DPS 2.0 Testing (Windows)

[yonathanz]

How do I check whether I use DirectSound or WASAPI?

My sound card has no effects. It’s an ESI Juli@.

[penguin]

You would know about it, because you would have needed to set it up yourself (in your player, audio renderer, etc.) to use WASAPI without DPS and DirectSound with DPS (because DPS doesn’t officially support WASAPI).
Let’s see what Joe has to say about your problem.

[xaqmusic]

yonathanz,

First, please email me at xaqmusic@bmtdps.com and I will get you the latest installer for DPS 2.0.

Regarding downsampling:  We have measured the effect of the sample rate converter in Windows.  While it is not pro-audio quality, it is pretty good for a real-time converter.  I can tell you the difference between music converted from 44.1kHz to 48kHz and playing native at 48kHz is very hard to hear.  Even music converted from 96kHz to 44.1kHz is difficult to hear unless you have a very good listening environment.  You should experiment with this without DPS by setting the output driver of your audio hardware to a different rate than your music file.  If you have a good listening situation you will hear the automatic sample rate conversion.

 An overall “boxy” sound you describe indicates there could be something else wrong or the profiles you are testing just aren’t right for your speakers.  Let us know what speakers you have and the profiles you have tested.   Maybe we can make a recommendation.

More details about DPS and audio quality:

The Digital Power Station virtual audio driver is acoustically transparent because it’s only job is to store audio sample in memory for processing by the DPS application.  However, it does turn down the volume by 0.5dB to prevent any signal from exceeding 0dBFS.  Exceeding 0dBFS sounds like nasty distortion!

In the older version of DPS processing there is nothing to prevent very loud sounds from distorting.  So DPS v1.2.4 does have a volume pad of about 4.5dB for external speakers and headphones modes.  The pad is in place to create headroom for DPS processing to occur.   But the result is DPS “off” is about 5dB quieter than when DPS is not running.  So when DPS is off there really is nothing happening to the audio other than Windows sample rate conversion (if the audio file and/or your output device is not set to 44.1kHz) and a small drop in volume.

Be careful not to mistake a drop in volume as a drop in audio quality!  This is an easy mistake to make since our ears change frequency response depending on the loudness of the source.  Look up Equal Loudness Contour.  Understanding this psychoacoustic phenomenon, we always try to be sure DPS “on” is very similar to or just a bit louder in volume than DPS “off”.  We actually calibrate this on/off relationship with VERY LOUD recordings like Rihanna’s SOS or something by Skrillex.  If the voice stays about the same when turning DPS on/off we know we have good calibration.

DPS 2.0 only has a 3.5dB pad (and we are considering removing this) because we now have a peak limiter to prevent any signal from going over 0dBFS.  This peak limiter gives us a lot of freedom to do more cool stuff with DPS without worrying about causing distortion by exceeding 0dBFS.

Just so you know, the internal processing of DPS occurs with floating point math so the end result is always of the highest quality.  We are always looking to create the best possible sound without a lot of hassle to the user.  That is why we are using a virtual audio driver even though that requires us to be limited to a single sample rate.  The next best solution is for a developer to take our brand new Windows SDK and put DPS directly into their music player!  Then no sample rate conversion will take place and you can be assured you have the cleanest possible audio path.

Whew!  Hopefully I answered your questions.   Let me know if I can clarify anything.

[penguin]

Thanks Joe, for the detailed explanations!
Why does the virtual audio driver have a 0.5 dB attenuation, if it doesn’t do any processing other than storing audio samples and DPS has its own? Is this a precaution for the Windows OS audio processing?
I guess both the attenuation in the virtual audio driver and DPS are output adjustments, because it shouldn’t matter when only storing data or using floating point math for processing?
Btw, what’s the new headphone enhancer in the SDK?
Sorry for being so nosy.  🙂

[yonathanz]

I set my sound card to 24 bit 44.1 khz. Made sure the DPS button is GREY. Played a YouTube video and some TIDAL music. It still sounds boxy, mono and muffled. I’ll send you an email, hopefully version 2.0 doesn’t have this problem.

[xaqmusic]

hans,

You are correct about the -0.5dB in the VAD.  It starts the process of making sure there are no samples that exceed 0dBFS.  Keep in mind the audio is captured in fixed point (PCM) format then converted to floating point just before processing.  Then, after processing is complete, the floating point samples are converted back into PCM samples.  This conversion back to PCM is where clipping may occur because floating point samples may exceed 0dB but fixed point samples may not.

We are currently investigating ways to take advantage of Windows floating point audio capabilities.  However, most audio files are not floating point and most output devices cannot take a floating point signal.

The new headphone enhancer is a nice little feature for providing lightweight (for the CPU) stereo field control and customization for headphones.  It provides a few easy presets for mixing left and right channels for more comfortable listening (especially for those old records where they put the drumset the left and the voice on the right) and lifting the stereo image.   This effect is applied along with your favorite headphone profile.

