Is this a new feature in Vegas 4.0d? I've never heard that this was possible. The general sense has been that MPEG -> MPEG renders will always involve decompression/recompression no matter what.

"The Vegas 4 help file says you can render mpeg2 files without recompressing them"

Where exactly does it say that? I'd need to see the exact citation & context thereof before saying the help file is wrong (I looked for a statement like this, couldn't find it) , but anyway, here's the deal:

MPEG source files of any type will ALWAYS be recompressed when rendered.

Is the quality hit survivable? That's for you to decide.

Well I tried just taking one mpeg2 clip and saving it again with a different name, and after comparing the same frame from each clip, it looks like it was recompressed. I made no changes at all, so it shouldn't need to be recompressed.

Chienworks: I'm new to Vegas so I don't know when it was introduced, but I'm using 4.0b and the help file says that it won't recompress mpeg2 files. Search for mpeg and there is a topic titled "Rendering Projects for Use in DVD Architect". It says that you can edit mpeg2 files with no recompression. Maybe you need to have DVD Architect for that option?

I think that means that they won't need to be recompressed when you burn to DVD, not that they won't be recompressed when editing.

This from the help file in 4.0d:
If you have DVD Architect, you can avoid unnecessary transcoding or recompression by using Vegas to render your media files in the appropriate formats prior adding them to your DVD Architect project.

Sonic Foundry’s AC-3 and MainConcept MPEG-2 encoders provide templates that will produce files that do not require recompression (unless the file size is too large to fit on a DVD).

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Cheers

Ok, I guess I just misinterpreted that. But isn't it obvious that a mpeg2 file won't need to be recompressed when authoring a DVD?

So is there a possiblity a future version of Vegas will allow for editing mpeg2 without recompressing? I know it's technically possible but I'm having a very hard time finding software that can do it. Is there a suggestion box or feature request email for Vegas?

edit: nevermind I found the suggestion box, I'm just a little blind :)

Yeah - I think it refers to rendering to Mpeg instead of DV AVI, ie you won't have to recompress if you do it that way ...

Cheers

Assumption proven wrong. I probably should have said "if that's the info Sony gives out."

While it is technically possible to edit mpeg and there is software that does it as afr as I know it's very expensive stuff. In any case any time you apply any effect the source has to be decompressed, effect applied and then recompessed, same as for DV.

mpeg can be much harder to deal with as it uses temporal compression, to determine the contents of one frame may mean stepping back a number of frames. Even worse is trying to edit wmv files. I've had one with only one I frame in two hours of video.

There are a few that do it OK as long as you do cuts only, and those on I-frames. Womble, M2 Edit, and I think TMPGEnc. Maybe even V-DubMod.

I would assume that for this process to work, all the source files and the output file have to have identical properties. The frame size, bitrate, bit depth, frame rate, I-frame distribution, audio format, etc, would all have to match exactly. I would think that if any of the files differed then those files would need to be re-encoded to match the output file even in a cuts-only situation. Does anyone know if this is true or not?

Acording to the doc's in TMPGenc, that's true: all settings must match up.

Some of the real time Matrox cards boast "mpeg-2 editing." But, it's using their mpeg-2 codec, in an AVI wrapper, and is incompatible with anything but the Matrox stuff (unless you have their codec's).

We're lucky Vegas supports mpeg-2 on the timeline: Every version of Premiere before Pro didn't! they said that profesional editors would never use Mpeg on the timeline (guess HDTV proved them wrong!) :)

>>>We're lucky Vegas supports mpeg-2 on the timeline: Every version of Premiere before Pro didn't! they said that profesional editors would never use Mpeg on the timeline (guess HDTV proved them wrong!)<<<

That is not true. A few years ago I did a 30 minute show on the A*Teens and it was right when their 2nd CD was coming out. In order to get a new video onto the show I got an Mpeg 2 (PAL) file sent to me. I placed that onto the timeline in Premiere 6.5 and converted it from Mpeg 2 PAL to DV-AVI NTSC with no issues. (ok there was a sync issue but I just took the song from the CD and plopped that in and it was perfect sync.) Now HD - that is a very different issue. Premiere 6.5 does not handle Mpeg 2 HD files, but neither did VV at that time. Prior to version VV 4.0 b (I think it was) I had to use Womble MPEG2VCR to transcode a HD file to a readable MPEG2 file for either program. Come to think of it I also placed that HD downsampled file onto the Premiere timeline and included it in a film. So to be clear - Mpeg 2 files will work on a Premiere timeline in versions other than Pro. HD MPEG files won't.

And by the way - Womble MPEG2VCR doesn't recompress. I wouldn't recomend it for editing however.

MPEG-2 obviously allows different bitrates in the same file. That's the whole idea behind VBR encoding. The bitrate changes all the time. Also, with advanced MPEG encoders, you can change GOP, I frames, etc. so that you get clean changes at scene transistions, etc. Therefore, I think (althought I'm not 100% certain) that a single MPEG stream can change the encoding parameters as it goes along.

When doing cuts-only editing on MPEG, the editing program must still re-compress a few frames at the transition around the cut. Everyone says this is tricky, but my guess is that for an engineer that knows MPEG, and who has access to the MPEG libraries, it is probably not all that difficult. It is certainly within the realm of the capabilities of amazing SoFo/Sony engineers.

I, for one, would definitely like to see MPEG editing added in a future release. As I've said in other posts, while MPEG is mostly a format for viewing, the fact that everything is going to be distributed on DVD means that we will all be faced someday with needing to edit material that only exists in MPEG format.

Really? I've never gotten Premere to work with Mpeg-2's good. Did you have any mpeg codec installed? That would prove useful at work! :)