V4L2 and ALSA: Kernel SPI or User API?

Posted by pnongrata on Super User See other posts from Super User or by pnongrata
Published on 2012-12-10T14:42:29Z Indexed on 2012/12/10 17:08 UTC
Read the original article Hit count: 254

Filed under:

linux

|

kernel

|

alsa

|

api

|

v4l2

I'm trying to understand what Video for linux and ALSA are (exactly), and I can't discern whether they're APIs for Linux application to use (the userspace) or if they are backend services that are only available to the Linux kernel (sort of a kernalspace SPI). Or, if they are something entirely different.

On one hand, those articles make it sound like its an API for applications to use. However, on the V4L2 page it has a section title Software supporting Video4Linux...

So is V4L2 a library that applications use, or is it a module that "snaps into" the kernel? I'm so coonfused, thanks in advance.

© Super User or respective owner

Related posts about linux

apt-get install and update fail

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I've got a problem with apt-get update and apt-get install ... commands . every time update or installing fails and errors are : Get:1 http://dl.google.com stable Release.gpg [198B] Ign http://dl.google.com/linux/chrome/deb/ stable/main Translation-en_US Get:2 http://dl… >>> More
kernel module compiling error

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
sh@ubuntu:/home/ccpp/helloworld$ make gcc-4.6 -O2 -DMODULE -D_KERNEL_ -W -Wall -Wstrict-prototypes -Wmissing-prototypes -isystem /lib/modules/`uname -r`/build/include -c -o hello-1.o hello-1.c hello-1.c:4:0: warning: "MODULE" redefined [enabled by default] <command-line>:0:0: note: this is… >>> More
Build-Essentials installation failing

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I am having trouble accessing the several critical header files that show to be a part of the build process. The "Ubuntu Software Center" shows "Build Essentials" as installed: Next I did the following two commands, which did not improve the problem: ~$ sudo apt-get install build-essential [sudo]… >>> More
Updating Debian kernel

as seen on Super User - Search for 'Super User'
I'm trying to update my Debian machine to 2.6.32-46 (which is the new stable). However, after doing apt-get update my apt-cache search linux-image shows me: linux-headers-2.6.32-5-486 - Header files for Linux 2.6.32-5-486 linux-headers-2.6.32-5-686-bigmem - Header files for Linux 2.6.32-5-686-bigmem linux-headers-2… >>> More
Serial connection over a single USB cable (Windows to linux, or linux to linux)

as seen on Server Fault - Search for 'Server Fault'
I'm helping out with a project for an embedded device that only has USB and no serial. This device is running Linux. These days, when we need to connect to a serial port on a device we typically use a USB to serial adapter (on something like a phone system or a load balancing device, etc). I would… >>> More

Related posts about kernel

Can't install kernel-uek-headers for currently running kernel

as seen on Server Fault - Search for 'Server Fault'
I have just created a VM in VMWare and installed a minimal install of Oracle Enterprise Linux 6.3. # cat /etc/oracle-release Oracle Linux Server release 6.3 It is running with the UEK kernel. # uname -r 2.6.39-200.24.1.el6uek.x86_64 When I try and install VMWare Tools, I get the following error… >>> More
Why does my laptop resume immediately after suspend?

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I seem to be having some problem with suspend mode. Every time I try to suspend my laptop, it just locks the screen. Or maybe it successfully suspends just to resume only an instant after. What could cause such a behaviour? I'm running 32-bit Ubuntu 12.04 with the 3.2.0-25 kernel on a HP dv5-1178er… >>> More
Fedora error log file

as seen on Server Fault - Search for 'Server Fault'
I am running a java application using this wrapper service yajsw. The problem it just stopped without any error in its logs file. So I was wondering will there be any system log file which will indicate the cause of it going down? Partial of the log file. Apr 6 00:12:20 localhost kernel: imklog… >>> More
External USB drive is failing

as seen on Super User - Search for 'Super User'
I have an external USB 2.0 drive WD My Book Mirror Edition, running in RAID 1 (mirroring) mode. A while ago the hard drive started to fail: it stops responding (directories are not listed returning an error after a big timeout). Sometimes it works for weeks before a failure, sometimes – few hours… >>> More
Problem with RAID5 (mdadm) - disk detached

as seen on Server Fault - Search for 'Server Fault'
Having these lines in /var/log/syslog Apr 18 16:53:05 Server kernel: [4487878.816036] ata4: EH in SWNCQ mode,QC:qc_active 0x1 sactive 0x1 Apr 18 16:53:05 Server kernel: [4487878.816058] ata4: SWNCQ:qc_active 0x1 defer_bits 0x0 last_issue_tag 0x0 Apr 18 16:53:05 Server kernel: [4487878… >>> More