Hi :)

I tested something for the Jack dev list.

Using this setup

    64 Studio 2.1rc1 upgarded to Lenny

    [EMAIL PROTECTED]:~$ uname -r
    2.6.21-1-multimedia-amd64
    [EMAIL PROTECTED]:~$ jackd -V
    jackd version 0.109.2 tmpdir /dev/shm protocol 22
    [EMAIL PROTECTED]:~$ qjackctl -v
    Warning: no locale found: /usr/share/locale/qjackctl_en_US.qm
    Qt: 4.4.0
    QjackCtl: 0.3.2
    [EMAIL PROTECTED]:~$ hydrogen -v
    0.9.3
    [EMAIL PROTECTED]:~$ ardour2 -v
    Ardour/GTK 2.5
       (built using 3525 and GCC version 4.2.4 (Debian 4.2.4-1))
      

Hydrogen and Ardour synced by jack transport, while frames are set to 128 and 
buffer is set to 2, the recordings have no jitter and a negative delay about 
5ms.

Using this setup

    Suse 11.0

    [EMAIL PROTECTED]:~> uname -r
    2.6.25.11-0.1-rt
    [EMAIL PROTECTED]:~> jackd -V
    jackd version 0.109.2 tmpdir /dev/shm protocol 22
    [EMAIL PROTECTED]:~> qjackctl -v
    Qt: 4.4.0
    QjackCtl: 0.3.3
    [EMAIL PROTECTED]:~> hydrogen -v
    0.9.4-svn84
    [EMAIL PROTECTED]:~> ardour2 -v
    Ardour/GTK 2.5
       (built using 3525 and GCC version 4.3.1 20080507 (prerelease)
    [gcc-4_3-branch revision 135036])
      

Hydrogen and Ardour synced by jack transport, while frames are set to 128 and 
buffer is set to 2, the recordings have no jitter and a delay about 0.25ms. I 
guess a quarter milli-second delay will be fine, I didn't made acoustic tests, 
just looked by Audacity, but this, especially without jitter, should be good 
enough. I guess it must be one click, without an early reflection like effect, 
and the phasing when playing the audio track and hydrogen unison should be 
always the same. Definitive the first beat won't be cut.

So it seems to be that Hydrogen 0.3.2 simply has to be changed by 0.9.4-svn84 
to solve this problem.

With frames set to 128 and buffer set to 2 also MIDI jitter seems to be a less 
serious problem, but depending to the kind of groove MIDI jitter can become a 
problem and if the frames and buffer have to be raised it will be a serious 
problem, because there's no headroom for the jitter. I guess if the Jack 
transport sync will raise, this won't become a problem, there seems to be 
headroom.

Cheers,
Ralf


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