editing vobs

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editing vobs

Permanent link to this post Posted by audio_pete » Sat Aug 05, 2017 9:20 pm

long time no squeak

When I view VOB_01_01 in Filmora on my mac
the sound comes in at 00:15:03:10

when I open VOB_01_01 in Audacity 2.0.3
the sound comes in at 00:14:49:00 (NTSC drop frames)

a difference of around 4 seconds
00:00:04:10

Where am I going wrong?
Shouldn;t they be the same / closer?
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Re: editing vobs

Permanent link to this post Posted by audio_pete » Sat Aug 05, 2017 9:57 pm

it is an 40 year old BBC production

the Filmora reading seems to be in PAL frames
(count 25 frames for each second in timeline display)
00:15:03:10 in PAL frames 25 fps

when I switch units in Audacity to PAL frames
it reads 00:14:49:01
still no match up
and not much different that the
00:14:49:00 reading in NTSC drop frames (29.97? frames per second)

seems like the PAL reading should be more different
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Re: editing vobs

Permanent link to this post Posted by audio_pete » Sat Aug 05, 2017 10:14 pm

turned audacity reading into PAL frames 22,226

approximate back calculating with 15 minutes
comes up with 24.69 frames per second
using 15.05 minutes is not much better
something seems amiss : (

what was supposed to be an easy pop the vob fix the sound job
has turned into a quagmire.

Need to try to figure what Filmora is up to
24 25 NTSC are ok
24.69 is not
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Re: editing vobs

Permanent link to this post Posted by kozikowski » Sat Aug 05, 2017 11:37 pm

Is one of the systems trying to do 3:2 pulldown?

http://www.kozco.com/3_2/3_2.htm

1000/1001 NTSC "distortion" isn't the only trick.

NTSC intentionally doesn't come out even to hide the analog color signals on the TV screen. Nothing lines up so you see a fine grain pattern instead of stripes.

23.976023976024...and etc.
29.97002997003....and etc.

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Re: editing vobs

Permanent link to this post Posted by kozikowski » Sat Aug 05, 2017 11:48 pm

Why do you think the system is converting with Drop Frame? It doesn't have to be. The error would be...ummmm...about a frame per minute, I think. Something like that.

A word on Drop Frame. It doesn't drop frames. It drops time. Perfect, sequential video frames might be labeled 1, 2, 3, 4, 6, 7, 8... for example. Video editors know how to deal with the missing numbers.

Welcome to NTSC, where an hour show doesn't fit in 60 minutes.

What does the Mac DVD Player think?

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Re: editing vobs

Permanent link to this post Posted by audio_pete » Sun Aug 06, 2017 12:18 am

Mac DVD player says NTSC and plays it just fine.

The fly in the ointment is that the original tape has been "dubbed" to a DVD
and either the tape has bad motor noise in the background
or the dubbing adds the motor noise to the DVD audio.

I want to split the VOB into audio and video
copy the audio
de-noise the audio
and then merge the audio and video back together again.
easy peasy right?

Audacity can edit the VOB
Filmora can detach the audio, delete the audio, add new audio files and export to DVD files
BUT
the fixed files are not in sync.
with some coaxing the files can be brought back in better sync
but its driving me nuts.

The tape appears to be NTSB, it plays well for there first hour
then tears up frequently in the last 40 minutes
so I do not think it is somehow a PAL tape.
But Filmora must think so because it has the frames at 25 per second, you can count them.

I just want to get the audio and video on the same timeline
so they play together
or I can fudge the audio to match the video.
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Re: editing vobs

Permanent link to this post Posted by kozikowski » Sun Aug 06, 2017 1:11 am

the original tape has been "dubbed" to a DVD
and either the tape has bad motor noise in the background
or the dubbing adds the motor noise to the DVD audio.

So this isn't a conversion or dub job. It's disaster recovery.

You have no idea of the show duration or frame rate at the time of the dub. Home tape players don't care.

If the player speed wanders, then Noise Reduction may fail. Noise Reduction makes you sample the noises at the start of the process (the Profile step) and then uses that sample through the show to know what to remove. That's like letting the dog sniff the shirt to know what to do.

If the noise is moving, the profile falls out of alignment.

Maybe the other elves will have ideas.

Oh, one other point.
and then merge the audio and video back together again.

Audacity can open up the audio portion of many video files, but not put them back together. For that you need a video editor or manager.

Many errors like this may seem to exotic file shifts, but turn out to be simple speed changes. Effect > Change Speed can be as simple as telling the tool what the two show duration values are and it will figure out everything else.

"I was expecting 1:31:15 and I got 1:30:04. Go."

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Re: editing vobs

Permanent link to this post Posted by audio_pete » Sun Aug 06, 2017 3:07 am

dub
is not my choice of wording.

It is an old commercial VHS tape
the LG DVD player calls playing a VHS tape and recording it to DVD at the same time as
Dubbing

that's not what I would call it

So not quite disaster recovery but an attempt to conserve a diminishing resource.

I am using Filmora as the video editor, am open to suggestion.
tried remux but did not seem to do the trick.
Working with Filmora but most seem unfamiliar with the product except for what they can read on their screens
:o
and I am so ignorant in this area, it has to be a challenge.
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Re: editing vobs

Permanent link to this post Posted by kozikowski » Sun Aug 06, 2017 4:04 am

You may be paddling your own boat there.

I think we can make the duration of the tracks come out right and maybe even help a bit with noise reduction, but reuniting the patched track to its video is not an Audacity job.

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Re: editing vobs

Permanent link to this post Posted by steve » Sun Aug 06, 2017 12:44 pm

audio_pete wrote:When I view VOB_01_01 in Filmora on my mac
the sound comes in at 00:15:03:10

when I open VOB_01_01 in Audacity 2.0.3
the sound comes in at 00:14:49:00 (NTSC drop frames)


Audacity uses FFmpeg (if available) to import audio from VOB files. FFmpeg extracts the audio stream and passes it to Audacity.
Is there any guarantee that the audio stream starts at the same time as the video stream in a VOB? I don't think there is.

audio_pete wrote:a difference of around 4 seconds
00:00:04:10

Is there also a difference in length?
9/10 questions are answered in the FREQUENTLY ASKED QUESTIONS (FAQ)
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