It is currently available to SDK customers and we will be putting it into DPS 2.0 shortly.

[xaqmusic]

yonathanz,

I’m not sure why the audio should sound “boxy” with DPS off.  Can you provide more details about your system and the playback application you are using?

Try this procedure to switch between DPS processing and straight audio path:

1. Open the Windows Sound Control Panel.
2. Launch DPS.  Notice Digital Power Station becomes the default playback device.
3. Play your test audio in your favorite player.
4. Be sure DPS processing is working by clicking the B Button on/off.
5. In the Windows sound control panel, notice the green audio level meters.  There should be meters in Digital Power Station AND your speaker or headphone output.
6. While audio is playing, make your headphone or speaker output the default playback device.  This should immediately bypass DPS and you will hear the normal sound of the audio player.
7. Make Digital Power Station the default playback device to switch back to DPS audio processing.
8. DPS 1.2.4 or the audio player may crash during this procedure.  Just relaunch to continue.  DPS 2.0 is much more stable during this kind of operation.

Let us know what you find.

[yonathanz]

When I set my speakers back to the default playback device, the volume level goes from whatever it was set to, to 80, which is a bit scary. It also happens whenever I quit DPS. Of course, the sound regains its clarity etc…

When I switch back to DPS as the default, I get the same problem, whether DPS’s processing is on or off.

So basically, no change.

[xaqmusic]

The drop in volume to 80 is built in DPS 1.x to address some laptop systems having distortion when volume was set to 100.  This is a legacy problem now.

Please try these tests with DPS 2.0.  There are settings available to disable all automatic volume adjustments as well as significant improvements in audio processing and handling.  We are focusing on making all changes in DPS 2.0 to replace DPS 1.2.4.

[yonathanz]

Well I gotta say, I’ve just installed version 2.0 and it seems that the problem is 80% gone. I say 80% gone, because there’s a volume increase when I quit DPS, HOWEVER, the actual volume setting doesn’t change. What I mean is that, it stays at whatever volume I was at, but it sounds quieter when DPS is running. I FEEL that there’s also a decrease in clarity when DPS is running (processing: OFF), but it might be due to the volume. My speakers have more volume than I’ll ever need, so I don’t mind this problem, but for laptop users looking to improve their sound, it’s kinda counter-intuitive.

I’ve also noticed that you can’t really use any profiles now, and the default one is rather bassy, even for movies. Anyway, it’s alpha, so I have high hopes for the final product. Will we need to re-buy it when version 2.0 is out?

[xaqmusic]

yonathanz,

The 3.5dB decrease in volume with DPS off could easily account for a perceived decrease in quality on many speaker systems.  However, the obvious point of comparison should be to compare a good profile with DPS ON to no DPS at all.

Regarding profiles in DPS 2.0, there is a selection of test profiles to choose from in the SETTINGS tab for each output category.  Refer to this help guide to get started.

Also, if there is a profile from 1.x you would like to try, please let me know and I can convert it for you.

One known issue in this build is Stereo Controls may not be active when you first launch DPS.  Turn Stereo Controls off then on to start the effect.

We are projecting the release of DPS 2.0 in mid October.  All profiles currently available in DPS 1.2.4 will be downloadable in DPS 2.0.   All current customers will receive a full upgrade for free.

[yonathanz]

Thanks for the continued support!

I have rather big speakers, with 8 inch woofers. They’re Samson Resolv A8. They’re marketed as studio monitors, but they aren’t too flat. The Sound on Sound review says the midrange is colored. Overall though, they’re fairly balanced. Could you recommend a profile for these?

[xaqmusic]

Most of the DPS profiles are designed to bring consumer-grade speaker or headphones up to studio quality.  I’ve heard Samson speakers before and while they are not flat (most studio monitors aren’t and shouldn’t be – that’s a separate discussion) they do have some issues reproducing midrange accurately.  In speakers of this level the highs and lows are usually bumped up to give the illusion of quality while sacrificing transient response and other factors that make a studio monitor really useful.   I am old scholl and still prefer Yamaha NS-10’s with the intended Yamaha amp.  I am also a fan of the KRK sound.

With that being said, I will port our TOOLS category profiles to DPS 2.0.   You will find them useful to your situation.  I’ll post a link here…

[yonathanz]

I really appreciate it. I should mention that I didn’t buy the Samsons for studio-purposed. I use them for music and movies, and the occasional gaming every few weeks… I really like them for this purpose, but would like to boost the bass a bit for movies, since I don’t have a separate sub. Is it possible to run DPS without applying any profile, so I could only use the Bass gain thingy?

[penguin]

There are bass boost profiles for music and movies in the tools section.

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