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Author Topic: Upsampling from 48 to 96 causing audible hickups  (Read 2821 times)

Trumpetguy

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Upsampling from 48 to 96 causing audible hickups
« on: November 04, 2011, 06:36:29 am »

I have tried several times since MC15 (now running latest beta 17) to play all sources at 96kHz sample rate. Just for convenience, I need to get my b**t out of the sofa and walk three steps to switch sample rate.

Lately I tried upsampling a 5.1 24/48 movie audio stream to 24/96 (and then using JRSS to expand to 7.1 and DSP, as always). Playback at 24/48 sounds perfect. Upsampled playback seems to lose information, much like fram drops in video streams. I am not sure, but it seems to happen more often when the GPU works more instensely, like slow panning. 

I have experienced the same for 2.0 audio, e.g. when scrolling the news in a web browser while listening to music. This was with an onboard ati video chip, not my new dedicated nvidia gpu.

Any explanations for this?

Is upsampling an cpu intensive process?
My computer is not the fastest, it ticks in at ~1300 on the benchmark. Can this be the cause? If yes, I have a pretty good excuse for upgrading my computer equipment...
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bunglemebaby

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Re: Upsampling from 48 to 96 causing audible hickups
« Reply #1 on: November 04, 2011, 06:58:57 am »

It does sound like you're overloading the cpu. I've had similar issues when scrolling web pages and listening to music. The music glitches coincided with the times when my task manager was reading high cpu loads.
That said, you'll want to determine if something else besides MC is hitting the processor while this is happening. In my case, I never get audio glitches unless something processor intensive is going on in the background. MC analyzing audio is a good candidate here, but there are countless other things too.
-Jon
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Audioseduction

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Re: Upsampling from 48 to 96 causing audible hickups
« Reply #2 on: November 04, 2011, 09:51:29 am »

The feature "upsample by sample rate" is working great for me.  I'm upsampling from 44.1 to 88.2 and it just sounds SO GOOD! The flexibility is superb! Thanks for the new feature JR!
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Vincent Kars

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Re: Upsampling from 48 to 96 causing audible hickups
« Reply #3 on: November 04, 2011, 09:53:19 am »

Sounds like your computer is high on latency.
You might check this using the DPC Latency Checker
http://www.thesycon.com/deu/latency_check.shtml
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Trumpetguy

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Re: Upsampling from 48 to 96 causing audible hickups
« Reply #4 on: November 04, 2011, 02:34:35 pm »

Sounds like your computer is high on latency.
You might check this using the DPC Latency Checker
http://www.thesycon.com/deu/latency_check.shtml


I will test that first thing when returning from our weekend trip. Thanks!
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Trumpetguy

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Re: Upsampling from 48 to 96 causing audible hickups
« Reply #5 on: November 06, 2011, 04:51:58 pm »

Sounds like your computer is high on latency.
You might check this using the DPC Latency Checker
http://www.thesycon.com/deu/latency_check.shtml


I tried that tonight. Even when playing back Bluray disc the latency does not exceed ~150microsecs (ok, maybe one peak up to 1500 once tonight). No transient behavior, i.e. no high latency peaks at regular or irregular intervals.

The report from the program is 'This machine should be able to handle real-time streaming of audio and/or video data without drop-outs.'

Too weak CPU is maybe the most probable theory yet?

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Matt

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Re: Upsampling from 48 to 96 causing audible hickups
« Reply #6 on: November 07, 2011, 02:20:32 pm »

I think a machine that benchmarks at 1300 is going to struggle converting 5.1 from 48 kHz to 96 kHz and then up-converting that to 7.1. 

There's simply a lot of CPU-intensive math that has to happen for that to work.

It might help to increase the primary buffering in Options > Audio > Output mode settings....
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Matt Ashland, JRiver Media Center
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