Uncompressing audio useing VirtualDub

[Pirate_King]

Ive had to uncompress the audio in some AVI's before I encoded them to SVCD cause TMPGEnc Plus kept saying the AVI was longer than what it was. Ive compared the audio from them to the one's I didnt have to uncompress and the uncompressed ones sound louder. Should I just uncompress all my AVI's audio before I encode them?

[andyp1]

If you are getting error messages saying things about incorrect runtimes etc , make sure the Direct Show Multimedia filter is at the higherst priority.
Have a look HERE and it will explain it for you.

It is always good practice to extract the audio from an avi and save it as an uncompressed wav with virtualdub and use the wav as your audio source in TMPGenc.

A lot of avi files have VBR audio and TMPGenc doesn't handle VBR well at all and it can give audio sync problems. Hence extracting the audio.

[Pirate_King]

What ive been doing is making a direct stream copy with uncompressed audio in virtualdub and saving it as an avi. Is this just as good as extracting the audio by itself as a wav?

[andyp1]

No , that sounds wrong.

Open the file in vdub
Click on audio
Select Full Stream Processing
Then select file and choose 'Save WAV'

It will take a couple of minutes.

Then you will have your original AVI file as is and an uncompressed wav

Open TMPGenc and you Browse for your AVI then click the browse button on the Audio and select the wav you just created.
Then just carry on with the rest as normal.

[johns0]

I dont use tmpgenc to encode the audio,i use besweet with gui and mux with bbmpeg.

[FulciLives]

You could also open the AVI into a WAV audio program such as SoundForge or GoldWave then save the audio as a 16-bit 48k Stereo PCM WAV file.

That works rather well

- John "FulciLives" Coleman

[Pirate_King]

No , that sounds wrong.

Open the file in vdub
Click on audio
Select Full Stream Processing
Then select file and choose 'Save WAV'

It will take a couple of minutes.

Then you will have your original AVI file as is and an uncompressed wav

Open TMPGenc and you Browse for your AVI then click the browse button on the Audio and select the wav you just created.
Then just carry on with the rest as normal.

I should have been more specific. I forgot to say that I set the audio at full processing mode and no compression along with direct stream copy on video and then I saved it as an avi. Does that sound right now?

[andyp1]

No , why do you want to save AVI , just save as WAV like I said.
You need to extract the audio as a seperate file . That's how you will solve your problem . I think I explained it clearly enough.

[Pirate_King]

Yeah, I got what you said about the wav but I was just trying to make myself clear that I was making a copy of my original avi with uncompressed audio. This way I just clicked one source for audio and video. I was just asking if this is just as good audio quality as the wav.

[andyp1]

https://www.videohelp.com/tmpgenc.htm#problems

https://www.videohelp.com/virtualdubaudio.htm

[Keithchr]

Sorry Andy... there is just one thing I don't get about all this, perhaps you could explain? I know that you have to extract the audio from an AVI using vdub. This results in a huge wav file. Is it because TmpEgenc cannot read mp3 files that you have to do this? Gspot tells me my AVI audio is Mp3. I thought that the whole idea of this was to reduce the size of the audio so that you could increase the bitrate of the video for higher quality...I am converting to Mpeg2.
Appreciate your comments

[mats.hogberg]

TmpEgenc cannot read mp3

Yes, it can, but VBR mp3 confuses TMPGEnc, so it has to be decoded to wav before being fed to TMPGEnc, along with original video. The size of your source material (in bytes) does not affect the size of your final mpg.

/Mats

[andyp1]

As Mats said.

As for file size
Your original Avi probably around 700MB
Expect an uncompressed wav for an average movie to be a little over 1GB.

This is absolutely normal. And the output will depend on what your final project is.

If I make a DVD from an avi I need to save the wav which would be about say 1GB then I would convert the wav to ac3 with ffmpeggui giving me a file size for the audio somewhere around 200-300MB.
I would encode the avi vidoeo only using TMPGenc . Then I would Add the ac3 back in at the authoring stage before burning.

As in this guide
https://www.videohelp.com/forum/userguides/186739.php

That is how you make the audio size smaller in order to get a higher bitrate for the video.

Hope that explains it.

[LisaB]

Andy, why bother extracting to wav in those cases when you are going to use ffmpeggui?

You can open avi's directly in ffmpeggui -- saves a lot of time to convert directly to ac3...

[LisaB]

FulciLives,

I have used GoldWave a bit, and the big problem with GoldWave is that when you open up a compressed audio source, you have to wait quite a while for it to "deflash to disk". For this reason, I think VDub is a much better way to extract a WAV (unless, of course you want to do processing with GoldWave).

