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MediInfo - discovering your video format


How do I use MediaInfo on a movie DVD ?

Launch MediaInfo and use the file menu to navigate to the Video_TS folder on any commercial DVD where you will find the ".IFO" (information) files. The actual movie will be in 'chunks' of 1Gb each held in ".VOB" files (VTS_01_1.VOB, VTS_01_2.VOB and so on).

The Audio_TS folder will be empty. This folder would be used for a DVD containing pure music tracks and has nothing to do with any Movie files (all the movie audio tracks are embedded in the video data stream).

Look for the .IFO file that corresponds to the first .VOB (video block i.e. movie) of size 1,048,404 kb (i.e. 1Gb, the main movie). So, if VTS_02_x.VOB is 1,048,404 then you want VTS_02_0.IFO. Typically, VTS_01_0.VOB will be the 'intro' and it's VTS_01_0.IFO may well contain data that differs from the main movie. The VTS_02_0.BUP etc. files are 'backups' in case the DVD is scratched (or corrupted) and the player is unable to 'read' the originals

Unless you have a HD (or Blu-Ray) disk, MediaInfo will show the video format is "MPEG Video version 2" (i.e. MPG2 video).

You will often see multiple Audio channels (Audio #1, #2 etc). This is because commercial DVD's typically include 2 or 3 foreign languages on the same DVD (English will typically be Audio #1). The Audio format will be "AC-3" (which should not be confused with AAC, the Apple iPod music format). AC3 is also referred to as "Dolby" - the number of 'channels' will be 2 (stereo) or 6 (for 5.1 surround sound).

If the DVD is in PAL format it will (always) contain material that is 720 (or 704**) pixels wide by 576 high. The aspect ratio will be EITHER 4:3 ('square' pixels) or 16:9 (width compressed pixels).

**No matter how many pixels 'wide' your movie, only the MIDDLE 704 pixels are actually seen 'on screen'. Commercial movie DVD's have material that is 720 pixels wide for compatibility with old analogue TV's which 'throw away' 8 pixels at the start and end of each scan line.

How do I make Media Info available as a 'Right Click' (context menu) choice ?

Double click My computer to open Windows explorer. Go to the Tools menu & select 'Folder options'. Choose the file Types tab & scroll down to find the file extension (eg .mpg) you want to add the RightClick option to. With the extension highlighted, click Advanced. In the Edit File Type window, Actions, click New. Enter the name you want to appear in the RightClick menu in the Action box (eg 'Show media INFO'). In the Application used to perform action box, Browse to Program Files, MediaInfo, and select MediaInfo.exe. That's it, OK

The alternative method is to directly edit the registry

What format are computer video files ?

If you use MediaInfo on a typical ".mpg" video file found on your computer, you should find the expected "MPEG Video version 2" video format but typically with "MPEG Audio Version 1 Layer 2" (MP2), or "MPEG Audio Version 1 Layer 3" (MP3), audio.

The aspect ratio will be declared as '4:3' (i.e. 'square' pixels) however the height and width will typically be 'Your_computer/ display' size (640x480, 800x600, 1024x768, 1280x1024 etc) or some sub-set, especially if sourced from a web-cam (e.g.. 320x240 or perhaps 640x360 or 1280x720 for a 16:9 display format).

Will a DVD player cope with computer video & audio formats ?

A1. Most domestic DVD players will cope with 'non-TV standard' Video resolutions, as will most modern TVs. However whilst filling the width of the display is no problem (remember - stretching pixels has to be done 'as standard') the height is another matter. As a result it's not unusual to find the result is 'aspect ratio distorted' with the video filling the width but with black bands at the top & bottom.

Since both your DVD player and TV will be 'second guessing' how the video 'should' be shown, unless you stick to the standard DVD Movie sizes you may find yourself looking at a tiny 'keyhole window' on your TV (surrounded by black 'bars' at the top / bottom & sides)

A2. Most players also support multiple Audio formats - indeed, some commercial 'Video Processing' software will 'cut corners' by skipping audio conversion if the original is in a form that the software 'knows' is supported by 'most' domestic DVD players (no doubt in order to 'beat the clock' when being compared to rival products)

However, once again, if you stray from the DVD standard (AC-3) and 'burn' with MP2 (or MP3) you will be relying on your DVD player being 'compatible' with this combination. One day, after your old player is replaced, you may discover all your home movie DVD's play without sound :-(

Audio conversion adds very little to the overall processing time so you might as well 'get it right'.

