Technical video issues that will bite you in the ass
- What you see on your monitor/viewfinder is NOT what you get. This is because almost all cameras record illegal superwhite values above white level (these values are 'brighter' than white). Some monitors will show these values. These really bright values will be slightly distorted and/or out of focus on a CRT. Other monitors won't and will not show them at all.
In post production, you should clip / throw away
these illegal values. Broadcast colors / broadcast safe filters will do this. You could also darken the image so that these values are no longer brighter than white. I prefer the latter solution.
you work on set, then you should view (proofs of) the final product to know what the video really looks like. Don't assume. The post production folks may use either method.
- If you are making work to be shown on a TV, you need to check your work on a TV and not a computer monitor. Still images in a video project may flicker and squares and circles may be the wrong shape. If you are importing odd formats, the field order may be incorrect and the video won't look right in motion. Also, what you see in your editing software's preview is often wrong.
- (Macs and Quicktime) If you are exporting footage to After Effects, always check that the image looks correct. Depending on what format you choose, you may experience Quicktime gamma shifts.
- (Sony Vegas only) Vegas will get your video levels wrong even with the default settings and in the most common scenarios. See the levels articles for your version of Vegas on this site.
- If you create a video DVD with a DVD burner, it will not play back on some DVD players.
- The earliest HD equipment don't do modern HD correctly (or SD converted to HD). One example is the very first HD prosumer camera by JVC. Most of the earliest consumer HDTVs also don't do SD->HD correctly. This is because they use the wrong set of luma co-efficients (but you don't really want to know the exact technical reason). So, all the colors will be wrong.
- Resizing images may create artifacts. If you throw images into a video project and want to pan and scan them, you may need to blur the image to prevent aliasing artifacts (e.g. crawling along the edges and shimmering on fine detail).
- Broadcast monitors that have to resize the image aren't that good. No non-CRT display will handle SD without artifacts. For HD work, your monitor will create artifacts if it isn't displaying the pixels 1:1.
Making Broadcast Masters
- When making masters, do not assume that the video scopes in your editing application are correct. Some do not look at the whole image (e.g. Final Cut), some are wrong unless the settings are correct (e.g. Vegas), and most are poorly designed. If you need to make broadcast masters on video tape, scopes in your editing software will NEVER work. For proper quality control, you want your scopes at the very end of the signal chain. This will allow you to capture problems that occur between your editing software and your master tape.
This site by Glenn Chan. Please email any comments
or questions to glennchan /at/ gmail.com