Friday, July 3, 2009

Quality Control for Web Video

Web video need to balance quality and size - you can't afford the bandwidth to make your video look perfect, so you have to accept some loss in quality. On the other hand, you don't want the loss in quality to be distracting to the viewers of the video.
When checking quality, you have to look closely at the video, and that can lead to your paying attention to artifacts that won't be noticed by the people watching your video, and possibly missing other artifacts that don't look as bad to you, but which are distracting when actually watching the video.

My method for identifying problems and knowing when I have fixed them is this:
First, I watch the compressed video straight through without pausing. I remember what distracts my attention from the video, and take notes.
I use these notes when working on fixing problems. I concentrate on those areas that distracted me the most. Although I might try to improve other artifacts that I see when working on problems, I make sure these artifacts are visible when playing at full speed.
When I think I have fixed the problems, I watch the fixed video again without pausing, trying to watch the way the expected audience would. If I don't see any problems watching like this, then the video quality should be acceptable.

1 comment:

NIGEL ALLEN's Official Airgun Blog said...

Hi Aaron.

Stumbled upon your blog quite by accident, but it's been most useful to someone who's just discovering all the complexity of video!!! I'm a photographer / journalist / designer and I can't believe how difficult it is to make the transition from stills photography to video.

As an experienced Photoshop user, I've stuck with Adobe and edit my videos using Premiere Pro. It's the rendering that's getting me confused. My camera is an HD Canon that records (flash) in AVCHD format [PAL - I'm in the UK]. I render this out in PP to H.264 .mp4 format, but 3-4 minute movies seem to be anything between 150 and 220 Mb when output at 1280 x 760. This strikes me as being extremely high and rather impractical for putting into a web page. If I try and make the output file smaller in dimensions, I seem to run into all sorts of problems, from flashing screens to jittery images. In truth, faced with all the output pre-sets in PP, I simply don't know what I'm doing!!!

I'm sure one should be able to get them down to more like 30-40Mb, but I just don't know how. They upload to YouTube okay (who then compress them), but I also want to upload my movies to iTunes. I think they're a bit big at the moment!

For website work, I'm currently just embedding in the YouTube html data - but it looks a bit naff!

Obviously, for iTunes, I have to store the original movie file on my own servers for them to access it... and space costs money! Would you be able to help me - even though my level of expertise is light-years behind yours when it comes to this stuff. Right now, though, I'm in serious need of a mentor... and your blog has given me hope that I'll be able to understand it all!!!

If you're able to find time to give me some useful pointers, you can contact me direct here: mail@nigelallen.net.
Thanking you in anticipation.

Kind regards,

Nige

HEEEEEELPPPPPPPPP!!!!!!!!