Quality inspection & black borders

[Yannis]

I use a typical simple way of keeping/reencoding the movie only in most cases. DVD2AVI to extract audio and make the d2v project, TMPGenc (2.9 and older versions), ac3delaycorrector, subrip, maestro, dvddecrypter.

After reencoding I want to check the compression quality and although it is not the most logical thing to do (human visual motion/perception issues ignored), I use PowerDVD to take snapshots from the original and the reencoded video streams and compare them.

1) Is this the best/only thing I can do for manual quality inspection?

2) Why PowerDVD gives me bigger black borders in the reencoded m2v/vob? TVs ignore the borders on the right/left effectively and the reencoded image does not look ~20 pixels more squashed, but I do not understand why this happens. I have played with most TMPGEnc settings with no result.

Thanks in advance

[FamousPerson]

Originally posted by Yannis
1) Is this the best/only thing I can do for manual quality inspection?

2) Why PowerDVD gives me bigger black borders in the reencoded m2v/vob? TVs ignore the borders on the right/left effectively and the reencoded image does not look ~20 pixels more squashed, but I do not understand why this happens. I have played with most TMPGEnc settings with no result.

1) That actually sounds like a great method for testing quality

2) Are you saying the black borders on the left/right get bigger from encoding or just from TV to PowerDVD? Because TV can cut off up to 60 or even 80 pixels on all sides. Even flat screens. PowerDVD does not.

[Yannis]

Thanks for the reply!

1) For *automated* inspection, we could examine the statistical distributions of low/high signal frequencies. We could even examine the coefficients themselves or use other signal correlation techniques from signal/image processing... But for a quick & dirty *manual* inspection (e.g. object edges and highly textured areas appearing more blurred in the re-encoded stream is obviously indicative for loss of detail...)
If your comment is ironic, you may suggest your way of inspecting, if not, then my way is not great as it depends on the alcohol you have consumed or the dust on your TV set :D :D :D

2) No, I am not talking about the dead area in the TV border. I am merely saying the *still* images generated by PowerDVD (snapshot icon) have different black border size... that's all and I do not know why :confused:

[FamousPerson]

1) no, I was serious. the ultimate test is if it looks good to you, right?

2) yes, I was talking about those borders. You don't see them on the TV because the tv doesn't show you everything, which I find annoying.