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Author Topic: .ac3 file support  (Read 2867 times)

rossp

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.ac3 file support
« on: March 07, 2003, 01:11:09 am »

Hello guys,
       Can you tell me if .ac3 support will be forthcoming. I have looked in the file list and it does not appear. This is the file format like mp3 but still contains the dolby surround information which is included on dvd-audio dvd's. It sounds great and is a must for MC...

Keep up the great work on MC, it is really coming together now...    ;D

Ross
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PhatPhreddy

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Re: .ac3 file support
« Reply #1 on: March 07, 2003, 07:51:25 pm »

I also vote for AC3 support (should be easy with DVD-Video codecs...) WinDVD is the best IMHO with PDVD very very close...

Of course this is not as good as true DVD-Audio sound but even greedy old me understands that a MLP decoder and licence is not going to happen anytime soon with JRiver...

M-Audio have written a full MLP decoder and driver set... They have paid the 10's of thousands for the licence... Now they are being held back from release !!!
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iCamp

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Re: .ac3 file support
« Reply #2 on: March 07, 2003, 09:22:02 pm »

I don't understand...

Why would you want to encode audio into AC3?  Unless you have a studio capable of recording discrete surround channels it doesn't do you much good (does it?)  I mean, you wouldn't use it to encode a normal stereo song, for example...or at least I don't see why you would.

I guess it might be usefull for ripping DVDs but since MC doesn't have DVD ripping functionality why add AC3 support?

The AAC codec (which MC should support, IMO) allows for multichannel encoding.  I believe WMA Pro and WMA lossless each have provisions for multichannel encoding as well (and are supported by MC).  I suspect the WMA lossless would sound better than AC3 as it's truely lossless.

PhatPhreddy

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Re: .ac3 file support
« Reply #3 on: March 08, 2003, 02:33:12 am »

You would not be encoding AC3 merely playing back the ripped audio track from a DVD-Audio disk (they have AC3 DVD-Video audio tracks for backwards capability)... If you dont know why we want DVD-A or high resolution multi channel formats then I am not goinf to start trying to campaign you...

We can rip lots of ways as no one wants MC to get sued under the DMCA as other ripping apps are... Once ripped however it sure would be nice to play them...

Yes, WMA is possible for multichannel encoding but I am curious as to what source you have access to that you can rip and or encode and still have it sound better than a DTS multichannel track... Currenlty unless you have access to an MLP decoder you cannot purchase a higher resolution source for PC based audio (please dont quote creative at me)...

As DVD is being supported handling the audio from DVD rips should be practical and doable...  
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rossp

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Re: .ac3 file support
« Reply #4 on: March 08, 2003, 06:21:20 am »

I agree with PhatPhreddy... Ripped ac3 files should be supported by MC. Can't be a huge change...

Ross
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rossp

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Re: .ac3 file support
« Reply #5 on: March 08, 2003, 06:21:23 am »

I agree with PhatPhreddy... Ripped ac3 files should be supported by MC. Can't be a huge change...

Ross
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iCamp

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Re: .ac3 file support
« Reply #6 on: March 08, 2003, 06:30:54 am »

Quote
WMA is possible for multichannel encoding but I am curious as to what source you have access to that you can rip and or encode and still have it sound better than a DTS multichannel track


DTS and AC3 are lossy compressed formats.  WMA lossless is just that, lossless.  That's what I meant...that WMA lossless should potentially sound better because it (like MLP) is not a lossy compression scheme.

The ability to rip the AC3 track off a DVD-A disc seems a waste of time to me.  The AC3 track doesn't sound nearly as good as the actual DVD-A track (based on MLP).  If you want to rip a DVD-A why bother with the lesser performance of the AC3 track?  I want all the resolution of DVD-A.  

As you mentioned, Meridian certainly isn't going to make that possible in the near future.

iCamp

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Re: .ac3 file support
« Reply #7 on: March 08, 2003, 06:33:06 am »

Quote
I agree with PhatPhreddy... Ripped ac3 files should be supported by MC. Can't be a huge change...


I would guess the license fee required by Dolby would be fairly steep.  I have no knowledge of such fees but I'm willing to bet AC3 (or even DTS) licensing isn't cheap.

rossp

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Re: .ac3 file support
« Reply #8 on: March 08, 2003, 06:36:00 am »

True, that could be the stumbling block. Can you convert from ac3 to wma keeping the dolby 6 chanel information.

Ross
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iCamp

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Re: .ac3 file support
« Reply #9 on: March 08, 2003, 06:52:56 am »

I don't know...I haven't actually played around with the WMA surround options.  Perhaps someone else will chime in with experience doing so.

Obviously, there would be one drawback to doing so: the surround WMA could only be played back on the PC...as standalone DVD players wouldn't recognize it.

PhatPhreddy

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Re: .ac3 file support
« Reply #10 on: March 08, 2003, 07:33:39 pm »

Yes you can encode from DVD to multichannel WMA... I would assume the lossless would sound great but am unsure of any space savings over DD or DTS (interesting may have to try this)...

Quote
I would guess the license fee required by Dolby would be fairly steep.  I have no knowledge of such fees but I'm willing to bet AC3 (or even DTS) licensing isn't cheap
I have heard the fees and you are right they are not cheap... The thing is given directshow JRiver does not need to licence the codec's... They can just ensure that AC3 is played through the default DVD renderer (or consider ways for us to manipulate the defaults or specify a favorite) so that we gain AC3 support if we have any SW DVD player installed...

soapbox
I have hammered this point before but if they allowed the connection to the WinDVD rendered it would also give us DPLII surround mixes for 2 ch audio... IMHO DPLII is better than JRSS (though inferior to CSII).. this is a relatively simple filter graph (I can build it in Graphedit) and I am puzzled that more people dont think that DPLII for free is not a good idea...
/soapbox    
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Ce.D

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Re: .ac3 file support
« Reply #11 on: March 09, 2003, 04:12:19 am »

Hey, here comes the discussion about AC3 again!

Launched a similar discussion months ago on the same subject... quality, file size... price!... etc...

My 2-penny thinking:
1. 5.1 sounds great... and let's please keep M$ out of it!
2. Anyone interested enough in 5.1 audio and DVD ripping can find ways (should it be a "wayz" !?!) to obtain the AC3 sound stream transfered to his harddisk (I understand why JRiver would not launch themselve in this arena).
3. AC3 decoding requires (expensive?) licensing, but what about AC3-passthru (feeding the .ac3 file directly to the soundcard SPDIF connector and then to an external AC3 decoder, like any home-theater amp; no decoding!) ? Well, to start with, I mean...

Currenty use PowerDVD for this (the passthru-stuff, I mean); those familiar with DirectShow should look at http://xvalex.hotbox.ru/programs/ac3filter/ac3filter_eng.html (great stuff!)... but it would be so much cooler to have AC3 along MP3 in MJ/MC!

I VOTE FOR!
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Great piece of soft, guys!

PhatPhreddy

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Re: .ac3 file support
« Reply #12 on: March 09, 2003, 08:13:34 pm »

But again, by using directshow MC can utilize the decoders of the DVD players... They are happy to do this for the video side why not with these files ??

There is even an open source Dolby Decoder on sourceforge and it appears as though Dolby license selling dolby branded products by giving away this reverse engineered decoder the legal consensus was this was legitimate.
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