The Grok

About eight years back, everybody was talking about the convergence of technology. Computers had newly gained the status of being called "multimedia" machines. One could watch full motion high resolution videos in tiny 320x200 windows played from a MASSIVE 650mb cdrom disc and listen to exciting FM music from tinny 8 bit cards. And then someone realized that every device on earth should be integrated into the computer. One can now find integrated 3d video cards, audio cards, mpeg decoders, internal modems, web cams, pluggable microwave (huh?), and most importantly TV Tuner Cards.

TV Tuner cards have existed for quite some time. Today one can pickup a TV tuner card for less than $50 or even find it integrated with the 3D/2D video card. Before you throw your TV set off the terrace, it would be worth contemplating the fact that most TV Tuner cards can hardly match the quality of any decent TV set. Unlike TV sets which run on an analog system and do not rely on image precision, computer CRTs have to display images with detail. In most cases due to the low resolution of broadcasts, the computer CRT cannot sharpely display the image. Computer CRTs display colors relatively less sharply and vibrantly compared to TV sets.

A TV Tuner card has three important components. The tuner chip is used to "listen" to a specific broadcast frequency. Most cards have major problems while tuning with weak signals, especially when an antennae is the input source. A video decoder chip processes the incoming signal and processes the broadcast format (PAL/NTSC/SECAM) and pushes it to an overlay area of the main video card. The overlay area is a part of the video memory which is directly written onto by the TV tuner to display the TV channel. Finally a sound decoder chip processes the audio signals and can additionally decode stereo/dolby signals before feeding it out to the speakers.

If you do however have the money, a TV card is a cool gadget to have on your computer. Besides catching up on news or sports while working in some software, you can also receive S-Video/Composite/RF signals and perform video/frame capture. Getting your TV card running under Linux is not very difficult. However there is a lack of easily visible documentation on the Internet. The standard bttv driver provided with most kernels has limited support for tuner cards.

This article will focus on getting your TV tuner card working with the latest
version of bttv under Linux. My test machine will be a Celeron 300@oc'ed at 450MHz, 64mb RAM, Redhat 6.1 running Kernel 2.2.12-20 and Provideo PV951 card installed. The article is applicable to all distributions of Linux.

PACKAGE INSTALLATION
You will need to be in superuser mode to do most of the setting up. The first thing you need to do is grab some important packages that you will need to be able to use your TV tuner card. Unless you are running a 2.4.x kernel, chances are that you need to download the new i2c stack. Download the i2c package in root directory.

URL: http://www2.lm-sensors.nu/~lm78
File: http://www2.lm-sensors.nu/~lm78/archive/i2c-2.5.4.tar.gz

Install the package,
# cd /root
# tar xzpvf i2c-2.5.4.tar.gz
# cd i2c-2.5.4
# make ; make install

In case the install copied the header files into /usr/local/include/linux, copy them into the linux kernel directory. This is necessary as bttv looks for the i2c header files for compilation.
# cp /usr/local/include/linux/*.h /usr/src/linux/include/linux

You need to make sure that your kernel supports video4linux. Check for availability of videodev.o in the /lib/modules/linux/misc directory. If it is not present, go into kernel configuration
# cd /usr/src/linux
# make menuconfig
and compile support for video4linux as a module. It is located under Character Devices->"Video For Linux"

# make modules
# make modules_install
to complete the installation of the module.

Next up is the installation of bttv. Download the latest version from the following address and move it into /root

URL: http://www.strusel007.de/linux/bttv/
File: http://www.strusel007.de/linux/bttv/bttv-0.7.49.tar.gz

To install the package,
# cd /root
# tar xzpvf bttv-0.7.49.tar.gz
# cd bttv-0.7.49

Now, you may need to edit the makefile before you can successfully compile. Open Makefile and update the kernel variable to reflect your kernel directory, for example:
kernel=$(shell basename /usr/src/linux)

Go into the driver directory,
# cd driver

Open Makefile and change KERNEL_DIR to
KERNEL_DIR := /usr/src/linux

and also, CURRENT
CURRENT := 2.2.1-20

# cd ..

Compile and install the package,
# make ; make install

All that is left to complete the initial setup stage is to download a TV viewer
like xawtv or kwintv.

kwintv
URL: http://www.mathematik.uni-kl.de/~wenk/kwintv/download.html

xawtv
URL: http://www.strusel007.de/linux/xawtv/
File: http://www.strusel007.de/linux/xawtv/xawtv_3.24.tar.gz

For starters, lets install xawtv:
# tar xzpvf xawtv_3.24.tar.gz
# cd xawtv-3.24
# make ; make install

MODULE MAYHEM
Next up is the loading of the i2c modules,
# modprobe i2c-core i2c_debug=1
# modprobe i2c-algo-bit bit_test=1

Now you need to load the video modules,
# modprobe videodev

Start an X Windows session and open a new terminal window to monitor your /var/log/messages file,
# tail -f /var/log/messages

Open another terminal window load the bttv driver to autodetect your TV tuner card,
# modprobe bttv

Alternatively, you can look at the CARDLIST file in the bttv package directory and locate your card number. The test machine had a Provideo PV951 which is listed as card no. 42 in the CARDLIST in bttv's directory. Once you have located the card,
# modprobe bttv card=xx radio=n
where xx=card no and n=0 for no radio, 1 for radio support

In my case as it is a PV951 without radio support,
# modprobe bttv card=42 radio=0

Now look at your /var/log/messages file in the other window. If detection went well, you should see your card name printed out by bttv and some initialization messages. Here is the output from my log,
kernel: bttv0: Bt878 (rev 2) at 01:0a.0, irq: 12, latency: 32, memory: 0xdc000000
kernel: bttv0: model: BT878(ProVideo PV951) [insmod option]
kernel: PCI: Enabling bus mastering for device 01:50
kernel: i2c-algo-bit.o: Adapter: bt848 #0 scl: 1 sda: 1 -- testing...
kernel: i2c-algo-bit.o:1 scl: 1 sda: 0
kernel: i2c-algo-bit.o:2 scl: 1 sda: 1
kernel: i2c-algo-bit.o:3 scl: 0 sda: 1
kernel: i2c-algo-bit.o:4 scl: 1 sda: 1
kernel: i2c-algo-bit.o: bt848 #0 passed test.
kernel: tuner: chip found @ 0x60
kernel: bttv0: i2c attach [(unset)]
kernel: i2c-core.o: client [(unset)] registered to adapter [bt848 #0](pos. 0).
kernel: i2c-core.o: adapter bt848 #0 registered as adapter 0.
kernel: tuner: type set to 1 (Philips PAL_I)
kernel: bttv0: i2c: checking for TDA9875 @ 0xb0... not found
kernel: bttv0: i2c: checking for TDA7432 @ 0x8a... not found

You can now proceed to use your TV tuner by loading up XawTV.

In case you are not hearing any audio, you need to load the tvaudio module
# modprobe tvaudio
This was required for my ProVideo PV951 card.

XawTV is a powerful utility for TV display and capture. One of the features that it lacks is the ability to quickly scan and set channels. KwinTV, one of the more popular softwares that has this feature.

Once you are happy with the settings you can move the settings into the /etc/conf.modules and add the following lines,
alias char-major-89 i2c-dev
options i2c-core i2c_debug=1
options i2c-algo-bit bit_test=1
alias char-major-81 videodev
alias char-major-81-0 bttv
options bttv card=42
options tuner debug=1
alias char-major-81-1 tvaudio

Happy TV watching in Linux!