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Discussion Starter · #1 ·
First I want to say that I'm French and my english is not as good as yours so ask me if you don't understand what I'm saying ;) .


So I would like to play DivX films (encoded in stereo) using the Dolby Prologic II, but I want that it would be the computer that decode the DPLII : in fact, I have already a surround system speakers, so I don't have an ampli : I have a SBLive! 5.1 + speakers DTT2200 from Cambridge SounWorks. It's perfect for Dolby Digital, for the DVDs, but I will be very pleased to hear my DivX in 5.1 too.


I know that PowerDVD 4 decodes the DPLII, but it's a very bad player in order to play DivX. I would be able to use the powerdvd filters' in another soft like Zoom Player, but I don't how I must do.


Do you have ideas ??


Thanks
 

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Hi flotheouf,


I hear that you can create divx's retaining the original AC3 (5.1) track. However the AC3 file will be large and you will most likely have to burn two CD's insteand of one.


However there is a new audio compression algorithm about called Ogg Vorbis. Its an exciting compression algorithm not only because it claims to have better compression/quality than MP3 but because it also has multichannel support (5.1/4 spkr etc).


My last attempt, a month ago, to get this to work with 5.1 failed due to software support. However I hear that people have been having success getting 5.1 working.


Have a look at the Articles Section and the forums at: http://www.everwicked.com


Best regards,


Obsidience
 

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Discussion Starter · #3 ·
Thank you for your answer.


I know the DivX encoded in AC3, and your new format looks terrible, but in fact I just want to manage to make an emulation of the stereo of films already encoded :confused:
 

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I also have been trying to find out a way to play back DIVX (and mp3, ape, or any other compresses format for that matter) files with Dolby PL II decoding. This would allow me to use a card such as the M-audio in 6 channel mode directly outputting to an amplifier. Unfortunately, it seems that the PowerDVD implementation of DPL II is very limited. Not only does the filter not work for multichannel output in zoom player, but even using the regular PowerDVD player only CDs or DVDs can be used with the DPL II decoding. No other files will work here. This is a stupid programming decision which I do not understand at all. Since after all this time of people trying to use the filters in Zoom is still not successful, I wouldn't hold my breath for anyone to figure it out soon. i am now waiting for winDVD 4 and hoping that it has better implementation of these features!
 

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Discussion Starter · #7 ·
yes I know that Powerdvd can read divx files, but it's very bad : the resolution of the film is not respected... Powerdvd resize all the films in 4/3 and it can't play films encoded in divx 5
 

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maybe it won't do mp3 properly because a lot of Mp3 files are joint-stereo.


Just a hunch, I noticed this because I get my enterprise episodes on VCD every week. The last epsiode I got was encoded with Joint stereo and I was unable to decode just regular Pro Logic with it.
 

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Actually, MP3 with joint stereo can hold a Pro-Logic signal quite well. Some studies have been done, IIRC it was on hydrogenaudio.org, that demonstrated that the newer releases of the LAME mp3 encoder held the DPL encoded information down to a bitrate of about 112, and at 128 consistently maintained all of the information, regardless of whether it was joint stereo or not. The problem with PowerDVD is not that it decodes mp3s improperly, but rather that it will not even attempt to decode them in the first place. Even if I go under the settings tab and enable DPLII, when I playback an mp3 or DIVX it reverts to two channel output without ProLogic.
 

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If someone figured out a way to get the PowerDVD audio filter to do decoding when used in other apps (like Zoomplayer) that might be a method. Sadly, this probably isn't likely :(
 

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Guess what guys... NO DICE. I downloaded and have been playing with WinDVD 4 Trial all day (see this thread http://www.avsforum.com/avs-vb/showt...hreadid=138939 ) and while the DPL II does work for music, including mp3s, it will not properly decode an AVI. I even tested this by demuxing the audio track from a DIVX that I made. When I played the standalone MP3 soundtrack (created from the original 6 ch AC3 using BeSweet and encoded to LAME --alt-preset standard), the DPL II decoded it perfectly into the discrete channels. When I played the AVI with the MP3 muxed, I simply got the same L/R channel signal on my fronts and rears, with no center channel output. So no DIVX DPL II in winDVD 4 :mad:


Despite this setback, the fact remains that the DPL II DMO filter in WinDVD 4 can properly decode a movie soundtrack mp3, as shown by my little experiment. So it may still be possible to get this to happen in graphedit or Zoom. I haven't had any success with this yet (see other thread for details), but I will keep trying and

i hope the rest of you will as well.
 

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I think you're missing the point when you apply this to 'DivX' films. Most of those available on the 'net, and AFAIK the way everyone backs up their own just downmixes the 5.1 to 2.0 stereo... You can't simply extract DPLII from that, it just won't work. OTOH of course, if you can ENCODE DPLII in your 'ripping' software, then yeah no probs, but this isn't the case is it?


Of course, I'm not talking about the AVI's where you'd use AC3 and this newfangled OGG5.1 thing, just any kind of 2.0 stereo. Though I suppose the 'simulation' offered by 4/6 speaker cards these days can sorta simulate the soundfield from the 2.0, but it definately a'int proper surround.
 

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What you are saying about DIVX audio (aka LAME MP3) and Prologic decoding simply isn't true. Using proper encoders (such as Azid + LAME, BeSweet, HeadAC3he) the Dolby Surround information present from the original soundtrack is entirely preserved. There has been many discussions and research into this at both hydrogenaudio.org and doom9.org. If done properly and at a bitrate minimum of around 112-128, the MP3 doesn't lose any of the Surround info.


As of today, there is nothing truly encoded anywhere (DIVX or not) in Prologic I or II. Prologic I or II is simply a decoding algorithm for recovering Matrix Surround information (aka Dolby Surround). What DPL II brings to the party is an inproved matrix decoder capable of retrieveing five discrete full range channels as opposed to three full range and a mono surround channel with a max freq response of 9khz. Additionally, the music mode of DPL II allows a 5 channel field to be created from the phase information contained in any 2 channel recording (aka the simulated surround). For a great demo test of how well this simulated sound works, play Madonna's Ray of Light (whether it is to your taste or not) with DPL II decoding, center width set to 3, and Panorama mode off. It really sounds amazing, as if it was recorded as a DTS 6 channel CD. If you want any more information on how DPL I and II work, look at www.dolby.com. They have a few papers on there that really explain what Dolby surround encoding is and how the ProLogic decoding algorithms turn it into mulit-channel sound



EDIT: Here is the link describing the principles behind DPL http://www.dolby.com/tech/l.wh.0007.PLIIops.html
 

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Prologic I or II is simply a decoding algorithm for recovering Matrix Surround information (aka Dolby Surround).

Exactly, what I'm saying is that with a 5.1 DVD you'll not preserve or generate this when converting to 2.0 (in any form, compression is largely irrelevant as you say). Though I suppose around 1/3rd of DVD's come with a 2.0 track, and that probably has the DPL stuff in it already.


Though looking at 'headac3he' .... :eek: ;)
 

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Joe,


Not true. One of its goals and what it does best is extract pre-encoded matrixed surround sound. But, if you go look at Dolby's site, it also attempts to create a pleasing multi-channel sound out of ANY stereo material. It is similar to CircleSurround or other spread-stereo-to-a-lot-of-speakers feature.
 
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