VP80a SD MPEG smart-rendering

owlsroost wrote on 1/15/2008, 5:53 AM

As this question pops up periodically in other threads, I thought I'd post a topic re my experiences......

Vegas Pro 8.0a/8.0b **can** 'smart-render' ordinary SD MPEG-2. It's not an advertised feature but it does work - I've done several simple projects recently using the feature.

The tricky part is that you need to create a custom MPEG-2 render template which matches the parameters of the source files i.e. bitrate (the value in the MPEG headers), CBR or VBR, frame size, frame rate, field order and GOP length. Vegas can't give you all of this information so you need another utility to find this e.g. Bitrate Viewer [url=www.tecoltd.com/bitratev.htm]. The GOP length is probably best sorted out by trial and error - it's almost certainly 12 or 15.

When it's all set up correctly, you should see a 'No recompression required' (or similar) message in the preview window during rendering (other than at the edit points).

I've tried this with both CBR and VBR files from a DVD recorder and another hardware encoder with good results - the output files play OK, and Womble's GOP checker utility doesn't find any timecode/PTS errors etc - which certainly isn't the case with the smart-rendered output from the Ulead products I've used in the past......so well done Sony (Mainconcept?) for getting it right first time.

It's not as fast as Womble either for scrolling during editing or output file production (I've used Womble and MPEG-VCR for years) - but I've never seen anything else that comes close to Womble for MPEG editing speed so this isn't too surprising.....

What are other peoples experiences with VP80a non-HDV MPEG smart-rendering ?

Tony

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musicvid10 wrote on 2/28/2008, 7:03 PM

owlsroost,

I'd sure like to get this working on my XP, Vegas 8.0b setup.
I've been able to tweak the render properties to get about half the frames to go through unrecompressed (is that a word?), but I don't have enough information to get the settings just right.

The Bitrate Viewer crashes on one of its own .dll's every time I try to use it. I've tried some others, but not enough info.

I am working with .vro files from my Panasonic DVD-RAM set-top and would love to edit out commercials and smart-render for quick authoring in DVDA (personal use only, of course).

Any advice or direction to another info tool is appreciated . . .

owlsroost wrote on 2/29/2008, 12:56 AM

You could try Gspot - [url=http://www.videohelp.com/tools/GSpot] - as an alternative to Bitrate Viewer.

What happens when you render - does the 'No recompress' message flash on and off rapidly ? - this seems to happen if the GOP length ('I-frames' in the MPEG render settings) is too short, so try increasing it to 15 or 18.

Tony

musicvid10 wrote on 2/29/2008, 7:03 AM

Yes, I get a flashing white-on-black message that varies with different settings of the I-frames but doesn't stay on screen.

I got the information from another utility that my GOP is 15 and IBBPBBPBBPBBPBB
All but the first are closed and all have sequence headers.
With I-frames at 15 and B-frames at 2 (the defaults) in Vegas I get the flashing.

I'll try the utility you suggested, maybe it will give me more info. Do I need to worry about the DC and VBV?

owlsroost wrote on 2/29/2008, 11:30 AM

I doubt DC and VBV make a difference (I'll try it just to check).

The GOP structure you've described is normal.

The first GOP of a stream/file is always closed and usually the rest are open, but having all closed GOPs is allowed - it makes editing easier, but reduces the compression efficiency so open GOPs are the norm. (A closed GOP has no references to pictures in the preceeding GOP - hence the first GOP in a stream is always closed).

I wonder if there is something strange about the .vro files - have you tried using something else e.g. Nero Vision Express/Ulead to rip the disc to MPEG files before editing in Vegas ? (I don't have a DVD recorder which uses DVD-RAM so I can't try it myself).

Tony

owlsroost wrote on 2/29/2008, 12:10 PM

Another thought - make sure the 'two-pass' box is NOT ticked in the MPEG settings.

Tony

musicvid10 wrote on 2/29/2008, 5:16 PM

Nothing strange about .vro afaik, it plays fine when named to .mpg or .vob in every app I have. Also, the import feature in Vegas saves an .mpg file to disc that authors without recompression in DVDA. The issue comes up with edits / cuts (commercials) in Vegas and a need to render a video file for DVDA without recompressing (read that all night on my machine).

The only difference (besides the extensions) in dvd-ram is that the .vro file, which unlike .vob files, is all in one piece, as opposed to the .vob "chunks" in dvd-rom. So it really should be identical to an .mpg source file for instance, unless there is something I am missing.

Since I am behind you on this learning curve, could I send you a 20MB or so clip recorded on my Panasonic and see if your could arrive at the proper smartrender settings?

I really appreciate your responses and the benefit of your experience on this. Also, is it possible to write a script to get the necessary info from the source and adjust the render settings to smartrender the output? I would happily pay $ for something like this.

owlsroost wrote on 3/1/2008, 2:10 AM

Since I am behind you on this learning curve, could I send you a 20MB or so clip recorded on my Panasonic and see if your could arrive at the proper smartrender settings?

Yes, sure - I was thinking that this might be the next step....click on my user name to email me.

I don't have any experience of scripting in Vegas, but Sony really need to add the MPEG analysis to Vegas (or better, automate the render template generation).

Tony

musicvid10 wrote on 3/1/2008, 8:44 PM

well, I got the results I wanted -- kind of.

By editing the dvd-ram on the set-top recorder (it certainly isn't frame-accurate), I got a .vro file that Vegas doesn't like at all. If I even move the cursor on the timeline, Vegas chokes and dies on the spot. The previews have lots of red frames and the last 25% of the audio peaks aren't built.

BUT -- if I JUST open the file and don't move the cursor, I can normalize and render the audio. Then I can open the video and audio in DVDA and author a DVD that plays. But when it gets to the end, it doesn't know its over, and just hangs there, probably because I edited material off the end.

Oh well, think I'll cave in and pay for Womble. I understand it takes care of everything for you.