Render from MPEG2 Source Blacks Out

Ron Lucas wrote on 8/19/2002, 9:55 PM
Using VV30c, I've rendered a few different 90 minute MPEG2 files with the field order set to "lower field first". When watching these videos, they plays back perfectly without any problems either in Media Player on my computer or on a DVD disk on my TV.

Now I'm trying to bring any of these 90 minute MPEG2 file into a new project in VV30c to create small video clips from the large videos. No matter what type of file I try to render to (WMV, MPEG1, MPEG2, or AVI) I get a short 1 second black out of video while the audio continues without a problem. This black out happens at different times in different videos.

In playing around with this, I tried setting the field order of the event itself to "None Progressive Scan" just to see what happens at the same moment in time. In this case, even though the field order gives me unwanted results in viewing the new smaller rendered file, the black outs do not occur. Therefore, it seems to me that VV30c is having trouble reading MPEG2 files, which it created, correctly to use as source material.

Any ideas? Has anyone experienced this? I did a search and found one person described a similar situation, but I did not see a solution. I understand that I might not want to use MPEG2 as source material, but I have no choice.



pelvis wrote on 8/19/2002, 10:40 PM
There are a number of tools available on that allow you to cut an MPEG file without recompressing (which Vegas always does with MPEGs of any type). TMPEG, I believe, does this and should work with Vegas generated MPEGs.

Ron Lucas wrote on 8/19/2002, 11:23 PM
Thanks for the suggestion. While you mention other utilities, I've been wanting a reason to upgrade to SoundForge 6. I've read that it can now read MPEG1 & MPEG2 files. Has anyone here tried to open an MPEG2 file in SF6, made some changes to it like cut the beginning and ending parts away, then saved it out as a new MPEG2 file or WMV file?

Ron Lucas wrote on 8/21/2002, 3:28 PM
Well, SF6 won't let me edit video by means of cutting - only audio, although it will allow me to open up video. So this won't work for me.

Sofo, have you seen what I'm talking about during a render to an MPEG2 using an MPEG2 event created by VV30c? I get about a 1 second blackout of video but the audio continues to play during the blackout. When I view the source MPEG2 video in Media Player, the video is all there. Help?

The MPEG2 source I created using the NTSC DV preset in VV30c so the field order is Lower Field First. Then I bring this video into a new project and try to create a new MPEG2 file using a trimmed section.

SonyEPM wrote on 8/22/2002, 10:03 AM
MPEG, especially VBR MPEG, is not in any way an ideal source format, but I guess that is your only option for this project...(?)

Anyway, last night I did a 60 minute test render, DVD NTSC MPEG source files, cut up and re-arranged, DVD NTSC MPEG output, didn't see any black frames on the timeline or in WMP.

If you send me the .veg project (send to and I'll take a look- not sure if it is something I'll be able to repro or fix, but might be worth a shot.
Blackout wrote on 8/26/2002, 9:11 AM

i have experienced this EXACT same problem. I posted a difinitive description in this forum a few weeks ago explaining same, but no-one responded.

I find the 1 second "blackout" happens consistently after an edit in the video in the timeline, usually about 1 min or so after the edit. My source is any mpeg2 file at 704x576 PAL. I am trying to convert them to DVD mpeg2 (ie. 720x576), so a non-destructive editing program is not for me, i also need to be able to adjust contrast etc. This should be bread and butter stuff for Vegas. Whether i out to Mpeg2 or avi i still get the black dropouts. I have also found that the blackouts occur consistently in the same place in the output file when i try to re-render.

Im using an AMD 2100+, Asus MB, 512 Meg, WinXP, VV 3.0c B138.

Please look into this bug now SF, expecially as it is now clear that i am not dillusional.

many thanks,

SonyEPM wrote on 8/26/2002, 9:26 AM
There must be a reason you are capturing as MPEG-2- what is that reason?

Is there any possible way you can use .avi (preferrably DV .avi captured with SF Video capture) rather than MPEG as your source format? Even if converting or capturing differently seems like a hassle, you WILL get better results with .avi.

Blackout wrote on 8/26/2002, 9:45 AM

thanks for responding SF...90% of TV cards capture "to air" programs to mpeg. My TV card has a timer on it to help with capture. is Vegas designed to be able to drag mpeg2 files into it or not? are you honestly telling me not to use vegas to convert an mpeg2 file to avi? i cant believe you are suggesting that i have to buy another program to do this now?

with thanks,
SonyEPM wrote on 8/26/2002, 10:42 AM
I have said before, and will say again: MPEG files are NOT an ideal source format and you may run into problems when using them, not matter what format you are rendering to. Just being honest here. Yes, you CAN drop MPEG files on the timeline- but that doesn't mean they will work perfectly in all cases. We have never claimed otherwise and we encourage users to use .avi source video files whenever possible.

