[SOLVED] color quality changes between players

[jdetwile]

I'm new to video editing (Cinelerra, ffmpeg, Totem, xine, mplayer), and have run into severe degradation of color quality on playback. So I did a controlled use-case as follows:

1. Download a screenshot of standard SMPTE color bars, save as an image and load into Cinelerra. Make a :10-sec video and render to .ogg file.
2. Play the file in xine, it looks just fine. Play the file in Totem and the colors are badly desaturated (to, say, 10%) and maybe shifted toward blue.

3. Now play the file in xine again - the colors are "bad" (like in Totem).

4. Reboot Fedora and play the file in xine - the colors are "good" again.

Any suggestions as to what's going on? Lots of detailed info available on request. Thanks!

[disturbed1]

Depends on which back end you are using for Totem. Totem defaults to using gstreamer, xine uses it's own. Gstreamer has it's own codecs which may not be the same version as the one xine uses.

It's like using WinDVD to view a mpeg2 file, and saying it looks different when viewed with VLC. Of course it would, because each program is using a different decoder.

In Linux, there are also several different overlay methods (xv, X11, GL, GL2, and on and on). Even if Totem is using the xine backend, each player may still look different depending on the overlay being used. Then you also have the problems with certain video cards and their drivers (ATI), which may work ok with some overlay methods, but fail with others. Or introduce artificial artifacts and tearing in the video.

When I edit video color in Linux, I use the TV out so I can see what the image actually looks like on a couple of different sets. Computer monitors look different than they do on TV. Even if you calibrate you monitor, there is no substitution for the real thing. I won't even touch on the in-abilities of consumer LCD screens to reproduce accurate colors/images, let alone moving pictures

Basically it boils down to, use the correct overlay method that best fits your video card. Choose a single player that you like. Use your TV-Out (or burn a test disc) to adjust your monitor as closely to the television as possible. I've found that if I calibrate my monitor to mimic my television, everyday computing looks like crap, so I just use the TV-Out for best results.

[jdetwile]

Thanks for your response. I think I understand, in general, what you're saying.

Did you notice, though, that (1) my 'color difference' is almost no color at all - it's close to B/W, and (2) the behavior of xine depends on whether or not I've launched Totem.

These aren't subtle differences in color rendition. Thanks/

[disturbed1]

Judging by Fedora 8, I'd say everything is pretty up2date :P
Check your gstreamer multimedia properties. If it's not in the system preferences menu, you can launch it with gstreamer-properties. Change the default plugin on video out to something else. This controls Totem's overlay options.

Please tell me you have an ATI video card, and you are using fglrx? If that is true, there is an option to pass in xorg.conf that will help with the overlay problems. ATI has issues with this, though it has improved slightly in the last 2 years.

I re-read, and read again, and read again your post. I guess my ADD got in the way of the whole problem. I've had a similar problem, but instead of unsatured colors, mine had the uv swapped. Everyone would look blue and green. At the time ATI's drivers were even worse than what they are today, I fixed by buying an nVidia card. I've also experienced issues with the i810 and Intel xorg video driver, not color problems, but just pure flakiness of over all quality.

There are other things as well that can cause/fix these problems, but you didn't let us know your video card, nor what driver you're using. With or with out AIGLX/XGL/Compiz.

[jdetwile]

I'm trying to keep up, but starting to get beyond my depth. If these aren't the right answers, I'll need more explicit directions on where to find the info. But thanks for digging in!

(1) gstreamer-properties shows:
Video Default Output
Plugin: 'Autodetect' (other options are 'SDL - Simple DirectMedia Layer', 'X Window System (no Xv)','X Window System (X11/XShm/Xv)', 'Custom'
Device: <gray>
Pipeline: <gray>

(2) Going to System > Administration > Display brings up 'Display Settings', and on the 'Hardware' tab is 'Video Card: Intel Corporation 82865G Integrated Graphics Controller'. The 'Configure' button displays a dropdown for 'model of video card', on which the selection is 'intel - Experimental modesetting driver for Intel integrated graphics chipsets'

I don't find any reference to AIGLX/XGL/Compiz.

Does this tell you anything? Thanks again!

[disturbed1]

It does

SDl, X, Xv, are types of overlay systems. Try each one, to see if it helps. "X Window System (no Xv)" - X for short, or "X Window System (X11/XShm/Xv)" Xv for short, would be your best bet. Hit the test button to see what happens. If, choosing either overlay type offers no improvement, since the problem seems to be with Totem/GStreamer, don't use that application for now. Totem is available with the Xine backend. Should be easy enough to install using your package manager. I did a quick search on Fedora's forums/no results, and the wiki just bulks with the search.

In a console -
cat /etc/X11/xorg.conf | grep Driver

To get which driver X is using. There are 2 drivers for Intel cards. i810 and intel. i810 is said to be more reliable, but for older hardware. "intel" is newer, and more experimental, but is said to work better with newer hardware. If you're not sure which graphics chip you have -
lspci | grep Graphics

If you really want to RTFM on Intel graphics and Linux - it's located here
http://www.intellinuxgraphics.org/documentation.html

in the man page for intel it states this

Option XVideo boolean
Disable or enable XVideo support.
Default: XVideo is enabled for configurations where it is supported.
So, unless you've changed the setting, it should be ok.

Perhaps a post at fedora's forums would be more fruitful?

[jdetwile]

I'm traveling out of town for a week, so won't have a chance to pursue this further just now. But, when I'm back, I will take your suggestion and move the matter to a Fedora forum - since it does appear to be a hdwr/driver issue. Thanks for all your guidance!