Edit Avi: VDub / VDubMod / Nandub

[Rinsin]

I have a vbr audio avi which I want to cut some parts out. I've been looking at this (old) guide: https://www.videohelp.com/oldguides/virtualdubedit

I get the well known warning about vbr when using Vdub. I also get a similar warning in VdubMod. Both suggest that the audio should be decompressed and recompressed as CBR.

Nandub on the other hand gives no warning at all.

I don't mind the edited Avi being vbr audio. What I don't want are any sync errors. Nandub seems to be the simplest solution *if* it is not going to lead to sync errors. Am I correct in assuming that the author of Nandub has implemented a solution which neither vdub (even the latest release) or vdubmod can offer: namely the ability to edit a vbr audio avi without decompressing / recompressing but still not getting sync errors?

[manono]

When using VDubMod, just answer 'no' to the question. I believe newer VDubs also have the ability to handle VBR MP3 audio now (maybe by also answering 'no').

[DarrellS]

When using VDubMod, just answer 'no' to the question. I believe newer VDubs also have the ability to handle VBR MP3 audio now (maybe by also answering 'no').

With the new version of Virtualdub, you just ignore the warning or turn it off in Options > Preferences > AVI > untick box next to "Warn when VBR audio is detected".

[Rinsin]

So, if I use the latest version of Virtualdub and turn off / ignore the warning, I will still get results which are in sync if I follow that guide (except that I won't have to use Nandub or Vdub Mp3 Freeze)?

BTW my speakers are currently broken so I can't check the results

[jagabo]

So, if I use the latest version of Virtualdub and turn off / ignore the warning, I will still get results which are in sync

Yes, usually.

[DarrellS]

With the new version of Virtualdub, that old guide is pretty much obsolete (as are all the old VDub Mods).

Now you can use plugins to load different file types and you can use smart rendering instead of direct stream copy to get frame accurate editing. Also, you can use filters in blend mode with the curve editor and smart render to get transitions without having to recode the whole movie.

[Rinsin]

With the new version of Virtualdub, that old guide is pretty much obsolete (as are all the old VDub Mods).

Now you can use plugins to load different file types and you can use smart rendering instead of direct stream copy to get frame accurate editing. Also, you can use filters in blend mode with the curve editor and smart render to get transitions without having to recode the whole movie.

OK, I'm interested. I don't need to do anything other than cut bits out of the vbr audio avi file really. Is there a simpler way than just opening up with Vdub, setting audio and video to direct stream copy, cutting out the relevant parts and then appending the files?

I also though it might only be able to cut and join on a key frame, is this the case or not (I'm guessing by your reference to "frame accurate" that I can improve on that)?

Edit: also, when Vdub says "blah blah may encounter sync errors when extracting blah blah" why does it still warn about that if it's no longer a problem?

[hech54]

AviDemux easily handles VBR.

[DarrellS]

With the new version of Virtualdub, that old guide is pretty much obsolete (as are all the old VDub Mods).

Now you can use plugins to load different file types and you can use smart rendering instead of direct stream copy to get frame accurate editing. Also, you can use filters in blend mode with the curve editor and smart render to get transitions without having to recode the whole movie.

OK, I'm interested. I don't need to do anything other than cut bits out of the vbr audio avi file really. Is there a simpler way than just opening up with Vdub, setting audio and video to direct stream copy, cutting out the relevant parts and then appending the files?

I also though it might only be able to cut and join on a key frame, is this the case or not (I'm guessing by your reference to "frame accurate" that I can improve on that)?

Edit: also, when Vdub says "blah blah may encounter sync errors when extracting blah blah" why does it still warn about that if it's no longer a problem?

By using direct stream copy, it will only cut at key frames. Using Smart Render (must use same codec as original), you can cut anywhere you want and it will only recode small sections where you made the cuts. If you want to put a transition where you made the cut, you can do that with the fill filter in blend mode, the curve editor and smart render.

You'll have to ask Phaeron in the Virtualdub forum why the message is still the same. I just turn off the message and don't worry about it.

If you're worried that the VBR audio may not play correctly in certain players then you could always recode the audio but you don't have to do all the special tricks that you had to do before. Just choose Lame mp3 with 44100Hz 128kbps CBR Stereo compression.

[jagabo]

In Direct Stream Copy mode any section you keep must start on a key frame (they can end anywhere -- at least on any P frame). This is because the key frame encodes the entire picture (like a JPEG image), B and P frames only encode the changes between frames. Without the keyframe of a GOP there is no way to know what the rest of the B and P frame should look like.

[Rinsin]

When using Avidemux to delete multiple sections from my vbr audio avi I'd like to know if using Smartcopy works in the following case (where the bold sections are the ones deleted, in one go, before I save as an avi in copy mode:

IBPBPBPBPBPBPIBPBPBPBPBPBPIBPBPBPBPBPBP

My confusion comes from my reading that "SmartCopy will only re-encode the frames that are located before the very first I-Frame." Does this mean if I do "multiple deletes" in one go that Smartcopy won't be smart enough to detect that the last section cut out also doesn't start on an I frame?

In other words will it just reencode the underlined frames below and not the italicised ones (and if so, is this a problem?):

IBPBPBPBPBPBPIBPBPBPBPBPBPIBPBPBPBPBPBP

[jagabo]

My guess (and that's all it is) is AviDemux will reencode the entire GOP.