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Hello,
I'm testing BO with Thesycon ASIO driver. Freq = 192kHz. The smallest jitter is 6%@(buffer=8192). Jitter = 33%@(buffer=2048). With smaller buffer size jitter has value more than 100%, for example, 5450%.
1. Could you please tell me how the jitter value is calculated?
How it can be >100%?2. I have compared jitter values for other sound cards.
USB card Stainberg UR22 mkII (Yamaha Steinberg USB ASIO) has jitter 0-2%@(buffer 3072).
PCI card M-Audio Delta AP192 (M-Audio Delta ASIO) has jitter 1%@(buffer 1024).With XMOS USB card and Thesycon ASIO driver, I can't get jitter less than 6%. What could be the reason? Is it the driver/PC/sound card issue?
Without getting too technical (because I don't have the terminology), it is all about the "frame rate" or the number of complete frames that fit into the allocated area. Obviously, the larger the buffer, the more frames can fit, so the jitter percentage drops. However, it takes longer to refresh the buffer, so the latency rises. So it's a compromise between low jitter and low latency.
Bottom line – if you can't hear artefacts of any sort, a higher jitter rate is not a bad thing unless you are playing music videos where the lip synch will drift from the audio. If you are synching with video, you should aim for the lowest jitter rate, or adjust the video delay (if an option) so the audio and video are synchronised.
The "Jitter" is the change in timing compared to other "blocks" of audio date coming/going.
It can be above 100%, even without actual skips in the analog audio, because there's more than one block of buffering being I/O at a time.
It's still not recommended, but whatever works sometimes is what has to be done, no matter what the numbers say.
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