As most of you know, I've been around here a lot trying to help people with various RPTV to DVD problems. Lately I've had a few guys send me samples that were un-usable to them. I've not found ONE single (of the 8 or 9 now) that I couldn't fix. Every one was able to be used to generate perfect DVD source material. Recently I was working with another guy who had run into a brick wall with a very long video. I got the first part of his video last night and again have authored a perfectly playing DVD from it.
However his problem was a little different and something that can be difficult to fix. I've found an easy way to find, and repair the problem. Although this post is a little long due to my trying to explain it non-visually, the actual technique is simple. But you'll need Womble and DVD-Lab to do it. (although if you have some other fully frame accurate editor that will show you frame numbers you should be able to use that) The reason for using DVD-Lab is because of something that is a by-product of it's use and I don't know if you can use other authoring programs in it's place.
I'm going to assume you are familiar with Womble and DVD-Lab so I won't dwell on how to use those programs.
Let's start with the RAW RPTV mpeg. For starters, don't do a thing to it. No GOP fixing etc.
First De-mux it with Womble. I'll call the result Movie.mpv and Movie.mpa for example.
Now open up DVD-Lab. Import those Video and Audio assets.
Don't do anything fancy. We are only going to do a test compile JUST to find the problem area. Just drag the audio and video to the movie window. Like normal. Then double click on the menu icon and just add a text "Play" on the blank background. No need to waste time with buttons, chapters and such.
Link that PLAY text to the beginning of the movie.
Now do your compile. Make sure you have checked to use a separate work/temp folder in the DVD-Lab compile window.
If you have a problem, it will bomb out. (this is good) heh heh. This shouldn't take you more than a couple minutes to get to this point..
Close the error window. Click on the "stop" compile. And exit DVD-Labs.
Now look in the work/temp folder and you will see a *.vob file. Drag this file into womble.
Change the Womble format from "time code" to "Frame". If you don't know how, look at the right bottom of the womble mpeg window that is open. Where the time code is displayed. You'll see a little red cross there. Click on that and a window will open showing the mpeg parameters and in the bottom left of that new window is a place to select either time code or frame.
Now back to the mpeg window .. scrub all the way to the END of the displayed VOB. (you can hit the right bent arrow in the time/frame display box and it will jump there)
NOTE the frame number. THAT my friend, is the last good frame that DVD-LAB was able to compile. The next frame or frames have problems. It's usually just one or maybe two. Wasn't it wonderful of Oscar to have a "built in" bad frame locater?
Now close that out. Delete the *.mpv and *.mpa and the temp VOB etc. Just leave the original ReplayTV program stream intact. Load that original mpeg program stream back into Womble. Scrub to the exact frame you had noted.
At this point there are a few ways to fix it. The most accurate (and the one that has the least chance of screwing up your audio) is as follows
Let's say the "last good frame" is number 7636.
Mark THAT frame as the out point.
Copy that segment to the clip list.
Now scrub the pointer two frames to the right. Mark that point as an IN mark. Then scrub to the END of the video and mark that as the OUT mark.
Copy the 2nd half you've marked to the clip list.
You should now have two movie clips in the clip list that are the first half and second half of your video MINUS the two screwed up frames in the middle. (You may only need to eliminate one frame but I always start with two myself)
Now delete the mpeg window and drag the first clip onto the work area.
Drag the 2nd clip onto the 1st clip in the work area.
Now save the whole thing as something called "FixedMovie.mpg" or what-ever. Make sure you select to save ALL.
Womble will paste the two clips back together AND as a normal operation re-build the joined area plus and minus a few frames. You'll only loose two frames (or 15th of a second) and you'll never notice it. When checking, the new mpeg should be minus the number of frames you cut, when compared to the original.
Now demux this new mpeg and import it into DVD-Lab and do your normal authoring. Or if you want to double check .. do a short compile using the above technique just to make sure it will fully compile. (I'd recommend this for a troublesome Mpeg as you may have more than one problem frame area)
This worked every time I did it. And it should only take you 5 or 6 minutes tops once you have the process down.
An Alternative way:
Instead of making a 1st half and 2nd half with the in-between frame or two not included, you could just mark the last known good frame as the BEGINNING mark, and then move a couple frames to the right and mark that frame as the ENDING mark and simply CUT that section out. This as opposed to saving two segments to be later re-joined. HOWEVER, as I've mentioned many times, doing a "cut" out of video often produces problems with sync. I think Womble does a better job joining two segments from scratch than cutting and joining all at once, if you know what I mean.
