Production Techniques

Often you find yourself repeating common transcoding tasks in virtualdub. After a while it becomes annoying to have to set the codec and other settings or event to load a VCF each time. Fortunately it is easy to make virtualdub load a settings file on startup, just follow the steps below..

1. Save the settings you want to use as a .VCF file called "foobar.vcf" (File>save processing settings)
2. Copy foobar.vcf to the directory where the virtualdub.exe lives (possibly something like C:\Program Files\VirtualDub\)
3. Make a shortcut to virtualdub.exe
4. Right click the shortcut and choose properties
   

VirtualDub is a very good application for reformatting AVI files - you can download it from virtualdub.org. A typical use would be to batch convert a load of AVI files for use in VJamm 3 Standard.

For the best quality in VJamm 3 Standard you need to make files that are 384x288 in size with PicVideoMJPEG compression - or Indeo compression if you do not want to buy picvideo.


Here is a VirtualDub Setting file for VJamm clips with PicVideoMJPEG compression.

In the first part of this series we looked at standard 4:3 content and saw how the relationship between pixel aspect ratio and dimensions go together to define the shape of the frame. In this article we will look at widescreen content and examine a range of methods for producing and displaying widescreen content.

Widescreen content is becoming more and more popular, not only in cinema and broadcast production but in live event video too. There are many different aspect ratios in use across these disciplines which makes things more complex than perhaps they need be. For the sake of simplicity we will look only at 16:9 widescreen as this is the most popular of the wide aspect ratios and is the ratio that the majority of plasma and LCD screens are available in.

16:9 content comes in three basic flavors

• Letterbox
• Anamorphic
• True 16:9

Letterbox content is normal 4:3 video which has black bars rendered across the top and bottom to mask off the central 16:9 display area. PAL video of this type has a frame size of 768x576 or 720x576, however the active video area is considerably lower resolution due to so much of the frame being masked off.

Letterboxed widescreen has the advantage that it can be displayed on regular 4:3 displays and mixed with normal vision mixers - all playback systems can deal with letter boxed widescreen as it is effectively the same as 4:3 content.

The majority of 16:9 displays (eg plasma and LCD screens) can be set to correctly crop the black bars from the top and bottom of the content so the display shows the active content area full screen

Aspect ratio is important - it defines what shape you video will be. if you display things at the wrong aspect ratio your video will be distorted.
Video comes in many different formats - for the purposes of this document we'll stick to looking at PAL video - we will look video that originates from DV cameras and video that is entirely created on computer.
Digital video's aspect ratio is controlled by two basic factors, the pixel dimensions of the frame and the aspect ratio of the pixels.

• Standard non-widescreen video has an aspect ratio of 4:3
• PAL Video is 768x576 square pixels
• PAL DV Video is 720x576 D1 Pixels
• D1 Pixels are rectangular they have an aspect ratio of 1.066:1
• Square Pixels have an aspect ratio of 1:1

Square Pixels (1:1)	D1 Pixels (1.066:1)	Overlay on one another its easier to see