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  #1  
05-09-2012, 03:01 AM
WuxiIxuw WuxiIxuw is offline
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Hello
What are the standard and default various Dimension & Aspect Ratio for videos ?
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  #2  
05-09-2012, 03:18 AM
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kpmedia kpmedia is offline
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This question is honestly too broad to answer. It depends on the intended viewing device.

It's like asking what are the standard/default sizes of car tires. It depends on what you're driving.

Most consumer video is 4:3 or 16:9.
Most SD NTSC video is encoded at x480 resolutions. 352/480/512/544/640/704/720 x 480
Most SD PAL video is encoded at x576 resolutions. 352/480/720/768 x 576

But you have to understand there's also a difference between display AR and storage AR. (AR = aspect ratio)
Video viewed at 1:1 square pixels will appear "wrong" using standard storage AR. The storage can be rectangle, not only square.

HD video is 1920x1080 or 1280x720.
Then there's 2K and 4K resolutions, above HD quality.

You also have plenty of lower resolutions below accepted x480/x576 standards, used for various computer needs.

There's a bunch of film resolutions (equivalency) and aspect ratios.

And on that topic, remember analog video is measured in non-resolution analog units. So resolution is always an equivalency.

Again -- far too broad of a question. It's easy to confuse somebody with info overload, on this topic.

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  #3  
05-09-2012, 06:24 AM
jmac698 jmac698 is offline
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That's easy, ITU standards have square pixels equivalent to 710.85x486 or 702x480, for NTSC. I should say, that area represents exactly 4:3 in square pixels. So for computer you would resize 702x480 to 640x480.
You can digitize full 720x486 but the 3 lines above/below are chopped off to fit round numbers for encoding.
If you view old analog tapes on dvd, they've been cropped.
Capture cards tend to vary on the vertical positioning, they can be shifted a few lines up or down.
But modern dvd's often have image in full 720x480, what does that mean? It means it's no longer 4:3 image. You have 3% more width. To really see a dvd in full quality you have to upscale (on a digital monitor).
I've looked into this by trying to warp the dvd version to the HD version, which is always square pixel. No conclusive results yet due to accuracy problems.
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  #4  
05-09-2012, 02:28 PM
WuxiIxuw WuxiIxuw is offline
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wow!
All these details !?
Well, please allow me to tell you more exact details so I can get an exact device instead of confusing you with my broad question.
We are a small media company located at Egypt, Cairo.
We have two departments in our company, one for web development and the other one is for media encoding.
We have many contracts with many local channels here in Egypt which broadcasting in the Nilesat Satellite.
Our contracts include two aspects:
1) Developing a website for any channel we have a contract with.
2) Uploading all channel shows or programs to its website on a daily base.
* some contracts include extra section for adding these videos to the social networks like YouTube, Facebook, twitter ...etc in the channel owned page or account or channel.
3) At the beginning when we started we used to receive an original DVD copy of the broadcasted episodes then do video encoding and upload to the website, but this became a time consuming by time because we are waiting for the second day to receive the copies then do the video encoding then do the upload in the 3rd day which became a time consuming by time and lead to lose some contracts.
4) Now we do it in a better way, we have a lab with 50 computers connected with a gigabit network and each computer include a PCI DVB card and only dedicated for recording, then we do transfer the .MPEG-2 recorded files to other monster computers with i7 processors to do the video encoding and then upload then ...etc. The reason for do it is to save a day and a half by recording locally and directly from the channel.
5) This was the starting point of our problems and the main reason for my search about Dimensions and Aspect Ratios.
6) Here in Egypt we have the default normal channels and only about 10 or so are in HD so channels we have contracts with is broadcasting using various Dimensions and Aspect Ratios like : 720x576 & 704x576 & some other Dimensions.
7) The local channels used to add some commercials in the bottom of the screen and some commercials in between the episodes (which was not existing in the original DVD we receive from the channel previously as we used to get the net pure episode).
8) so now we do it our self to remove all these because all uploaded previously were pure and audience will not like it this way.
9) so now when do a crop I get a mess ... so this is the reason I asked my 1st question about Dimensions and Aspect Ratios.
10) Now we are need to upload various Dimensions like 640x480 and others.
11) what I do so far like the following:
  • - use MPG2CUT2 to determine required parts.
    - do crop.
    - When we do the 640x480 when the channel is 720x576 and I do crop for 10% from the bottom, so the new size is 640x432 to have a pure acceptable size.
    But if the channel is not that size I do not know how to adjust it?
    And to make a more small size like 480 or 360 or 352 I do not know what are the Dimensions and Aspect Ratio?
    So please advise.