Should I 'convert' my computer video into DVD format ?

Some 'DVD maker' software will offer to adjust the Width and/or Height or even to 'crop' the data during conversion. Others won't offer == they just do it anyway and get it wrong (i.e. they generate 'tall and thin' from letter box to TV or 'short & fat' TV 4:3 to letterbox 16:9).

If the original video is very low resolution (e.g. from a mobile phone or basic web cam - both typically 320x240), some player / TV combinations will play this as a small window in the centre of the screen - others will stretch it - needless to say, whatever you expect & want, your DVD player or TV will do the opposite. If you want to fill the TV screen with low resolution (eg 320x240) use your DVD authoring software to 'double up' to 640x480 and make a DVD with that (it will give a better (sharper) result than letting it 'interpolate' to 720 x 576).

The length of any video clip from a phone or web-cam will typically be short enough to allow you to experiment to find the best compromise between processing time and final display appearance. Note, however, that although you can 'stretch' the data to fill the screen, you will never end up with any more detail than exists in the original clip.

What other resolutions might I see ?

It's not unusual to discover a digital 'FreeView' broadcast movie has been transmitted (and recorded) at 544x576 16:9. Since this requires 25% less digital bandwidth (than 720x576) it is presumably a way to squeeze in extra channels. Remember, 16:9 square pixels is 1024x576 ... so the 544 will have to be expanded by almost x2 to fill the wide screen and this is noticeable on most modern LCD / Plasma TV's as a 'smoothed' or 'un-sharp' effect

How do I get the aspect ratio 'correct' on a DVD made from PhotoStory 3 ?

A1. PhotoStory 3 will 'crop' your images to using an EXACT 4:3 'square pixel' template. This means you get 768x576 in your .wmv output file.

Since TV's (and thus movie DVD's) have never had 'square' pixels, when you use Windows Movie Maker to convert into AVI, the 768 pixels will be 'squashed' into 720 = and the DVD player will then 'spread out' these 720 pixels to fill the (4:3) TV screen.

So you need do nothing for 4:3 output - Windows Movie Maker will do the 'squeezing' for you.

A2. It's a different matter when it comes to 16:9 display. Remember - PS3 can only 'crop' 4:3 (768x576) and WMM is going to 'squeeze' this into 720x576 which the DVD player will then 'spread out' to 16:9 TV screen (1024x576)

To avoid everything becoming 'fat and wide', you must 'aspect ratio distort' your original photos so that your start with it 'tall and thin'. When the PS3 makes it's 4:3 crop, it must actually 'get' 16:9 data (i.e. a 768x576 crop of a distorted photo must 'contain' 1024x576 data).

There are 2 ways to achieve this distortion. The first, obvious approach, is to squeeze the photo width from 1024 to 768 pixels (i.e. resize each image WIDTH to 75% of it's original). This results in the required 'tall and thin' photo that, after being expanded 'fat and wide', will end up being displayed correctly.

The second, less obvious way, to start with 'tall and thin' is to increase the photos height ! Plainly it is better to start with 'more' pixels rather than 'less', so, to get 16:9, start by resizing & expanding the HEIGHT of all your photo's to 133.33%

What about frame rates (NTSC and PAL) ?

Finally there is the video "Frame Rate" (and colour "Standard"). You might think that you can't 'cheat' on these (you need the 25fps PAL Standard for UK TV's) .. but again, most DVD players will handle the NTSC Standard and 30fps Frame Rates (29.8 fps) just fine, as will most modern TV's.

Most software is written in (or made for) the USA - this means your 'movie maker' is likely to generate NTSC (29.8fps) 'by default'. If this happens, and you can go back to the 'source' material and re-output to obtain a 25fps PAL version you should do so. If this is not possible, it's better stick with 30fps NTSC than to try to find conversion software that will do a decent job of converting it.

Note that some format converters allow you to choose a 'bit rate' ... the higher the bit rate the better the quality .. DVD movies range from 3 Mbit/s to 9.5 Mbit/s (and the bit rate is usually 'adaptive') with an 'average' of 6mbs. If your movie is just slightly too long to fit onto a single disk, you can try re-recoding with a slightly lower bit rate.

Note most movies shown on TV are broadcast at a data rate between 2 and 3.5mbs (so plainly 6mbs is 'overkill' :-) )

Finally you may ask, what about HD (movies and TV's) ? Well, that's another guide for another day ...

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