Chapter entry point is about 1 second behind

[pbhalerao]

I followed Sefy's VCDEasy Guide for ripping DVD to VCD. I added chapters using ChapterXtractor. However, I found that the raw data for chapter entry point is approximately a second behind the new chapter.

In other words, the chapter entry point is actually the last point of the previous chapter. So my NEXT button moves the current chapter to the last frame, plays that frame and then moves to the new chapter.

What am I doing wrong here?

[adam]

Chapters can only be placed on an I-Frame. Unless you place an I-Frame in the exact same place as it was on your source, then your chapter points will be as much as 1 sec off with normal GOP settings, and can be way off if you tweak the GOP Structure.

Here is what you do next time you encode a VCD. I assume you are using TMPGenc btw. In ChapterExtractor go to the Format tab and modify one of the presets so that under the FORMAT blank it says %f

Now when using this preset it should give you the frame numbers for each chapter. Highlight all of the numbers and right click and select copy. Paste this into a txt file and name it anything you want. (Is it me or did ChapterExtractor used to let you export a txt file? My version doesn't have that option.)

Anyway, before encoding your movie go to the GOP Structure tab in TMPGenc and check force picture type setting, then click on the setting button next to it. Click load and point it to your txt file. Now hit ok and encode as usual. It will place I-Frames at these specific frames and your chapter points should be perfect.

[pbhalerao]

Hi Adam,

Thanks for the suggestions. I was using TMPGEnc. The rip process tools were:

SmartRipper 2.41 --> DVD2AVI --> TMPGEnc 2.57 --> ChapterXtractor --> VCDEasy 1.1.4 (or is it 1.1.14)

The ChapterXtractor does have the option to save to a text file. I will follow your suggestions and I am sure that they will work.

Thanks again.

[Sefy]

@adam, regarding Chapter-X-Tractor, in version 0.962 there is a button to Save to TXT, you must be using an older version before that button

[pbhalerao]

Adam,

Followed your instructions. The problem I have found is that the ChapterXtractor Entry Points do not match the I-Frame in TMPGEnc. Is this a problem with bitrate or something? For example, here is the info on T2 -Special Edition:

a) According to ChapterXtractor the start point of Chapter 2 is frame 1704.
b) When I has imported these frame points in TMPGEnc on the GOP structure, I found that the chapter actually started at frame 1710.
c) The I-frame started to stray incrementally with each chapter from the original. For example 6 for Chapter 2, 17 for chapter 3, 29 for chapter 4 and so on.
d) For the last chapter (chapter 80) this was off by a whopping 200+ frames
e) I can safely say that ChapterXtractor Entry points are correct because the Chapter start time from ChapterXtractor matches the actually start time on PowerDVD player. It also matches the info returned by SmartRipper.

So I am guessing the Frame Numbers on TMPGEnc do not exactly match ChapterXtractor. Is there any tweak for this?

Regards,

[adam]

Is the fps in ChapterExtractor set correctly? If your PAL obviously it will autodetect it correctly as 25fps...but if you are NTSC make sure it is set to 23976. And then in TMPGenc you of course have to be encoding at 23.976fps as well.

[pbhalerao]

Adam,

The T2- Special Edition was NTSC/Region 1. I am converting it to a VCD because this is watched quite often at the home and I wish to preserve the original. I don't have a DVD writer as yet.

I thought that most NTSC movies are 29.97 fps. The SmartRipper Info information also says 29.97 fps.

As per your suggestion, does it not imply frame rate conversion? I will try anyway.

Thanks for the inputs.

[adam]

The NTSC standard requires 29.97fps but that doesnt mean that you have to, or that you should, encode at that framerate. The vast majority of NTSC DVDs, excluding anime and things like tv series, are stored as 24fps and have pulldown flags embedded in the stream which instructs the dvd player to do a real time telecine to 29.97fps as it plays. Since you have roughly %20 less frames to encode, you save yourself that much more bitrate. This translates into a very noticable increase in quality, eliminates common artifacts caused by interlaced sources, and decreases encoding time. There are very few instances when you would ever want to encode a 24fps NTSC source at 29.97fps.