    Thanks and really very sorry for being chatty but just to let you know more exact details to better help me.

    Thanks for your time
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  #5  
05-09-2012, 07:31 PM
jmac698 jmac698 is offline
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Hello,

Regarding step 8) commercial cutting, this can be fully automated with http://www.videohelp.com/tools/Comskip
mpeg2cut2 is not specifically supported, however you can automatically cut with another free tool. After automated processing I suggest you review it quickly in mpeg2cut2, but still this will save time One good hint is the final time of the file, is 22 minutes or 44 minutes, for 30/60 minute TV show, depending on how commercials are in your country.

The different sizes of your recordings are a standard defined by DVB, they are listed here
http://en.wikipedia.org/wiki/Mpeg2#DVB
720, 704, 544, 528, 480 or 352 576 pixel, 25 frame/s

The websites standards are listed here.
YouTube:
http://en.wikipedia.org/wiki/YouTube#Quality_and_codecs

FaceBook:
http://www.facebook.com/help/videos/uploading
"The larger edge of the video is constrained to 1280px (pixels). We do not rescale videos that are below this maximum in both dimensions.
Aspect ratio must be within the range of 9:16 (0.5625) to 16:9 (1.7777). Videos with aspect ratios that fall outside this range will be rejected. "

Twitter:
From what I can tell, it does not do video hosting, but allows embedded links to YouTube, so YouTube guidelines apply.

The best match for your videos on YouTube is 480p, however it seems that YouTube will do it's own cropping. You'd have to test this. It seems that 640x432, is bigger than the 360p format listed, but fits into the 480p format; my guess is YouTube will do it's down cropping/centering and put the video into 480p format.

If your website does not display your 640x432 in an acceptable way, or it's rejected, then I suggest you encode to 640x480 with a black bar. This has an issue, that you have to re-encode the video, because black bars cannot be added losslessly to mpeg2. You also don't need to make 640x, just use 704x480 or however it came.

I hope this helps!
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  #6  
05-09-2012, 11:06 PM
WuxiIxuw WuxiIxuw is offline
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Hello,
Do not know how to exactly express my confusion with all these details ... Really thanks a lot for all these tips.
It seems that I will need to study many things here.
Please I will review all mentioned stuffs and feed you back.
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  #7  
05-09-2012, 11:27 PM
WuxiIxuw WuxiIxuw is offline
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1st thing to start with ... to avoid stretching of the screen.
If the video is 704 x 576 ... and I did crop from the bottom by 10% minimum or 25% maximum, the main question here is:
What is the new dimension? to avoid screen stretching and make the video looks normal?
Because removing the bottom commercials by using crop while keep the same exact file dimension will make it looks bad like actors in StarWars
What is the equation to determine the new dimension of the video?
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  #8  
05-10-2012, 01:31 AM
jmac698 jmac698 is offline
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The website you are using is forcing the video to a certain size. I don't know what that size is. It's easy to find out; just download the video from that site. You can do that with http://www.videohelp.com/tools/MediaBox or some such software. The website is forcing the videos to some size, and stretching your upload.

There are two solutions,
1) Crop equally on all sides,
10%
640x512

25%
528x432

The formula: .9*704, .9*576, but make the result equal parts of 16. Example, .9*704=633.6, 633.6/16=39.6, 40*16=640, so use 640 (closest one).

2) Cover the commercials
Make your videos with a black bar. By black bar I mean DO NOT CROP, you need to use an editing program that can add black COVERING the video, and keeping the same size.
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  #9  
05-10-2012, 01:40 AM
WuxiIxuw WuxiIxuw is offline
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Which software to be used to add the horizontal black bars at the bottom over the screen?
Also when I try to upload the original broadcasted video to youtube for example I found it not full viewed to screen but also has some black area around the video from all parts.
so how to fix this?

Regarding the result you mentioned above about the size, what equation you used?

also if the original video is 704/720 x 576 and i want to reduce the size while keep the same exact aspect ratio, how to do so?
for example, if i want to make it 480x360?
I found some parts from the screen get removed after converting to the new size from the top and the bottom of the video.
So how to fix such a thing?
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  #10  
05-10-2012, 02:10 PM
WuxiIxuw WuxiIxuw is offline
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Gentle reminder!
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  #11  
05-10-2012, 02:53 PM
jmac698 jmac698 is offline
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I don't have time to experiment with uploading videos to YouTube. You can add black covering using VirtualDub. I've given you the formula and also showed you the calculation already, please read the message again. There's no way to force a certain aspect ratio with your website, you only have to find dimensions which display correctly, and place your video inside those dimensions, also padding with black if necessary.
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