Playback stuttering, low cpu, gets worse as I increase block size

[KranVaux]

Shouldn't playback be smoother (with more latency) the higher your block size? I've been really impressed with Reaper over the past few months coming from Studio One, but this has been bugging me. I'm getting to the point in some projects where I need up the block size to handle my plug in count. I switch to 2048 and even though the displayed CPU is hovering around 20 -30 it is just a distorted cracklin mess. 1024 is a bit better but still stutters enough to make work fatiguing. I've made sure my interface and reaper are the same sample/block size. It's bad on ASIO saffire driver but the other drivers (WASAPI, Direct Sound) still have the same issue. I used the DPC latency checker but no spikes were showing up even though the playback was still stuttering. I've tried to go through and ensure my drivers, are up to date....I'm at a loss. Maybe someone else has experienced this? Any advice would be greatly appreciated. I'd like to continue to use Reaper but if I can't resolve this issue I may have to go back to Studio One.

My laptop: https://www.asus.com/us/ROG-Republic...pecifications/

Intel® Core™ i7 4700HQ Processor

Windows 10

24 GB DDR3L MHz SDRAM


Interface: Focusrite Saffire Pro 24 DSP firewire to thunderbolt through adapter

https://www.sweetwater.com/store/det...ire-pro-24-dsp

[DVDdoug]

Shouldn't playback be smoother (with more latency) the higher your block size?

Yes, that's usually what you expect... Usually...

This is a "big topic" and there is a FREE online book about optimizing your computer for audio. (The book seems to be oriented to minimizing latency for live use, which isn't your problem, but it's all tied-together.)

though the displayed CPU is hovering around 20 -30

That probably means your CPU isn't the bottleneck. But it's tricky because it's not just average/overall CPU usage... If some driver/process/application "hogs" the CPU for a couple milliseconds too long, you get a glitch. A faster CPU usually helps because it can finish everything faster.

Maybe it's your hard drive? Are you "playing back" a multi-track mix or playing virtual instruments so the hard drive is trying to read a bunch of files at the same time?

[JamesPeters]

I second the above post's recommendations for that guide. The part about your "power plan" is something that I'd say most people initially don't even realize needs to be changed. I bet that has something to do with it.

Also your Thunderbolt chipset might have something to do with it. On another thread with a similar-sounding issue (this person had the Focusrite Pre8X), the problem was cured with a BIOS setting change (since the TB device was on the mainboard).

https://forum.cockos.com/showpost.php?p=1980964

Also if your TB chipset (your computer's TB port) is TB3, it may not be compatible. I've read that TB2 should be compatible with Focusrite devices, but some people have had reported trouble with TB3. It seems your system has TB 1 or 2 by the way the port looks (and the year of manufacturer) but since I have no experience with TB, I thought I'd mention it just in case.

Anyway those block sizes are a bit large. If using 512 helps, maybe consider that. Some devices don't like using large block sizes.

[KranVaux]

Originally Posted by DVDdoug

Maybe it's your hard drive? Are you "playing back" a multi-track mix or playing virtual instruments so the hard drive is trying to read a bunch of files at the same time?

In these sessions there are no virtual instruments, just plugins running on tracks. My plugins are saved to my OS SSD and all my media files are saved on another HDD so not sure if that has any effect on the issue.

Thanks for the link to the book. Just looked over the table of contents and can see I'm in for some reading haha >_<

I've been using Studio One for years on this laptop/interface and have never had these issues. Block sizes worked as they're "supposed" to. Small block sizes were low latency but couldn't handle too many tracks/VSTs. Higher block sizes had more latency but less drop outs. I would usually be running on 2048 during the middle/end of most mixes. The problem I ran into with Studio One was the crazy CPU usage and random spikes.

I loved switching to Reaper for many reasons, the stability and cpu usage being major. The block size thing confuses me as to why it would act normally in other programs. Didn't know if there was some buffer setting or something that might address the problem.

Originally Posted by JamesPeters

Anyway those block sizes are a bit large. If using 512 helps, maybe consider that. Some devices don't like using large block sizes.

Lower block sizes in Reaper do seem to help but even at 512 I get intermittent dropouts. 1024 is ok but worse, and 2048 is a nightmare. For a long time I was working at very low block sizes like 64 and 128 and I didn't notice any problem. As some sessions got beefier though I upped the blocksize and started hear the dropouts.

That's a good thought about the whole Thunderbolt chipsets. I'll check out that thread thanks. My only thing with that is that all other audio performance on my computer has been fine for the most part when I run it through the focusrite. I'll definitely look into the Thunderbolt thing deeper though.

