m2t to HD Mpeg2 smart render problems

Steve Hamilton wrote on 3/10/2008, 11:24 AM

Hello all,
I'm testing prior to (hopefully) purchasing Vegas Pro 8 and have run into a problem with smart rendering m2t to HD Mpeg2 files. I am unable to smart render an m2t (captured w Vegas,30 seconds length, no transitions, effects, etc.) to an HD Mpeg2 clip of the same compression settings (1440x1080, 25Mb/s CBR, 29.97 fps). The smart render process begins (preview displays "no recompression required"), progresses for a while and then stops with an error (exception 0xC 0000005). If I turn off smart render, the clip renders normally.
I CAN smart render w/o problems the m2t file to another m2t file w/o problems.
I then non-smart rendered the m2t file to another m2t file and an HD Mpeg2 file to assure the GOP structure is properly reconstructed. The new m2t file will still not smart render to HD Mpeg2, but the new HD Mpeg2 file will. I can also smart render the HD Mpeg2 file back to m2t successfully.
So, the problem seems to be specifically the m2t to HD Mpeg2 smart render conversion.

Has anyone done m2t to HD Mpeg2 smart rendering?

Thanks,
Steve

Thanks,
Steve

Back to post

Comments

owlsroost wrote on 3/12/2008, 5:10 PM

There is a guide to the MPEG encoder settings here [url=http://download.sonymediasoftware.com/whitepapers/mpeg_overview.pdf] - a bit out of date but still useful.

Tony

NickHope wrote on 3/12/2008, 10:42 PM

I'm just concerned about the start and end where it can't smart render because it doesn't have a full GOP. I'm archiving for stock so I need the best quality even at the ends.

Here's what that Sony white paper says about the quality slider:

Video quality

I'll do some testing with 1080i50 material at extreme settings of the slider.

Wolfgang S. wrote on 3/13/2008, 2:19 AM

The white paper is outdated really - I think it came long before smartrendering, and long before HDV.

owlsroost wrote on 3/13/2008, 2:45 AM

It dates from 2003, so before HDV and smart-rendering.

Basically, if rendering time for the re-encoded parts isn't an issue just set the slider to 31 and forget about it.

The 'quality' control for most encoders controls how much effort (= time) is applied to motion estimation and other picture analysis. Put very simply, if the motion estimation is poor the difference pictures get bigger and have to be compressed more (= become more blocky and posterised) to keep within the bitrate limit.

Tony

NickHope wrote on 3/16/2008, 6:23 AM

Just rendered some 1080-50i HDV m2t material to the same format with a logo overlay in the corner (so it wasn't smart rendered) with the slider at 0 and then with the slider at 31.

I can't see any difference at all in the rendered footage. Maybe the slider has no relevance for HDV, which is why they would leave it at 15? Or maybe its effect only shows up if one is doing more complex effects or compositing.