Optimal VPO SW/sound option for my next step

[ziggi55]

Thanks to all who responded. I identified and "fixed" the problem. First to answer some questions: The noise was heard on *all* ranks, and as I pinpointed later, only in the left stereo channel. As to the nature of the sound, it was more akin to the kindling starting to burn in the fireplace. A faint, random crackling, present *only* when a manual was being played, starting a second or two after the keys were touched, and lasting a split of second after all keys were released. Moreover, I tried two GO samples, Pitea and the demo version. Both behaved the same way.

Now, for the "fix", I set the sampling rate from Stereo/24 bits to Stereo/20 bits, and the problem disappeared. The double quotes are here, because I do not consider it a real fix, just a workaround, trading better sound quality for a clean sound. I personally am OK with the resolution, but wanted to report it here for completeness.
Zdenek

[samibe]

Try some some of the stuff addressed in this: https://download.cantabilesoftware.com/GlitchFree.pdf

It sounds like you might need to adjust your buffer or sample rate to fit your computer's processing speed (or eliminate other non-essential tasks so your computer has more resources).

[ziggi55]

It looks like I spoke too soon. A day after my last post about adjusting the sampling resolution (not rate) to 20 bits, the problem came back. So, I tried several adjustments based on Sam's list above, but the issue did not improve. Still, it is (mostly) in the left channel, and it definitely "follows" the start/end of music playing. It is rather annoying.

[rjsilva]

[ziggi55]

I understand that. My attempt to decrease the resolution was to test whether or not the higher processing CPU capacity needed to process 24 bits instead of 20 is the culprit of the noise (which, in the 64-bit processing world, is probably a moot point).

[Admin]

The fact that this problem occurs mainly on one channel leads me to believe that your problem is not related to signal processing issues on your computer. Such issues will usually affect both channels equally and manifest themselves as spurious clicks and glitches, not a continuous noise that starts and ends with the playing notes. They will also be more prevalent when higher degrees of polyphony are required. Pitea is relatively dry without long reverb tails, so polyphony requirements are not particularly great.

Again, a recorded sample of what you're actually hearing would be very helpful, as would information on your computer and sound card configuration.

[ziggi55]

I finally got around to do a quick recording. Note that there is no noise before the phrase is played, then during the phrase, you can see the "kindling burning" noise in the L channel, and then after the music, no noise.
Z
http://longfinal.com/rnd48084762/OrganTest.wma

[Leisesturm]

I finally got around to do a quick recording. Note that there is no noise before the phrase is played, then during the phrase, you can see the "kindling burning" noise in the L channel, and then after the music, no noise.
Z
http://longfinal.com/rnd48084762/OrganTest.wma

I could be wrong, because I've never actually had hands on with VPO tech but it 'sounds' to me like what people experience when the BUFFERS and other parameters of their audio processing software are not optimal for the amount of RAM they have or their processor resources or what have you. What are you working with as far as system resources?

[ziggi55]

I got a 16GB, 3+GHz machine, and I applied several of Sam's (samibe) suggestions from his pamphlet. (See previously in this thread). If you want to see a particular setting, please be specific. The GO sometimes runs on an empty (Win 7) system, and the noise is unchanged.
Z

[Admin]

This does not sound like a buffer or processing problem to me. As I said previously, that type of problem would not be confined exclusively to one channel. Buffer problems are the result of the CPU not processing data fast enough to keep the sample buffers full. This can occur due to insufficient processing power and is usually associated with CPU and disk intensive background tasks, such as virus scans and file indexing, that steal processing time interfering with keeping the buffers full. When the buffer underflows, or becomes empty, the audio stream is interrupted, causing a glitch, and perhaps a pop or tick. But there's no reason to expect that if this was occurring it would only affect the left channel buffer.

Buffer problems are more likely to occur when there are high signal processing demands, such as when large amounts of polyphony are required. Polyphony can be increased by increasing buffer sizes, but the tradeoff is that larger buffers mean greater latency. The example is a single note melody played on single rank. Polyphony requirements, and hence processing requirements, couldn't be less and a multicore processor running at 3GHz should have no problem handling this. You can always monitor CPU and disk usage while the problem is occurring, but I'm sure you'll find that they are not being heavily taxed by a single note melody.

I think this an audio problem. It may be due to a bad sound card or maybe electrical noise from the computer circuitry is bleeding into the audio. Inaudible high frequency oscillations in the audio path often manifest themselves as light ticks and frying.

[ziggi55]

This does not sound like a buffer or processing problem to me. As I said previously, that type of problem would not be confined exclusively to one channel. Buffer problems are the result of the CPU not processing data fast enough to keep the sample buffers full. This can occur due to insufficient processing power and is usually associated with CPU and disk intensive background tasks, such as virus scans and file indexing, that steal processing time interfering with keeping the buffers full. When the buffer underflows, or becomes empty, the audio stream is interrupted, causing a glitch, and perhaps a pop or tick. But there's no reason to expect that if this was occurring it would only affect the left channel buffer.

Buffer problems are more likely to occur when there are high signal processing demands, such as when large amounts of polyphony are required. Polyphony can be increased by increasing buffer sizes, but the tradeoff is that larger buffers mean greater latency. The example is a single note melody played on single rank. Polyphony requirements, and hence processing requirements, couldn't be less and a multicore processor running at 3GHz should have no problem handling this. You can always monitor CPU and disk usage while the problem is occurring, but I'm sure you'll find that they are not being heavily taxed by a single note melody.

I think this an audio problem. It may be due to a bad sound card or maybe electrical noise from the computer circuitry is bleeding into the audio. Inaudible high frequency oscillations in the audio path often manifest themselves as light ticks and frying.

I agree on all points, but this is happening exclusively with GO, and it is NOT present in Hauptwerk or any other sound app (youTube, iTunes, etc.) running on the PC. Do you know if the GO designers are still responding to their chat group? I may try to ask these questions there.
Z

[Admin]

What operating system and version are you using? What sound card/device are you using?

[j reimer]

Do you know if the GO designers are still responding to their chat group? I may try to ask these questions there.Z

They certainly are. At https://sourceforge.net/p/ourorgan/discussion/

John Reimer

[ziggi55]

What operating system and version are you using? What sound card/device are you using?

I run Win 7 (latest updates), the sound is on NVIDIA High Definition Audio, but I just noticed the driver is 5 years old. I will try to update it.

[ziggi55]

While I am waiting for a response from the GO forum, I'd like to throw out this, no doubt rather loaded, question and observation: In the past few months, I got a chance to compare the sounds of Hauptwerk and GrandOrgue on different types of samples and also types of music. My impression, as a complete novice mind you, is that GO's sound is "harsher", "pricklier", and with some level of (call it "intermodulation") distortion. IOW, I seem to hear various artifacts, seemingly stemming from frequency interference. It is even more apparent when one pipe (sometimes in the same rank) is a bit louder than another one. OTOH, HW's sound is rather distortion-free, smoother and generally more "balanced" and pleasant.

I definitely do not want to disparage the tremendous efforts of the GO designers - still a magnificent and generous feat by them. I am more like fishing here for an opinion. And yes, I realize that while GO is free, "you get what you paid for". So, *I* may be the one doing something wrong. Currently, though, I have the sampling rate and bit resolution set at their highest levels (96000, 24).

Anyone has a similar observation? (Of course, for the purpose of this note, it has nothing to do with my "noise problem".)
Opinions? Zdenek