SVCDs use the same type of pulldown flags as DVDs, and VCD actually require no flag at all. So what you want to do is encode at 23.976fps and let the DVD do the telecine for you.

My suggestion is to use forced film in dvd2avi to preserve the 24fps source. Of course preview the vobs first and make sure that it lists %95 or higher film, which as I said applies to almost all NTSC DVDs. Then encode at 23.976fps in your encoder. Generate the I-Frame list with ChapterExtractor set to 23.976fps and all of your chapters should be correct and you should have a significant increase in quality as well.

[pbhalerao]

Adam,

I used the 'Forced Film' option in DVD2AVI and encoded at 23.976 fps in TMPGEnc. The I-Frames mapped correctly to the chapter entry points in TMPGEnc.

However, VCDEasy does not get the correct entry point. For example, if the chapter entry point (in ChapterXtract Raw file) is 4:05:00, VCDEasy reports it as 4:04x or 4:06x. The thumbnail also shows the wrong frame. I tried to manually enter the exact I-Frame but the entry point is not shown correctly.

Another user (dark_knight_b) has reported the exact problem:

https://www.videohelp.com/forum/viewtopic.php?t=141153

[kidknicky]

8)

Yes, I too am finding the chapter points are not the same. I am finally ready to test another disk with chapter points, but every time I check them, the numbers do not match.

I have split my mpg almost in half, rounded to the nearest chapter because I know it needs 2 disks anyways...alas, it's out by 1 sec (chapter start point "actual" --->tmpgenc vrs "ifo+chapter extractor")

I will try adams tech to see how it turns out...

[Phlexor]

The error is in TMPGEnc. It somehow does not close the GOP properly or something like that. So even if you have an I frame at the chapter point, VCDEasy does not recognise it. Doing the same things but using Panasonic MPEG 1 Encoder and they will work, but it gies are poor picture quality in my opinion (colour seems dull).

[adam]

Ahh, yeah I've noticed this when encoding DVDs. TMPGenc doesn't seem to adhere to the set GOP length. I didn't think it would affect I-Frame placement but I guess it probably does. The solution is to set it to closed GOPs. Your chapter points should hopefully be correct now, but unfortunately you will lose some picture quality, not much though.

[Phlexor]

Not a good solution really. Why can't they fix that bug? You try reporting it and everyone assumes you are an idiot who doesn't know what you are talking about. I've been using TMPGEnc for 2 years now and this bug has been annoying the hell out of me. I mean you do exactly the same encode on TMPGEnc and Panasonic MPEG1 Encoder with the same input file and same settings and TMPGEnc always screws it up but Panasonic doesn't. I find you get the most trouble when encoding dark or fade to black scenes, it must have dependancies between GOPs because of being all back. Also for some reason TMPGEnc doesnt always obey CCIR601 color levels when encoding all black scenes (RGB 0,0,0 input) it doesnt adjust the levels up to RGB 16,16,16. If these long standing bugs could be adressed I'd die I tell ya. Why can't the author of TMPGEnc listen?

[hitechjunkie]

Doing the same things but using Panasonic MPEG 1 Encoder and they will work, but it gies are poor picture quality in my opinion (colour seems dull).

i discovered long ago that dull colors using the panny encoder is caused by the PC gamma setting. use the TV gamma setting instead.

[Sefy]

That's interesting! I always used the TV Gamma Settings, because I knew I was going to watch it on the TV, so it seemed more logical for me 8)

[hitechjunkie]

I find you get the most trouble when encoding dark or fade to black scenes, it must have dependancies between GOPs because of being all back.

could this be the result of the "detect scene change" setting and how each encoder treats or defines a scene change? i saw some odd things happen on my standalone during playback whenever i used that setting in TMPGEnc so now i never use it.

[vitualis]

Doing the same things but using Panasonic MPEG 1 Encoder and they will work, but it gies are poor picture quality in my opinion (colour seems dull).

i discovered long ago that dull colors using the panny encoder is caused by the PC gamma setting. use the TV gamma setting instead.

