We also suggest you to launch XFree / X.org in 16bpp rather than 24 or 32bpp.

With all these suggestions, XdTV fullscreen will be perfect even if you don't use Xv extensions.
 

• How to know if I use XFree4.x / X.org or version 3?

Check the existence of that log file: /var/log/XFree86.0.log or /var/log/Xorg.0.log
 

• Can I use XdTV with root rights?

This is not advised!!!! You must start XdTV (or XFree / X.org) only as a normal user. This is a general rule on all Unix Operating System.
Root user must only be used to administrate your system.

• When I launch XdTV these messages appear: "can't acces mixer" and / or "can't access vbi":

This is a general access right problem for these devices: /dev/dsp, /dev/vbi, /dev/video, /dev/mixer, etc...
firstly, you must verify if /dev/video device exists and if it's a symbolic link for /dev/video0 device.
If needed, you can create this symbolic link: ln -s /dev/video0 /dev/video (with root rights).
You can do the same thing for /dev/vbi device: ln -s /dev/vbi0 /dev/vbi 

Now we are going to resolve problems with groups...
In recent Linux distributions, if you want to access to some specific devices, your account must be added into a specific group, one group for each device.
For example, the audio device /dev/dsp belongs to root and to the audio group. So, if someone wants to use this device (listenning to music for example) he must be included into the audio group.
To access to the TV card, you could meet the same problem as with the /dev/video0 device. This device belongs to root and to the video group.
The CDROM device (/dev/cdrom) belongs to the cdrom group.
The printer owner group is lp or printer
The modem owner group is either modem or uucp or dialup.
.......
So to use all these devices, you must belong to all these groups: cdrom, audio, video, lp, uucp....

This method allows the administrator to thightly control all access rights!

Nevertheless, the group must have the rights to use devices. So you just type these commands into a shell with root rights:

$ chmod g+rw /dev/video0
$ chmod g+rw /dev/vbi0
$ chmod g+rw /dev/audio0
$ chmod g+rw /dev/mixer
$ chmod g+rw /dev/dsp

You can also check to which group these devices belongs to. For example, on a Mandrake 8.0 distribution, for the video and audio devices:

$ ls -l /dev/video0

=> crw-rw---- 1 root sys 81, 0 Apr 14 13:06 /dev/video0

$ls -l /dev/audio0

=> crw-rw---- 1 root audio 14, 4 Apr 14 13:06 /dev/audio0

So, you must belong to sys and audio groups if you want to get video and sound.

How to add a user into a group?
For this example, lets assume your user name is USER1. Firstly, we are going to verify in which groups you belong to. Type this command in a shell

$ id -a USER1

This command gives this answer:

uid=993(USER1) gid=21(USER1) groups=21(USER1),22(cdrom),43(usb),80(cdwriter),504(xgrp)

USER1 is a user which default group is "USER1" and which belongs to the cdrom, usb, cdwriter and xgrp groups.
To let this user USER1 belong to sys and audio group, you have to type this command in a shell with, of course, root rights:

$ usermod -g USER1 -G USER1,cdrom,usb,cdwriter,xgrp,sys,audio USER1

"-g USER1" parameter meens that USER1 is its principal and default group
"-G USER1,cdrom, .... ,audio" parameter means that USER1 belongs to all these other groups. Be careful, when you want to add a user in a new group, you have to write all the groups he used to belong to as well as the new ones.

To activate these modifications, USER1 have to logoff then logon in the system.
 

• What is "memcpy":

Memcpy is a C function which copies the content of a memory area to another memory area. It is abusively used for buffer transfers and the more this function is efficient, the smoother the images are. At the very first start, different memcpy implementations are tested by XdTV : the C library one, the kernel one, a MMX optimised one, etc... the fastest is selected and the result is stored in the .xdtv/memcpy_method file in order not to run the test every time XdTV is started.
 

• Which sound driver should I use?

There are two sound drivers: OSS and ALSA. Alsa is an OSS GPL compatible sound driver. We suggest you to use ALSA driver. Why?

• Because, this driver can give you a Full Duplex sound
• Because, the synchronization between sound and video is very good 

 

• How to get, for my graphic card, informations on Xv, V4L (Video for Linux) and BTTV?

