Card, Kcontrol->count) 0) {Up_write (card->controls_rwsem);err =-enomem;Goto error;} list_add_tail (kcontrol->list, Card->controls);Card->controls_count + = kcontrol->count;Kcontrol->id.numid = Card->last_numid + 1;PRINTK (kern_err "%s Kcontrol numid=%d name=%s is already present\n",__FUNC__,Kcontrol->id.numid,Kcontrol->id.name);Card->last_numid + = kcontrol->count;Up_write (card->controls_rwsem);for (idx = 0; idx Snd_ctl_notify (Card, S

What is Bluetooth-alsa?The BLUETOOTH-ALSA project aims to make Bluetooth headsets of all types work the AS-is with Linux computers, from a standard de Sktop to a limited embedded device. ALSA drivers and daemons for using Bluetooth audio DevicesHow are Bluetooth-alsa now?Posted by: BmidgleyDate: 2007-10-07 07:47Summary

After one upgrade in Centos7, a lot of software was found unable to play sound. To solve the problem, in the terminal to open Firefox, play the Sound of the Web page, there are prompts: ALSA Lib pcm_dmix.c:1022: (Snd_pcm_dmix_open) Unable to open slaveFeeling is PulseAudio problem, reinstall PulseAudio, the problem remains. With Rpm-qa | grep alsa Check, found only these three packages:

ALSA Programming HOWTO According to ALSA write a simple PCM application, we first need to open a handle for the PCM device (Handle), and then specify the direction of the PCM stream is played or captured (playback or capture), we can also configure some of the parameters we want, for example, Buffer size, sample rate, PCM data format, and so on. So we have a broad framework, simple and efficient, as follow

ALSA is the abbreviation for Advanced Linux Sound architecture, the Advanced Linux Sound architecture, which provides audio and MIDI on Linux operating systems (musical instrument Digital, Music Device Digital Interface) support For more information, refer to this article:http://mysuperbaby.iteye.com/blog/932729 Here are two simple examples to achieve playback, recording functions, respectively /********************************************************

(config_snd_mixer_oss_module) 45. struct snd_mixer_oss * mixer_oss; 46. int mixer_oss_change_count; 47. # endif 48 .};Creates sound card functional components (logical devices), such as PCM, mixer, and Midi.The creation of each component will eventually call snd_device_new () to generate an snd_device instance and link the instance to the snd_card devices linked list.Generally, the Alsa-driver has provided some common component creation functions, in

Using the ALSA, in this process involves some hardware settings and testing, need to understand the ALSA configuration file, a little summary. For alsa files, there are three packages to focus on: Alsa-lib,alsa-utils,libaudio. In alsa.conf, both/etc/asound.conf and ~/.ASOUND

Statement: the content of this blog is composedHttp://blog.csdn.net/droidphoneOriginal, reprinted please indicate the source, thank you! 1. struct snd_card 1.1. What is snd_card? Snd_card is a top-level structure of the entire ALSA audio driver. The software logical structure of the Sound Card begins with this structure. Almost all audio-related logical devices are under the management of snd_card, the first action of the sound card driver is to cr

The first and most important is: I talked big, this article is a train of thought just, if you are music playing small white also want to understand the principle can look down, otherwise, return-1; The existing music format is very different, so there is a ffmpeg saying that this framework is really good, audio and video transcoding are not alone, I am a dead brain, met do not understand the always want to understand, for music playback feeling is confused, after a few days of research after th

snd_soc_register_dais in the probe callback of the corresponding platform_driver; Implement probe, suspend, and other callbacks in the snd_soc_dai_driver structure; Implement the callback function in the snd_soc_dai_driver field in the snd_soc_dai_ops structure; Snd_soc_register_daiThis function has been introduced in the previous article about the codec driver. For details, refer to: Linux ALSA sound card driver 7: Codec in the ASOC architecture.

The link list structure in ALSA In the ALSA design to many of the linked list structure, understanding these lists can better understand ALSA A) card->devices The establishment of Card->devices linked list facilitates the registration process and equipment management of card related equipment. Through this linked list, in the process of registering the equipment,

alsa:advanced Linux Sound architecture, which includes kernel-driven collections, API libraries, and tools. The user-layer program invokes the Libsound API library directly, without the need to open the device and so on, so programmers do not need to know the underlying details. The core code of ALSA is not analyzed here, and how to program the sound card at the user layer is simply introduced to add a sound card driver on the

Mini-series recently developed embedded Linux playerThere's a lot of sweat in the first few moments.Q1:alsa control volume requires amixer. But Amixer can only control the system volumeHow do I control only the software volume?Google said it can use the Softvol plugin, but the small part to pass the program control volume.Q2: Player requires foreground music volume is larger, background music volume is smaller.Do you want to do this technology or refe

Just contact Alsa, I learned no one's words really very laborious. A lot of information on the internet did not have this explanation, finally see the official plug-in configuration document according to the personal understanding of the written experience:(1) First look at the route plugin description:This plugin can convert channels and change the volume. The configuration instructions are as follows:Pcm.name {Type route # route Volume Conversion P

Http://mypyg.iteye.com/blog/845954 In the past two daysProgramChange from the OSS interface to the Alsa interface. After the audio output is modified according to the Alsa example, the sound generated during playback is intermittent and there is a great noise. In the beginning, we thought that there was no correct format, but it still didn't work if we set all the formats again. It's okay to convert the so

The ALSA architecture is now a standard audio architecture for Linux and has many advantages over the past OSS.ALSA provides a large number of tools and a complete library of links that can be cross-compiled on Ubuntu CentOS.I am the 22 version of Alsa compiled on Ubuntu latest version 14.Http://www.alsa-project.org/main/index.php/Download contains some historical versions of the

This design idea: first open a normal WAV audio file, from the 44 bytes in front of the defined file header, remove the file header definition message, placed in a file header structure. Then open the ALSA audio driver, from the file header structure to remove the sampling accuracy, the number of channels, sampling frequency three important parameters, using the ALSA audio-driven API set parameters, finally

, Dai_list, platform_list, all codec, Dai, and platform in the system are connected to these three global lists when registering. The Soc_bind_dai_link function scans each of these three lists, matching them according to the names in card->dai_link[], and assigns the corresponding Codec,dai and platform instances to card->rtd[after the match (Snd_ Soc_pcm_runtime). After this process, Snd_soc_pcm_runtime: (CARD->RTD) saves the Codec,dai and platform-driven information used in this machine. Snd_s