adding LFE to GOUT (Released)

I’m not really what you’d call a basshead, but lately I’ve been interested in all that deep bass stuff you hear in movies these days.  I’d go to movie theatres and there would be lots of bass going on, and then later I’d see the same movie at home and it would be lacking in that kind of impact.  When I discovered why this was, I made it a priority to get a subwoofer and a receiver capable of processing the digital audio on DVD’s.  I’ve had my subwoofer for a month now (an excellent little beast from AV123) and I’ve been having a blast hearing all that bass I’d been missing out on.  It also works wonders for music.  But when I watch Star Wars, as much as I love the oldschool sound mixes, they don’t have the same kind of low frequency effects, particularly when compared to the special editions.  Aside from once in the theatres, I’ve only seen the '97 versions on stereo VHS, so I can’t really comment on the 5.1 mixes for those, but the 2004 versions have tremendous bass in some places.  It’s quite startling when you’re used to having no sub, but it sounds really cool.

I could, of course, just watch the special editions if I want that kind of effect–and occasionally I do–but most of the time I want to see the original versions.  Particularly for the first film, because the 1993 soundtrack on the GOUT is a far superior mix to the abomination that is the 2004 version.  There’s so much wrong with it, sound quality wise–large sections of the movie have a distorted sound as if they’ve been badly equalised, the levels of many elements including music are too loud or too quiet, and some sounds are out of synch to where they shound be or not present at all.  The LFE channel, however, sounds very good, and contributes greatly to the movie experience.  And so, given this fact, I hit upon a mad idea: what if I were to combine the LFE from the special edition with the main soundtrack from the GOUT?

I spent quite a bit of time pondering how to do this.  My resources are rather limited; I’m not really able to purchase expensive audio programs that would enable me to do this sort of thing, and even if I could (or sneakily downloaded cracked versions), I probably wouldn’t be able to use them effectively anyway.  Plus I use a Mac, and there aren’t many options that can do what I need.  I’ve improvised using what I have available–using the subwoofer line out from my receiver connected to the input on the computer, I recorded the LFE effects into Sound Studio, being careful to avoid clipping .  I then synched them all up to the GOUT soundtrack as closely as I could (Belbecus’ PCM version, which I downloaded some time ago and then forgot about).

I ran into a bit of a problem at the AC3 encoding stage, since the only program I can find to do the job is ffmpegX, which outputs only stereo, mono, or 5.1 AC3 files.  I wanted to make a 2.1 soundtrack, since this would match my current speaker configuration, but this doesn’t seem to be possible with what I have.  Mixing the LFE directly into the stereo mix at appropriate volume levels causes clipping, and reducing the bass volume to avoid it yields results hardly any different from the soundtrack on its own in some places.  This seems to rule out an altered 2.0 soundtrack, since I need the 10 decibel boost from the Dolby Digital decoder to get the proper results.  I hit upon the less-than-optimal solution of creating blank tracks for the center and rear speakers, allowing me to encode the whole thing as a 5.1 track.  For now, it works, but if I add more speakers to my system I won’t be able to use them for this mix.  I also haven’t found any programs to decode the Dolby Sorround cues in the soundtrack to take advantage of the extra speakers.  Ah well.

For all the limitations I’ve had in doing this, I have to say the results I’ve obtained are rather good.  (I know everyone talks about how superior the laserdisc PCM is to the GOUT audio, but the quality difference isn’t large to my ears.  Even in PCM form, there is a sort of harshness to the sound of the movie which I think is a limitation of the source material, and compression doesn’t affect it a whole lot.)  Anyway–with the addition of the LFE material, the “movie experience” is fantastic!  I still have to tweak the levels somewhat, but only in a few places.  Numerous explosions and ship flybys really shake the place, and subtler effects like Vader’s Force grip and the Falcon caught in the tractor beam are deeper and stronger while still sounding “correct”.  There is also a really cool sound effect, which occurs only in the LFE channel, around when Han says “we came out of hyperspace through a meteor shower . . .”, it is some kind of frequency sweep, which progressively gets louder and deeper and then recedes, as if the whole ship were shaking horribly.  I love it.  I thought the slightly exaggerated nature of the bass ala modern movies wouldn’t blend well with the older version, but for the most part it really does . . .

There are a few sounds I omitted, because they accompanied special edition changes and would not be appropriate to the original model shots.  These include the CGI sandcrawler and the CGI rebel fighters flying towards the Death Star (the bass gets louder as the ships come closer to screen and fades as they recede, which doesn’t work for the relatively static model shots of the original).  There are a few similar places I will reduce the volume to blend better.  But these are minor changes only.

