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Lossy or Lossless? Please use this forum to post spectral and frequency analysis posts about shows you have your doubts about.

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  #1  
Old 2008-05-29, 06:27 PM
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Lossy or lossless?

I have a DVD with low volume AC3 audio @256;

I extract the audio to wav with IMToo DVD ripper;

run it through Goldwave and increase the volume;

encode to AC3 audio at same bitrate-256-with Sony Vegas.

Do I have a lossy or lossless DVD?
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  #2  
Old 2008-05-29, 06:45 PM
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Re: Lossy or lossless?

Genuine LOSSY. All you did was amplify it, and probably made it worse.
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  #3  
Old 2008-05-29, 07:24 PM
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Re: Lossy or lossless?

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  #4  
Old 2008-05-30, 05:14 AM
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Re: Lossy or lossless?

Very funny Leif!
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  #5  
Old 2008-05-30, 01:29 PM
roomful
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Re: Lossy or lossless?

Quote:
Originally Posted by tgunn2760 View Post
I have a DVD with low volume AC3 audio @256;

I extract the audio to wav with IMToo DVD ripper;

run it through Goldwave and increase the volume;

encode to AC3 audio at same bitrate-256-with Sony Vegas.

Do I have a lossy or lossless DVD?
That's double lossy. One encoding to lossy is bad enough, but decoding lossy to wav then encoding again to lossy will really make it sound terrible. All the negative aspects of lossy compression will be much more apparent upon listening.

If you want to edit/process it, and preserve the quality, you will have to leave it as wav after running it through Goldwave, and use LPCM audio for your DVD.
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  #6  
Old 2008-05-30, 01:34 PM
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Re: Lossy or lossless?

Quote:
Originally Posted by Karst View Post
Very funny Leif!
thanks.. I made that last year...
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  #7  
Old 2008-05-30, 01:36 PM
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Re: Lossy or lossless?

Quote:
Originally Posted by roomful View Post
That's double lossy. One encoding to lossy is bad enough, but decoding lossy to wav then encoding again to lossy will really make it sound terrible. All the negative aspects of lossy compression will be much more apparent upon listening.

If you want to edit/process it, and preserve the quality, you will have to leave it as wav after running it through Goldwave, and use LPCM audio for your DVD.
this is the correct answer.


but - to address another of the questions in the first post, there's no such thing as a "lossless DVD". All video on DVDs is compressed. The audio COULD be lossless - but AC3 is not.
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  #8  
Old 2008-05-30, 03:15 PM
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Re: Lossy or lossless?

Quote:
Originally Posted by jameskg View Post
thanks.. I made that last year...

I was going to say courtesy of jameskg, but I decided if anyone besides you really cared, they'd quote it and see it was yours.
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  #9  
Old 2008-05-30, 05:58 PM
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Re: Lossy or lossless?

Quote:
Originally Posted by jameskg View Post
this is the correct answer.


but - to address another of the questions in the first post, there's no such thing as a "lossless DVD". All video on DVDs is compressed. The audio COULD be lossless - but AC3 is not.
I think we covered that all DVDs are compressed, I personally do not see a problem in the method I proposed because you are compressing the audio to the same specs. All you doing really is boosting the volume. You do not put any date back to the file when decompressing, and not removing anything that was not removed the first time.

I will try it my way just to see how the audio turns out. I doubt that it will sound "horrible". In fact I expect it to sound much better than the original.

I am also sure it will not be allowed on the tracker, but I was not planning to seed it.

I thought about keeping the wav audio, but that would require a DVD9.
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  #10  
Old 2008-05-30, 06:04 PM
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Re: Lossy or lossless?

Quote:
Originally Posted by tgunn2760 View Post
I personally do not see a problem in the method I proposed because you are compressing the audio to the same specs. All you doing really is boosting the volume. You do not put any date back to the file when decompressing, and not removing anything that was not removed the first time.
Wrong.

What you are asking is if 256 @ AC3 will become lossless if you amplify it, then re-encode it to 256. That is the same as going mp3 256 > wav/cdr > mp3 256. It's double lossy.

It's the same thing as re-sizing a picture, really.
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  #11  
Old 2008-05-30, 06:44 PM
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Re: Lossy or lossless?

Once something is lossy, there's no going back. You cannot get something from nothing.
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  #12  
Old 2008-05-30, 07:35 PM
roomful
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Re: Lossy or lossless?

Quote:
Originally Posted by tgunn2760 View Post
I think we covered that all DVDs are compressed, I personally do not see a problem in the method I proposed because you are compressing the audio to the same specs. All you doing really is boosting the volume. You do not put any date back to the file when decompressing, and not removing anything that was not removed the first time.

I will try it my way just to see how the audio turns out. I doubt that it will sound "horrible". In fact I expect it to sound much better than the original.

I am also sure it will not be allowed on the tracker, but I was not planning to seed it.

I thought about keeping the wav audio, but that would require a DVD9.
not true, more information will be removed. Do it enough times and it will be nothing but static.

Try it out just to see how it sounds. I guarantee you will notice the effects of compression in cymbal heavy and loud passages.

What's wrong with a DVD9? They are seeded here all the time.
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  #13  
Old 2008-05-30, 10:23 PM
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Re: Lossy or lossless?

Tgunn, you've been schooled by both Leif & roomfuloftubes. They're right. If you don't understand why, you need to read-up on digital data compression, as it is used for digital audio. You don't have a grasp on it yet.
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