[PD-dev] Re: [PD] RME hammerfall

[Tim Blechmann]

(moving to pd-dev)

i just tested the alsa interface on my hdsp ... basically it works fine
for large buffer sizes ...
but there are a few points:

- i can't get below 2902 us of latency with 44.1 kHz / 2666 us with 48
  kHz ... so basically a period size of 128 ... the hdsp is capable of
  64
- using these lowest latencies, i experience glitches:
  44.1 kHz: every once in a while (about one every 5 seconds)
  48 kHz: strong glitches for about 500 ms followed by about 3 ms more
          or less clean sound
  88.2 kHz: continuous glitches
  96 kHz: similar to 48 kHz, but scaled by factor 2

on the other hand:
- jack runs with 64 samples on my machine without any problems (at 44.1
  and 48 kHz only)
- the lowest buffer size for 96kHz on my machine is 128 (64 will kill
  jackd when connecting)

all these test where done on 2.6.12-rc2-mm1, devel_0_38, using realtime
mode for pd / jack ... for jack, i wasn't using the callback-based
scheduler.
basically the callback-based scheduler will reduce the latency by one
buffer size, because the input data will be directly processed without
any additional buffering ...

cheers ... tim

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