I want to do the same for Empire and Jedi, eventually.  They have many more instances of bass than Star Wars, so getting them all synched will be considerably more difficult, but doable.  They only real problem with them is that due to the longer lengths of the films the multichannel wav file needed to encode to AC3 5.1 would be over 4 gigabytes, the file size limit for wavs.  Doing 2.1 wouldn’t be a problem–if only ffmpegX could encode it this way.

Is anybody else interested in such a thing?  I might be able to upload to a file-sharing site, I’ll have to see.  Either the AC3 directly or else the mono LFE channel in FLAC form, I suppose.  As a side note, does anybody know if Prologic II works on 2.1 tracks?  I don’t know if the presence of a subwoofer channel would confuse it or not . . .

Long live the original trilogy!

Well, since my original post I've had some breakthroughs on my little project.  I've since gained the ability to separate the LFE channel from the special edition soundtrack directly, rather than having to record it through the receiver (thus avoiding digital-to-analog and analog-to-digital conversions).  I also bit the Microsoft bullet and dug out a semi-old Windows laptop so that I could use the Aften AC3 encoder, which offers considerably more options than the limited ffmpegX implementation.  Since the majority of synching had already been done on my first effort, all I really had to do was synch up to that version, touch up on places where I had been slightly off, and tweak the levels a little.  I was able to skip the space-consuming multichannel wav step, since Aften could accept multiple mono inputs, and didn't have to create dummy files for unused channels.  This time I encoded the file as a 2/0 + LFE AC3 at 448 kbps.  There should really be a Mac version of Aften . . .

The following is a rundown of the various bass effects in the movie and what changes, if any, I made to them to fit better with the 1993 soundtrack.

Star Destroyer low rumble/Tantive hit/reactor shutdown:  I boosted each of these effects by 3 db--the 93 soundtrack is so loud here that they weren't very noticeable otherwise.

Stormtroopers blast through the door/Vader enters: No changes necessary.  The rumble just before the explosion is particularly forceful; Vader's appearance is ominous.

Escape pod launch: A subtle effect, not really necessary but neat.

Artoo falls over: Some people will probably disagree with me on this one.  I left this absurdly loud sound effect in the movie, although I did reduce it by 1.5 db so it isn't quite so ridiculous.  In the original soundtracks, Artoo hitting the ground sounds like a trash can falling over; in the special edition, it's somebody overturning a huge friggin' dumpster. :P  It definitely veers into the territory of modern-day exaggerated bass, and my initial inclination was to remove it, but what the hell, I kinda like it.

Jawa sandcrawler: Two shots of the sandcrawler driving along.  In the SE, the second shot was CGI'd, longer than the original, and much more bassy.  I had to delete this sound effect since it didn't match up at all, but I replaced it with the same sound from the first shot, at slightly lower volume since the sandcrawler is farther away and the music is also quieter than in the first shot.

Star Destroyer approaches Death Star/Vader's Force grip: I think I achieved a "best of both worlds" effect here, since the special edition has deeper bass for the grip than the original, but the older soundtrack has a windlike upper bass that the SE seems to lack.  Combining the two yielded good results.

Door slams in Leia's cell: A subtle effect, after Vader brings in the interrogator droid.

Millennium Falcon takeoff/jump to hyperspace: The Falcon's engines are reinforced by some seriously powerful LFE throughout the movie, beginning with the escape from Tatooine.

Alderaan explodes: I had a bit of trouble with this one, because it didn't quite blend the way other sounds did.  In the SE, the bass, while loud, isn't nearly as loud as the explosion sounds coming from the main channels.  It grows as the unfortunate CGI shockwave approaches the camera, and hangs on for a moment after the shot changes to Luke practicing his lightsaber.  (The original explosion sound, of course, ends as soon as the shot changes.)  The solution I eventually came up with was to increase the earlier part of the bass by 3 db and then to fade out the ending, so that it sounds more like the planet itself is causing it and not a (non-existant) shockwave, and it doesn't hang on quite as long or loudly afterwards.  It's not perfect, but it's better than leaving it unchanged, I think, or not having it at all.