Thanks so much to both of you for your quick responses! Another reason I love Reaper is the community here

[KranVaux]

So I worked my way through the entire "Glitch Free" book. I've heard much of the advice before but there were also a lot of deeper tips that were new to me. On top of that also feel like I have a better grasp of computer processes after reading it so thanks for referring me to it! Unfortunately, after following all the advice in the book, my problem still remains. My audio is intermittently glitching at 512, bad at 1024, and useless at 2048... I ran LatencyMon tests that came out fine:

latmontest.txt

Testing out whether or not Thunderbolt was the issue - even when I disabled the driver and ran the audio through my laptop soundcard still had the dropouts. That all leads me to believe it's not my firewire to thunderbolt setup.

I've scoured google but I haven't been able to find anyone with an similar issue (playback getting worse as buffer size increases) I have never experienced this with other DAWs I've used on this system (Studio One, CakeWalk, Ableton). I'm at a loss... I love Reaper but this problem really isn't something I can just live with. Are there any hail mary settings that I may have missed??? Any other resources someone could point me to??

[anomar]

I had a similar problem it was resolved when I restricted the number of cpus in preferences from 0 to 15, it is at 2 to 15 now.
That option is localized in:
Preferences/General/Advanced UI_system tweaks

[KranVaux]

Thanks for the response! I tried restricting the number from 0-7 to 2-7 but alas no difference. I randomly tried reducing the Audio threads from 8 to 2 and at 2048....it worked?! not perfectly, a glitch here and there. reducing audio threads to 1 was much worse and increasing to 3 and up was worse. So 2 is the sweet spot. Not a perfect fix but definitely progress.

Reaper's response still seems glitchy, lagging. For example muting a track has noticeable lag and when I unmute I get a lag and maybe a little glitch. Starting/stopping playback can be laggy/glitchy.

I fired up Studio One 4 and loaded a similar session and it was running fine. CPU processing was reported at 75-90% (As opposed to 20-35% in REAPER) but had little to no dropouts. Buffer size worked as it should, 2048 was pristine, 512 had a few dropouts. Controls were very responsive such as tracks instantly responding when muted, playback more responsive, etc.

As far as I can tell the issue must be REAPER? I guess I'll uninstall and try a clean install? I already deactivated any scripts I had running, which weren't many. Hope I can get this working because REAPER really lets me create an awesome workflow. If I had any hair I'd be pulling it out by now >_<

[foxAsteria]

Removing/bypassing plugins from the master track usually helps. I've noticed more than 2 track channels on many tracks that didn't need it and that drains cpu too.

Anticipative fx processing has a big impact as well.

[ivansc]

Originally Posted by KranVaux

I used the DPC latency checker but no spikes were showing up even though the playback was still stuttering.

Just noticed this: Just wanted to confirm that this is the output from resplendence.com`s latency checker & not DPCLat, which has been unreliable since I think WIn7 & still is afaik.

Don`t suppose it will help but it might narrow things down. I am still wondering about using Thunderbolt on a PC via an adapter.... Tbolt on my Mac works fine but I have never got it running reliably with an adapter on my i4700. There again firewire is pretty flaky on that machine too.

[KranVaux]

So I did a clean install and still same issues -_-

Originally Posted by foxAsteria

Removing/bypassing plugins from the master track usually helps. I've noticed more than 2 track channels on many tracks that didn't need it and that drains cpu too.

Anticipative fx processing has a big impact as well.

Yeah I went through a session bypassing all the plugins and one by one enabling tracks. On a session with 87 tracks playback seemed ok until I got to the final few busses. I do a fair amount of sidechaining, One thing I do is have two mix buses routed to the master, one is the normal mix and the other is a highpassed mix which is sidechained to the compressor on the master bus. I noticed when I enabled the fx on the sidechained sub it had notable effect on glitches.

Though all of this my CPU is still reported as under 40% though so not sure where the problem is....

Originally Posted by ivansc

Just noticed this: Just wanted to confirm that this is the output from resplendence.com`s latency checker & not DPCLat, which has been unreliable since I think WIn7 & still is afaik.

Don`t suppose it will help but it might narrow things down. I am still wondering about using Thunderbolt on a PC via an adapter.... Tbolt on my Mac works fine but I have never got it running reliably with an adapter on my i4700. There again firewire is pretty flaky on that machine too.

Yes I used the LatencyMon from Resplendence. Here's the report: Attachment 35606

The reason I don't think it's my firewire/thunderbolt is because I don't experience these issues except in REAPER/ So maybe it's the way REAPER is handling my firewire/thunderbolt. Who knooows.... I've been planning on building a pc soon so I guess we'll see if the issue is present on that machine. Anyone have any resources they would suggest for building a pc optimized for audio production/engineering?