Software Stereo => DPL II (Dolby Pro Logic 2)

[Tyler_Durden]

hi @ll,

just thought it would be very nice for people without a
dolbyprologic ii receiver, but a dolby digital 5.1 one, to get films with stereo-signal played in dpl ii.

why?
because dpl ii sounds way better than dpl i or normal stereo when the film was originally downsampled from dd5.1 to stereo(most 2chanel dvd rips of newer films are like this).
it almost sounds like dd5.1 when the soundstreamquality of the film is good!

btw: i have a dpl ii capable receiver, but i know a lot of people with a dd 5.1. set without dpl ii, so i think this would put a smile on their faces.......

[IndieRockSteve]

i'm going to second this, because i have dd5.1 but no dplii, just dpli.

and

i hate having to switch between output to all channels being on and off depending on if i want to watch a video or listen to music. if this was enabled, all the dpl encoded shows i watch through the xbox would be output as the proper 5.1 signal and not the hack that it currently does(which works great for music but horrible for the audio that accompanies shows). plus, the audio would be converted in the digital domain for people who's receivers would do it in the analog one.

thanks!

[joniS]

it would be a really nice feature for us that dont have dplii, but do have 5.1 dd.

/ j

[jmarshall]

just to let you know:

this is feasible assuming the following:

1. the algorithm is available (dpl1 is, not sure about dpl2)
2. you don't mind sacrificing a bit of quality

reason for 2, is the 2 channel source is likely compressed anyway in some form - it will be decompressed to pcm, resampled to 24bit, 48khz by the xbox mcp, then we can do the processing etc. before it is reencoded to ac3 in real time. quality is effected, but it may still be suitable to do this.

first and foremost, we will require information on the algorithm. if you could search this out, that'd be a great help.

note that it is not a high priority, though - i'm more of a quality person than a stuff around with the sound person.

cheers,
jmarshall

[Gamester17]

this is feasible assuming the following:

1. *the algorithm is available (dpl1 is, not sure about dpl2)
2. *you don't mind sacrificing a bit of quality
fyi devs can get dpl2 algorithm here (link to ac3 & dts downmixed to dolby pro logic ii feature request) (http://sourceforge.net/tracker/index.php?func=detail&aid=817087&group_id=87054&atid=581841) http://www.xboxmediaplayer.de/forums/non-cgi/emoticons/wink.gif

[Tyler_Durden]

hi @all,
nice to see some movement inside this post;-))

hope the link supported bei gamester will help
some devs(possibly one without a dplii receiver;-)) to implement this feature....

i think when more people had the possibility to hear the difference between a movie played in normal stereo and dplii (btw. like the gamecube puts out) more would join this idea.......

have a nice time

[kabtoffe]

i would like too see options for analog surround output, similar to matrixmixer (and ac3filter). i have an old dolby pro logic amplifier and would like to enjoy surround sound.

[Diggedy]

i love the idea of a dpl2 mode being implemented. like others here i have a 5.1 reciever but not dpl2 decoding. dpl2 sounds much better on a 2 channel source in it's movie and music modes that regular pro logic.

[IndieRockSteve]

i'd just like to bump this because i think its a great feature to have and i haven't really seen any talk about it.

thanks!

[bOOka!]

i'd love to have this feature as well!
i only have dpl1 and i have considered buying new receiver just to get dpl2..

[|vibez|]

bump! i'd love to see this implemented too :)

[Dolfhin]

+1 i would love to see this :d

[vnm]

+1

[jlbcnous]

already exist a home made vst plugin for convet stereo to surround music. i tried it, and is wonderful.
http://forum.doom9.org/showthr....umber=1 (http://forum.doom9.org/showthread.php?threadid=85446&perpage=20&highlight=ambisonic&pagenumber=1)
would be feasible to integrate this in xbmc?

[pike]

is it opensource (gpl'd) ?

[jlbcnous]

i dont know, but i will ask to the author.

[Dolfhin]

i see this is listed as possiblity for the new dvd core, any news on that front? e.g is it going to be possible at all?

[Gamester17]

i see this is listed as possiblity for the new dvd corehuh?, what do you mean by that?, ...do you mean my list of suggestion (http://www.xboxmediaplayer.de/cgi-bin/forums/ikonboard.pl?act=st;f=5;t=10877;st=1)?, that is just a list of requests, not planned nor working features.
anyway, no, it is not supported xbmc yet nor do i know of anyone specifically planning on coding it, ....anyone if free to code it though.

[Dolfhin]

i see this is listed as possiblity for the new dvd corehuh?, what do you mean by that?, ...do you mean my list of suggestion (http://www.xboxmediaplayer.de/cgi-bin/forums/ikonboard.pl?act=st;f=5;t=10877;st=1)?, that is just a list of requests, not planned nor working features.
anyway, no, it is not supported xbmc yet nor do i know of anyone specifically planning on coding it, ....anyone if free to code it though.
yes, indeed, i saw it on your list of requests.

basicly what i'm asking for is that xbmc will output a dolby pro logic ii signal in ac3, xbmc encodes the stream and sends the result out as a ac3 5.1 signal. that would give all ac3 decoders pro logic ii and upgrade pro logic i encoders to pro logic ii!
it will allow a lot more people to use surround, enhance the experience for people with an older receiver and make xbmc usefull with cheap 5.1 sets!

i really would love to have this feature included in xbmc, it might not be very attractive to the people with hdtv's and expensive 5.1 sets but for people on a tight budget (and due the xbox being a game console a lot more people than you'd suspected have a tight budget).

