Stereo Tool

Hi,

We are running ST 7.60 x64 Standalone on Win2K8 Server.

Sound card is external (USB) ASIO @ 192KHz and works fine with RDS using MPX into our FM TX gear.

After a few days (sometimes a day and a half) I hear the audio start to get choppy, usually for about 15 - 30 mins and then ST will automatically resolve the issue by resetting / rebuffering the FM output - then the problem goes away for another day or so.

I have looked several times now at the FM Output buffer when this is happening and found that the buffer is actually showing OK - it shows around 50% on the coloured bar, which is normal, however the audio is choppy as if the buffer is running out.

To resolve it immediately, I can restart sound cards or drag the buffer from 5 seconds to 0 and back again - ie: resetting the buffer makes the problem go away.

I would like to know if anyone else has come across this issue and if there is a fix for it.

The only thing I can think of is the buffer is being very slowly drained as I have seen it low at times, but high again later.

Many thanks

BeDazzler.

Can you tell exactly which inputs and outputs you're using? And from/to which sound cards or streams?

Hi Hans,

Yes for sure, here is my test config.

I am running...

SPL (Station Playlist) Output @ 44.1 -> Stereo Mix (Windows 2K8 internal - shows as "Speakers ASUS Xonar DX")

Then into...

ST 7.60 x64 Standalone: Input Device ID = "Stereo Mix (ASUS Xonar DX Audio)"

Then through ST processing and into...

ASIO External USB Sound Card @ 192 - "Cypress DCT-16 ASIO Driver"

The external USB device contains left/right analog where I run composite MPX into a test FM TX unit on Left and MPX for STL on Right.

It's a generic external USB sound device, but it's not too bad. I have been tuning via spectrum analyzer with success.

All record and playback devices are set to 192KHz 16Bit.

Everything works as expected from declipper through to RDS.

CPU Quality currently set to 65% but FM Output buffer still slipping over time - I am addressing this by moving ST to a Dual Quad Core machine.

I noticed the buffer issues started once I began using pre-emphasis and RDS. Before that it was never an issue.

Many thanks for your help.

BeDazzler.

Since you're using 2 different sound cards, my first question is: Do you have "Synchronize to output" enabled for the input sound card? If not, you would get this behavior after a while (however I don't understand why the output buffer doesn't show an issue).

Hi Hans,

No I don't have "Synchronize to Output" under Input -> Synchronize with Different Output Sound Card (not ASIO).

When I check that box the FM Output buffer drains and then the audio drops out.

After that it rebuffers but lasts about 10 seconds.

BeDazzler

That would mean that your CPU can't handle it... If you use different sound cards the software has to do something to match the sample rates and that's relatively expensive (it doesn't have to be, but then you get artifacts).

Hi Hans,

The other sound card (the ASUS Xonar) is not really doing anything, it's providing a pseudo interface where the Stereo Mix audio can be passed through to Stereo Tool.

I can also use Virtual Audio Cables, which I tried today and the same problem exists.

For my CPU, this is a HP Proliant Server, 2x Dual Core with 8GB RAM. Surely that would be enough to run audio processing ?

The old Orban gear we have would not be a quarter of one CPU on this server.

Anyhoo I have another Proliant server in the test lab with Dual Quad Core CPUs - I will load that up tomorrow (Wednesday) and see if I can get any further.

I've spent a lot of time optimising the sound with ST so I really want to make this work for production use.

BeDazzler.

Hi,

*any* combination of different sound cards (Virtual Audio Cable is also a sound card) will give this effect. Because the sample rates will never match perfectly.

First thing to do is to lower the Resampling Quality setting. That might be sufficient. If not, I will help you but in a few days (I'm at the NAB in Las Vegas now and it's just way too busy).

Thanks Hans. I know you are busy, we are all busy

I have lowered the resampling rate all the way down to 5 and it it still falls over. The input buffer drains first then the FM Output buffer falls behind and audio stutters.

I will rebuild onto the more powerful hardware first.

Enjoy the show, it's a good one this year and so many vendors.


BeDazzler.

Hi Hans,

I resolved this by...

1. Not using my preferred preset (Customised GAP Knockout)
2. Switching to Orban 8600MX and customising it
3. Enabling Synchronisation of input with output, resample quality 8.

This has stopped the issues, but at the expense of using my preferred sound settings.

I will spend some time working on the Orban 8600MX config and see if I can enhance to a more 'full' sound.

If I can't get that to work I will go and buy an Orban 5500.

Before the Orban bashing starts.... my competitors are all using Orban and are very loud.

BeDazzler.