Dolby Surround captured tracks - options

[spoRv]

Well, it "could" be also 4.0, but at this point I'd leave it "as is"...
At the end, I will NOT try to "stereoize" the surround channels, only copy it - and the .1 will contain just the low frequencies of other channels... this is to avoid the intervention of the Dolby-"etc" decoder at all...

What do you think? Always open to your opinion, as usual - because you know audio MUCH BETTER than me!

Also, a way to capture 4ch audio using two sound cards in the same PC will be really appreciated!

[jerryshadoe]

Ok, assuming that you just copy the "s" into an "s2" and create the LFE based off the original 4.0 mix, then - YES - this should reproduce a proper sounding mix into 5.1 since nothing is being modified.

As far as capturing 4ch audio using two soundcards on same PC... honestly, not sure. It can be done, yes technically but... here, it's a matter of the software. Not sure which software supports capture from two different cards simultaneously... damn it, Andrea Now I have to go google and educate myself real quick

[spoRv]

I'm after this in the last hour, still no (good) results, though...

[PDB]

I think the best solution is a 4.0 or 4.1 wrapped in a 5.1 container (dual mono surrounds). That's what I was shooting for. I assume spoRv technique was the same. Duplicating the surround channel into dual monos (s to s2). Even though the Dolby Stereo spec started out as a pure 4.0 matrix it quickly included the home Pro Logic additions of a crossover and sub so I think have a sub isn't modify the track out of spec. It's not like you are going to get much action out of it anyway.

[spoRv]

Guess what? I found a way to do that!!!

How? Simple... after A LOT of internet searches, nothing was what I wanted - a simple audio router which mix two stereo inputs into one four-channels input...

I had an idea: because I have two audio interfaces (one is the onboard audio card, the other is the audio of the hybrid TV/capture card) why can't I record two stereo sources at the same time? So, after many tests, I found the capture card audio actually doesn't work - don't know if it's due to drivers, other capture card "interference" (even if the latter has no audio), cables connection - it's a complicated Sony HTPC with "default" hardware sometimes difficult to replace completely...

Then, flash of genius! The PC has two stereo rear inputs - one sound card, one capture card - and another on the front - sadly, connected to the capture card, hence unusable... BUT... there is also a mic input on the front... OK, it *maybe* could not be as good as the RCA inputs, but... it is a test, after all!

I connected the two audio outputs of the Pioneer HLD-X9 to both rear input and front mic input and... IT WORKED!!! I record two stereo audio tracks at the same time! Don't ask me how it could work, because I always suspected one (cheap, onboard) audio card = one input at time!!!

This basic onboard card seems not so basic, after all!

Now, let's face the potential problems; I used VirtualDub to capture one of the stereo track; as this capture at "only" 16bit, I thought to use it with the mic input and center/surround channels, as they *should* have "less important" signal; so, Audacity will be used to capture the left/right channels via the RCA inputs; should I capture them at 24bit - then eventually process the C/S channels at 24bit, too, or should I stay at 16bit?
Also, levels could be a problem... it will be quite difficult to reach a perfect balance - even if it's always possible to fix it later, I'd prefer to capture them with the right levels from the start... I can't remember if my Pioneer SP-07D have a test signal; if so, I'll try to use it to set the levels.

Wish me luck for the definitive test, and choose a great Dolby Surround track, preferably present only on Laserdisc - write down some titles, don't be shy... I have a lot of titles, so mainstream films would probably present in my collection...

[PDB]

Sounds like you have a pretty good plan of action, spoRv. Good luck!

[jonno]

This is all intriguing stuff fellas. It had never occurred to me that my receivers have been doing a subpar job of the matrix decoding (though I'm relieved to confirm that at least my 2-month-old Yamaha RXV677 has a Pro Logic setting present and correct).

Given that you're reassigning the channels in a fairly purposeful way, and most listeners with surround setups will be using a 5.1 layout, it makes sense to adopt that model and give each channel a job (left, right, centre, dual mono surround, lowpass filtered sub). While it's worth noting that Fox adopted 4.0 or 4.1 scheme for their legacy Dolby Stereo and 6-track mixes (see Predator, Point Break, Alien/Aliens), that may well have been for space reasons rather than authenticity (and the bitrates aren't too impressive).