Gotchas
I've found that most of the time the problem frame(s) is during a fast cut from a slow scene to a fast scene. Especially if it's like a "talking head" AND they "merge" right to a high action scene. I believe the ReplayTV mpeg encoder starts with a very low bit rate (the little movement talking head scene) and then has to change quickly to a very high bit rate (the action scene) and IF there is some kind of transition between the two, the encoder screws up the GOPS, bit rate and who knows what else? And it's almost impossible to find, even when viewing frame by frame. It has to do with "motion estimation" and is very hard to do "real time" at 30 FPS. This is why "real" DVD mpegs are done with multi-pass non-real time encoding. Each pass fine tunes the mpeg more precisely. The poor ReplayTV encoder doesn't have that luxury and has to do it's encoding "real time", in one pass.
Another common problem is more viewable. This is where the encoder looses it's video signal for a split second. The result might be one or more frames with "blocks" or generally messed up video. You CAN see this when stepping one frame at a time. I've seen that when this happens, it usually is for at least 2 frames and sometimes several.
Most of the time, just cutting one or two of the frames immediately after the last known good frame is enough. But sometimes you might have to cut more.
I've also forced Womble to do a re-encode of the bad area by INSERTING a special effect there. (only good if it's right at a scene change) This is the fastest and easiest and doesn't require ANY cutting etc. Just hit the insert trans. arrow and do it.
You will find the "problem" frame to be either visually damaged OR look perfectly normal. In the latter case, it's the GOP sequences and bit rate etc that are all screwed up and you would never know it. The Womble GOP fixer only fixes header information and GOP things as such and I don't think it "rebuilds" the video at the GOP level at all.
And in the aforementioned case of actual viewable bogus frames, using the DVD-Lab compile technique can find them a lot faster than if you were scrubbing through a hour's worth of video frame by frame.
This isn't a solution for every known problem with the ReplayTV mpegs. But I think it will show you a fast and easy way to eliminate at least a couple of them that have not been really discussed here.
Womble with it's GOP fixer can fix most of the "non-video" problems. It's great frame accuracy will allow you to get around video problems. If your problem is simply bad header information then DVD-Patcher can help there. And you can use this "hidden" feature of DVD-Lab to at least find the rest of the hard to find problems.
Lastly ... There CAN by operating system specific problems and/or parameters that can make working with mpegs difficult. There HAVE been a few guys who have had NO success at all, until they re-installed their operating system. This is NOT common but can be an issue. I would only recommend this if you found that someone ELSE was able to use your mpegs and you couldn't (using the same software and techniques of course)
Good luck ..
However his problem was a little different and something that can be difficult to fix. I've found an easy way to find, and repair the problem. Although this post is a little long due to my trying to explain it non-visually, the actual technique is simple. But you'll need Womble and DVD-Lab to do it. (although if you have some other fully frame accurate editor that will show you frame numbers you should be able to use that) The reason for using DVD-Lab is because of something that is a by-product of it's use and I don't know if you can use other authoring programs in it's place.
I'm going to assume you are familiar with Womble and DVD-Lab so I won't dwell on how to use those programs.
Let's start with the RAW RPTV mpeg. For starters, don't do a thing to it. No GOP fixing etc.
First De-mux it with Womble. I'll call the result Movie.mpv and Movie.mpa for example.
Now open up DVD-Lab. Import those Video and Audio assets.
Don't do anything fancy. We are only going to do a test compile JUST to find the problem area. Just drag the audio and video to the movie window. Like normal. Then double click on the menu icon and just add a text "Play" on the blank background. No need to waste time with buttons, chapters and such.
Link that PLAY text to the beginning of the movie.
Now do your compile. Make sure you have checked to use a separate work/temp folder in the DVD-Lab compile window.
If you have a problem, it will bomb out. (this is good) heh heh. This shouldn't take you more than a couple minutes to get to this point..
Close the error window. Click on the "stop" compile. And exit DVD-Labs.
Now look in the work/temp folder and you will see a *.vob file. Drag this file into womble.
Change the Womble format from "time code" to "Frame". If you don't know how, look at the right bottom of the womble mpeg window that is open. Where the time code is displayed. You'll see a little red cross there. Click on that and a window will open showing the mpeg parameters and in the bottom left of that new window is a place to select either time code or frame.
Now back to the mpeg window .. scrub all the way to the END of the displayed VOB. (you can hit the right bent arrow in the time/frame display box and it will jump there)
NOTE the frame number. THAT my friend, is the last good frame that DVD-LAB was able to compile. The next frame or frames have problems. It's usually just one or maybe two. Wasn't it wonderful of Oscar to have a "built in" bad frame locater?