I think that it is the other way around (actually I KNOW it is since I still use the Panasonic encoder).

If you set it to TV, it compresses the colours to the CCIR601 color levels. If you are coming from a DVD source, the colours are ALREADY in those colour levels and so you loose even more of the colour space --> faded out colours.

If you set it to PC, it just leaves the colour space alone --> and hence appropriate from a DVD source --> a VCD.

Regards.

[hitechjunkie]

u are correct!

the PC gamma setting leaves the video image attributes alone!

it is the TV gamma setting which attempts a "correction" on the video image, causing it to differ (in many cases, resulting in washed out colors) from the original.

thx for catching that, vitualis!

[Phlexor]

As for using the TV scale in panasonic, I set DVD2AVI to PC scale and panasonic to pc scale and then compare a frame from the mpeg1 and frame from the mpeg2(dvd) in paintshop pro and then do the same thing with tmpgenc and you will see what I mean (all using 0-255 PC scale). Panasonic is so faded compared to the DVD original and the TMPGEnc mpeg1.

[vitualis]

It may be how you are using DVD2AVI +/- its interaction with Panasonic then. I don't use DVD2AVI with Panasonic, rather I use FlaskMPEG and Panasonic as a plugin. The colour fidelity is excellent.

Regards.

[Sefy]

Vitualis, I think we are the only ones left who still do VideoCD's, how'd you liek that ?

[hoyboy]

You're not the only ones!!!!

[vitualis]

I just like VCDs... A well made VCD has reasonable quality, is just damn compatible with just about everything... and perhaps I'm one of the few people here who still owns and uses a stand-alone VCD player that plays VCD2.0 and nothing else (it will freak even on trivial XVCD).

Regards.

[VidGuy]

Just out of curiousity - I've seen this problem in the forums a couple of times about the chapters.

I've also noticed that DoItFast4U has chapters that are 1 second ahead of the chapters from Chapter extractor.

Is this some kind of bug in Chapter Extractor that the author of DIF4U knows about that we don't?

[Sefy]

@Vitualis, I also have a VCD Standalone (MP3/VCD combo) and it's nice and you can carry it anywhere and watch movies on someone elses TV without anything special.

As for the Chapters, I recall it's with the TMPGEnc, you need to do Closed GOP for it to work properly, I think a year ago or so it was mentioned and Virtualis (don't kill me, i'm sinile!) said you need it for proper chapters.

[vitualis]

Yes, closed gops is necessary (or manually putting in the chapter points in TMPGEnc before hand).

Regards.

[Sefy]

Well, atleast i'm not a complete sinile

[pbhalerao]

Vitualis, I think we are the only ones left who still do VideoCD's, how'd you liek that ?

VCD Players are quite common in China and South-East Asia. In India, there are stand-alone players, boom-boxes with VCD 2.0 capability and even diskman's that play VCD's.

[Sefy]

I Believe i'm gonna stick to VCD even when DVDR's are cheaper, cause then I can use the DVDR to record whole seasons of TV shows on a single disc using VCD, which for me is sufficent quality for my backup purposes

[nufdude]

For chapters, I use ChapterXtractor get the frames then actually create individual tracks for each chapter. I make sure that chapter begin/end at exact frames using the Source Setting in TMPGEnc.

I do this for following reasons:
1. I can stop the encoding if I need to use the PC of some reason (which I need quite often). Then I only loose only a partial encoded file (time lost is typically under 10mins)

2. I realized this chapters problem some time. I just assumed that I was not doing something right. so rather than chasing for a solution, I picked an alternate route!

3. some times, movies wont fit on 2 CDRs. (if more than 160min) then rather than using a 3rd CDR for ~10min, I just choose some "chapters" which do not have lots of visual effects and reduce the bit rate, thus reducing the file size.

Also by doing so, I was able to do multi play list on VCD easily(using Adaptec Easy VCD).

Nuf