Sony MXF Questions

VRodder wrote on 1/1/2010, 3:37 PM

I was having some trouble rendering a blu-ray project using AVCHD video and numerous image sequences, along with jpgs and other effects.

What I ended up doing to get the job done was, converting the individual AVCHD clips to Sony MXF.

Then I rendered the timeline in parts (5) to MXF again;

Finally, I put those parts together on a new timeline and rendered them to blu-ray.

My question is:

How much am I losing in quality by having to do this? I'm under the impression that initially rendering the AVCHD clips to Sony MXF doesn't effect the quality much if at all.

How about then adding effects, titles, transitions, etc. and rendering to MXF again? Seems like I should be trying to get to the final output here instead of rendering yet again to MXF, then finally out to the final destination....

How bad am I hurting myself?

Back to post

Comments

Rob Franks wrote on 1/2/2010, 4:14 PM

Good analogy... but not quite as simple. With stuff like avchd... mpeg2...etc, there's this thing called GOP to worry about. You can't re-write a few frames then go instantly back into smart render mode. If you alter so much as a single frame within a particular gop structure.... then that entire GOP structure must be re-written.... so shifting in and out of smart render mode isn't the easiest thing in the world to do. Now you COULD streamline smart render by only allowing a cut or a change at a particular points of the gop so that the whole gop doesn't have to be re-written.... but then that's not what Vegas is all about... It's about editing with frame by frame accuracy.

BudWzr wrote on 1/2/2010, 5:11 PM

I'm deleting posts because I'm trying to be careful. Sometimes a patently funny but outrageous statement can be misinterpreted.

Bill Ravens wrote on 1/2/2010, 5:12 PM

who is rob franks?
all of a sudden, he makes 29 posts in december. he talks like he knows what he's talking about. for that matter, who is bill ravens? just some dork who pops out of nowhere?
something to ponder......

Harold Brown wrote on 1/2/2010, 6:08 PM

[link=]http://www.videopia.org/index.php/read/articles-mainmenu-229/576-lossless-codec-quick-survey.html[/link]
Lossless Codec Quick Survey

Jay Gladwell wrote on 1/3/2010, 6:34 AM

Link is broken.

Try this.

ingvarai wrote on 1/3/2010, 12:32 PM

VRodder:
>How much am I losing in quality by having to do this? I'm under the impression that initially rendering the AVCHD clips to Sony MXF doesn't effect the quality much if at all.

I am under the same impression. Some people here in this newsgroup claim that the quality loss is even "very visible". I wonder what test they carry out. I have done my own tests, and see [almost] no quality loss at all when rendering out AVCHD from my Panasonic HMC 151 (MTS files) to MXF, using the "Main" template in Vegas. In my case it is 1280x720 50p.
If anyone can give advice on how to test, in a way that shows me the alleged quality loss, I would appreciate it. I, on my side, can upload a video where I explain the way I test, and you could advice me what I do wrong, to get the negligible quality "loss". Because I see no loss at all.
Ingvar

VRodder wrote on 1/3/2010, 2:59 PM

I did a little test this morning of my own. I took a few clip samples, plus some image sequences and did a split screen render to blu-ray; left side original, right side previously rendered to MXF. Popped the disk into my Oppo player and could not tell any discernible difference between the two. So I think it's fine for at least one generation...

So I think from now on I'm going to convert my AVCHD clips to Sony MXF before dropping any of them on the timeline. Same for my image sequences.

Hopefully that'll improve Vegas' editing performance and cut down on the "low mem" issue I've been fighting when final rendering.

Jay Gladwell wrote on 1/3/2010, 4:09 PM

Ingvar, try this...

Subject: RE: Need Help Understanding Codec Differences

ingvarai wrote on 1/3/2010, 4:21 PM

Jay,
thanks!. I have however tried this and a related test method. I also used the Vegas scopes for the difference. Saw no quality loss.
When time permits, I will upload my test procedure to YouTube and let you judge, and tell me if I am using a "forgiving" source.
Ingvar

ingvarai wrote on 1/3/2010, 4:27 PM

> Hopefully that'll improve Vegas' editing performance
Yes it definitely will. I often use MXF as proxy files. eventually I also started to use MXF for intermediate renders too, since I did not see any quality loss. When used as proxy files, I revert back to the original AVCHD files for my final render, mixed with the intermediate MXF sources.

I also would like to mention that while I hated the AVCHD stutter and jerky playback, I have got used to it and found out it is not that bad after all. So often I now use AVCHD as is. I have acquired Adobe After Effects, and in comparison Vegas runs like oil, AE like molasses :-) So I am not that picky with non-real-time preview anymore.
Ingvar