About 5.1 to Stereo Downmix

I am not sure how downmixing covered on the forum exactly cuz i couldn't find much. It kinda is easy with a DVD-A disc, DVD Audio Extractor does the job. Also foobar does the job with flac files but there's a catch to it. I used Refused - The Shape of Punk to Come DVD-A to experiment. Ripped it (as 5.1 to 2.0) with DVD-A extractor and dynamics are intact with the result (DR14). Then ripped it 5.1 and used foobar to convert to stereo. Crushed it. Dynamics gone (DR4). Then i tried Pink Floyd - The Division Bell 5.1 flac with foobar. DR shows 12 (track, Coming back to Life) with original 5.1 flac. Downmixed it to stereo with foobar, now it clocks at DR13. Ok, now this is flac. Tried Opeth - Ghost Reveries AC3, downmixed. DR10. Ok as were the original AC3. I am now not sure if foobar does the job or what. What changes the result? What is causing the increase or decrease of DR with the result file? I just want a stereo file as dynamic as the original and i want a way to make it somehow with a standard result. is it possible?

 

Good question, I've tried this also, not sure about the DR issue but have noticed my fold downs most of the time sound like poop, so I don't attempt them anymore

 

kinda bugs me to but most of the time these are the best files to listen to

 

I agree, it seems with most of mine the 5.1 are from the old masters, not remasters used for the two channel

 

There are two issues with stereo downmixing that makes it a nightmare:

1. The software needs to do a 2-pass operation in order to find the proper output volume and prevent clipping. foobar2000 does not.
Clipping is most likely the reason for your low DR with foobar2000. You can verify this by converting your foobar2000 downmixed music to a single wave file and opening it in a sound editor like Adobe Audition. Then do an Amplitude Statistics Scan and check for Possible Clipped Samples.

2. The disc needs to be authored/mastered correct otherwise it will sound horrible when downmixed. I have done three albums, all SACD, and all needed to be downmixed differently:

David Bowie - Reality
I believe this one is mastered correct because a downmix of all 5.1 channels sounds perfect and offers DR 10-13.

David Bowie - Heathen
The center channel is used for Davids vocal in some of the tracks, but it is way too quiet when doing a normal 5.1 downmix. I have tried increasing the center channel volume by as much as 12 dB, but it still sounds wrong. The problem is the two surround channels - they are near-copies of the fronts so when downmixed the fronts are way too loud.
The way to downmix this album is to mute the two surround channels. This is done by converting the entire album to a 6-ch wave file and opening it in a sound editor; then mute the surround channels and save the wave file; finally downmix the 6-ch wav.
The result sounds very close to the vinyl and offers DR 9-12.

Epica - Consign to Oblivion
Much like Heathen, except the bass was way too loud too.
I did this downmix with Left-Right-Center channels only.
Sounds okay with DR 10-13.


I used the free software called eac3to for downmixing. It is a command line program and is used like this:
eac3to.exe -downStereo -downlfe input.wav output.wav (full downmix)
-or-
eac3to.exe -downStereo input.wav output.wav (skip the LFE channel)

In order for eac3to to work properly input.wav needs to contain the entire album, otherwise the volume will differ from track to track. This is done easily with foobar2000 converter to wave with cue sheet. Unfortunately it also limits the sample rate to 44.1 or 48 kHz, because of the 4 Gb filesize limit. There are probably ways around this, but I am no expert.

 

Thanks for the detailed info, appreciated

 

Forgot to mention something. I use foobar on my brother's laptop, i got a mac. I used Eternal Rains Will Come from new Opeth record. 5.1 flac DR12, downmix with foobar DR10. I tried it with TwistedWave on my mac, result came at DR13. I haven't purchased TwistedWave, still at trial session. But for both downmixing and downsampling this app rules out any other way i tried. It does normalizing when downmixing. I am quite happy with results.

 

I ran into the same issues using Foobar. I now use dBpoweramp, it actually preserves the dynamics properly when downmixing, and it's quick and easy to use.
It is paid software but it's relatively cheap, it can also convert just about any audio format.

 

Ok, gonna try that one too, thank you. I heard dBpoweramp but never used it.

 

Great, thank you so much for sharing this info! Somehow, i just couldn't get my downmixes to sound good, not with Audacity or Foobar, but DBpoweramp does the job very well!

 

You guys might wanna try to use, say, 8dB pre-attenuation (-8db preamplification) with fb2k when downmixing 5.1 to 2.0. Then check the album peak and adjust your pre-amplification value accordingly (so the donwmixed album peak will be at, say, -0.3dB)...

 

No.1 - 5.1 downmixes sound awful and all over the place compared to the stereo mix IMO.
No.2 - If you're talking about DVD-Audio, why not just listen to the stereo mix track?

Forgive me if I've missed something.

 

I agree 5.1-2.0 downmixes can sound bad - but some sound fantastic.

As for foobar, it's what testikoff says: attenuate before down mixing (I've found 7dB works best most of the time). The DR of a downmix should always be the same from program to program - if it's less it's because of clipping.

 

Andrew, what you are missing is this, sometimes 5.1 mixes are the only available dynamic masters. Or the most dynamic one... Some are just awesome (like Opeth - Still Life or Refused - The Shape of Punk to Come).
I agree, they sound all over the place where the sound is "moving" thru channels. Most of the stereo mixes are not that dynamic. They usually use the cd master with high resolution.
It's also quite fun sometimes.

And testikoff and Tmtomh, i'm too lazy for such things. Thunderwave did good, without the clipping and all.

 

The only issues that doing a proper 5.1 to 2.0 conversion should cause are phase issues. Otherwise it's a bad mix.

 

The 5.1 Downmix on the Velvets Loaded box is nice BTW