![]() Standards-compliant USB audio devices should work with the kernel and ALSA USB modules. Both are available with a break-out box for easy access to their audio and MIDI ports, and both provide a handy S/PDIF digital audio interface. If your needs are more modest you might be happy with the Creative Labs SBLive and Audigy cards. The M-Audio Delta systems are popular for serious desktop and project studio production, while the RME Hammerfall is the preferred interface for fully professional recording houses. If you need professional-quality results from your Linux audio work, then your choices are few and clear. For Linux audio people that means hardware (our native software is famously inexpensive), and in this domain hardware means microphones, instruments, amplifiers, speakers, cables, mixing consoles, computers, and of course, soundcards and audio boards. ![]() Some problems are directly due to economic necessity, i.e., what you can and can't afford. Sage advice to the interested reader: Scale your expectations. To permanently add this setting to your boot options, become the root user and run the following command :Įcho "-user-freq=1024" > /etc/nfīy the way, you should always copy the original file to a back-up location before working on it. Use this command to check set the clock to its optimal value :Įcho 1024 > /proc/sys/dev/rtc/max-user-freq Media-optimized kernels will activate the RTC as a matter of course, but if you're in doubt (or if your application has responded with an error regarding the RTC) you can check its status with the cat /proc combo : Some MIDI programs require that the kernel include an active realtime clock (RTC). If it is not you will need to either install a distribution with an optimized kernel or you will have to configure and install your own kernel. If this value is set too low your MIDI streams may feel sluggish and unaligned. The default kernel configuration includes a setting (under Processor Type & Features) for the timer frequency resolution, which affects the timing resolution of a MIDI data stream. One special MIDI problem exists for Linux. Check your hardware connections and power-on status, make sure your MIDI devices are actually supported by ALSA and that the correct drivers are installed, and check the virtual connections between your sending and receiving devices. The problem-solving flowchart remains essentially the same for MIDI as with audio. ![]() Figure 1 shows off the gmidimonitor at work receiving a program change message sent from amidi. The amidi tool can be used to send an arbitrary MIDI command string to any MIDI device in your system, and the MIDI monitor can watch the data stream to see if your command was correctly sent and delivered. Your MIDI troubleshooting toolkit should include at least a MIDI monitor program and the ALSA amidi utility. ![]() As you might already know, MIDI does not carry audio data, and the tools for troubleshooting MIDI problems are quite simple to use and understand. MIDI problems are generally easier to diagnose than audio difficulties. In this final section I'll present some MIDI-specific troubleshooting tips, along with a brief description of the setup here at StudioDave, a few closing remarks, and of course some links to the Linux music-maker du jour. ![]()
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