MPEG-2 still broken

gbohn wrote on 2/1/2002, 9:32 AM
O.k., I broke down and tried to update the MainConcept MPEG-2 encoder as described in a previous topic. I downloaded the 2.0c demo for Video Factory, and installed it on my Win 2000 SP2 system. I uninstalled the demo, with the expectation that this is supposed to leave the updates for MPEG-2 behind (as also described in a previous topic).

I then tried several of the renders that previously failed. They still don't work.

I have a fifteen minute test DV clip I was trying to render (no effects), and this is what I still see:

*) Tried using a Constant bitrate of 6,000,000 bits per second. I select Render/MPEG-2/DVD NTSC template/custom/click CBR (leaving the rate at 6,000,000)/advanced/check 'allow field based motion'. I close the settings and let it render. After about 50 minutes the program stops, saying 'An error occurred while creating the media file xxxxx.mpg, the reason for the error can not be determined'.

The only improvement here is that the program produces this pop-up. VV3 previously would stop responding and need to be killed with Task Manager.

*) Tried the same thing with a CBR of 5,000,000 bps with the same result. Prior to applying the demo, I tried CBR at 9,800,000 which ran to completion. Only problem was that this produced a file whose bitrate was apparently too fast for my Panasonic DVD player and the file would not play without skipping/jerking video. (Dividing the size of the physical file produced by the number of encoded seconds yielded an average bit rate of 10,760 Kbps...)

*) Tried using the Variable VBR on a shorter DV section of only about 20 seconds using the same DVD NTSC template. Using the default values for min/max/average bitrate I created files using Q of 1, 10, and 20 (and again field motion compensation). This produced identical output files for all three Q values. Do I just misunderstand what the 'Q' setting is for, or is this broken?

If I perform an 'about' on the MPEG render page, It says it is Version 1, build 36. Is this what I should see after using the 'Videofactory 2.0c Demo' update procedure to patch the MPEG code?

These same DV clips encode in tmpgenc and LSX-MPEG LE in Adobe Premier without any similar problem, so I don't believe it is the fault of the clips themselves.

So, do I really have the 'fixes' (in which case MPEG is still broken), or did the fixes not 'take'?

Thanks;

-Greg Bohn

Comments

RichMacDonald wrote on 2/1/2002, 9:46 AM
Strange stuff. I'm having no problems with VBR from 5Mbps to 8Mbps.
Download the foloowing free bitrate viewer and take a look at these files.
It will show you bitrate and Q as a function of time.
Might help figure out what is going on.

http://www.tecoltd.com/bitratev.htm
gbohn wrote on 2/1/2002, 10:45 AM
>Strange stuff. I'm having no problems with VBR from 5Mbps to 8Mbps.
>Download the foloowing free bitrate viewer and take a look at these files.
>It will show you bitrate and Q as a function of time.
>Might help figure out what is going on.

I've only tried a quick/short test using VBR, as I mention above. My concern expressed above was that changing the Q appears to have had ZERO effect on the output (as the output files are identical in size and binary content).

Are you saying that when you encode a clip using a given set of render and VBR settings(Based off of the DVD NTSC template), and encode it again changing only the Q, that the files produced are not the same when you try this?

I did look at the short test VBR mpeg I produced using the bitrate viewer, and I can see the output Q vary substantially over the (admitedly short) time of the clip.

-Greg Bohn
stevemil wrote on 2/1/2002, 11:58 AM
I've heard mixed claims about uninstalling the VF demo. Some say if you uninstall it, then Vegas will revert back to the old encoder. I find that hard to beleive, since I'm assuming the VF demo replaces the encoder, so the old version is not even around anymore.

I just installed Vegas and VF 2.0c on a clean machine (dual 2.2 Xeon, 1 GB PC800, Windows XP Pro) and am having much better luck with encoder than I did on my old machine running Vegas with VF 2.0b. I haven't done CQ yet, but my VBR tests seem to be more accurate than before. When I click on the "About" button in the "Render As" dialog, I see "Version 1.0 (36)" as the version of my MC encoder.
SonyEPM wrote on 2/1/2002, 12:16 PM
MC MPEG, version 36, shipped with VideoFactory 2.0c.