Millennium Falcon emerges from hyperspace/flies to the Death Star: Serious bass going on here.  The ship's engine is very loud, especially on the flybys as it pursues the TIE fighter leading them to the Death Star.  Quieter bass occurs as they are caught in the tractor beam and enter the hangar bay.  But the best part of the sequence is just after they come out of hyperspace into the debris--an ultra low frequency sweep kind of effect that pulsates louder and deeper while slowing down.  It's as if the whole ship were shaking horribly, and I love it.  This sound is well beyond the capabilities of most main speakers; if you don't have a decent subwoofer, you're really missing out.

Stormtroopers blast into cell bay/Leia blasts garbage chute: Two loud explosions.  I didn't change the volume any, but I did alter the timing by shifting them both forward about a quarter of a second.  In the SE, they have the curious quality of occurring just after the main channels, which works fine there, but when combined with the different explosion sounds used in the '93 mix, sounded wrong.  Changing the timing so they occur simultaneously with the mains was much more satisfying.

Garbage chute: Various quiet sounds reinforcing the walls closing in, etc.

Chasm door slams: This doesn't really stand out if you're not listening for it, but it's neat.

Escape from the Death Star: Bass in the Falcon's engine, the ship shaking just before the fight, and the TIE fighter explosions.  Cool stuff.

Falcon approaches Yavin: More of that powerful engine stuff, but less loud.

Death Star approaches Yavin: Deep and ominous.  First shot seems louder than second.

Hangar bay/X-wing liftoff: There's a really quiet bit, I think it's just after Han says "I know what I'm doing", and a louder bit as Luke's X-wing rises into the air.

Battle of Yavin: Lots of bass here, obviously.  The CGI shot of X-wings flying towards the Death Star had LFE that grew louder as they came towards the camera and faded as they flew away, which didn't match the model shots.  I reduced it by 10 db, making it a subtler sound that blended much better.  Explosions sound really cool, some louder than others.  The Y-wings descent into the trench has bass; closeup shots of the massive turbolasers firing have reinforcement as well.  Only a couple things I needed to change at the end: for the Falcon destroying Vader's first wingman, the LFE synched up correctly, but for some reason the effect was too long and started way before the actual explosion (the ending is on time).  Fading in so that only the explosion part was loud seemed to solve that.  The Falcon flying away from the trench was too loud, due to the CGI replacement swerving about (hey, look how cool our new effects are!), so I reduced it by 6 db.  As for the Death Star explosion itself, it wasn't nearly loud enough, but the absurd shockwave was much too loud, again.  I increased the beginning of this by 6 db--I mean, come on, don't you think the friggin' Death Star exploding should be the loudest bass in the movie?!  Where's the sense of proportion?--and reduced the shockwave part by 3 db, so that it comes across as a little aftershock rather than a huge thing.

Whew!  That's a lot of bass.  Of course none of it's really necessary; the original soundtracks don't need to be changed.  They are immortal, classic.  I make no claims towards authenticity; this isn't really an attempt to recreate the 70mm soundmix or anything like that.  I just think it sounds cool to combine the bass from the special editions with the oldschool sound mix that has the best frequency and dynamic range.  The bass is all encoded in its own LFE track, of course, I didn't make any changes to the 1993 mix itself.  It is still straight 2-channel, with ProLogic encoding.  Playing the AC3 file with ProLogic 2 seems to discard the bass channel for some reason, but DTS Neo:6 retains it, thankfully, although the placement of elements is probably different.

If anybody is interested, I can of course share this effort.  The good news is that since so much of the LFE channel is silence, lossless compression reduces the file size to less than 10 megabytes, making uploading and downloading a piece of cake!  I'm currently working on doing the same thing for Empire, and eventually for Jedi.  I don't have the PCM tracks for those two movies, though.  I would certainly appreciate it anyone could upload those or inform me how else to get them (no newsgroups).

Long live the original trilogy!

Cool!  I was born in 1978, so I wasn't around to witness Star Wars in a theater until the 1997 disaster.  But, according to my father, one of the fond memories he has of the film was right at the beginning when the Star Destroyer flew by and shook the entire theater.  I was hoping for that experience in 1997, but I guess they had everything nailed down too well.. hehe.  Anyhow, as my 18" sonotube sub project is reaching completion, your work couldn't have been better timed.  I'd love to get my hands on a copy of this.  Thanks!

Moth3r: I looked all around for a way to extract the ProLogic channels from the stereo PCM, but didn't have any luck, particularly as far as Mac options.  If you've got a way to do that, though, I'm sure it would sound great.  Of course I'd like to have a proper 5.1 mix, but I think creating such a thing is currently beyond my capability.  Since my system right now is stereo speakers with a subwoofer the 2.1 file suits it perfectly.  Eventually I'll be adding a center and rears; I'm hopeful that using DTS Neo:6 will provide good enough results on that account.

