A customer wrote in this morning with a technical issue with HD, and it reminded me of why we need MPressionist.X in the first place.

Many of our customers are beginning to rely on MPressionist as the defacto 'scope' which gives them both a birds-eye view and a microscope of their compressed movie files; the files which represent the results of many hours of pre-production, production and post-production.

The first thing to understand about MPEG-1 and MPEG-2 playback, is that the goals of a playback decoder, and the goals of a diagnostic decoder (MPressionist) are completely opposite. MPEG-2 video, and its predecessor, MPEG-1, were designed from the get-go for operation in noisy environments, where bitstreams could be sliced, diced, lost, mixed up etc.

And so the goal of playback decoding is to leverage the unique error resiliency of MPEG to mask or hide any errors that might be in the video bitstream. By masking these errors, the viewers experience is maximized, especially with scratched or damaged discs and areas of weak satellite reception. It could even be that Mrs. Manfredjinsinjin next door turns on her vacuum, causing your lights to dim and the power source to your set-top-box to become so noisy as to be digitally hostile. Whatever. The point is that MPEG is well-suited for drop-outs, and every piece of well-designed playback software will do whatever it can to mask or hide errors, missing data and strange sequences of bits that it finds in the video bitstream.

And we like it like that.

MPressionist.X, on the other hand, is designed to do exactly the opposite. Everywhere MPressionist looks, it looks for errors, inconsistencies, and does its best to help you to locate, identify and evaluate artifacts and errors in the video bitstream. And it gets better at this with each passing month.

And I'd say its importance escalates any time you need to employ MPEG-2 assets that were encoded by 3rd parties: service bureaus, contractors etc.

When I look at these commercial DVD titles with breaks in the 2:3 pulldown flags, I have to wonder? Did they even know? My guess is that they did not. Looking for errors in what amounts to a few hundred KB of repeat_first_field bits in a file 4GB in size - I mean - whodathunkit?

Most people test their DVD discs by watching them on whatever they have handy. This is a form of ad-hoc testing, and if it works for you, great. But we must understand that ad-hoc testing is no substitute for engineering discipline. MPressionist is no blanket-catsup solution either. Rather it is one part of the solution which does a job that, as far as I know, no other tool can do, which is allow you to 'see' the bitstream by its bitrate and compression profile and correlate changes in the underlying compression with the visual moving picture.

And as your production schedule steps up, you may want to encode as many times as necessary to get a clean picture, and you may find that having this tool helps you find and eliminate problems earlier in your production.

Better to find bitrate problems before you try and build and format your disc.

Better to find compression artifacts before you send a comp to a client.

And finally, much better to be sure of the quality of the moving picture, all 2hrs of it, before you send the master to the pressing plant for replication.