v2: No audio because of zombification by jackd

• Jun 26, 2015 - 00:07

I started using mscore (v2) about 3 weeks ago.
Many times I could not get audio out of mscore. In the jack patch bay the audio output was shown on start of mscore, but most times the mscore output port in jack disappeared when loading a score. Jack works fine for other applications. And mscore can be heard by routing it's midi output to a (soft) synth.

After building the latest version of mscore from the source and running from a console window, I finally figured out why, and found a workaround (at least for me).

when loading the score, an error message is shown in the console that mscore "is zombified and disconnecting from jack"

Some research learned me that probably mscore does not meet the real-time requirements of jack. (looks related to the score loading process and/or initializing the internal synth).

My work-around:
- start mscore and first load a very small document: 1 staff, 8 bars, using same soundfont and instruments as the next score (not sure which items are relevant)
- then also load the score I'm working on (6 staves, 28 bars), it now loads normally, with audio sitll connected in jack.

Some things that might help (but that I did not check)::
- update to jackd2 (have seen notes that it does not zombify applications as fast as v1), also it does use multi-core processors when available.
- switch real-time mode off in the configuration for jackd (but that is not why I chose a real-time kernel for audio apllications)

I would appreciate it if mscore could run reliably with real-time jackd.

(I am using: freshly installed FX-Studio linux distro, 64-bit with realtime kernel and jackd(1) in realtime mode, on an older pc: Intel core-i7 2.4GHz, 6GB, 128GB ssd system disk; Yamaha P-105 digital piano via usb, Korg nanoKontrol +nanoPad.
Windows-7 64 bit (not for music).

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