Would there be a way to smooth out audio dips in a vhs capture?

[yoda313]

I am capturing a retail vhs movie to my hauppauge hdpvr. I am using a panasonic dmres46v to dub it.

The picture quality is decent but the audio shifts from stereo to mono. It is a bit distracting on a stereo tv which is how I will be watching it most often.

I am capturing in h264 (obviously) to m2ts. The audio will be ac3 at 384kbps. When I'm done recording it is there a way to force mono from the stereo? I'd like to smooth out the dropouts to reduce the suedo popping noise.

If this is not possible or very tricky I could live with the dropouts (its not technically a dropout - there is audio throughout the tape - but it shifts continously from stereo to mono and is a bit distracting).

Is there a way with audacity? What about cloning the left and right?

I guess I'm not even sure if this is possible since there are stereo signals in the recording but its not stable.

---------------------------------

One thought I do have an old analog TEAC EAO10 audio graphic equalizer. It has about 5 sliders for left and right audio. Would it be better to recapture the tape with the equalizer in between? Would that create a synch issue if there is delay from the vcr to the hdpvr? Also would that do anything to smooth out the cut outs from stereo to mono during the capture?

[davexnet]

If you install the FFmpeg Audacity component you can import the AC3 and convert to mono.
I'd be more inclined to figure out why the audio is bad in the first place.
Is the tape damaged ?

[yoda313]

If you install the FFmpeg Audacity component you can import the AC3 and convert to mono.

Is that included with the basic audacity package? I already have it installed. Do I need to get a plugin?

Is the tape damaged ?

Not visibly so. The picture quality was decent. But the audio would shift to mono and get quiter then shift to stereo again (it is retail and is supposed to be in stereo).

I'll try your suggestion out and see how it goes.

[davexnet]

See this about installing FFMpeg into Audacity:
http://manual.audacityteam.org/index.php?title=FAQ:Installation_and_Plug-Ins#installffmpeg

[yoda313]

@davexnet - thanks.

However I am having problems starting audacity. I am on windows vista 32bit. I think I have used it before on this computer. Put it this way I had it installed on the computer. It was an old 2007 version. After clicking it it simply said audacity not working and refused to boot. I uninstalled it and reinstalled it but no luck. I just downloaded the latest version from the tools section here on videohelp and the same issue popped up.

Is there another program that can do that like audacity? I was trying to extract the ac3 from the m2ts with tsmuxer but it would only give me a .264 file. I used vdubmod and got a wav out of it. I want to turn the suedo stereo wav into a regular mono wav to smooth out the dips in the audio.

Thanks for the help.

[davexnet]

I'm not aware of other audio editors opening ac3 directly. Continue with the wav conversion. It's been the tried and trusted
way of doing it for years. Open it in the editor and see if you can figure out what is wrong.

Does your capture device create the ac3 directly ?

[yoda313]

@davexnet -

Actually I clicked through my stuff I already have and forgot I had wave studio from creative (I have a creative xfi soundcard). It can output to 48khz 16bit mono.

It can open my wav that I extracted with vdub. If I save it with creative wave studio will that make it true mono? I'll have to try it to see if it does the job or not.

---

The hauppauge hdpvr does the muxing together and creates a single file. Its a m2ts file that I recorded to. As I mentioned for some reason tsmuxer didn't see an ac3 stream - thats why I did the vdub wav step. Would another ts program work with hdpvr files?

[vhelp]

As an alternate option, you can use FFMPEG to downmix to a one channel (mono) audio:

(1- i know it works because I just tried a minute ago, using an .avs script as source)
(2- remember to alway include "" in your d:\filename in these command line tools)
(3- the snipplets below already have WAV in the source file, we assume we have wave)
(4- the ffmpeg ver i was using was an old one and seemed slow, but i was testing it)

ffmpeg -i "c:\AVsource.avs" -acodec pcm_s16le -ac 1 -ar 48000 -y d:\audio_mono.wav
or
ffmpeg -i "c:\AVsource.avi" -acodec pcm_s16le -ac 1 -ar 48000 -y d:\audio_mono.wav

pcm_s16le = sample @ 8 or 16 bit rate
-ac 1 = downmix to 1 channel audio, mono, 2 for 2 channel stereo
-ar 48000 = audio sample rate, other ie 22050 or 44100 khz

-vhelp 5424

[yoda313]

@vhelp - thanks for the option.

@davexnet - thanks for your help too.

I had downloaded the trial version of goldwave since no matter what I did reinstalling and uninstalling I couldn't get audacity to work on my pc. In goldwave I selected 48khz 16bit mono. It ended up saving a file that was half the size (about 700mb from a 1.3gb wave file). I checked the wave form graphically and it was a combined file - no left or right.

I played it back as just audio and unfortunately the same dips were in the mono version. I guess its that old adage gigo - garbage in garbage out.

One thought I had was to do this manually on a recapture. I was scouring the forum and found a post mentioning that you could use a y splitter or combiner and hook up just a single line and capture that the first time.

I checked my previous recordings and the panasonic that I'm using said "MONO R" when the audio would pop off of stereo mode.

