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  #16  
Old 2008-05-19, 10:30 AM
tgunn2760's Avatar
tgunn2760 tgunn2760 is offline
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Re: Re-encode AC3 to LPCM using TMPGenc

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Originally Posted by MeFirst View Post
Honestly, what's the point of all this since judging from the description of this particular video it's just people talking. Who cares what the sound quality is like anyway unless there's music involved.

To point out a few things though, there are not many standalones that record audio in LPCM, most will use AC3 so that higher video bitrates can be used. Although it is possible to use video bitrates over 8000kbs with LPCM resulting in a "non-standard" DVD, most DVD players these days won't have any trouble playing them anyway.

Also, many people assume because AC3 is a form of compression they immediately equate it to the horrible MP3 compression, which is totally different. AC3 is hardly a "crappy compressed" format, it's used on virtually every commercial DVD released (yes, AC3 is Dolby Digital). Due to the bandwidth limits of a DVD, Dolby Digital is preferred so that the higher video bitrates can be used for smoother video.

And as Kool Kat pointed out, most cable and satellite broadcasts use audio compression to begin with, so you're not getting true lossless audio right from the start. Your VCR (or Beta in this case) recorded it in LPCM of course, which is basically the same thing as plugging in your portable MP3 player to your PC and using a software audio recorder to record the music off it to WAV in real time (not that broadcasts use MP3 audio, it's just an example). So right from the beginning, the damage has already been done. Of course, recording from the VCR to LPCM keeps the audio the way it is without further compression which would be best, but when it comes right down to it, AC3 is really not a bad compression format. If it were, it wouldn't have been used by pretty much every single movie studio for the past 16 years or so.
If the audio is compressed during the broadcast, then you would be compressing it a second time if you used anything BUT LPCM during the transfer from VHS to DVD. MPEG2 to AC3 or AC3 to AC3 would be a second compression, especially if the bitrate is different.

8000 kbps video compression and LPCM audio is not bad for one hour of music. I have seen excellent video at lower bitrates. Most programs at about one hour, some are two hours, minus the commercials it's 90 minutes, those can fit on two DVD5s. A one hour program with lossless audio is about 4 GBs.

So, if Vlad can get a SA DVD recorder that will record audio at LPCM he would be better off. I am sure he can hook up his VHS to it and dub, and also record new programs in lossless audio.
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  #17  
Old 2008-05-19, 10:53 AM
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saltman saltman is offline
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Re: Re-encode AC3 to LPCM using TMPGenc

I thought I would summarize my thoughts on the issue.

With interviews as a category LPCM is not as critical since the dynamic range is typically less but would be nice. If the source is something merely recorded from TV then LPCM is not that critical since it is almost always already compressed. If it is an interview that you actually filmed yourself than sure LPCM would be much better. Keep in mind that taking broadcast ac3 and then recompressing again to ac3 with a standalone is less than ideal. PC transferring would be much better.

The notion that ac3 is acceptable because hollywood uses it is naive. The encoders Hollywood uses are FAR superior to what a consumer uses especially one that encodes on the fly like a stand alone. Consumer AC3 is garbage and mp3 is a good analogy. IMO it is worse than mp3 and yes I have done tests.
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  #18  
Old 2008-05-19, 10:56 AM
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Re: Re-encode AC3 to LPCM using TMPGenc

Quote:
Originally Posted by saltman View Post
I thought I would summarize my thoughts on the issue.

With interviews as a category LPCM is not as critical since the dynamic range is typically less but would be nice. If the source is something merely recorded from TV then LPCM is not that critical since it is almost always already compressed. If it is an interview that you actually filmed yourself than sure LPCM would be much better. Keep in mind that taking broadcast ac3 and then recompressing again to ac3 with a standalone is less than ideal. PC transferring would be much better.

The notion that ac3 is acceptable because hollywood uses it is naive. The encoders Hollywood uses are FAR superior to what a consumer uses especially one that encodes on the fly like a stand alone. Consumer AC3 is garbage and mp3 is a good analogy. IMO it is worse than mp3 and yes I have done tests.
Such a shame. I have so much more to share.
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  #19  
Old 2008-05-19, 11:00 AM
tgunn2760's Avatar
tgunn2760 tgunn2760 is offline
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Re: Re-encode AC3 to LPCM using TMPGenc

Quote:
Originally Posted by saltman View Post
I thought I would summarize my thoughts on the issue.

With interviews as a category LPCM is not as critical since the dynamic range is typically less but would be nice. If the source is something merely recorded from TV then LPCM is not that critical since it is almost always already compressed. If it is an interview that you actually filmed yourself than sure LPCM would be much better. Keep in mind that taking broadcast ac3 and then recompressing again to ac3 with a standalone is less than ideal. PC transferring would be much better.

The notion that ac3 is acceptable because hollywood uses it is naive. The encoders Hollywood uses are FAR superior to what a consumer uses especially one that encodes on the fly like a stand alone. Consumer AC3 is garbage and mp3 is a good analogy. IMO it is worse than mp3 and yes I have done tests.
AC3 is great for movies, LPCM is far superior for music.

Nowdays you see more and more DTS audio for commercially released music DVDs.
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Text file of over 1500 DVDs:

https://docs.google.com/file/d/0BxX3...Q2M/edit?pli=1

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http://db.etree.org/public_wantlist....erid=tgunn2760
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  #20  
Old 2008-05-19, 11:19 AM
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saltman saltman is offline
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Re: Re-encode AC3 to LPCM using TMPGenc

Quote:
Originally Posted by vladsmythe View Post
Such a shame. I have so much more to share.
I do not mean my statement to be directed at you personally. You SA transfers are less than ideal but it sounds like they are the best source available at the moment and are acceptable according to our present standards. The only thing that would be better would be if they were PC transferred, IMO.
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  #21  
Old 2008-05-19, 11:30 AM
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vladsmythe vladsmythe is offline
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Re: Re-encode AC3 to LPCM using TMPGenc

Thanks for the positve and informative response saltman. I will have to buy another PC to do it, as my wife would kill me if I suggested doing it in my bedroom or the recroom/office. She likes things uncluttered. So when I buy a new box I'll give it a whirl in the Graceful Duck Archive storage vault (my garage). Until then, trust me to provide the best possible content in the best possible manner for now. Thanks again for the help.
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  #22  
Old 2008-05-19, 12:23 PM
scratchie scratchie is offline
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Re: Re-encode AC3 to LPCM using TMPGenc

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Originally Posted by vladsmythe View Post
She likes things uncluttered.
Women!
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