Does Saving a VHS-to-VirtualDub2 Capture as MP4 RE-encode The File?

[Avagadro1]

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[aedipuss]

lesson 1. vhs is analog. there is no file on vhs tape. no direct transport to a digital file unlike DV, miniDV, and HDV.

lesson 2. your capture of analog data off a vhs is only as good as the equipment you use.


lesson 3. virtualdub2 is not the same as virtualdub.


i'm done for today.

[Avagadro1]

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[aedipuss]

knock knock. wake up dude.

Does Saving a VHS-to-VirtualDub2 Capture as MP4 RE-encode The File?

there is no "file" on a vhs tape.

no more time for losers.


bye.

[davexnet]

Why don't you try it and see? You may be opening yourself up to dropped frames and audio sync problems.
Also, interlaced H.264 is something to consider; don't want to accidentally capture as progressive;
trying to de-interlace on the fly is only asking for more problems.

If the capture device is capable of delivering the uncompressed digital data, best to capture lossless using HuffyUV, UT codec, etc,etc.

My old Avermedia M780 card had a HW mpeg-2 encoder onboard, activated by using their software;
but it could also pass the lossless stream to Virtualdub. I used this method much more often when I was doing this
10+ years ago

[Avagadro1]

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[davexnet]

Method A) is better capturing lossless- end of story

[lordsmurf]

Does Saving a VHS-to-VirtualDub2 Capture as MP4 RE-encode The File?

Yes.

I am capturing VHS video using VirtualDub. I normally use the HuffYUV codec; save the VirtualDub AVI file.

Good.

For the present project I want the final video as an MP4 file.

Easy. Use Hybrid. Deinterlace QTGMC + encode H.264.

A) Retain my VirtualDub AVI for archive but then copy it

Yes.

B) Use VirtualDub2 for capture (same lossless compression) but immediately save it as MP4 (no intermediary use of Handbrake).

No.

At first glance it may seem that using VirtualDub2 and going straight from capture to saving as MP4 would be the obvious choice

Not at all.
- The lazy way, yes. (If that even works, I don't think it will. Not all codecs can be captured to.)
- Quality, no.

VirtualDub2 captures as AVI, and then, upon saving, if one chooses to save as MP4, VirtualDub2 re-encodes the capture as MP4.

That's not automatic. And VirtualDub uses the VFW version encoder, and it's pretty craptastic, very outdated method.

Why don't you try it and see?

Wasted time, wasted effort. Not sure what he's getting into. Hence his question.

You may be opening yourself up to dropped frames and audio sync problems.

Yep.

trying to de-interlace on the fly is only asking for more problems.

Yep.

[Avagadro1]

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[dellsam34]

Capturing lossless and encoding later gives you the option to do some work on the video before encoding, If you encode on the fly any problems are baked in you can't reverse the process, yes it's time consuming but worth the effort especially if archiving is the goal, If you want to just run a quick transfer for whatever purpose it wouldn't hurt to capture in mp4 as long as you keep the tapes for later if needed.

[jagabo]

At first glance it may seem that using VirtualDub2 and going straight from capture to saving as MP4 would be the obvious choice

Note that MP4 is a container. It can contain audio and video compressed with a variety of codecs. But I'm assuming you mean an MP4 container with h.264 video and aac audio (or other highly compressed streams).

In theory there is no difference between a two step process of capturing with a lossless codec then converting that cap to an MP4 video, and capturing directly to an MP4 video. In reality, high compression codecs are too slow (each frame must be compressed in the amount of time it takes for the capture device to capture it, typically 1/30 or 1/25 second -- if the encoding is too slow you will miss frames) and sometimes require video streams be read out-of-order, not linearly. So generally, you cannot capture directly to MP4. The lossless codecs used for capturing are designed to be fast and never make out-of-order requests.

[Avagadro1]

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[davexnet]

dellsam34 and jagabo:


By the way, I think my original inquiry remains interesting: In the underlying operation of VirtualDub’s capture processes, when in the chain of events is the capture actually saved to AVI, as contrasted to held in temporary status until “File>Save” is executed?

Thanks again for your help and suggestions.