Calamari: Congrats on the awesome sub!  I bet this will sound really awesome played on that.  My sub isn't nearly that big, but it's got really good sound quality.  28 hz is enough extension for most movies, but I'd love to get a big SVS that rocks down to 15 hz someday.  :)

For anyone who is interested in this, what form would you like it uploaded?  I currently have the LFE track saved as a FLAC and in Apple Lossless.  The Apple format only takes up 9.3 megabytes, but the FLAC is over 20, if that makes a difference in terms of downloading capability.  It's completely synched to Belbecus' PCM track, including the 1.017 seconds of silence at the beginning to line it up with the GOUT video.  If necessary I could try uploading my AC3 file, in case someone wants this but doesn't have the main channels to match it with, but that is 388 megabytes, so it's less convenient.  Just let me know . . .

I've uploaded the LFE channel as a FLAC file for anyone who wants it.  To use, simply combine with the 1993 PCM soundtrack from Belbecus.  It already has the 1.017 seconds of silence at the beginning, so make sure your PCM has this at the beginning as well.  Then simply load your wavs for each channel into the AC3 encoder of your choice.  For those without high-end software, I recommend Aften (or a gui thereof) as it's free and easy to use.  I encoded as 2/0 + LFE format at 448 kbps, to preserve the best possible quality for DVD.  If you have the ability to derive 4 or 5 channels from the stereo mix, using some kind of ProLogic/ProLogic 2 emulation software, feel free to do so.

If you are working on a GOUT-synched preservation project using HD footage and creating a custom 5.1 mix using the '93 and '97 soundtracks, please feel free to use this if it's to your liking.  (lol)

Here's the link: http://www.sendspace.com/file/zchhv8

Well, after a while of not doing anything with this, I've completed work on GOUT-synched LFE tracks for the entire original trilogy.  When combined with the 1993 soundtracks these make for an awesome movie experience.  The sound becomes more powerful and thrilling while retaining the authenticity and rightness associated with the laserdisc mixes.

I put flac files of each track together into one rar file, which can be found here: http://www.sendspace.com/file/70v75n

I also created a demo AC3 file containing some of the bass highlights.  If you're interested in the bass but aren't sure whether you want to see the movies this way or not, this should give you an idea what it'll sound like.  It includes the opening Star Destroyer flyby, the destruction of Alderaan, the Falcon's emergence from lightspeed, and the destruction of the Death Star from Star Wars; the probe droid launch and the beginning of the battle of Hoth from Empre; and the destruction of the sail barge in Jedi.  Can be downloaded here: http://www.sendspace.com/file/7rt40m

This demo is in 2.1 format; that is to say, the sound will natively play from the left and right speakers and subwoofer only.  Turning on Prologic 2, on my receiver at least, drops the extra bass because it sees it only as a stereo signal.  DTS Neo:6 mode keeps the LFE in place.  Some people prefer the DTS mode for surround, some like Dolby's version better, it's a matter of preference and results probably vary based on the source material.  More advanced implementations such as Prologic 2x might not ignore the LFE, although I can't say for sure.  One could always upmix the soundtracks into five channels on the computer and combine with this LFE to get a 5.1 mix; I am sure that would sound fantastic.

With this release I have improved upon the early version of Star Wars that I put out last year.  The first flyby has significantly louder bass than before--whenever you hear about the 70mm soundtrack the roar of the Star Destroyer is the thing that stands out in people's minds, but in the special edition it really wasn't all that strong.  The Alderaan and Death Star explosions are much better than before as well.  R2's fall with the Jawas is reduced to a more reasonable level, so it doesn't feel like a Star Destroyer just crashed into the planet when he hits the ground.  Empire and especially Jedi needed less work; I only had to change the volume in a few places.

Feel free to comment here on your experience with teh bass, and what kind of subwoofer you've got, etc.

For my personal version of Star Wars, I replaced the first cell bay shootout from the 1993 mix with that section from the original stereo mix in order to get rid of the annoying broken glass effects.  The rest of the '93 changes are good, or at least tolerable, but changing this part gets rid of the "glaringly inauthentic" feel it otherwise has.  The result combined with the bass gives it a decidedly "70mm-ish" vibe.  :)

I have to have these.  Sounds incredible and I want to check it out on my system (119" screen, RS2 projector, Paradigm 7.1 with Buttkicker)

Great work.