i can also imagine that the people with a 5.1 set hooked up to the xbox using something else than the optical output will love this (that is, it will allow them to have surround sound if xbmc encodes 5.1 movies to pro logic ii and output it using the two l and r stereo cables), a cheap pro logic ii receiver will be all that stands between a more enjoyable experience and them).
imho this would greatly improves the valua of xbmc for a lot of people with tight budgets. basicly it would make the difference between having 4.0 out of your sets and true 5.1 goodnes!
it would be great for those divx/xivd movies with 2 channels and ofcourse for tv series that often have only 2 channels (unfortanley often found on dvd's).

i'm not asking anyone to make this their top priority but if anyone, anyone at all, has some intrest in this and some spare time consider doing it. i don't know how hard it will be (making an opion, if option is enabled then output the mplay audio stream into this encoding mechanisme put the output to the xbox's audiochip,xbmc already does some decoding (adjust frame rate, downsampeling so it should be possible)) but it would certainley be something that would greatly enhance xbmc for me and a lot of people. the amount of people that use xbmc and only use a pro logic decoder is probably far greater than you would expect.

information about the difference (to see if it's actually worth it ):
http://forums.audioholics.com/forums/showthread.php?t=13089
http://forum.ecoustics.com/bbs/messages/3/6180.html
http://forum.ecoustics.com/bbs/messages/3/6268.html
http://forums.dvdfile.com/archive/index.php/t-19685.html
http://www.audiorevolution.com/equip/surround/ (go down to matrix surround)

some information about how it works (i have no clue if this is usefull to any developer at all but i include this just in case ;))
http://forum.doom9.org/showthread.php?s=&threadid=27936
http://en.wikipedia.org/wiki/dolby_pro_logic
http://www.wildwestelectronics.net/lisguidtodol1.html(basic i doubt that it will help a developer but it might be an intresting introduction)

a quote from the wikipedia to end this post :

in 2000, dolby introduced dolby pro logic ii, essentially a redesigned version of dolby pro logic. dpl ii uses two stereo surround channels, an lfe (subwoofer), greatly enhanced steering logic compared to dpl, and as a result, offers an exceptionally stable sound field that simulates 5.1 to a much greater degree than the original pro logic

[Themicles]

to start: yes, i searched the faq. i've searched the wiki, and i've searched the forums here. i have been unable to find any specific info on what, exactly, xbmc does when upmixing stereo to all speakers.

which one of the following does xbmc do to upmix stereo media to 5.1 when using the spdif output?
stereo x2 (plays the same in both front and rear speakers)
stereo x2 with effects (simulates room acoustics)
or does it use a matrix mixer of some sort?

i ask, because out of all the various upmix setups i've heard over the years, i've become quite partial to the matrixmixer directshow filter made by the same author that made the ac3 decoder for winamp (which is also available as a directshow filter).

if xbmc does not already include such, i think i might submit a feature request on the sourceforge project.

[jmarshall]

it doubles left and right to the rear channels, and mixes the fronts into the center which is then attenuated (in order to keep stereo separation).

please note that directshow filters aren't much use as xbox doesn't use the same system. xbox does, however, have a fairly high-spec audio processor, which we aren't taking advantage of as noone has taking the time to look into it (multichannel upsampling being done reasonably well in most receivers).

cheers,
jonathan

[Themicles]

i understand that it doesn't use directshow filters, but the matrixmixer source is available at http://sourceforge.net/projects/matrix-mixer

you have answered my question, though, thanks. i recently picked up the advanced a/v pack and ran my optical cable between the a/v pack, and my audigy 2 zs (don't have a tv, play on my pc using a tv tuner ;) ). the effect you guys already have there is plenty good, while not fancy. props on a great piece of software overall. makes me wish for a pc version. ;)

anyway, if i had the knowledge, or the means, i'd offer to try porting the code of the matrixmixer... but as it is, i don't even know if it would be possible, let alone how to do it. i know some html, some php, and some nwscript... all useless for this. heh

[jlbcnous]

in doom9 forums we can find a vst plugin "v.i. stereo to surround" that is the best metod to convert stero music to 5.1. the autor, steve, don´t have any incovenience of help integrating his vst plugins in xbmc. he thinks that the best metod would be adding overall vst hosting to xbmc. what do you think? it is possible?

[jlbcnous]

anyone?

[jlbcnous]

we have the opportunity to integrate a wonderfull plugin that convert stereo music into 5.1 far better than dplii, and nobody is interested?

[jmarshall]

you realize your lovely conversion will then be completely rubbished by the hardware ac3 encoder, right?

[jlbcnous]

actually this plugin is in vst form. it has 2 channel input, and 5.1 channel output, easily adressable within 5.1 input of ac3 encoder. this plugin use ambisonics to extract surround information of stereo music, and later reproduce the surround atmosphere

[Loto_Bak]

does compression 'ruin' dpl2 matrix encodings? if it does that will ruin 99.9% of uses regarding video. 2 channel audio is nearly always encoded. if it is not then usually you have a 5.1 track available anyways.

regarding dpl2 with music, perhaps my reciever is not 'up to snuff' (its dpl2) but i find its stereo -> surround reletively poor. though i can see the desire for people wanting more than a 'output to all speakers' feature. there are many modes for the music function in dpl2, would need an interface.

the only other feature i could see is dpl1 encoding for people with older surround systems. this could enable ac3 -> dpl1 encoding and outputing music to dpl1 center and rear channel. note dpl1 only has 1 rear channel. the left and right channels are not discreete

[jlbcnous]

the software that i talk about is similar to dpl ii, but the diference is that this plugin is free and we have the help of the autor