Temporary status? When the file is captured, it's written out to a file, the capture file

[jagabo]

Both VirtualDub and VirtualDub2 are based on a one-frame-in-one-frame out process. A frame is captured, compressed (or not), then written to the output file. Out-of-order codecs may buffer several frames innternally while they are being worked on. But VirtualDub(1 or 2) has nothing to do with that.

[Avagadro1]

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[lordsmurf]

Best of all was your word craptastic. I'll check my OED!

Bart gets credit for that one, sometime around season 10 maybe (when The Simpsons was a better show than now).

is it instantaneously saving/encoding the digital flow to the AVI container, or is it capturing and temporarily “holding” the information

Instant encoding to destination.
Low CPU and non-video compression allows realtime without drops, internal HDD allows good I/O with no drops.

and not actually placing it in an AVI container and saving it as such, i.e., encoding it, until one executes the “File>Save” command?

No.

If VirtualDub captures and immediately encodes to something in the AVI container, then it is “there”

Correct.
Note that capture>encode is instant.

As contrasted to VirtualDub, however, VirtualDub2 can save the capture as an MP4.

No.

and if one then executed the “save as MP4” function, then VirtualDub2 would be a re-encoding,

Yes. After capture.

As it turns out, it appears to be the strong recommendation of members lordsmurf, jagabo and dellsam34 that the best practice would be to capture lossless to an AVI container. And then if I wanted an MP4, go ahead and copy the AVI file and convert to MP4.

Yes.

(Needless to day there are some real jackasses on this site as well (look above), but that’s fodder for discussion at a different time.)

Sometimes good people have bad days. (When I'm having a bad day, I usually just stay offline.)

held temporarily until “File>Save” is executed?

Nothing is held temporary. Not enough RAM or swap for it. (Not to confuse, but something like Hybrid encodes to temp folder, and the muxes final destination. But that's not what's happening here.)

[Avagadro1]

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[lordsmurf]

The audio sync issues are due to lack of TBC, and dropped frames.

There are likely NOT constant drops, so audio skew correction will not work well.

[jagabo]

My final task will be to ensure that I capture Interlaced with proper field order

AVI doesn't really have a field order flag. You have to keep track of it yourself. You have no choice of field order. The capture device determines it. You just need to figure out whether it's top or bottom field first. Open one of your captured videos in VirtualDub. Add the Bob Doubler filter -- select either top or bottom field first. Step through the video frame by frame, a horizontal panning shot is good for this. If you get back and forth motions you picked the wrong field order. Now you just have to tell your editor the video is interlaced and which field order it is.

[Avagadro1]

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[Cornucopia]

You say you bought that deck solely from recommendation of the digitalFAQ site, but that site clearly says that you should use an external, fullframe tbc, and that that is your best bet to avoid dropping frames (with accompanying audio desync). The builtin line tbc is good for many things, but it is not a fullframe tbc and cannot correct those kinds of errors. The site did explain that.


Scott

[Avagadro1]

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[Avagadro1]

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[lordsmurf]

My VHS machine is a JVC HR-S9800U, which I purchased solely for the purpose of digitizing my old VHS tapes. I purchased the particular model primarily because it has built-in TBC, as explained on the DigialFAQ website. My captures (all experimentation up to now) have all been done with the TBC engaged.

Great deck, but it's just half the equation.

Because this has been experimentation, projects have not been more than fifteen minutes or so in length. Perhaps when I get to the actual projects, some up to two hours in length, the built-in TBC will be insufficient to keep audio in sync with video.

^ This.

You say you bought that deck solely from recommendation of the digitalFAQ site, but that site clearly says that you should use an external, fullframe tbc, and that that is your best bet to avoid dropping frames (with accompanying audio desync). The builtin line tbc is good for many things, but it is not a fullframe tbc and cannot correct those kinds of errors. The site did explain that.

Correct.

Then I wrote that the particular model was purchased because it has built-in TBC, as explained on the DigialFAQ website (though, by the way, it was a "recommended machine" on that very helpful website. That was a COMPLEMENT to the folks at the DigitalFAQ website.

Thanks.

[Avagadro1]

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