Start Xawdecode with this parameter: -hwscan
This option gives you that near result:

This is xawdecode 1.3.10 running on Linux/i686 (2.4.8-26mdk).
looking for available devices
MIT Shm extension available
Number of Xv adaptors available: 1
port 58-58 [ -xvport 58 ]
name : Matrox G-Series Backend Scaler
type : Xvideo, image scaler
format supported on port 58 : YUY2 YV12 I420
v4l: bttv version 0.7.72
/dev/video0: OK [ -c /dev/video0 ]
type : v4l
name : BT848(MIRO PCTV)
flags: capture tuner overlay clipping frameram scales

This option doesn't exist any more with XdTV.
You can also start XdTV in a debug session. To do that, type into a shell this command : gdb /usr/bin/xdtv
This method gives you that near result:

[user1@localhost user1]$ gdb /usr/local/bin/xdtv
GNU gdb 20010813 (MI_OUT)
Copyright 2001 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "i386-mandrake-linux"...
(gdb) run
Starting program: /usr/local/bin/xdtv
[New Thread 1024 (LWP 2003)]

This is xdtv 2.0.0 running on Linux/i686 (2.6.8.1-20mdk).
wmhooks: netwm
DGA: server=2.0, include=2.0
VidMode: server=2.1, include=2.1
available video mode(s): 1024x768 800x600 768x576 640x480
Selected XvImage adaptor with YUY2 support: Matrox G-Series Backend Scaler on port 58
x11: 1024x768, 16 bit/pixel, 2048 byte/scanline
v4l: 1024x768, 16 bit/pixel, 2048 byte/scanline
v4l: framebuffer base=0xe3000000
v4l: mmap()'ed buffer size = 0x410000
......

.......
MMX and SSE detected.
......

• My fps (Frame per second) is very bad: How can I correct it?

With some linux distributions (like Mandrake 7.2 distribution), you could meet this problem. We suggest you to install XvBogus (you can download it from xawdecode download section) or launching, at startup, Xawdecode with the -noxv option. (Xv method is better than noxv. noxv need more CPU).

This problem doesn't exist any more with XdTV.

• XdTV is very slow: why?

Best results are obtained with XFree4.x / X.org and Xvideo extensions. If you can't use Xv, we suggest you to launch XFree / X.org with 16bpp rather than 24 or 32 bpp. You can also activate MTRR support in your kernel. If you use XFree86 version 3.x, you will have to indicate to the kernel where to find graphic card memory. This method is explained into the "Linux DVD HowTo".
   

• On my screen, I have some white parasitic points when I switch from a grabdisplay channel to an overlay one (and vice-versa):

You have to activate, in your xdtvrc configuration file, this parameter: colorkey = 123456. This problem is related to the Xvideo colorkey which uses black color as color of transparency. So it is not a XdTV issue but a Xv one.
 

• When I reduce window size, image is more and more deformed. What must I do?

If the bottom of the image disappear when you upwards stretch this image (this problem could appear when you switch from Xawtv to Xawdecode), the reason could be a non Scalling support of your Xv video driver. To correct it, you can:
Firstly, upgrade XFree86 from version 3 to version 4
Secondly, add, in your xawdecoderc configuration file, this parameter: hw_scaling = off

This problem doesn't exist any more with XdTV.
 

• Could you explain us what are the differences between each deinterlace filters?

Explanations about XdTV filters can be found into the DScaler project documentation web site: (http://deinterlace.sourceforge.net)...

• Video Deinterlace (Bob) (This is the BOB filter used in XdTV)

 This method is based on Gunnar Thalin's VirtualDub filter. If it detects weaving artifacts in the current image it uses bob to get rid of them.
This method has a tendency to bob rather too much and gives poor results on fine static images.
 

• Video Deinterlace (Weave) (This is the WEAVE filter used in XdTV)

 Similar to Video Deinterlace (Bob), however this method has a tendency to weave on moving images.
 

• Video Deinterlace (2-Frame)

 This method uses the current frame and the last two to determine whether to bob or weave a given pixel. This gives better results on both stationary and moving images than the above two methods however it uses more CPU.
 

• Simple Weave

 This method just combines the most recent even and odd fields. This causes motion artifacts and is provided for comparison.
 

• Simple Bob

 This uses only the most recent field and fills the lines in between with interpolated pixels. This method has in may ways been superceded by Scaler BOB.
 

• Blended Clip

 The BLENDED CLIP Deinterlace method is designed mostly for experimentation by those interested in what works for video deinterlacing. When it is selected it will pop up a control panel with many controls to adjust various parameters.
 These all correspond to Blc... parameters in the [Deinterlace] section of the DScaler.ini file and are documented there. It is probably not the single best method for anything but it can be used to create custom deinterlace methods for special purposes. These can be saved in a separate ini file and invoked by a command line parameter when starting DScaler.exe. Somewhat CPU intensive
 

• Scaler Bob

 Uses the DirectDraw hardware bob feature (if available), this uses the current field and lets the video card scaler size the picture to fit the screen.
 Produces good results for fast moving images.
 

