Celestia Forums

I have not had much luck with using the full frames uncompressed movies. They dont seem to always be readable on my differnt machines.
I dont know why. Other compression formats work but arent my favorite choice.... so the question is for future celestia version maybe there could be an export option for bitmap sequence so we can compress movies on our own? Is that hard to do programatically verses current methods?

Maybe someone out their has created a script to create a jpg screen capture sequence? Anyone know of one?
thanks.

Full frame uncompressed movies is actually quite close to that.
You just need to separate the frames and pour them into images.

Writing such an exporter isn't difficult, but making it work efficiently and gracefully takes some time.
About the image format choice: jpg is a lossy format and there for a very bad decision, it would be better to use a lossless format such as e.g. png or jpeg-LS (jpeg lossless).


Or you can transcode the video to a sequence of images with this free converter:
By using virtualdub: http://virtualdub.sourceforge.net/
Here is a discussion about doing that with someone explaining how to do it with virtualdub:
http://www.videoforums.co.uk/general-so ... mages.html

Using Avidemux: http://avidemux.sourceforge.net/

Or search one here:
http://wareseeker.com/free-video-to-image-sequence/


Another way out is using a general screen capture program.
Which is specially designed for this task.
They can capture any screen/window/region with a better choice of codec/output files than Celestia itself.

PNG works well when the image contains large areas where the colors don't change much, such as screenshots of Notepad, simple educational graphics and so forth. In cases where the image is "busy" and contains lots of detail like in a photograph then JPEG is better.

posfan12 wrote:PNG works well when the image contains large areas where the colors don't change much, such as screenshots of Notepad, simple educational graphics and so forth. In cases where the image is "busy" and contains lots of detail like in a photograph then JPEG is better.

PNG is a lossless graphics format, unlike lossy JPG! Hence a comparison between PNG and JPG better focusses on somewhat different aspects.

Fridger

posfan12 wrote:PNG works well when the image contains large areas where the colors don't change much, such as screenshots of Notepad, simple educational graphics and so forth. In cases where the image is "busy" and contains lots of detail like in a photograph then JPEG is better.

This is completely false. JPEG is used in photography because it's (lossy) format save space on memory cards. Try to convert a good PNG to JPEG and then zoom in it. In the JPEG you will see the textels while in the PNG not.

In professional photography where quality is the issue, and post-processing is required, RAW and lossless formats are mandatory. JPG is only ok for consumer snapshots (ie. point and shoot compact cameras, cell-phone cameras, etc) or where no editing will ever be required.

--- edit ---

Why did Joint Photographic Expert group came up with it?
I mean, don't they care about the quality of the work of their members?

The highly compressed, lossy JPG format has it's clear merits when (file size AND quality) require a good compromise. Lossless formats are indispensable in pro environments, where quality is the ONLY constraint.

See also my explanations here:

viewtopic.php?f=3&t=15997

I discuss there, how JPG format can be of excellent quality (including text!) despite compact file size, if the settings are chosen properly. Most people simply ignore that there are crucial settings (besides the somewhat better known "quality" setting).


Fridger

duds26 wrote:Why did Joint Photographic Expert group came up with it?
I mean, don't they care about the quality of the work of their members?

They created it because it has it's uses (...if I remember rightly, the emergence of the WWW was one of the primary motivations for the creation of this format, as an efficient means of sharing images over computer networks).
Consumer Digital Camera's adopted the JPG format at a later stage.
In fact, I think most of the original digital cameras (which typically were digital backs for professional cameras), created lossless formats as huge files, not JPG's.
The main thing, is that you have an understanding of JPG's limitations and use it appropriately. It's small size /high compression ratios are good for WEB publication as images will require less bandwidth and pages will load faster, but it is a very bad practice to produce jpegs at intermediate steps in POST production as further editing operations on JPGS will result in artifacts and loss of information. These will accumulate at each intermediate step.
Fine as a final output though, depending on the application.

A professional photographer will generally also avoid capturing in JPG like the plague. Camera RAW formats contain a lot of extra information which cannot be encoded in a JPG, which provides many essential advantages in POST, including, to list just a few:

the ability to fix over or under exposed images
recover lost highlights and shadow detail
adjust White Balance and correct color casts
etc...

The best analogy with the old film days is to say that the RAW file is analogous to a negative, and the JPG is analogous to a print.
ie. You can always produce a JPG from a RAW, but not the other way around.
The process of post-production on a computer in the digital realm is analogous to what happens in the Photo-LAB to convert your negative into a print.

PRO's will insist on producing prints from TIFF's or other lossless formats (if they don't, they're probably not a PRO).
They won't object to producing JPG's for WEB use though.

Hope this clarifies it for you.

--- edit ---

john Van Vliet wrote:so the use of jpg's is for the most part habit ( a bad one at that ) and profit for the telecoms less data transferred on there networks at a overly high price at a per/month rate .

Interesting that you mention the telco's role, because that brings to mind my favorite rant about how the telcos invented the idea of txting and then convinced an entire generation of people that it should be the preferred mode of communication.
Typically the $cost of a text is maybe 1/4 to 1/2 the cost of a voice call (YMMV), but in terms of network cost it's a tiny fraction (a few bytes per txt), compared to a few kilobytes/sec for the audio of a voice call.

It's no surprise then that telcos make some of the biggest profits of any companies.
TXTs == pure profit

It's unfortunate that a whole generation (< 20yrs?) doesn't seem to realize that a 30sec (duplex) voice call can communicate a vastly larger and richer content, far more efficiently (at least in terms of our own precious time) than 10-15 minutes of (simplex) TXT's firing back and forward.

IMHO, TXT's are very bad value for money (not to mention time, and associated medical costs, RSI, deformed thumbs, etc... )

... but definitely a marketing triumph for the telcos!

End of rant.

PS. I wonder if each generation is dumber than the one that came before it....

Chuft-Captain wrote:
PS. I wonder if each generation is dumber than the one that came before it....

From few smarts (prehistoric men) to more dumber (now). It's just Thermodynamics.

Fenerit wrote:

Chuft-Captain wrote:
PS. I wonder if each generation is dumber than the one that came before it....

From few smarts (prehistoric men) to more dumber (now). It's just Thermodynamics.

Correct ...ever increasing Entropy.

F.

Fridger wrote:

Correct ...ever increasing Entropy.

I believe the younger generation spells that Etnorpy.

VikingTechJPL wrote:[I believe the younger generation spells that Etnorpy.

V gd, but IMO, tha wud spel it: NTRO P

--- edit ---

CC,

I thinque wee hadd thuh saim speling teechur.


John V V,

Your links induced a true OMG experience. OMG! You're probably also aware of the stories about state legislatures trying to legislate the value of pi. Some are myths, but this site purports to have the real story:
http://scienticity.net/wiki/Legislating_the_Value_of_Pi
Check out the links in Notes near the bottom.

-G

VikingTechJPL wrote:CC,

I thinque wee hadd thuh saim speling teechur.

That was actually my attempt at TXTlish.

john Van Vliet wrote:well in the UK the people DO want the 2d law repealed
http://yourfreedom.hmg.gov.uk/repealing ... dynamics-1

http://science.slashdot.org/story/10/07 ... modynamics

Usually the Economics and the economists are against the Thermodynamics; since they are based upon "pre-theory of heat" Adam Smith's statements of "balance" and "invisible hand". One should look at such from a physical point of view. But nonetheless, how to sell they? The economics' message is that of a world ruled by the law of economics, on other hand economics is ruled by the laws of physics; and this doesn't like to the economists. A rought analogy with the 2nd law is that in a global economics (one isolated source of heat) is impossible to make work (occupation).