Stereo Tool
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Stereo Tool 6.00
https://forums.stereotool.com/viewtopic.php?t=2811		 Page 35 of 72
Author:  phoenix [ Wed Jan 26, 2011 2:17 pm ]
Post subject:  Re: Stereo Tool 6.00
Hans, is it possible that you could make the CLI accept float 32 bit uncompressed wave files or pipe in and out that format? Would make transcoded files sound better.
Author:  Bojcha [ Wed Jan 26, 2011 5:00 pm ]
Post subject:  Re: Stereo Tool 6.00
I just do some Latency measurements again.This ime using latest beta.

First what i found is less latency with 192kHz input. Now with 192kHz at input - L/R in/out - i can set buffer to 0.006sec!
With 48kHz selected - 0.011
With 1024 latency L/R out can be set at 0.008sec - 192kHz Input.

On Juli@ soundcard i can set lowest buffer 48samples. Interesting is that BA Asio can't work at this 48 samples. Minimal must be 128 or 256 samples at soundcard.

So, Latest ST beta..
- 192kHz input selected - 512samples - no PhaseRotator L/R Output 23ms, with Phase rotator ON 25ms.
- 192kHz input selected - 1024samples - no PhaseRotator L/R Output 33ms, with Phase rotator ON 36ms.
- FM out is 1-2ms more

- BA Asio, FM output latency 21ms!

Used Juli@ with direct wire, recorded one channel source and second chanel processed.

smal request:
- FM output buffer size in 3 decimal number. Like Notmal output (?)
Author:  eldoradofm [ Wed Jan 26, 2011 8:45 pm ]
Post subject:  Re: Stereo Tool 6.00
Isn't there a way to calculate and set the optimal buffer size for each latency? Like in BBP Asio there isn't even a buffer setting. There you just have to select the latency at the soundcard.
Author:  Bojcha [ Wed Jan 26, 2011 9:02 pm ]
Post subject:  Re: Stereo Tool 6.00
Good question Eldorado!
Automaticly set at ST startup minimal latency buffer size (possibly +1ms)
That's for Standalone.
Author:  hvz [ Wed Jan 26, 2011 9:25 pm ]
Post subject:  Re: Stereo Tool 6.00
I was actually planning to look at the ASIO driver in Stereo Tool tonight...

Here's how it works:
- Say the latency is set to 512 samples, quality at maximum (full overlap, ie. the last 50% of the current block overlaps the first 50% of the next block).
- So first I have to wait until a multiple of 256 (!) samples has arrived. To make sure that I don't loose any time here, ASIO buffer granularity must be at most 256 samples. (based on 44.1/48 kHz input/output)
- Now I need to do some processing. This will typically cost around 3 ms (depending on settings and CPU).
- Next I write the output to the ASIO buffer. This goes in a burst (ie. I write 6 ms of data immediately).
To do this, I need at least 3 ms of ASIO buffer size - but as little more as possible. This value can differ depending on the the CPU load - so I cannot accurately predict it.

Currently, the ASIO buffer size that I'm using is a multiple of the 'preferred' ASIO buffer size returned by the ASIO driver. I think I should make that configurable.

Also, currently I write a sample when I receive a sample. Unfortunately this means that I wait an ASIO buffer block after doing all the processing - I can only do the processing when the full data block has arrived, and then at the next sample I output one sample. This is probably not really an issue because the processing takes some time anyway, so when that's finished a lot of data will be 'pushed' through the chain in a burst.

First thing I'll do is make the ASIO granularity configurable.
Author:  hvz [ Wed Jan 26, 2011 10:01 pm ]
Post subject:  Re: Stereo Tool 6.00
ASIO bug #1: Hm... Something went wrong with switching between low latencies and normal latency. Due to this, I was ALWAYS treating the ASIO input as if it was coming in with blocks of 288 samples... :shock: Now changed to 32 (64, 128 at higher input sample rates) - that should help!

#2: That's not very useful either. It should match the actual ASIO buffer granularity.
On top of that, processing must be reset such that the start of a (time consuming) processing action always corresponds with the reception of a complete ASIO buffer.
Author:  hvz [ Wed Jan 26, 2011 11:42 pm ]
Post subject:  Re: Stereo Tool 6.00
I've fixed the 2 issues I mentioned before. I expect the new version to be better, but... the ASIO support of my Juli@ card on my Windows Vista 64 system has always been extremely buggy, meaning that sometimes I can start it once after booting, and after that it's just dead. So I'm unable to properly test this new version. (I have tested it in a virtual machine, there the green bar stays filled much better than before, but there's no audio to hear if there are artifacts).

If anyone can point me to an ESI Juli@ driver that functions properly in Windows Vista 64, I would be very grateful. The (latest) 1.07 driver on the ESI site does not work...

Anyway, I'll build a new version with these changes, and then just hope for the best...

EXPECTED improvements:
- Buffer size was 288 samples (which is a really odd number), 6.5 ms at 44.1 kHz (1.6 or 1.5 at 176.4 or 192 kHz). Since this doesn't usually correspond to a supported ASIO latency, I think it leads to twice that latency - ie. 3 ms at high sample rates, upto 12 at low sample rates.
- Because some buffers were not cleared, the behavior depended a lot on what was done previously (setting latency to 2 ms could result in frequent hiccups, then increasing it to 3 and decreasing to 2 again could solve those). Buffers are now cleared, behavior is expected to be optimal in all circumstances.

I'm now also displaying the ASIO buffer size granularity in samples (that's the preferred ASIO latency selected in the sound card driver), I've not yet made that configurable.

Output latencies can now be set in multiples of 0.1 ms - a bit extreme (given the fact that it's rounded to ASIO buffer granularity multiples) but at least it can be specified upto very small detail.

Hint: Set the Stereo Tool priority as high as possible when testing extremely low latencies.
Author:  Bojcha [ Thu Jan 27, 2011 12:13 am ]
Post subject:  Re: Stereo Tool 6.00
Hans,
Can you make option "RealTime Priority" somewhere in Stereo Tool ?
I already know that this helps a lot. I even make .bat file witch starts ST in RealTime Priority mode, but will be better to have like an option.
Author:  eldoradofm [ Thu Jan 27, 2011 12:18 am ]
Post subject:  Re: Stereo Tool 6.00
I noticed something in version 24. When i look at CPU-history i see one core is using a lot more then the other. But when i set the buffer size just one click higher, or lower it swaps. So then the other core is high and the other low. I will test this with the next version to see how that behaves.

Yes auto Realtime priority would be great.
Author:  hvz [ Thu Jan 27, 2011 12:38 am ]
Post subject:  Re: Stereo Tool 6.00
- Real time priority: Good idea
- Swapping of CPU usage: Doesn't really matter, Windows does that a lot - and in this case, changing the latency causes some threads to be cleaned up and created again.
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