In that case should I use a y splitter to take all the sound from the right analog out and turn that into fake stereo? My only problem is I went through the setup menus on the panasonic and could not find a way to force a mono output from the vhs side - nor the dvd side for that matter.

Would this forced technique work?

I don't think I'll be able to do another test with the vcr until the weekend. But in theory could this help bypass and limit the dips I experienced?

In the meantime I decided to bite the bullet and just go ahead and convert the original capture intact to dvd. I'll just mark on the disc audio dip problem and live with it for the time being - the picture quality is good so that is the more important factor at the moment.

Thanks for any advice and for those who have posted already.

Edit - my only problem with doing a forced mono is when it is actually pumping out a stereo signal won't my fake mono be only receving the right audio if I take it off just the right output? Is there any way to take the left and right audio and combine it into mono than back out to stereo with converters? I have a ton of the y splitters and combiners for analog plugs.

[davexnet]

Yoda313, why don't you post a section (a couple of minutes) of your stereo wav file?
Perhaps myself and others may be able to offer some specific advice.

It's a shame you can't get Audacity to work (Is the problem with the install or the running of it? )
Have you tried installing as the Administrator ?

Once it + the FFMpeg pack is installed you can drop the m2ts straight into Audacity and it will open the audio for editing.

[yoda313]

@davexnet - crap I just deleted my ripped audio from the video capture. Doh!

I'm doing a bunch of encodes with avstodvd right now. Probably through the night for those. WHen I'm done with those I'll work on posting a clip.

What I can do is post the audio sample of the thx hum that plays at the beginning of the movie. THat is a great example of what goes on throughout the capture. It will sound crisp and clear and then pop to a lower mono and back to clear stereo. But like I said I'm in the middle of some encodes right now and I'll post it later.

Actually audacity installs just fine it just won't start. When I double click it it goes through the motions of loading but than windows flashes the "program won't start" message but doesn't give any details or warning messages beyond "won't start".

[davexnet]

OK - lets wait until you can provide some sample.

Have you tried right-clicking on the Audacity icon and selecting "run as Admistrator" ?

If that doesn't work, uninstall and re-install - but start the setup program as above.

[yoda313]

audacity2.jpg

No luck. Tried it on both of my internal harddrives no luck. Tried it as run as administrator no luck. Each time I get the same message as above.

Is it something to do with vista 32bit?

I do have a xp pc but its a slow old single core amd pc and this will be a 1.3gb wav that I'd be loading onto it. That will take forever to do anything with it.

[davexnet]

Yoda - I've got Vista installed on my triple boot box,
I'll give a try and let you know.

In the meantime, see if this helps -
http://forum.audacityteam.org/viewtopic.php?f=16&t=6642
http://audacity.238276.n2.nabble.com/Audacity-exe-has-stopped-working-td290513.html

[yoda313]

@davexnet - ok I've checked out the one link and couldn't find the .cfg file - I did check to add the hidden files and couldn't find it. So I am at a loss there.

Here is the sample

thxsample.wav

This is the effect I get off and on throughout the movie. It will click clean stereo than go off and go back. There are long stretches that are ok but this will happen quite often. Disconcerting when a big action sequence will start and the background orchestral music ratchets up then pops out of stereo. I'd actually rather have it stable mono than this. But I'm not sure how to do that either post processing or some kind of trickery on "live" capturing.

------------------------

Mods - if this would be a violation please remove the link and give me a yellow card - I just want a second opinon and didn't want to wait for clearance. However the thx logos have got to be out on the net for free download - I know the dolby trailers are I think..... Any way..

---------------------------------

So any suggestions?

If the upload does get removed pm me and I'll forward a link.

[davexnet]

yoda I looked at your sample in an audio editor, the right channel looks normal,
while the left appears to flatten slightly for two seconds and then goes back to normal.
Is this the problem?

You can certainly convert it to mono - but it doesn't solve the problem, because you get a loss
of volume at that point (highlighted area)

[yoda313]

the right channel looks normal,
while the left appears to flatten slightly for two seconds and then goes back to normal.
Is this the problem?

Bingo.

You can certainly convert it to mono - but it doesn't solve the problem, because you get a loss
of volume at that point (highlighted area)

So are there any realtime tricks I can do to force a stable recording? I do have an old audio graphic equalizer but I don't know if that would do any good or not.

Am I just stuck with it?

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By the way thanks for all the help davexnet.

Edit - I know it would be impossibly boring and probably not worth doing for the whole 2 hour movie but would artificially boosting the volume at the dipping points smooth it out? Or would that simply amplify the loss of the clear audio and be more noticeable than a dip?

[davexnet]

Edit - I know it would be impossibly boring and probably not worth doing for the whole 2 hour movie but would artificially boosting the volume at the dipping points smooth it out? Or would that simply amplify the loss of the clear audio and be more noticeable than a dip?

It can be done - the result depends entirely on your patience and skill in the editor.

For example, you could very carefully mask or select the area, and try and make the left the same level as the right.

Wouldn't you be better off finding out why it's bad it's the first place? Do you have a dodgy cable or is your capture device
involved? Or is the problem in the source ?

