Sunday, October 16, 2011

more on alsa v4l2 saa

1.sox is a master application used to test many sound related functions
2.alsa 1.0.19/21/24 are latest needed for nvidia gt400 pro working
3.alsa has tools that list the properties of sound card
4.aplay can play mp3s or wav
5.alsa can be compiled from source
6.saa alsa usually comes with kernel with saa dvb,tuner,radio etc , it doesnt have a separate branch outside to compile with any needed kernel
7.tuners are designed for saa specification, all analog , digital tuners are complaint
8.saa71xx is for video and saa71xx-alsa for audio
9.these are interfaced to v4l2 and alsa in the system
10.v4l2-ctl can show details of all video devices in the system
11.pinnacle pctv 310i can do sound in 2 ways , through an internal wire it can give the sound to
real sound card IN hence the sound cards LINEIN can be used as capture device
or
it can expose a sound device interface
12.issue with saa incompatibility b.w in kernel saa alsa and external updated alsa
13.v4l2 sees video devices as /dev/video0
14.saa alsa? sees devices as /dev/dsp /dev/dsp1
15.latest alsa sees devices as hw:1,0 plughw:1,0 ??
16.like alsa oss and pulse audio are independent drivers , they can run sound without alsa
17.can work parallely on different devices, on one device only one can work
18.pulse and oss have a glue layer for alsa??
19.there are sound stack for each of them independently
20.digital video devices are /dev/adapter/dvb0
21.xbmc needs plugin to show bind with vdr
22.vdr needs components from private repo to be functional
23.video with hw accel and non hw accel has different drivers, according to what driver is loaded
for the device hw accel is exposed or disabled.
24.powerful card can expose sterio functionality if old drivers are loaded for it
25.video drivers have persistant switch entries in conf files only at restart they are looked up
26.there is always way to bring up vga
27.codec stack comes on top of saa,and other alsa drivers
28.similar to alsa nvidia and other hw will have latest in place compilable oss and pulseaudio
drivers provided by vendor
29.similarly for video v4l2 ES 1/2/3 compatible drivers updated
30.codecs eat on low level v4l2 and alsa drivers
31.v4l2 and alsa provides apis to apps
32.main apps like flash will use plugins that use these apis
33.xclient startx will use these apis for remote/local sessions
34.for a 5.1 system each channel is a sound device
35.linux has a master firmeare directory used to keep latest fw of all devices
36.vpdau is a v4l2 specification ie from v4l2 to vpdau driver, ES is specification from within vpdau to real hw
37.lirc is v4l2 of ir commn
38.fm radio other radio uses tuner devices and alsa
39.tuner will have /dev/vvv alsa with /dev/aaa
40.they can use v4l2-ctl for scanning and freq
41.so tuner device , sound device, video device basics of multimedia