Now close that out. Delete the *.mpv and *.mpa and the temp VOB etc. Just leave the original ReplayTV program stream intact. Load that original mpeg program stream back into Womble. Scrub to the exact frame you had noted.
At this point there are a few ways to fix it. The most accurate (and the one that has the least chance of screwing up your audio) is as follows
Let's say the "last good frame" is number 7636.
Mark THAT frame as the out point.
Copy that segment to the clip list.
Now scrub the pointer two frames to the right. Mark that point as an IN mark. Then scrub to the END of the video and mark that as the OUT mark.
Copy the 2nd half you've marked to the clip list.
You should now have two movie clips in the clip list that are the first half and second half of your video MINUS the two screwed up frames in the middle. (You may only need to eliminate one frame but I always start with two myself)
Now delete the mpeg window and drag the first clip onto the work area.
Drag the 2nd clip onto the 1st clip in the work area.
Now save the whole thing as something called "FixedMovie.mpg" or what-ever. Make sure you select to save ALL.
Womble will paste the two clips back together AND as a normal operation re-build the joined area plus and minus a few frames. You'll only loose two frames (or 15th of a second) and you'll never notice it. When checking, the new mpeg should be minus the number of frames you cut, when compared to the original.
Now demux this new mpeg and import it into DVD-Lab and do your normal authoring. Or if you want to double check .. do a short compile using the above technique just to make sure it will fully compile. (I'd recommend this for a troublesome Mpeg as you may have more than one problem frame area)
This worked every time I did it. And it should only take you 5 or 6 minutes tops once you have the process down.
An Alternative way:
Instead of making a 1st half and 2nd half with the in-between frame or two not included, you could just mark the last known good frame as the BEGINNING mark, and then move a couple frames to the right and mark that frame as the ENDING mark and simply CUT that section out. This as opposed to saving two segments to be later re-joined. HOWEVER, as I've mentioned many times, doing a "cut" out of video often produces problems with sync. I think Womble does a better job joining two segments from scratch than cutting and joining all at once, if you know what I mean.
Gotchas
I've found that most of the time the problem frame(s) is during a fast cut from a slow scene to a fast scene. Especially if it's like a "talking head" AND they "merge" right to a high action scene. I believe the ReplayTV mpeg encoder starts with a very low bit rate (the little movement talking head scene) and then has to change quickly to a very high bit rate (the action scene) and IF there is some kind of transition between the two, the encoder screws up the GOPS, bit rate and who knows what else? And it's almost impossible to find, even when viewing frame by frame. It has to do with "motion estimation" and is very hard to do "real time" at 30 FPS. This is why "real" DVD mpegs are done with multi-pass non-real time encoding. Each pass fine tunes the mpeg more precisely. The poor ReplayTV encoder doesn't have that luxury and has to do it's encoding "real time", in one pass.
Another common problem is more viewable. This is where the encoder looses it's video signal for a split second. The result might be one or more frames with "blocks" or generally messed up video. You CAN see this when stepping one frame at a time. I've seen that when this happens, it usually is for at least 2 frames and sometimes several.
Most of the time, just cutting one or two of the frames immediately after the last known good frame is enough. But sometimes you might have to cut more.
I've also forced Womble to do a re-encode of the bad area by INSERTING a special effect there. (only good if it's right at a scene change) This is the fastest and easiest and doesn't require ANY cutting etc. Just hit the insert trans. arrow and do it.
You will find the "problem" frame to be either visually damaged OR look perfectly normal. In the latter case, it's the GOP sequences and bit rate etc that are all screwed up and you would never know it. The Womble GOP fixer only fixes header information and GOP things as such and I don't think it "rebuilds" the video at the GOP level at all.
And in the aforementioned case of actual viewable bogus frames, using the DVD-Lab compile technique can find them a lot faster than if you were scrubbing through a hour's worth of video frame by frame.
This isn't a solution for every known problem with the ReplayTV mpegs. But I think it will show you a fast and easy way to eliminate at least a couple of them that have not been really discussed here.
Womble with it's GOP fixer can fix most of the "non-video" problems. It's great frame accuracy will allow you to get around video problems. If your problem is simply bad header information then DVD-Patcher can help there. And you can use this "hidden" feature of DVD-Lab to at least find the rest of the hard to find problems.
Lastly ... There CAN by operating system specific problems and/or parameters that can make working with mpegs difficult. There HAVE been a few guys who have had NO success at all, until they re-installed their operating system. This is NOT common but can be an issue. I would only recommend this if you found that someone ELSE was able to use your mpegs and you couldn't (using the same software and techniques of course)
Good luck ..