Semi Sluggish Playback on Dev build for dos

[ratix98]

When playing certain midis there seems to be a slowdown issue that seems to be only present on a 486 class cpu clocked at 50MHZ.
This does not seem to be present when using a Pentium-S PC and is not present when using version 1.6.1 of the program on either PC.
As an end user the only difference I see when using the dev build is how fast the time updates during playback.

If an example snippet is needed i can put one together.

[Wohlstand]

Hello! I can only give a note that I changed from using of BIOS clock with alternates frequency into timer interrupt usage because it was a serious stuck problem that may occur much more often if play music with a time on clock close to midnight. And just, because old way causes real-time clock being skewed and showing a wrong time. Even it's a code that restores time back, it still worked messy.
And, the side effect from the switching to interrupt handler of course the slowdown that occurs if music has too often granularity and handling of ticks doesn't fit in a time of one interrupt tick. Another problem that I still didn't resolved yet that if try to play under Windows, it will just freeze forever since I didn't applied DPMI locks to memory regions yet.
On, another problem that interrupt handler solves successfully is the ability to play music with correct tempo while opened from under Windows. Old build just fails to change clock frequency, and that causes tempo being extremely slow. But when quitting pure DOS mode, it worked.

[Wohlstand]

By the way, you can try to upload music samples so I will try to test them on mine. My is 486DX2 with 66 MHz, it can lag too if play some files. In parallel I have Pentium MMX 166 MHz, Pentium II 300 MHz, and Pentium III 500 MHz for other tests.

[ratix98]

Sure thing. Also I do find it funny that you mentioned the clock close to midnight. If I had actually set my clock time to the proper time every time I fired up my PC I would have seen that issue more often due to the actual time. I came across a random crash a few times and now that i think about it i had changed the clock to the actual time. I never set the date and time anymore unless I have to.
Attached here are a few midis that seem to play a little slow. It could always just be me though.
I should dig out the pentium 233mhz PC as that has built in sb16 that had the exact issue you mentioned while playing under windows.

samples.zip

[Wohlstand]

Usually to fix the problem I had to open MIDI file using Sekaiju and reduce the resolution of the song. I may guess I can apply this dynamically while loading the MIDI file. I can, since I build all the MIDI data into internal structures, that allows me to load any MIDI or MIDI-like format like MUS or something also, and store in the same format and use same code to handle everything, and apply custom special events parsed from different formats differently.