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undefined symbol: PaAlsa_EnableRealtimeScheduling prevents mixx application from opening

bd flag
Chris P

In this machine, we have Ubuntu 20.04 (i suppose). After a few hardware configurations (some cables) (i don't really know about to explain), the mixxx software doesn't open.

So, it shows up in the Activity bar but then it doesn't open.
I tried to kill the process with killall command.
I tried to restart the machine.
I tried to reinstall the Mixxx software from the ubuntu software center, and from the console with the apt-get command.

Any advice would be useful.

I don't have physical access to the machine right now but I can manage it from my house with AnyDesk software.

(P.S.: I am not familiar with ubuntu software almost at all, so please give explanation answers :) )

enter image description here

Edit:

epalxeis@epalxeis-To-be-filled-by-O-E-M:~$ mixxx
mixxx: symbol lookup error: mixxx: undefined symbol: PaAlsa_EnableRealtimeScheduling
epalxeis@epalxeis-To-be-filled-by-O-E-M:~$

I tried to install it from source (link). Same error.

epalxeis@epalxeis-To-be-filled-by-O-E-M:~/Desktop/mixxx-2.3/build$ cmake --build .
Scanning dependencies of target benchmark
[  0%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/benchmark.cc.o
[  0%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/benchmark_api_internal.cc.o
[  0%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/benchmark_name.cc.o
[  0%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/benchmark_register.cc.o
[  1%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/benchmark_runner.cc.o
[  1%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/colorprint.cc.o
[  1%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/commandlineflags.cc.o
[  1%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/complexity.cc.o
[  1%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/console_reporter.cc.o
[  1%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/counter.cc.o
[  1%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/csv_reporter.cc.o
[  1%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/json_reporter.cc.o
[  2%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/reporter.cc.o
[  2%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/sleep.cc.o
[  2%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/statistics.cc.o
[  2%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/string_util.cc.o
[  2%] Building CXX object lib/benchmark/src/CMakeFiles/benchmark.dir/sysinfo.cc.o
...
...
...
[ 99%] Linking CXX executable mixxx-test
/usr/bin/ld: libmixxx-lib.a(sounddeviceportaudio.cpp.o): in function `SoundDevicePortAudio::open(bool, int)':
/home/epalxeis/Desktop/mixxx-2.3/src/soundio/sounddeviceportaudio.cpp:340: undefined reference to `PaAlsa_EnableRealtimeScheduling'
collect2: error: ld returned 1 exit status
make[2]: *** [CMakeFiles/mixxx-test.dir/build.make:1659: mixxx-test] Error 1
make[1]: *** [CMakeFiles/Makefile2:1155: CMakeFiles/mixxx-test.dir/all] Error 2
make: *** [Makefile:163: all] Error 2
87
1 + 3
bd flag
Chris P
@user535733 did it as you tell.
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user535733 avatar
cn flag
user535733
Now you are making progress. Looks like some kind of alsa-related problem, not specifically mixx. I have added the 'alsa' and '20.04' tags to your question, and made your title more specific. These changes make it more likely that alsa gurus will see your question.
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bd flag
Chris P
@user535733 I have added some additional inforation.
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Score:1
avatar Ubuntu
bd flag
Chris P

I have just comment(//) lines339 and 340 of file /home/epalxeis/Desktop/mixxx-2.3/src/soundio/sounddeviceportaudio.cpp changing this:

#ifdef __LINUX__
    if (m_deviceTypeId == paALSA) {
        qInfo() << "Enabling ALSA real-time scheduling";
        PaAlsa_EnableRealtimeScheduling(pStream, 1);
    }
#endif

to this:

#ifdef __LINUX__
    if (m_deviceTypeId == paALSA) {
    //    qInfo() << "Enabling ALSA real-time scheduling";
    //    PaAlsa_EnableRealtimeScheduling(pStream, 1);
    }
#endif

and then I ran:

sudo cmake --build build --target install --parallel `nproc`

and now mixxx opens.

I don't know what side effects this custom install may do, so feel free to comment.

0 + 3
terdon avatar
cn flag
terdon
Hmm... Sounds like you should file a bug with mixxx. The best way would probably be to report this on their github page where you got the source. Also, could you please edit your answer and include the specific lines you commented out? Line numbers are likely to change with any minor change to the project, so having the actual code will be helpful in case anyone else faces the same issue. Oh, and "epalxeis", λολ :)
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terdon avatar
cn flag
terdon
I added what I think you changed, please check and correct if needed.
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bd flag
Chris P
@tendon: also check lines 23-26 of the same file. There has `LINUX` instead of `__LINUX__`
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