Profound Revelation & Cutting/Joining Question

[AlecWest]

For the longest time, I used TMPGenc to do cutting/joining and was never completely satisfied with the result. The point at which cuts took place was sometimes "pixelated" and the audio, on a long project, sometimes fell out of sync. So, a while back, I asked for recommendations of a utility (hopefully free) that would do a better job.

Baldrick recommended Cuttermaran. But, when I first tried to use it, it didn't make much sense to me. However, recently, I decided to try it again ... and this time, it seemed easy and intuitive from the get-go. I didn't even have to refer to a help file (grin). Weird how sometimes you're confronted with a program that leaves you scratching your head ... but tried later, seems like a piece of cake. Must have been some kind of profound revelation.

In any case, I had a question. I did I-Frame cuts/joins to edit and bring together 19 files. Cuttermaran did it like a champ ... without any pixelation at the cut-points ... and with audio remaining in sync throughout the entire joined end-file. But, the fact that Cuttermaran is free and that I had to pay for TMPGenc Plus makes me curious. As I understand it, TMPGenc Plus relies on some other kind of frame cutting scenario (delta frames maybe). But, if I-Frame cuts/joins are superior, and assuming it's not some deep dark secret, why hasn't TMPGenc Plus incorporated this kind of scenario into their software? Anybody know? And, are there specific times when I-Frame cuts/joins are not considered desirable?

[Stormin Norman]

Cuttermaran is a very cool Mpeg program.

[bugster]

Cutting/joining on I-Frames is the easiest way. If you cut/join anywhere else, then unless the GOP where the cut/join takes place is re-encoded you will get some strange artifacts. Because of this many mpeg editors restrict you to I-Frames. Some allow you to cut/join anywhere. the better ones will re-encode the relevant GOP.

HTH

[spectroelectro]

You asked "But, if I-Frame cuts/joins are superior, and assuming it's not some deep dark secret, why hasn't TMPGenc Plus incorporated this kind of scenario into their software?"

Either laziness or gross incompetence. Anytime you do a join edit at a point not an I-frame w/o re-encoding, you'll get green pixelated crap because the mpeg player doesn't know how to interpolate from one compressed frame missing some video info to another compressed missing some different video into without an I-frame in between to tell what the missing info is.

There are a heck of a lot of things TMPGenc should do, and I've owned it since the days it cost $50 (and a good investment, too). For instance, the guys who are doing TMPGenc really oughta get someone to look at the innermost loops on the MPEG-2 encoding code and unroll 'em and translate 'em into assembly code. TMPG needs to be seriously sped up. Mainconcept does about as good a job but runs 3 times faster, and CCE runs ridiculously faster. Also TMPG still has known bugs, like the fact that the audio sampling rate will *still* default to the last rate unless you do CTRL-N to clear memory. And so on.

So it's disappointing but not surprising that TMPG is still using a crufty junky time-based method of join editing instead of the much better I-frame-based method used by Womble or M2 Edit Pro or Cuttermaran. As for your question "And, are there specific times when I-Frame cuts/joins are not considered desirable?" the answer is yes. If you absolutely positively need frame-accurate edits, cutting or joining at an I-frame won't do it. OTOH if you need frame-accurate editing, you should be working with Type 2 DV or huffyuv avi, not mpeg-2, which was never meant to be edited in the first place.

[AlecWest]

Thanks to everyone for their input. From now on, I'll use Cuttermaran for cuts, edits, and joins. It never ceases to amaze me what's out there that's available for free ... and that sometimes, paying for software doesn't ensure a better product.

[adam]

I think its more of a case of TMPGenc trying to bite off more than it could chew. By not limiting yourself to I-Frame cuts you allow for frame accurate editing, which is of course better, but only if the output doesn't get garbled in the process. TMPGenc hasn't yet perfected the method of re-encoding the set frame to an I-Frame an re-encoding the remaining frames in the GOP. Most other mpeg editors don't even try.

As for speeding up TMPGenc. The author of the program stated that someday he will have it completely rewritten in faster code, but that it is such a daunting task that he has been putting it off for years.

[reboot]

FYI, Cuttermaran can also be paired up with tmpgenc plus, to re-encode the portions of video you DO cut on non-I frames.
I use Cuttermaran all the time, and my only complaint is that it will only use tmpgenc for this.
If I had the option of choosing Canopus or MC, it would be a (near) perfect app.

[JeffM]

I have a MPEG2 VRO file that I want to cut. Why do I have to demux it into video and audio files?
I would rather edit it as one file. I don't want to mess around with two files.