Cutting a video with TMPGEnc

[Kazuya_UK]

I have been trying to cut mpg vids in half (so that they fit on 2 cd's) using TMPGEnc, but for some reason the video never gets cut exactly where I tell it to do it... its usually a few seconds (or even more) off.

Sorry if this has been asked before, but does anyone else get this problem and is there a way to fix it? Or should I just use another program?

[Vejita-sama]

Editing MPEG files is tricky busniess at best. Since I assume that you also encoded with TMPGenc the best thing to do is to use the source range option (settings | advance - source range) and select the part of the video you want to encode. For VCDs 1min=10MB (for x(S)VCDs it's going to vary depending on the bitrate you use).

With that said, yes when I try to cut MPEG files w/ TMPGenc it's always off +/- a few seconds. I don't know anyway to fix this. So I guess this post is more for future encodes

[Nelson37]

One thing that may help is to use latest version of VirtualdubMod to determine the time of the cut point and manually enter that time in TMPGenc for the cut. This reduced my inaccuracy from 2-3 MINUTES to more like 1-2 seconds. Make sure you use the Key Frame button in Vdub, as TMPGenc will only cut on I-frames. It also seems to consistently cut late on the beginning cut and early on the ending cut.

[puertorican138]

You could use bbMPEG to cut your file.

[puertorican138]

You could use bbMPEG to cut your file.

Example:

Part 1

Start second: 0
End second: 1984

Part 2

Start second: 1984
End second: 3729

:P

[adam]

The reason the cut points are off is because you can only cut on an I frame. From my experience...TMPGenc does an ok job with mpeg1. If your cut point doesn't fall on an I Frame, which will almost always be the case, it will add an I-Frame at that point and re-encode any files in between it and the previous I-Frame. For the most part, its accurate. With mpeg2 this all seems to go out the window. It just cuts on the nearest I-Frame so it can be as much as 1 sec off with standard GOP settings, sometimes even more.

BBMpeg is subject to the same limiations, it can only cut on an I-Frame, but it seems to do a much better job.

As Vejita-sama said, the most accurate way to cut mpeg is to use the source range feature in TMPGenc, since it can automatically add an I-Frame at the cut point. The only other accurate way to do it is to manually add an I-Frame at the point that you know you will want to eventually cut at.

From my experience, the dvd player always cuts off the last half second or so of my video anyway, so I'm really not too concerned about pinpoint cutting by the exact frame. I just overestimate by about 1 second and leave it at that. Usually it all turns out about right.

[Nelson37]

bbMPEG, now there's an idea!

Is there any way to use multiple cut points, for cutting out commercials? I know I could make multiple clips and then merge, but a one-step process would be nice.

TMPGenc gets close enough for just trimming beginning and end, but for commercial cuts I often get a quick logo splash, often with loud fanfare music for 1/2 sec or so, just enough to be really annoying.

[adam]

There's no way to do multiple cuts in bbmpeg...you set a start and and an end time (or size) and that's all you can do.

If you want to do this type of editing, removing commercials and such, the easiest thing to do would be to edit it out while its in avi format...you are capturing to avi right ? You could very quickly and easily cut out all the unwanted parts in vdub and then frameserve to your encoder.

Other than that, you could use avisynth and tell it to encode in frame intervals...I forget the syntax but basically tell it frames 0 through 2000, 2500 through 4000, etc... You essentially cut out all the unwanted frames and have all existing ones merged.

You can only do this type of editing either with avi files or during encoding. You can't cut and merge mpeg files all in one go, at least not very well. Those pesky b and p frames just don't allow for this type editing.

[Nelson37]

Actually I am doing real-time MPEG-2, CVD, with real-time IVTC on movies. The IVTC definitely works, and quite well.

I have done AVI and hi-bitrate MPEG capture with re-encoding and editing, this no longer presents a challenge.

I am getting very respectable quality with 80+ minutes per CD on the movies, for episodes I raise the bitrate, go SVCD res, and do not use IVTC. Frame accurate cutting IS possible with M2-Edit, I have been attempting to avoid using this expensive program. TMPGenc gets very close when given accurate time info, as I get closer to defining its direction of inaccuracy I am better able to compensate for this.

My current goal is real-time cap WITH AC-3 SURROUND SOUND, as yet the required sound card is too expensive but that will change soon. Being able to watch the commercial-free episode 30 minutes after broadcast, with FF, RW, and Prologic sound, is very satisfying. The only problem so far is unpredictable filesize, which MMC 8.0 will hopefully rectify.

[marcelr]

Use virtualdub to cut, it is easier.