BillyBoy wrote on 8/26/2002, 11:03 AM
I've used MPEG source files a lot, because for a huge project I've been working on for over a year that's all I have to work with. Sometimes a 'blackout' will appear on the timeline, that doesn't show up when played in a viewer like Microsoft's Media Player. I've played such video from within Vegas Video and my experience has been sometimes the backout shows up in preview, sometimes, not.

What I've saying is I can play the same MPEG source file five times, not change a thing and sometimes a black frame will flash by, other times not. It may or may not show up on the timeline, probably due to how far I'm zoomed in.

What I've been able to do is split the source file at the point the backout happens, cut it out, only to have a new blackout appear to the right or left of where the original backout appears. Again playing through the section, even at frame by fame it may appear, then again it may not. I suspect this has something to do with "I" frames and with MPEG's that's just the limitation. Conclusion, if for whatever reason you're using MPEG as source files, just something you'll have to live with.
Cheesehole wrote on 8/26/2002, 11:28 AM
perhaps TMPGEnc can do what you need. it is very inexpensive and is also one of the best MPEG encoders you can get. I'm not sure it can do this, but it's worth a look.

here's something from the latest version's release notes. looks like you are in luck, as long as you have one of the recommended software DVD players. (i use cyberlink powerdvd)

"TMPGEnc 2.57 reads MPEG-2 files only with specific official commercial legal MPEG-2 decoders made by CyberLink, Ligos and, Sony so that TMPGEnc reads MPEG-2 files most appropriate way by operating these decoders directly from TMPGEnc.
Blackout wrote on 8/26/2002, 12:07 PM

the sad truth is, TMPGenc can split up the mpeg2 at several edit points, as it converts to 720x576, and re-encodes to mpeg2 (in better picture quality than what the Mainconcept Vegas plugin can)....and it has NEVER left black dropouts in this process....the same file in Vegas editing on the same spots (editing out the same commercials) causes black dropouts. So please dont blame the "mpeg2" process SF. A $40 program can do it just fine...why vegas cant is still a mystery. Now we have at least 3 ppl here that have this same problem with 3.0c.

I would rather use Vegas as otherwise it is a far better user interface and more elegant, and easier to do things like fade video in and out, adjust sound volume and EQ, etc...things that are not so easy to do in TMPGEnc. Its also meant to be a lot more "pro". I dont have Premiere but i can only assume that those users can drag a 704x546 mpeg2 file in and output a clean DV avi. Please just say its a bug SF and lets move on...

Saturn49 wrote on 12/6/2002, 3:05 AM
I have seen this same problem. I have no option to use .avi as a source, and I absolutely need to re-encode my mpeg source (to lower the bitrate), so there is no workaround for me.

SF, if it helps, I saw a similar problem in 3.0a, except instead of the video blanking, the image froze while the audio continued, for quite some time (on the order of minutes), probably until the next cut, when the video resumed normally. Now, in the places where it used to freeze, there is a brief (~1sec?) video black out. So, naturally, the black out is a much better scenario than the video freeze

I am also rendering as Interlaced, top field first.

My source material is 480x480, whereas I'm rendering in 720x480 (but at a lower bitrate).

Has anyone at SF been able to reproduce this problem? I realize this thread is a little old, has this been resolved by chance elsewhere?

SonyEPM wrote on 12/6/2002, 8:47 AM
As an experiment, I tried rendering a 4 minute DV sequence to MPEG-2 (DVD NTSC template), then rendered it back to sync or glitch problems (other than a quality hit), then back to MPEG-2 (DVD NTSC) and that played ok on my computer and ok when burned to DVD. So it can be done- I just did it. The i/b/p pattern of the MPEG source file likely has a lot to do with the issues described above in this thread, as does the decoder used to read the files- both of those are very difficult to analyze/troubleshoot since they tend to vary from file to file, machine to machine, app to app.

Anyway I have no doubt you are running into the issues you describe, and in the interest of providing a solution, my advice for reliably re-encoding MPEGs is to:

1) Open the files in TMPEG and render them to AVI, ideally uncompressed if you want the best possible quality. This worked pretty well for me in all but one case (which could have been a user error on my part).

1a) If you don't want to go the TMPEG route, try rendering the MPEGs back to .avi within Vegas, and check that .avi first before re-encoding. With some MPEGs (like mine) this works just fine.

2) Load the .avi into Vegas, do your edits if needed, then recompress back to MPEG-whatever.

Expect quality to degrade no matter what you do. Good luck-
Saturn49 wrote on 12/6/2002, 10:20 AM
Are you doing edits (simple cuts) when you render from MPEG back to DV? The problem seems to occur about 1 out of every 4 cuts or so, and like previous posters said, it happens approximately a minutes after the edits.

