Help: Audio quality degrates when importing .AVI file

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funboy99
Posts: 3
Joined: Tue Mar 30, 2010 6:48 am

Help: Audio quality degrates when importing .AVI file

Post by funboy99 »

Hi there,

I have used Goldwave before on an .AVI movie file and successfully get the audio into the program for editing. However, I'm finding that the audio quality is much worse than the audio when I play the entire .AVI as a movie in VLC or Windows Media Player...

Why is this? How do I fix it so that the audio is of the same quality upon importation into Goldwave?

Thanks in advance!

Stiiv
Posts: 327
Joined: Sat May 15, 2004 7:29 pm
Location: Fallentown, PA

Re: Help: Audio quality degrates when importing .AVI file

Post by Stiiv »

What format is the avi audio? Are you using a codec pack or ffdshow or another 3rd-party decoder?
Stiiv

DougDbug
Posts: 2065
Joined: Wed Feb 16, 2005 3:33 pm
Location: Silicon Valley

Re: Help: Audio quality degrates when importing .AVI file

Post by DougDbug »

Is the sound distorted when you open and play it in GoldWave, or only after you re-save it?

Here's something you can try - Open the original AVI file and Effect -> Volume -> Volume Maximize. A window will pop-up showing the current maximum. If it's over 1.0 (0dB) you may be getting clipping (distortion). If you're going over 0dB, click OK and Maximize will buring the peak level down to 0dB if necessary.

I'm sure there is a way to extract the audio with results identical to what you get with VLC. In fact, there may be a way to extract the audio with VLC. I've never tried it, but I found this. You can also try SUPER (FREE!!!) or AoA Audio Extractor (FREE!!!). I use SUPER (it's kind-of a screwy program, but it's got me out of trouble a few times). I've never tried AoA Audio Extractor.

------------
FYI - "AVI" is a "container" or "wrapper" format and it can contain audio & video in an infinite number of compression formats &combinations. In the AVI file header there is something called the "FourCC" code that tells the player software what CODEC to use. It's likely that you have a format that's not directly supported by GoldWave, and you have a 3rd party CODEC is not working properly.

If everything's working properly... In theory... You should not get any additional loss/distortion when you open (decode/decompress) the audio. Since most formats used with AVI are "lossy" compression, you can loose quality when you save or re-save... The data/quality is lost during compression, not during decompression.

funboy99
Posts: 3
Joined: Tue Mar 30, 2010 6:48 am

Re: Help: Audio quality degrates when importing .AVI file

Post by funboy99 »

Stiiv,

Thank you for taking the time to reply...
Stiiv wrote:What format is the avi audio? Are you using a codec pack or ffdshow or another 3rd-party decoder?
I'm afraid I'm quite a newbie and I have no idea what format the .avi is... can you please tell me how I can find out when looking at it? I installed a bunch of codec packs onto my PC and so I'm not sure which one is being used to decode it... But I'd love to learn how to tell.

funboy99
Posts: 3
Joined: Tue Mar 30, 2010 6:48 am

Re: Help: Audio quality degrates when importing .AVI file

Post by funboy99 »

Hi Doug,

I am very grateful for the length and detail of your reply... Thank you! As I just mentioned in my reply to stiiv, I am quite the newbie, so forgive my ignorance of the basics. Here are my answers to your follow-up questions:

1) The sound is distorted within GoldWave itself.

2) I've tried experimenting with the volume effect filter, but can't make good progress on imoproving the quality. If it helps, the default evaluation of the sound shows left/right current maximums of: .3411 (-9.34dB)

3) It's great you provided me with links to alternate tools & how to use them... The VLC info was seemed the easiest and most direct, since that's where I'm successfully playing the movie to optimal sound begin with and it would seem most logical to grab the audio in that proven environment, at source. However, while I did find the option to convert, it was titled slightly differently from the explanatory link you provided and didn't seem to do anything for me when I tried to use it. Here's what I did in VLC:

a) Menu option: MEDIA... ADVANCED OPEN FILE...
b) <ADD> button...
c) [x] Show More Options
d) Clicked the button that looks like a "V" at the bottom of the window, beside the <PLAY> button, which reveals a combo box & selected "Convert"
e) In the resulting pop-up:
- I typed destination c:\test.mp3
- [x] display the output
-Settings Profile changed to: Audio-MP3

and then I clicked <START>... but nothing happens, besides streaming the file in the viewer (no .mp3 generated) :(

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

4) Again, like for Stiiv's reply to me, I don't know how to tell what is in the AVI "container"/"wrapper" ... how do I look at this "FourCC" code in the avi header? What tool will let me uncover what's contained within?

5) Thanks for outlining where the lossy-ness happens during compression & not de-compression - I appreciated every tidbit of your note!


DougDbug wrote:Is the sound distorted when you open and play it in GoldWave, or only after you re-save it?

Here's something you can try - Open the original AVI file and Effect -> Volume -> Volume Maximize. A window will pop-up showing the current maximum. If it's over 1.0 (0dB) you may be getting clipping (distortion). If you're going over 0dB, click OK and Maximize will buring the peak level down to 0dB if necessary.

I'm sure there is a way to extract the audio with results identical to what you get with VLC. In fact, there may be a way to extract the audio with VLC. I've never tried it, but I found this. You can also try SUPER (FREE!!!) or AoA Audio Extractor (FREE!!!). I use SUPER (it's kind-of a screwy program, but it's got me out of trouble a few times). I've never tried AoA Audio Extractor.

------------
FYI - "AVI" is a "container" or "wrapper" format and it can contain audio & video in an infinite number of compression formats &combinations. In the AVI file header there is something called the "FourCC" code that tells the player software what CODEC to use. It's likely that you have a format that's not directly supported by GoldWave, and you have a 3rd party CODEC is not working properly.

If everything's working properly... In theory... You should not get any additional loss/distortion when you open (decode/decompress) the audio. Since most formats used with AVI are "lossy" compression, you can loose quality when you save or re-save... The data/quality is lost during compression, not during decompression.

DougDbug
Posts: 2065
Joined: Wed Feb 16, 2005 3:33 pm
Location: Silicon Valley

Re: Help: Audio quality degrates when importing .AVI file

Post by DougDbug »

1) The sound is distorted within GoldWave itself.

2) I've tried experimenting with the volume effect filter, but can't make good progress on imoproving the quality. If it helps, the default evaluation of the sound shows left/right current maximums of: .3411 (-9.34dB)
OK, you don't have a clipping problem... I didn't think so, but it was worth checking.
Here's what I did in VLC:...
I've never tried a conversion with VLC. But, I've read that it can do conversions & rip DVDs, and since you were already using it I did a search and found that link. You might try extracting to WAV. I assume VLC can play MP3 "out of the box", but it might have to be configured to make an MP3.
4) Again, like for Stiiv's reply to me, I don't know how to tell what is in the AVI "container"/"wrapper" ... how do I look at this "FourCC" code in the avi header? What tool will let me uncover what's contained within?
Try GSpot. Again, I haven't used this tool (I haven't needed it) but I've read about it.

Stiiv
Posts: 327
Joined: Sat May 15, 2004 7:29 pm
Location: Fallentown, PA

Re: Help: Audio quality degrates when importing .AVI file

Post by Stiiv »

Yes, GSpot will tell you what you need to know re: which audio & video codecs are used in your avi file.

One thing I forgot to ask: in Goldwave, is there an indication of the audio format in the status bar (bottom of the GW editing window)?

My hunch is that perhaps GW is playing the audio back using a different decoder than your video players are using. I had something similar happen a few years ago with a vid that had an ac3 audio track, IIRC.
Stiiv

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