Realising that not everyone has the main channels from the 1993 laserdiscs to combine with the LFE tracks I posted above, I decided to upload my AC3 files for each film to make this more accessible for those who might be interested in it.  They are all in 2.1 format, encoded in Aften at 448 kbps using all the maximum quality settings, split into several RARs.  See above comments about using DTS mode to achieve surround sound if desired.

Star Wars:

part 1: http://www.sendspace.com/file/s8ngzo

part 2: http://www.sendspace.com/file/nc68mk

part 3: http://www.sendspace.com/file/xdz3x5

part 4: http://www.sendspace.com/file/rqfjek

Empire:

part 1: http://www.sendspace.com/file/0shomm

part 2: http://www.sendspace.com/file/ij36cx

part 3: http://www.sendspace.com/file/1u5q1b

part 4: http://www.sendspace.com/file/1l6eci

part 5: http://www.sendspace.com/file/hyc1gf

Jedi:

part 1: http://www.sendspace.com/file/dpyd29

part 2: http://www.sendspace.com/file/zmd91f

part 3: http://www.sendspace.com/file/7bhtmc

part 4: http://www.sendspace.com/file/8ydrdd

part 5: http://www.sendspace.com/file/pkya6l

For the most part these are straight from Belbecus' GOUT-synched 1993 laserdisc mixes.  Aside from the obvious addition of low frequency effects, there are a few other changes I made.  In Star Wars I replaced the cell bay shootout with the equivalent section from the 1977 stereo mix, to get rid of the breaking glass sounds, and made a small and (hopefully) unnoticeable edit to remove the sound of spitting after Luke says, "What good will it do us if he gets himself killed?  Come on."  When the Falcon emerges from hyperspace I also put in a few seconds of the winding/deceleration effect that appears in the mono soundtrack, derived via low-pass filter, mixed out of phase so it will appear in the rear channels.  Since that effect occurs with considerable force in the LFE a few seconds later, it made sense to include it, not to mention it plain sounds cool.  :-)

In Jedi, I put back the deleted music from Luke and Ben's conversation on Dagobah--ever since I first heard it I felt the scene would play better that way.  As it is, they're just sitting there and Ben speaks with his distant echoing voice and the revelation about Leia being Luke's sister sort of falls flat; the music gives it back some dramatic weight--which is not a slight on Alec Guinness.  I really don't know why they decided to cut the music in the first place, but I think they made a mistake.  My source was ABC's remastered soundtrack (props to him for his excellent work!), resampled to 48 khz via the high quality Izotope resampling algorithm.  I considered putting some deleted music in Empire as well, but that would be opening a much larger can of worms than I was prepared to deal with at present.

Hopefully my results will be enjoyable to those interested in this project!  I feel that using the soundtracks I have uploaded (plus the original stereo and mono mixes for Star Wars), combined with the GOUT video processed by G-Force's AviSynth script, will yield an excellent home theatre experience for the entire original trilogy.

Fantastic work! Can't wait to give these a listen.

One snag - my GOUTs are PAL format, and I'm guessing these are NTSC (i.e. correct) speed.

Any tips on changing the speed of a full 2.1 file? Or will I have to decompress/adjust/recompress?

Crud, I hadn't thought of that . . . these are NTSC speed.  I suppose you could decode these into their separate channels and speed them up, then re-encode to AC3 again, but that would be more of a quality loss . . . or I could apply the shift to PAL speed myself, going from the original PCM files directly, so there will only be one lossy encoding stage.

Edit: Adywan posted before me--I didn't realise you could do that with BeSweet.  Does that involve re-encoding, or is it a lossless process?  If so, that would be the easiest and best way to go.

Thanks for the input guys.

I've popped the files into Besweet (well, Belight anyway!) ESB was rejected for some reason ("Error 32: No input-data was found (wrong substream?)"), but RotJ seems happier. (EDIT: I re-extracted the RAR and it works fine now, so please disregard that part!)

However, there are only two output modes - stereo or 5.1. I'm guessing the stereo will discard (or downmix) the LFE, and the 5.1 will be just, well, wrong?

I imagine the problem with direct encoding is that 2.1 isn't widely supported as a typical input (or output) format...

Well, I tracked down the v0.6 b61 GUI and even with all the downmix/remix options off, it insists on converting to 5.1 (how, I'm not entirely sure...)

I might take a bit of a breather from this now ;-)  Any further thoughts would be welcome...

It really looks like I'm going to have to go the source route.