Extracting the WAV with GoldWave will take nearly twice as long as with VDub.

If you know of some way to make GoldWave faster, please share...

[FulciLives]

FulciLives,

I have used GoldWave a bit, and the big problem with GoldWave is that when you open up a compressed audio source, you have to wait quite a while for it to "deflash to disk". For this reason, I think VDub is a much better way to extract a WAV (unless, of course you want to do processing with GoldWave).

Extracting the WAV with GoldWave will take nearly twice as long as with VDub.

If you know of some way to make GoldWave faster, please share...

I just prefer to use GoldWave for this because of the way it processes the audio as opposed to VirtualDub.

As for speed well what can you do? It doesn't bother me as I don't deal much with this type of situation.

I don't do this with captures only for downloaded files with *ucked up audio formats like MP3 etc.

My captures are already 16-bit 48k Stereo PCM WAV so VirtualDub just EXTRACTS it and doesn't really "process" it at all.

- John "FulciLives" Coleman

[andyp1]

Andy, why bother extracting to wav in those cases when you are going to use ffmpeggui?

You can open avi's directly in ffmpeggui -- saves a lot of time to convert directly to ac3...

Well , would you believe it , so it does.

Thanks LisaB

[Keithchr]

TmpEgenc cannot read mp3

Yes, it can, but VBR mp3 confuses TMPGEnc, so it has to be decoded to wav before being fed to TMPGEnc, along with original video. The size of your source material (in bytes) does not affect the size of your final mpg.

/Mats

Please excuse my quickly reducing ignorance!..

If the size of the audio source material doesn't affect the size of the final mpg, then why bother converting it to AC3, why not just leave it as a wav?

ie 1) Extract wav from AVI with virtualdub
2) Encode AVI video only with TmpgEnc
3) Author with TDA adding in original wav file?

Can some kind soul put me out of their misery...I just don't get it.

[andyp1]

I'll have a go.
I did say about this in my post above , but ina different way.

These aren't exact figures just estimates.

TMPGenc doesn't like the mp3 in avi's so you extract the wav.

Your Blank DVD hold approx 4.37 GB .

If you use TMPG to encode the video and audio to MPeg1 for vcd you avi is 700MB you aduio is 1GB . You encode and your final output is 900MB for a 1.5hour movie which you can burn as vcd.
Bitrate for a standard vcd is 1150.

For DVD we want a higher quality picture so we want to achieve as high a bitrate as possible.
The same move encoded in the same way as DVD Mpeg2 to produces a m2v video file and wav file , the m2v may be around 3.2GB and the bitrate may be 5600 , The wav is around 1GB.

The higher the bitrate the better the quality.

So by converting the audio to ac3 which has a file size of around 230MB.
Now we have 4GB to use for the video and may be able to achieve a bitrate of around 7300 ,



So a DVD 1.5hr movie
= Video 3.2GB Mpeg2 5600kbps , Audio 1GB Wav
or Video 4GB Mpeg2 7300kbps , Audio 230MB ac3

You see the difference.

Oh by the way and it hasn't actually been mentioned , Converting the file to ac3 is a way of compressing the audio without any noticable quality less, while achieving a much smaller file size.

I hope this makes sence.

[Keithchr]

Thanks for the time taken there Andy..as usual very helpful for newbie.
I tried the tip above of just loading the complete AVI into ffmeggui and extracting the audio to AC3 - this saves time - I assume there is no point in extracting the Wav in virtualdub just to change it to AC3 later then?

So having extracted the audio to AC3 in ffmeggui, I then encode the AVI video only in TmpgEnc at a higher bit of say 7600 then load the encoded mpeg2 into TDA, add my AC3 audio file and author to dvd (Iassume).

I think I'm finally getting there thanks to you guys.

[andyp1]

Almost , don't guess at the bitrate , use the DVDRHelp Bitrate Calculator and enter the length of your movie and it will give you the correct bitrate to use for a particular file to fit a DVD-R.

Apart from that you seem to have grasped the rest of it.

I didn't know ffmpeggui would accept an avi , it saves about 5 minutes.

Once you have ac3 you can keep to this guide

https://www.videohelp.com/forum/userguides/186739.php

[fritzi93]

Pardon me, but it's still the best policy to extract the audio to WAV first, I've had a couple occasions where ffmegGUI exhibited strange behavior doing it that way, e.g. it finishes in about a second, 0 MB finished file size; or the audio causes problems for dvdauthorGUI. The exception is if the audio is already AC3, just demux in VirtualDubMOD and bypass ffmpegGUI altogether. It only takes 5-10 minutes. YMMV

[andyp1]

Good point , it may not be worth the risk for a few extra minutes.

