Crash if a midi note is recieved while the SFZ file is reloaded

[Sylv1o]

Hi, I use SFIZZ in Synthedit, so unsure it also happen in SFIZZ VST or Standalone.

Here is the message I posted in the Synthedit group :

I worked a lot on my percussion sampler, things are very promising but...now that my project has became bigger (especially the SFZ files), I noticed a very problematique bug :

If the SFZ player module recieve a midi note while it is reloading the SFZ file, SE crash, same in exported plugin.

Basically in my big project, I need to wait one or two seconds after a change before playing a new note, or SE crashes. If the SFZ file is very small, It's harder to make it crash but I've been able to do it by playing many notes while adjusting some parameters. So of course, the bigger the file, the longer the wait...

[Sylv1o]

It's now fixed in Synthedit. I was able to reproduce the bug in the SFIZZ VST3.

[essej]

Ummm, did they make a fix in the libsfizz code or in how they used it? Sounds like we need a PR from them...

[redtide]

heh, I was about to ask it: what do you mean, that it was a bug in SE or still a bug in sfizz but fixed only there?

[Sylv1o]

I asked Jeff (Synthedit creator) to send the fix here

[Sylv1o]

He has just filter incoming midi notes while files are reloading

[Sylv1o]

Here the link to the changes (line 166)

[paulfd]

I was able to reproduce the bug in the SFIZZ VST3.

Just playing midi notes data while reloading made the plugin crash? There should be a process lock so that'd be a bug.

I could see to make the doc clearer but:

    /**
     * @brief Send a note on event to the synth.
     ...
     * @par Thread-safety constraints
     * - @b RT: the function must be invoked from the Real-time thread
     */
    void noteOn(int delay, int noteNumber, int velocity) noexcept;

and

    /**
     * @brief Empties the current regions and load a new SFZ file into the synth.
     ...
     * @par Thread-safety constraints
     * - @b CT: the function must be invoked from the Control thread
     * - @b OFF: the function cannot be invoked while a thread is calling @b RT functions
     */
    bool loadSfzFile(const std::string& path);

I guess a different wording could be that no @b RT functions must be called while the loadSfzFile function has not returned.

We removed locking within the library on purpose because it's usually much cleaner to do it at the "plugin interface" level where you can possibly leverage abilities offered by hosts.

[Sylv1o]

The solution implemented by Jeff in Synthedit seems perfect, I can't see anything wrong with it. One just want the midi to be filtered while the instrument is reloading...

[paulfd]

The same mechanism is implemented in the VST plug-in, but you mentioned in a previous comment you managed to make it crash. I was curious to know more about the context in how you made it crash (I.e. which daw, sfz instrument, ...). If you remember :)

[Sylv1o]

It seems the mechanism you mention don't work. I've just tested again in Cubase 12 with SFIZZ vst3, I load an instrument, and play some midi notes while the instrument is loading : no problem. Then I open the SFZ file in a text editor, make a useless change (just add a line), then I save the file and immediatly play some midi notes : Cubase crash.

[Sylv1o]

I can make it carsh with any SFZ file, but if the file is very small, it take too little time to load to make Cubase crash. Try with any big SFZ file, it should crash easily.

[essej]

Double check the version of the sfizz plugin you have installed, this sounds like a bug that was fixed last year.

[Sylv1o]

I'll check but I use sfizz for less than a year...

[Sylv1o]

1.2.1

[essej]

You need 1.2.2! :)

[Sylv1o]

Indeed not the last one, I'll check with 1.2.2

[Sylv1o]

I'm so sorry, indeed bug is fixed in 1.2.2

I don't even know why I had this old version...

My mistake, the fact that this bug was still there in the Synthedit version had made me wrong...

Appologies again.

[redtide]

No worries :) So can close this?

[Sylv1o]

I think so yes