Perhaps it's worth getting in touch with Hairy_hen over at OT? His reconstruction of the 6-track 70mm mix for Star Wars originated from the 1993 Definitive Edition surround mix, which he would have (somehow) deconstructed to create the discrete channels prior to re-editing. He may have a trick or two to share.

By the way, is this the place to admit that I'm having a lot of fun listening to DS mixes through the Yamaha's DSP processor? In addition to decoding the channels, it adds acoustic simulation to create a cinema auditorium experience (the ambience being generated by an additional two front channels). I don't use it for everything, but for big dumb fun like Predator it's surprisingly effective!

[spoRv]

Message sent to Hairy_Hen: waiting for his reply; homeworks to know more about the Pioneer SP-07D done: its chip (Zoran ZR38500) is also found into the Dolby CP-500, so it could be not that bad... and, according to what Disclord (he is sorely missed) wrote in this LDDB thread:

For 48 kHz sampled 2-channel Dolby Surround encoded MUSE titles the 99 will let you apply its superb Pro-Logic processing - although Pioneer used the standard Sanyo PL chip at the time, they implemented it better than anyone else, including Dolby in their CP-65 cinema processor. It sounds truly discrete with no logic artifacts.

this seems confirmed; of course, not only MUSE titles will work well, but also simple Laserdisc PCM tracks - or even analog tracks, from LD or VHS!

Now, I'm waiting for some title suggestions...

P.S. SP-99D = SP-07D (apart the fact the latter is champagne like X9!)

[DoomBot]

How about Raiders of the Lost Ark for a real test.

[spoRv]

UPDATES:

It was too good to be true... indeed, as the X9 has two analog audio outputs, I was sure the simultaneous recording from different inputs of the same card worked well, but, as I discovered later, this is not possible - at least on Windows... the fact is, when you change input in a software, it changes automatically even in the other opened software, even if it doesn't show up...

So, I thought to use the capture card audio... after all the afternoon spent on trying to solve the mystery, I discovered that the capture card audio works, but only when used together with video part... so, I tried to capture audio and video with VirtualDub, but it freezed the PC, every time... I disabled the other capture card, loaded new drivers, tried any audio/video path combination, nothing... at the end, I discovered that, with a less known plugin, is it possible to record audio with Foobar2000... so, opened it, opened Audacity, record both stereo tracks (L+R via capture card input in Foobar2000, S+C with Audacity) and it worked! Finally!

Of course, it was too simple - I spent just almost the whole day at this point; indeed, noise floor using capture card audio was way too high - that's why, maybe, I haven't used it in the past, but who can remember that?
Add to this the voltage converter I used to connect the Dolby decoder almost dead... luckily after an hour of rest, it worked again, but was forced to find another on, digging thru drawers, boxes, closets etc.

Moral of the story: I recorded first the analog stereo output of the laserdisc, 48KHz 16bit, directly; then first the L+R channels thru the Dolby decoder, then second time the S+C; took the four channels, replicate the surround, and left blank the LFE (for this test); then the stereo output was converted via Foobar2000 to discrete multichannel files, using four different plugins - to hear the difference between the hardware solution, and the software... at the end, recorded via SPDIF the DTS track, included as well in the test.

What movie? No movie, just few seconds small logos: DTS and THX, taken from Toy Story.

Now, it's your turn: if you have spent few minutes to read the story 'til here, now you MUST download the test files, and hear them using your 5.1 audio system:

https://www.sendspace.com/file/pznffg

The RAR file contains the following tracks:

• PROLOGIC - made using the hardware decoder
  
• ANALOG - stereo untouched track
  
• DTS - decoded DTS track
  

and the ones converted using Foobar2000 and different plugins:

• ANALOG_ATsurround
  
• ANALOG_chmixer
  
• ANALOG_freesurround
  
• ANALOG_prologicII
  

Need to know your opinions, before futher testings!!!