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5.1 to 7.1.4 Source Separation Remixing

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zeerround

Moderator
Joined
Apr 11, 2010
Messages
268
I was listening to Porcupine Tree's Fear Of A Dark Planet in 5.1 and it occurred to me to up/remix it to 7.1.4 using Source Separation.

Steven Wilson mixed this in a convenient way, in that there are no drums in the center channel, so I was able to do Stereo Source Separation on the front pair of channels, and the rear pair, to get 4 drum channels for the height speakers.

That would have been enough to give a 5.1.4 results but I wanted to go for 7.1.4 so tried another experiment that I think came out well.

I took the bass stems, resulting from the fronts AND rears stereo pairs, and routed them to the Side Surround channels in the 7.1.4 remix. At first this resulted in a mono bass sound, that felt as if it was coming from right overhead, and it wasn't as distinct from other instruments as I would like. So, I tried a producer's trick for widening a mono bass track and added a crossover at 180Hz (chosen by ear), routing the low end to the left side surround and high end to the right side surround. Now the bass sits in the "bed" layer of speakers, is distinct as a separate instrument source, and clearly in "stereo" as you get the growl from the left and the snap from the right.

Tools Used:

AudioMuxer to extract the 5.1 PCM track from the DVD and resample things when needed​
Plogue Bidule to make stereo pairs from the 5.1 (but other tools could have been used)​
Demucs for Source Separation​
Plogue Bidule to remix/remaster 9 stereo stems into the final 7.1.4 (front and back seperated sources and the original C and LFE stereo pair)​
A 7.1.4 capable version of my ebur128 measurement tool, to make sure the dynamics of the final 7.1.4 product were within 0.5 dB of the 5.1 source​
Here's what the remix/remaster PB looked like:

5.1 to 7.1.4 Source Separation Remix.png


And here is what the resulting 7.1.4 track (Let's Sleep Together) looks like in foobar2000:


Let's Sleep Together 7.1.4.png
From top to bottom the first 5 waveforms are the 5.1 "bed" layout, 6 and 7 are the side surrounds (stereo bass in this case) followed by the front height and rear height speakers (4 channel drums in this case).​
As I mentioned this track has only Steven's lead vocal in C. No drums or other instruments.​
For comparison, this is what you get with Penteo16 Pro 5.1 to 7.1.4:​
Let's Sleep Together Penteo 7.1.4.png
So nowhere near the "WOW" of separate instruments in different channels (plus it looks to be mixing signals from LF and RF into C).​
I'm happy to share the PB layouts if anyone is interested, although it does use some non-free VSTs for remastering, Namely SoftTube Drawmer S73 for analog warmth/character and to add back some "air" that gets lost with source separation.​
 

zeerround

Moderator
Joined
Apr 11, 2010
Messages
268
The next experiment was to tackle something that DOES have drums and other non vocal stuff in the 5.1 Center channel.

For this, I chose Soundgarden's Black Hole Sun, from the Superunknown Blu Ray. Heavy drums and more in the center channel.

So, I used demucs on three stereo pairs from the 5.1. Fronts, C&LFE and Rears, giving a total of 12 stereo stems. Bass, Drums, Vocal, and Other stems for each stereo pair.

The Fronts and Rears stems got the same treatment as in the Porcupine Tree above.

For the C&LFE stems the right channels of all stems (LFE in the 5.1) were fed to LFE in the 7.1.4.

The left channel of the bass stem (C in the 5.1) was fed to the crossover for delivery to the side surrounds in the 7.1.4.

The left channel of the Other and Vocal stems (C in the 5.1) was fed to the C channel in the 7.1.4.

The left channel of the Drums stem (C in the 5.1) was cut by 6dB then fed to both Height Front channels in the 7.1.4 (resulting in equal drum volume to the original).

Also a very positive result. The 5.1 had similar wave forms for fronts and rears, so the resulting waveform is not as dramatic as with Steven Wilson's 5.1 work, but still very pleasing as to filling the room with distinct sounds from different instruments coming from different channels.

1602965418523.png


Again, from top to bottom the first 5 waveforms are the 5.1 "bed" layout, 6 and 7 are the side surrounds (stereo bass in this case) followed by the front height and rear height speakers (4 channel drums in this case).
 

MC Maniac

300 Club - QQ All-Star
Since 2002/2003
Joined
Dec 31, 2002
Messages
366
Location
Ontario Canada
I was listening to Porcupine Tree's Fear Of A Dark Planet in 5.1 and it occurred to me to up/remix it to 7.1.4 using Source Separation.

Steven Wilson mixed this in a convenient way, in that there are no drums in the center channel, so I was able to do Stereo Source Separation on the front pair of channels, and the rear pair, to get 4 drum channels for the height speakers.

That would have been enough to give a 5.1.4 results but I wanted to go for 7.1.4 so tried another experiment that I think came out well.

I took the bass stems, resulting from the fronts AND rears stereo pairs, and routed them to the Side Surround channels in the 7.1.4 remix. At first this resulted in a mono bass sound, that felt as if it was coming from right overhead, and it wasn't as distinct from other instruments as I would like. So, I tried a producer's trick for widening a mono bass track and added a crossover at 180Hz (chosen by ear), routing the low end to the left side surround and high end to the right side surround. Now the bass sits in the "bed" layer of speakers, is distinct as a separate instrument source, and clearly in "stereo" as you get the growl from the left and the snap from the right.

Tools Used:

AudioMuxer to extract the 5.1 PCM track from the DVD and resample things when needed​
Plogue Bidule to make stereo pairs from the 5.1 (but other tools could have been used)​
Demucs for Source Separation​
Plogue Bidule to remix/remaster 9 stereo stems into the final 7.1.4 (front and back seperated sources and the original C and LFE stereo pair)​
A 7.1.4 capable version of my ebur128 measurement tool, to make sure the dynamics of the final 7.1.4 product were within 0.5 dB of the 5.1 source​

I have listened to these tracks and compared most of them to 5.1 to 12 channel upmixes I did using Penteo 16. Zeerround's version are definitely better. The isolation of the drums into the 4 ceiling speakers, opens up the fronts and creates more discreteness. Penteo doesnt put much info into the ceiling speakers.

Sound quality is also very good - much less artifacts than we typically find with stereo to 5.1 upmixes.

Compliments for the effort put into this!

Penteo 16 does have one major plus - it is very simple to use - drop all songs into Reaper batch tool and in one step generates the 12 mono wav files.

If Zeerround is able to automate most of these steps , preferably without Plogue, I'd definately be using it.
 
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