Stereo Tool

when using st with sam4 it seams to be the final step in the air chain. i get some pops when other windows open and close. this does not happen with other dsp's. is there anyway to adjust input or out buffers? i have tried sams buffers settings and even at 1 sec full st still causes pops when i do other things on the pc. ideas?


mike
khel973

ok setting sam pipeline config to time critical helps some but still getting hiccups when a web page loads and the screen updates in browser.

cpu runs at 30% on 2.8 P4
I can't use loudness as cpu goes to 48% and 100% if i use browser window.

mike
khel973

Welcome Mike,

I'm developing Stereo Tool on a 2.4 GHz machine, and I don't have any of the problems that you mention. 48% CPU usage with all processing and Loudness on sound about right if you have an older processor - the Loudness filter is rather expensive (on newer processors it's often around 10-15%). But, especially with a 1 s buffer in SAM, you should not get any hiccups. (I've ran some tests with a 0.5 s buffer, and I'm getting no hiccups when opening or closing windows).

Note that this is on Windows XP. In case you are using Windows Vista: Vista is known for the really expensive graphical effects... Which might then indeed cause hiccups even at buffer sizes of ~ 1 s).

I cannot really think of any reason why Stereo Tool would behave differently than other DSP plugins - except maybe if the CPU load is higher. If that's the case, it might also help to increase the priority of SAM as a whole, instead of just the Stereo Tool processing... Also, set the quality to Low or Normal, not High (especially when using the Loudness filter, which takes up about 5 times as much CPU power when the quality is set to High).

Could you try turning some features off and see what happens? If the cause is the CPU usage, that should immediately solve the hiccups. Alternatively, you could set the buffer size even higher.

If the problem only occurs when opening or closing windows, you could also - as a workaround - turn off some of the visual effects. In Windows XP, go to Start -> Control Panel -> System -> Advanced -> Performance Settings, and disable "Animate windows when minimizing and maximizing".

Ok, my sound card had a buffer setting as well. I use m-audio delta 66.(very high quality card ) it has 4 channels in and out, using balenced 1/4 plugs. i'm using the second set as the control room cue, and first set as mixer board in and transmitter out.
setting the buffer to 768 cured most of the popping on the cue out. air side seems to get priority as it sounds solid even if the cue side pops at lower rate settings below 512. i was albe to lower the sam buffers to 600 ms. cue side still pops sometime when using the pc but air is solid. this seems to be related to this type of card. maybe someone with 2 sound cards can comment about their experence. maybe Xp handles second card priority lower and buffer time differently. I have solved another issue about sound quality but will post that in the preset topic.
mike
97.3 khel FM
http://www.khel973.com

About the sound card buffer setting: At 176.4 kHz (the sample rate of the on-air channel), 768 samples is only 4.4 ms. Given the fact that Windows process scheduling is only accurate at about 10 ms, I can imagine that using such low (or even lower) values can cause problems. (Windows should keep the buffers filled, Stereo Tool only offers the data to Windows. And if the Stereo Tool buffer is large enough, there should always be enough data available.)

The default sound card buffer setting is probably intended for 44.1/48 kHz (where 768 is 17 ms).

I'll put a remark about this in the FM stereo transmitter help page.


The popping in the low latency channel is there by design! The reason: Whatever happens, the low latency channel may never disturb the on-air signal.

For example when sending the data to different sound cards, the timing might be slightly different. Because of issues like that, if a piece of sound cannot be sent to the sound card immediately (eg. the buffer is already full), it is dropped.

If the processing is done in bursts (which happens among others when some other process uses a lot of CPU power), this will happen a lot.

There is a great utility for those that are using ASIO driver sound card that has helped in setting the sampling and kernal buffer.

The utlity is called " ASIO4all " it maybe worthwhile checking it out as it may help.

regards

mapleleaf