Jazz++ MIDI Sequencer




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Jazz++ FAQ

Here you will find some of the most Frequently Asked Questions that the Jazz++ team get asked by Jazz++ users, along with helpful answers to those questions.

This area is broken down into two parts --

The User FAQ deals with general user questions regarding the operation and use of Jazz++ itself.

The Developer FAQ deals with specific questions related to the Jazz++ code itself, and possible problems when compiling/using that code on the platforms/OS' currently supported by Jazz++.

User FAQ

Q. I see the following error when I try to start Qjackctl, what's wrong?


cannot use real-time scheduling (FIFO at priority 10) [for thread -1210526016, from thread 
-1210526016] (1: Operation not permitted) cannot create engine

Related Error:

[other programs] Error message reading:  "system timer resolution is too low"

Problem: Optional Linux kernel 'low latency' configuration not used with kernel build.

Cause: Many Linux distributions defaultly install a 'voluntary pre-emption' optioned kernel for 'Desktop' type installations. What is required here, is the kernel 'low-latency pre-emption' option to be included at the time the Linux kernel is compiled. If you are running a mainstream Linux distribution, you might try checking your distribution's website to see if a pre-compiled binary Linux kernel package is available, with the various low-latency configuration options enabled.

Solution: If you cannot find a binary kernel package pre-compiled with the necessary low-latency options, then you will have to install your Linux kernel sources package, then reconfigure the source with the appropriate options, recompile and install the new kernel and modules, reboot to the new kernel, and then these error messages will go away. Unfortunately, help with doing this task is beyond the scope of the Jazz++ manual, however if you are going to recompile and reinstall your Linux kernel, the relevant configuration options are listed in the Jazz++ user manual Appendix.

Note: This situation may change in the Linux kernel at some future time. It would seem patches are available that allow for a voluntary pre-emptive kernel to act in a pre-emptive I/O fashion, and maybe some of these patches will find their way into the Linux kernel tree in the future.

Developer FAQ

Q. When I run configure, I get the following error...

A. If you are trying to build/compile Jazz++ from sourcecode tarball or the Jazz++ svn repository, you may encounter one or more of the following errors. Check through this list of errors below and see if the error message you've encountered has already been noted before emailing the Jazz++ developers about these sorts of problems. These are typically not problems with Jazz++ or the Jazz++ source itself, but usually more indicative of a problem with the 'host' computer system software setup.


../jazz/configure: line 4844: AC_PROG_LIBTOOL: command not found

configure.ac:44: error: possibly undefined macro: AC_PROG_LIBTOOL
If this token and others are legitimate, please use m4_pattern_allow.
See the Autoconf documentation.
autoreconf: /usr/bin/autoconf failed with exit status: 1

Problem: The libtools package is not installed.

Likely Cause: [Linux] 'desktop' installation, SDK not installed

Solution: Install the libtools package and retry.

During the installation stage of most all Linux based distributions, the person installing the system is given a choice as to what sort of system they would like to install. Typically the choices are something like 'Server', 'Desktop', and 'Work Station'. The Linux SDK (software developers kit) is *NOT* routinely installed as part of a standard 'Desktop' type Linux installation, and this is true for most all mainstream Linux distributions. However the SDK *IS* routinely installed by most Linux distributions when the 'Work Station' install option is selected, and this is how some people end up with the SDK and others not...who end up seeing this sort of error. It's not a problem - you don't have to reinstall everything, you just need to add the SDK packages.

Adding the SDK packages is where some people have problems. The Linux SDK is a -collection- of packages, not just a single package. That said, there is a 'single' package entry in most Linux distribution 'package managers' which is itself a 'meta-package' containing a list of the packages needed to be installed to have a complete SDK installed. Some people make the mistake of installing the GCC package onto their system, thinking this is the SDK itself (or that the other required packages of the SDK will be installed as dependancy packages). In actuality, GCC is both a part of the overall SDK -and- a valid stand-alone installation target, so installing it won't pull in any other the other required SDK packages at all.

TODO: add SDK meta-package names for various Linux distros


Project.o: In function `JZProject':
undefined reference to `tAudioPlayer::tAudioPlayer(JZSong*)'
undefined reference to `tAudioPlayer::tAudioPlayer(JZSong*)'
collect2: ld returned 1 exit status

Problem: ALSA library headers missing, Alsa-dev package not installed.

Solution: Install ALSA development package and retry.

Most Linux distributions do not defaulty install all 'development' packages. These development packages contain all the runtime library header (and sometimes 'C' code) files needed for other programs (like Jazz++) to compile. Jazz++ depends on the ALSA API function declarations to build on Linux, so you need to install this package before attempting to compile Jazz++ from source tarball or the svn repository.

TODO: add ALSA devel package names for various Linux distros

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