[yoda313]

Or is the problem in the source ?

That is my first guess. The capture device (hauppauge hdpvr) seems to be just fine on other source material from the same vcr.

It can be done - the result depends entirely on your patience and skill in the editor.

For example, you could very carefully mask or select the area, and try and make the left the same level as the right.

Interesting. When I have some time to devote to it I'll try it on the sample I created. Then I can determine if its feasible for the whole movie.

Wouldn't you be better off finding out why it's bad it's the first place?

Well not in this case. The movie in question is actually available on commercial dvd. This was just something I was fooling around with. I'm not going to go to pieces over it if I can't tweak it just right. But I did want to see if there was some "quick fix" I could employ. But I'll definitely fool around with volume boosting or cloning the left and right at those points.

-------------------------------

Here's a thought. Is there a way (I'm looking at simplifying this for a two hour file - about 1.3gb wav file) to automate cloning the right channel? Can I simply copy the right on to the left?

ALso I've seen those threads on creating seudo 5.1 from 2 channel sources. Is it possible to make seudo stereo from a single channel? THat way it would trick the ear into thinking it was stereo even though it was from one channel?

I know the technical best way to go is to boost the existing left channel audio since that is actual audio and not faked but that could take a long time. I'll have to toy with it when I can.

Thanks for the tips.

[davexnet]

In the audio editor it should be possible to clone the right channel - but then you lose half of the stereo audio. Any sound effects,
voices, etc recorded on the left will now be missing...

If you want to try deleting audacity.cfg as we mentioned earlier, I installed it in Vista myself, and the location is:
\users\your_id\appdata\roaming\audacity\audacity.c fg

[yoda313]

@davexnet - thanks.

I guess I"ll try the manual volume boost on the dip portions for the left channel. I'll try it on the sample clip I made. If it shows promise I could consider doing it for the whole movie - though that would take a lot of resolve to push ahead with that - hopefully it wouldn't be too many portions that would need tweaking.

Regarding audacity - something is cursing me with this - in the roaming folder there is no audacity folder!?!?!?! Wtf? - fyi its still installed.

[davexnet]

I gave up with the Vista "search", turned off indexing and installed Agent Ransack.
It's fast, simple interface, reliable.

[yoda313]

bump

Just thought I'd let you know I got a panasonic ag1970 svhs player yesterday used at a great price.

I tried this same problem tape and walla - no audio dips! It works PERFECTLY. I played the opening thx intro and the sound was crystal clear with no dips or drop outs.

I'll definitely be redubbing this particular tape.

Thanks davexnet for all the advice. In the end it seems the playback device was the source of the issue. Which is weird because I've done clean caps from the same vcr on other commercial tapes. I'm not sure why it had problems with this particular one. But the svhs player with tbc on played it back flawlessly.

[intracube]

Just thought I'd let you know I got a panasonic ag1970 svhs player yesterday used at a great price.

I tried this same problem tape and walla - no audio dips! It works PERFECTLY. I played the opening thx intro and the sound was crystal clear with no dips or drop outs.

Just to add, I've had similar problems with a Panasonic SVHS machine - particularly on LP recordings from other recorders. In addition to switching between stereo and mono, I've noticed artifacts on the audio including a buzzy hum on recordings with loud content, and intermittent 'ticking' sounds. It was a budget machine, which may partly explain the problems. The remote had a button to manually select the left, right, stereo, and linear mono audio tracks - so it could be forced into mono mode permanently (although with an obvious quality drop).

An older Sony VHS machine (~1995) had virtually no problems with the sound on any tape I threw at it - it was a significantly better quality machine IMO, (and significantly more expensive).

Unfortunately in the last few years it's developed a habit of chewing tapes, something that a trip to the repair shop couldn't fix (although it might be possible to do a better quality home repair than they did).

I've just done a search for your machine and found this:
http://www.youtube.com/watch?v=V3NR9YivyCM

Veerrrry nice

[yoda313]

Just to add, I've had similar problems with a Panasonic SVHS machine - particularly on LP recordings from other recorders. In addition to switching between stereo and mono, I've noticed artifacts on the audio including a buzzy hum on recordings with loud content, and intermittent 'ticking' sounds

Just to clarify the panasonic svhs player actually corrected the error on my tape.

I've just done a search for your machine and found this:
http://www.youtube.com/watch?v=V3NR9YivyCM

Veerrrry nice

Thank you. It is. I think I will be enjoying this purchase very much.

[intracube]

Just to clarify the panasonic svhs player actually corrected the error on my tape.

Sorry, bad quoting on my part - I was referring to the Panasonic dmres46v in your first post.

[davexnet]

Congrats on the AG1970 - now you should get the best video and audio from your old tapes.
Every now and again they turn up at second hand shops, goodwill, etc. (I've yet to be so lucky as to find one myself though!)

[yoda313]

they turn up at second hand shops, goodwill, etc

Actually I did get it at a goodwill store

now you should get the best video and audio from your old tapes.

Thanks. I already dubbed a full length widescreen tape and it looked nearly perfect. I shall be enjoying this.