My source is 30 minutes, after cuts, around 20 minutes, typically 5 cuts (beginning end, and middle). The blackouts occur approximately 1-2 times per file.
Ron Lucas wrote on 12/7/2002, 3:31 PM

I can take an MPEG2 file I created in VV30c and render it back to AVI with no problems if I render the ENTIRE MPEG2 file without any changes to the length of the MPEG2 event in my timeline.

The problem of blackouts seems to occur when I make adjustments to the MPEG2 event in my timeline and render it to AVI. An example of an adjustment would be cutting out a segment within the MPEG2 event and only rendering it to AVI.

I believe this is what Saturn49 is also describing.

Saturn49 wrote on 12/9/2002, 9:52 PM
bump? Sonic Foundry - any word on being able to duplicate this? Any possible workarounds? It appears to be an issue with MPEG decoding (since render to AVI contains the glitches), and as far as I've seen, there are no settings to tweak for any sort of decoding.

SonyEPM wrote on 12/10/2002, 9:29 AM
the workaround is to convert MPEG files to avi prior to editing.
Saturn49 wrote on 12/11/2002, 3:39 AM
I see. Unfortunately, that isn't really an option for me since I don't have the disc space for uncompressed video, and re-encoding (again!) would lose even more quality, not to mention time.

TMPEnc doesn't support frame accurate edits.
MPEG-VCR supports frame accurate edits (without re-encoding!) but messes up the audio sync.
VV creates blackouts after edits.

I guess I'm going to try to render the MPG to DV first, then edit. Seems like it shouldn't be necessary to do this though...
SonyDennis wrote on 12/15/2002, 12:09 AM
From the descriptions of how your various applications deal with this MPEG file of yours, I'd say the problem lies with the file. It's probably VBR with long GOP lengths, and each program's MPEG decoder is having a hard time randomly seeking in the file, with different consequences for each. I agree with SonicEPM on this one: your cleanest, most accurate, solution would be to transcode to DV, then edit that and render. The transcode should be from frame 1 forward, so no seeks are necessary.

CBR MPEG I-frame, or I/P only, makes a decent source format. As soon as you go VBR and add B frames and long GOPs, it's not a source format, it's a delivery format.

kerrying wrote on 12/17/2002, 1:27 AM
Good to know I am not the only poor soul out there. Had exactly the same problem: work on mpeg files (high bitrate master, play just fine without blackouts in Windows Media Player and PowerDVD), bring them into VV project to put together a mpg to be put onto a VCD later, perform lots of edits with them and, SO FAR, the blackouts occur twice, in 2 different events, close to the end of 2 different events in the rendered video approx. 25 minute in length. 1 of them appear in both preview and rendered video, another in just the rendered video. My project has not finish, and I expect more blackouts...

Interestingly, rerendering the project DO NOT help: the blackouts appear at exactly the same place. BUT, making a selection around where the blackouts occur and then render the, say, 5-seconds selection, with extra running-time before and after the blackouts, the blackout disappear.

I try (very paintakingly, especially if you have lots of source videos taking up lots of hard disk space and are working on not-so-high-end computer...) doing many other things and playing with the setting adjustments and looking around for solutions, no luck. And my conclusion is: I rrrrrreally think it is a bug after trying out so many things...

Beside using AVI as source, anyone knows of any other REAL solution for us all?

Thanks a lot, folks. Great learning experience from you all.

Blackout wrote on 2/11/2003, 6:18 AM
Hi all,

i just did some tests and it seems that Vegas 4 has this problem solved...woo hoo!!!

good work SF....finally.

kerrying wrote on 2/11/2003, 9:21 AM
SF solved this issue in VV 4.0? Now, that is excellent news!!! This blackout thing really is driving many people crazy. Does SF has any official explaination on this, you know, some soft technical article on how and why this happen and the solution to the problem... ?
SonyEPM wrote on 2/11/2003, 9:56 AM
I'd say you got lucky- if you use MPEG source files on a regular basis, you will almost certainly see the black frames again at some point.

cef wrote on 2/12/2003, 2:35 AM
hi everyone. i saw this thread and i just HAD to set up a user name. anyways, i had this problem as soon as i did my update from the old vv version to vv3 and rolling back to the old version never helped. i have already deleted the email response i recv'd from tech support who somehow managed to point the finger of blame (in a nice way of course) to the manufacturer of my mpeg2 capture card. i have given up on importing mpeg2 as my source file, however i remember doing some experimentation before i gave up. the blackouts happened less frequently (spaced farther apart) if my mpeg files were captured using a higher bitrate (around 6mbps) and as you go down using lower bitrates, the blackouts happened more frequently. what's even more interesting? i tried importing mpeg1 blackouts!!!!!! crappy picture but no blackouts!