Hairy_hen, I wouldn't ask you to do the PALifying for me, but could I trouble you to upload the PCM source files somewhere so I can process them myself? Only if it's no trouble.

I would of course upload the results for any other PAL types to make use of...

It might actually be easier for me to do the PAL speedup myself and upload new AC3 files--wouldn't take as long to upload.  But then, if you had the PCM files to work with, you could put them through an upmixing algorithm like the one Satanika posted above to get five channels and then combine with the LFE to get 5.1 format, since some receivers might not like 2.1 files.  I might have done that myself, but none of the processes I've tried have worked on my computer, although I'm sure they would work on other people's computers.  I experimented a bit with doing it manually, ie combining them at various volumes and using phase cancellation to derive each channel.  I think it sounded reasonably good, but the channel separation wasn't that high, certainly not when compared to what Prologic 2 or Neo:6 can accomplish, so I ultimately concluded it wasn't worth continuing, at least not for my setup.

Moth3r said:

I would not recomend Besweet - it uses ac3enc for the re-encoding which is known to be buggy and gives poor quality results. If your going to alter the audio, extract the channels to PCM, speed up, then use Aften to re-encode.

To be honest though, it would be preferable to convert the video to NTSC.

 I have been using EAC3toGUI for quite a while and love it for converting dts to ac3 or slowing 25 pal to 23.976 ntsc. I have not experienced any bugs and have no problem with the quality.

-Will

Thanks for the tip, Will, but it seems that EAC3to doesn't like the 2.1 format ('non-supported data format')  :-(

Hairy_hen, if it's really not a problem to upload a full PAL version, that would be just swell!

But it would be good to have the source to play with anyway - as you say, 5.1 is a little more universal. I suppose the real trick would be to extract the surround information from the encoded stereo, and position it discretely - and what about the centre channel? Perhaps fudging it with an automated upmixer, then plugging in the discrete LFE, would be the best approach for a pleasing surround effect...

This guy (reviewing the GOUT release) seems to think it's Pro Logic matrixed:

The audio here is plain old Dolby Digital 2.0, the exact same audio track included on the 1993 Definitive Edition LaserDiscs converted to Dolby Digital. It includes the same Pro Logic matrix cues that the 1993 LaserDiscs had, so today's Pro Logic II decoders will have an easy time with it, but I really would have liked to have seen an uncompressed PCM stereo audio track included as the primary audio track. Since we're being limited to two channels anyway and these discs are essentially a sort of "archive" copy of the versions that Lucas has now deemed to be simply rough drafts, it would have been a nice touch. It would also have been nice to see a Dolby Digital 5.1 track derived from the old Pro Logic mix as a secondary option for folks without Pro Logic II decoders.

http://www.prillaman.net/starwarsdvdreview-trilogy_le.html (read down)

Satanika - I did as you suggested and patched over that section of Empire with the GOUT mix.  It's only for a couple seconds when the Falcon is making its "attack" run on the Avenger, and even knowing where the transition is I can't hear it, so I think nearly everyone should find it quite unnoticeable.  I still don't know what exactly caused that glitch, but I suspect my computer crapped out for a second when it was converting to Apple Lossless, and unfortunately I foolishly deleted the rars for the wav file before realising there was a problem.  All the GOUT mixes are dialnorm'd about 4 decibels down compared to the laserdiscs, but for some reason Empire also has dynamic range compression while the others don't.  But I got it to a point where it shouldn't be a problem at all.

Jonno - that review is correct that these mixes are ProLogic encoded.  My concern about getting these into a workable surround format is mainly for the benefit of others who have such a setup (myself when I can afford to get a centre and rear speakers added; right now 2.1 is my system configuration).  A while ago I took my gout dvd for Star Wars into Ultimate Electronics and played some of it on a 5.1 system with ProLogic 2 enabled.  My impression was that a lot of the time it sounded pretty similar to stereo playback, but it just filled the room more, greater ambience, etc.  Hard to describe it specifically, because it's not going to sound like the best discrete 5.1, of course.  The rears made themselves known whenever there were surround cues built into the soundtrack.  I couldn't actually say how DTS mode compares--shouldn't be all that different but I think it separates the channels a bit more.

Sorry, I was showing my ignorance earlier - Prologic's channels are left, right, centre and mono rear. So if they could be decoded within the digital realm (no idea if this is possible), it would be a simple case to reassign them to the respective channels within 5.1, dupe the mono surround to both rear channels, and slot in the LFE.

The levels might need a bit of fiddling, but really it's the decoding that would be the hard part. Any ideas?