• Even Fields Only

 Odd Fields Only (This is the ONE FIELD filter used in XdTV)
 These use only one field out of each pair and use hardware scaling. This reduces bob artifacts at the cost of loss of information. These were originally intended to be used with game consoles.
 

• Adaptive Deinterlace

 This method uses the amount of motion detected to select the best deinterlacing alogoritm. Currently by default it switches between 2-Frame and weave.
 

• Greedy deinterlace method

 The GREEDY Deinterlace method is designed to give good results on low motion video source, using less CPU than some others. Good on slower machines but it will give awful results on high motion video material like sports. Quite by accident, it can also do a decent job on poorly mastered 3:2 or 2:2 pull down film source material like some anime movies, regardless of low or high motion.
 Try it if you have a movie source that is not giving good results with normal Auto Pull Down processing.
 

• Greedy 2 Frame method (This the GREEDY filter used in XdTV)

 This method tries to combine the best features of the 2-frame algorithm with the looking ahead ability of the greedy method. I find this methods works well on sports and other high motion material. With static images and low quality
 sources there may be unacceptable levels of bobbing.

• Linear Blend method (This the LINEAR BLEND filter used in XdTV)
  

Linear Blend operates by taking a line, then averaging the pixel values in it with the line below, effectively blurring the frame. This almost completely eliminates the effects of interlacing - at times you may notice slight ghosting (instant transition from one thing to another), the image appears to persist for a fraction of a second. This is absolutely not a serious issue, as far as I am concerned - in fact it's really only noticeable if you are me, and a perfectionist.
 

• I have some strange colors on screen when I play a Xawdecode avi file. How to correct this problem?

We suggest you to use the last version of your favorite avi file player (mplayer, aviplay or xine). If you still have the problem, you can force the avi player to use the divx4 codec: option -vc divx4 for aviplay or mplayer, and for xine, modify your xine config file (~/.xine/config) with "codec.divx4_priority:6".

This problem doesn't exist with XdTV.
 

• I can't select any deinterlace filter: why?

In fact this problem is very simple. If you start Xawdecode with -noxv option you can't use deinterlace filters. You can only use these filters with Xv and Grabdisplay mode. These filters have been extracted from xine and dscaler source code. To use them you must be able to display YVU images, so, as it is not the case with the noxv mode, we can't use them. Also, in noxv mode all references about deinterlacing are discarded.

This problem doesn't exist with XdTV.

• With devfs, video devices numbers are distributed automatically without any order. How can I force devices numbers?
  

options bttv pll=0 radio=0 card=1 tuner=3 video_nr=1 vbi_nr=1 gbuffers=4 fieldnr=1
######### End Tuner TV #########

You could do the same thing with Webcam. Use this parameter: dev_hint:

For example:
######### USB Webcam #########
alias char-major-81-0 pwc
alias sound-service-1-0 audio
alias sound-service-1-3 audio
alias sound-service-1-8 audio
alias sound-service-1-12 audio
options pwc dev_hint=0
post-install pwc /sbin/insmod --force /lib/modules/2.4.19-16mdk/kernel/drivers/usb/pwcx-i386.o.gz >/dev/null 2>&1 || :
pre-remove pwc /sbin/rmmod pwcx >/dev/null 2>&1 || :
######### End USB Webcam ######

• XdTV compilation and optimization:

If you compile XdTV on you own PC, it will be optimized for your own CPU. It's possible to avoid this and to make (to build rpm or deb packages) a standard compilation. To do this you just need to add this option to the ./configure script :  --disable-cpu-detection

• How to move or resize a window without any "window decoration"?

It's very easy. You just have to read this article (into this help file): "test window decoration"

• I have some sound problems: sometimes there are some conflicts between XdTV and Xmms and XdTV sound become mute:

If you use Kde, this problem could be an artsd problem (artsd daemon). I advice you to never use this daemon and to desactivate it!

• XdTV / Xawtv freeze after several minutes:

here is one explication:
"IRQ sharing is known to cause problems in some cases. It works just fine in theory and many configurations. Neverless it might be worth a try to shuffle around the PCI cards to give bttv another IRQ or make it share the IRQ with some other piece of hardware. IRQ sharing with VGA cards seems to cause trouble sometimes. I've also seen funny effects with bttv sharing the IRQ with the ACPI bridge (and apci-enabled kernel)."

So you just have to add this option to bttv in your modules.conf file: triton1=1
"The triton1 insmod option sets the EN_TBFX bit in the control register. The vsfx insmod option does the same for EN_VSFX bit. If you have stability problems you can try if one of these options makes your box work solid." (Thanks to Mat)

• How to install nvtv (TV out pour nvidia) to watch XdTV on your TV: