MPG with A/V sync to AVI with horrible A/V sync?

[RedPenguin]

Your problem isn't with VirtualDub, it's dealing with the source. So any other software is likely to have similar sync issues.

If you want to upload a moderate sized sample somewhere I'll take a look at it.

Do you have an idea on how much sample you would need?

A friend of mine told me about a site that apparently is supposed to be able to take up to 100MB of a file for free for others to download.

I realize you may not need that much, but I don't want to shortchange you from analyzing it properly.

[jagabo]

I need enough to duplicate the problems you're having. If it takes 100 MB that's ok. If you can duplicate the problems with a smaller file that's better.

[RedPenguin]

I am working on the sample.

Now I have another problem though.

One the one ClearQAM channel, it makes the size 1920*1080 and a bitrate of 10.5Mbps (17.3Mbps) (according to MediaInfo) and VirtualDub can't even play the MPG with A/V sync issues.

It plays like it's just doing a slideshow with a broken audio record.

It plays like it's doing a slow motion bit.

[jagabo]

VirtualDub is not optimized as a media player. It probably just can't decode and display the video fast enough on your computer. For half or quarter speed you could shoot 720p60 and cut the frame rate in half or one quarter.

[RedPenguin]

I'm not sure how to give you a nice sample because WinTV records with a DVD 2048bytes and that's it on my TV Tuner card.

So that makes just a 1min recording 100MB, which makes it not that great of a sample, I think.

[jagabo]

I'm not sure how to give you a nice sample because WinTV records with a DVD 2048bytes and that's it on my TV Tuner card.

So that makes just a 1min recording 100MB, which makes it not that great of a sample, I think.

If the problem can be duplicated with that short a sample it will be fine.

MegaUpload.com allows up to 1024 MB. I guess it will take forever to upload that much though.

[RedPenguin]

http://www.megaupload.com/?d=9BIYX9D0

I had to do a 153MB or so file.

I noticed the A/V sync is right on, until you go towards the end once the paid programming starts playing, it then gets off.

[jagabo]

It looks like there are many discontinuities in the file. The movie is encoded progressive with 3:2 pulldown flags. The ads are encoded interlaced. The audio skew changes at the transitions from movie to ad, and ad to ad.

I don't know of any tools that will dynamically adjust the audio skew. The only way I know of dealing with it is to cut the video into segments with DgIndex as suggested earlier.

You might try using DirectShowSource("sample.mpg") to open the MPG file. Depending on what DS filters you have installed that might work. AV sync was much worse for me that way.

[RedPenguin]

Something is not working right.

I cut up the video in to segments of only the video I want to keep in DGIndex by selecting the beginning and end.

Then using the following example scripts to put them in to VirtualDub

LoadPlugin("DGDecode.dll")
video=MPEG2Source("AMEN001-Part2.d2v")
audio=DirectShowSource("AMEN001-Part2 T80 2_0ch 128Kbps DELAY -44ms.ac3")
AudioDub(video,audio)

I still get A/V sync issues except not as bad.

[jagabo]

With the sample you provided I found that the audio skew reported by DgIndex wasn't always accurate. I believe there were three reasons for this:

1) Since the audio is skewed in the source if you mark-in right at the start of the segment you want to keep, you may find the audio at that point is still the audio from the previous segment. The new audio (along with its new skew value) hasn't started yet. So DgIndex is reporting the skew from the previous segments audio.

2) Since DgIndex only allows mark-in on keyframes, the mark-in frame may still be part of the previous segment. So, once again, you may get the audio skew from the previous segment.

3) The audio may not appear in chunks the same temporal duration as each frame of video. The video frames may each represent 1/30 of a second but the audio may appear in chunks that are 1/20 (or some other arbitrary value). So they may be interspersed irregularly through the MPEG stream. Using V to represent a video chunk (one frame) and A to represent an audio chunk, a file with an equal number of video and audio chunks might look like VAVAVAVA... But with the Audio chunks 1.5 times longer than the video chunks it might look like VAVVAVAVVA... The skew will depend on where you happen to start a segment.

In the end, the audio skew value you need to input into VirtualDub may be different than that reported by DgIndex.

I forgot to mention that with DirectShowSource() you can also try using the FPS and ConvertFPS options:

DirectShowSource("filename.mpg", FPS=29.97, ConvertFPS=true)

That may or may not help...

[RedPenguin]

What I don't understand is this.

Why can you play the original file and get no problems at all?

Also, why would TV channels do all of this strange encoding making it so hard to convert?

Is this done on purpose or something?

I mean, just recording one station, makes it 3.93GB just for a half-hour. That's nuts, in my opinion.

[jagabo]

Why can you play the original file and get no problems at all?

Media players dynamically adjust to these discontinuities. Unfortunately, none of the editing tools I'm aware of can do that. They all assume frame rates and audio skew remain constant throughout a file. Some of the problems may be caused by the software which is converting the MPEG transport streams into program streams while recording.

Also, why would TV channels do all of this strange encoding making it so hard to convert?

The video and ads are individually prerecorded, each with its own settings. The broadcaster cues them up in a player. The player then puts them out over the air, one after another. TVs are able to adjust to the discontinuities between files.

Is this done on purpose or something?

As long as TVs play the files properly they are happy. They aren't concerned about you editing your recordings.

[RedPenguin]

I know what you are saying.

It's just like a catch-22 though.

If I record analog, I get snow but can convert easily.

If I record digital, I get no snow, but can't convert easily.

I think I should just go back to the snow, seems like life was easier then.

I will keep trying, but the more I try, the more new recordings suck up my hard drive space.

[RedPenguin]

I forgot to mention that with DirectShowSource() you can also try using the FPS and ConvertFPS options:

DirectShowSource("filename.mpg", FPS=29.97, ConvertFPS=true)

That may or may not help...

Well, that definitely got the A/V sync to work like a charm. The A/V is fine when you preview the video in VirtualDub, I am going to have to convert to try out the output though.

Seems like I can only use this method on my Dual-Core CPU laptop.

When I try it on my 2.4GHZ Single-Core Desktop, it chokes. Basically it plays the video slow in VirtualDub and the output video ends up the same way in any player. Plus the A/V is not as smooth as it is on my laptop with the same original video file.

My TV Tuner Card can't do ATSC well on my desktop either, especially HD, seems like my laptop can only do that as well.

Is 2.4GHZ really not enough for video in this case?

[jagabo]

DirectShowSource() uses whatever DirectShow MPEG file reader, splitter, and decoder is installed in the computer. Performance will vary depending on what software is installed, even the order the software was installed.

I would expect a 2.4 GHz single core CPU to be fast enough to decode and display MPEG2 video, even at 1920x1080. In a media player at least, maybe not in VirtualDub.

[RedPenguin]

DirectShowSource() uses whatever DirectShow MPEG file reader, splitter, and decoder is installed in the computer. Performance will vary depending on what software is installed, even the order the software was installed.

I would expect a 2.4 GHz single core CPU to be fast enough to decode and display MPEG2 video, even at 1920x1080. In a media player at least, maybe not in VirtualDub.

Now I got something strange.

The video is all A/V synced fine when hitting the play button in VirtualDub before any converting.

Yet, the output video doesn't show the same.

How can that be?

EDIT: A/V sync works in output on desktop but still plays slow as heck. Trying, ffdshow's encoder of Xvid with same settings, oddly enough says bigger yet same settings, so who knows.

EDIT #2: I fixed the slow issue with the desktop. I don't know what was decoding before, but I installed ffdshow, set MPEG2 to libmpeg2 and it plays nicely.

Still checking if I have the A/V sync after convert even though good before.

EDIT #3: I have no idea why it didn't work on my laptop but on my desktop, I have zero problems and A/V sync is great. I think I will have to check the codecs on my laptop. Maybe one doesn't like Vista or something.

[RedPenguin]

I am making another reply because the previous one got too flooded with replies.

So far this is where I stand.

On my desktop, A/V sync is perfect through preview and conversion.

Yet, it for some reason skips part of the video after a network advertisement, so it messes up the video.

My laptop does not do the above, but makes the output not A/V synced.

I am going to try and diagnose what's wrong with the desktop, because it seems like my better option.

[jagabo]

Like I said, when you use DirectShowSource() you're at the mercy of the DirectShow components you have installed. You can try using GraphEdit or GraphStudio to see which filters are being used to play via DirectShow. The latter gives more information.

[RedPenguin]

Thank you, I forgot all about those two programs.

It looks like I solved my laptop, all I did was uninstall ffdshow, reinstall it telling to reset all settings, then put mpeg2 back to libmpeg2, and all is well.

Now I still gotta find out why my desktop skips part of the video, but it looks like my laptop is all ready to go.

Thank you so much again, for all of your help, I was so ready to just give up and delete the recordings, but now I finally can get to converting instead of troubleshooting.

Also, though it all, I found out that DivX has the same settings that XviD had for me, and it actually encodes in almost half the time.

[jagabo]

I found out that DivX has the same settings that XviD had for me, and it actually encodes in almost half the time.

It depends a lot on how high you set the motion search precision. At the very fastest settings of each codec, Divx is much faster (but you would only use these settings for realtime conversion while capturing). At the higher motion search precisions they are about the same speed. Xvid has better compression when you enable the Adaptive Quantization option.

[RedPenguin]

Graphedit really helped me out.

I found out that my laptop was using MainConcept MPEG Demultiplexer while my Desktop wasn't.

MainConecept doesn't skip that part of the video but for some reason can't keep the A/V sync.

I just used my desktop, cut off the bad part, lost a tiny bit of the intro, but I wish this station would clean it self up.

The station is RTN of WJAC, they will play a network advertisement, suddenly interrupt it with a commercial, or will interrupt a commerical with another one, for a little while they were only playing 10 seconds of a commercial then going to another one.

Kinda sucks because the channel has good shows but it's sure sloppy on timing, doesn't really appear professional.

EDIT: I found out, DivX is not half as fast, just turns out when I used the Demultiplixer that was not keeping the A/V sync, it was processing more frames per second.

[RedPenguin]

Now I have one more problem.

I got the A/V sync perfect.

Yet, all out of the blue, parts of the video I want to keep are completely skipped.

I have been playing around with the codecs and graphedit and have not gotten anywhere.

I am going to keep trying though.

EDIT: I may have fixed it using MPEG-2 Splitter instead of MPEG-2 Demultiplexer.

Wow, these are definitely the hardest to convert videos I have ever seen. They are worse then copyright-protected or something to that nature.

EDIT #2: FINALLY! Looks like that definitely did fix the problem, it is no longer skipping parts of the video that it was skipping before.

[jagabo]

All these MPEG reader/splitter/decoder incompatibility issues are annoying, aren't they?!

[RedPenguin]

All these MPEG reader/splitter/decoder incompatibility issues are annoying, aren't they?!

yes, especially since now I have to fix the A/V sync again.

I don't know how to win, one skips part but keeps A/V sync but another doesn't skip and doesn't keep A/V sync.

Uhh, back to more troubleshooting.

Something really strange is going on, the only one who keeps the A/V sync is MPEG-2 Demultiplexer but it gets clogged and sometimes when two segments meet, you will get overlap, where you will see a second of the following video before the current video and it just freezes.

I think I will have to try and see why the others just don't want to A/V sync like MPEG-2 Splitter.

[RedPenguin]

I tried setting various filters/splitters/what have you to go in front of MPEG-2 Splitter and Demultiplixer and nothing seems to want to work.

I eventually got Hauppauge Splitter to open but not File Reader.

I think I'm running out of options again.

Figures I finally get the A/V synced but now parts of the video are skipped. Uhh....

EDIT: I'm STUCK at it skipping minutes of the video, even though A/V sync is fine through out the entire video.

[RedPenguin]

I went back to the DGIndex split method.

I was getting no where trying to find the properly delay in VirtualDub, but then I figured, maybe if MPC can play AVS files.

I was able to and found the delay of 580ms even though DGIndex claimed -1979ms, which is WAY different. That was just the first part and no piece had the correct delay as DGIndex reported. I think it's because of how you said it may play previous video. At the start of the segment, you here a split second of previous audio than new. It's kinda a choppy moment, even the video pixelizes for a second or gets a bunch of what looks like squares everywhere for about the same amount of time.

Thanks again, I am so glad I finally got it working right.

These are some good shows and I hate to not be able to convert them properly. I mean, what's the sense of paying for cable and not being able to get recordings, especially since I'm often not home to watch it.

EDIT: Actually I have to admit, finding the delay of each part takes a tad more time, but using DGIndex cuts out the commericals quicker than through VirtualDub.

[RedPenguin]

One last problem

I have all 3 parts nicely encoded but the middle piece gets A/V sync meeded up when trying to join them with VirtualDub.

I can join them fine with AVISynth but then I would have no Direct Stream Copy, lowering the quality again.

What can I do here?

[jagabo]

This thread discusses problems that occur when the audio doesn't end at the same time as the video:

https://forum.videohelp.com/topic370540.html

In your case, it might help if you keep a little extra video at the start and end of a segment with DgIndex then use the mark-in and mark-out tools in VirtualDub to cut off the extra at the ends. That way audio will not start or end before or after the video.

For example, if V is a video frame and A is the audio, DgIndex marks out a region:

VVVVVVVVVVVV
AAAAAAAAAAAA

But the audio is advanced or delayed so ot has to be skewed:

    VVVVVVVVVVVV
AAAAAAAAAAAA
    |           | (mark-in, mark-out)

After encoding with VirtualDub the audio ends before the video:

VVVVVVVVVVVV
AAAAAAAA

So what you need to do is make sure there's enough padding before and after the video so that every video frame has audio associated with it. Using v and a for extra audio and video at the ends:

vvvvVVVVVVVVVVVVvvvv
aaaaAAAAAAAAAAAAaaaa

skewed:

    vvvvVVVVVVVVVVVVvvvv
aaaaAAAAAAAAAAAAaaaa
        |           | (mark-in, mark-out)

encoded:

VVVVVVVVVVVV
AAAAAAAAaaaa

Of course, you may now end up with audio glitches as you get little bits of audio from the ads before or after a segment.

[RedPenguin]

I am trying it out now.

Of course I already get glitchy audio here and there.

Mainly because, it seems like, they don't put nice transitions from the ending ad back to the program.

They just end the ad and instantly go back to the program.

Most stations seem like they put in at least some nice second or so of black screen than the program.

I think maybe the TV station is not putting their ads in correctly that allow it to match the national feed properly.

[RedPenguin]

That worked fine. Thank you.

I got my entire method worked out now, I just have to pay attention what AviSynth script is what because I actually mixed up a few here and there, but luckily I noticed them, otherwise I would end up with a video with like two part 1s and one part 3.

EDIT: No real choppiness of audio, so all good there as well.