[LisaB]

Well, fritzi, ffmpegGUI will not work and behave exactly the way you say in 2 cases I've found so far:

1. the audio is OGG
2. there is more than one audio stream in the AVI

Anyway, if it doesn't work just loading the AVI in directly, then you've only lost a second, and you can do it the long way. No need to always do it the long way just because sometimes the short way doesn't work. It is very obvious when it doesn't work.

As far as i know, both VDub and ffmpegGUI would both be using the same system codecs to decode the source...

[fritzi93]

Well, fritzi, ffmpegGUI will not work and behave exactly the way you say in 2 cases I've found so far:

1. the audio is OGG
2. there is more than one audio stream in the AVI

Anyway, if it doesn't work just loading the AVI in directly, then you've only lost a second, and you can do it the long way. No need to always do it the long way just because sometimes the short way doesn't work. It is very obvious when it doesn't work.

As far as i know, both VDub and ffmpegGUI would both be using the same system codecs to decode the source...

That's fine, and YMMV, but it's annoying if you've spent a lot of time setting chapter points, authoring, etc., and find your authoring program doesn't like your audio. Recently I had a two part AVI with VBR audio and hurried the process, no scan in VirtualDub MP3 & Video Freeze, no extraction of WAV file. The ffmpegGUI conversion sailed right through, but there was a glitch at the join which dvdauthorGUI choked on. Nearly an hour wasted and no indication beforehand that anything was wrong. A second go-round with a WAV file worked fine. Downloaded AVIs not infrequently have problems.

Agreed that ffmpegGUI is not as fussy as, say TMPGEnc. You may go a long time before encountering a problem.

[LisaB]

Hi Fritzi,

I'd be curious how you went about the 2-part avi conversion.

As far as I know, whenever you join 2 AC3 streams, it is important that you run the joined AC3 through AC3Fix, otherwise you'll run into problems at the join....

Even if your authoring software didn't complain, you should always run joined AC3's through AC3Fix to avoid audio synch problems.

Another approach is to join the source audio *before* converting with ffmpegGUI...this *should* eliminate the need for AC3Fix, though I admit I haven't dealt enough with this situation to be sure....

I believe the most efficient way to deal with your 2-part AVI is as follows:

1. load both avi's into VDub (using append segment)
2. set audio to direct stream copy and save the audio out (this will be the joined mp3 file)
3. set video to direct stream copy and save out a joined avi.
4. convert joined mp3 file with ffmpegGUI
5. convert joined avi with TMPGEnc or whatever...

If the audio is not mp3, but is already AC3, then you don't need to convert with ffmpegGUI, but you *do* need to fix it with AC3Fix.

Now obviously, the other solution is to process the original AVI's with ffmpegGUI, join the resulting AC3's, and run the joined AC3 through AC3Fix, but I figure if you're gonna have to join the audio anyway, why not do it *before* converting (thus avoiding AC3Fix), and do it using VDub, since I think that is the easiest way.

[fritzi93]

I don't do AVI conversions habitually, but I've done a fair number just to play with various programs. I've come to the conclusion it's not really worth the trouble. (Unless it's something really hard to find otherwise.) Therefore, I'm no expert at it.

Anyway, my first go round with that file was precisely as you laid out in 5 steps. The VBR MP3 was converted apparently successfully in ffmpegGUI. Unfortunately, DVDauthorGUI failed at the beginning of the second (joined)segment. The log stated there was an error in the audio, bad frames, if I remember correctly.

The second go, instead of Direct Stream, I used Full Processing, no compression, Save WAV. The AC3 I then created with ffmpegGUI worked fine. If it hadn't, I figured I'd have to start over and mask or remove bad frames. That's another thing, scanning for bad frames isn't such a bad idea either. And yes, if the audio is AC3 to begin with, BeSliced or AC3Fix should be used on the demuxed file. (BTW, BeSliced (BeSplit) can fix corrupted AAC, VBR MP3, AC3, and corrupted WAV headers. Also remove wav headers.) But if you're going to take the time to use BeSliced or whatever to fix the file, you could do Full Processing, Save WAV instead and VirtualDub will fix the file just as well with little extra time taken. No real advantage unless hard drive space is at a premium.

Everyone has their own preferences, and they're welcome to 'em, there's usually more than one way to do something. Whatever works for you.