Random Static upon start with some games

[Former user]

Original [issue 118](https://code.google.com/p/genplus-gx/issues/detail?id=118) created by Darkone180 on 2010-08-29T20:49:18.000Z:

What steps will reproduce the problem? 1. 2. 3.

What is the expected output? What do you see instead?

What version of the emulator are you using (official, SVN revision,...)? R501

Please provide any additional information below (Video settings, Console region,...) ok for some reason when i went to go start "phantasy star 2"(ntsc-u rev001) or "Test Drive 2 - The Drive"(Ntsc-u) ill sometimes get really annoying static,though if i go to turn off "High-Quilty Fm" then resume the game then turn it back on the static goes away,im not sure if the behavior is reaccuring in other games or not/=

Settings Genplus-gx R501

Sound Settings: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ V V High-Quilty Fm:on Fm-rolloff:99.50% Fm Resolution:Max Fm Volume:1.00 Psg Volume:1.50 Psg Noise Boost:on Filtering:on Low Pass Rate:50%

Video Settings: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ V V Display:interlaced Tv Mode: 60 Hz Gx Bilinear:on VI Trap:on VI Gamma:1.0 Ntsc:Composite Borders:V-Only Aspect:Original(4:3) Position:+05,-5

System Settings: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ V V Console Region:Usa System Lockups:on 68K:on Tmss:on Lock-on:off Swap:off

[Former user]

Comment # 1 originally posted by Darkone180 on 2010-09-07T02:24:08.000Z:

hmm please look into this

[Former user]

Comment # 2 originally posted by gora.patrick on 2010-09-08T16:56:16.000Z:

can't confirm this. just tried at least Phantasy Star 2 US Rev01 with r501 and your settings and everything is fine. no stuttering or "static".

[Former user]

Comment # 3 originally posted by Darkone180 on 2010-09-08T19:04:57.000Z:

alright well ill see if maybe i can catch a video of it later on

[Former user]

Comment # 4 originally posted by Darkone180 on 2010-09-08T19:31:03.000Z:

at the very beginning before i got to the settings you should be able to hear it http://www.megaupload.com/?d=U7ICSVIU

[Former user]

Comment # 5 originally posted by gora.patrick on 2010-09-10T19:26:45.000Z:

i've been now booting up some games because i wanted to do some screenshots for the Game Select menu and this bug appears for me as well now. i guess its game unspecific. the sound just gets broken and sounds totally scratchy. turning on/off Sound Filtering works for me either, instead turning on/off HQ Sound. But i have to reboot the game.

[Former user]

Comment # 6 originally posted by ekeeke31 on 2010-09-11T18:17:15.000Z:

I noticed this, yes but it's quite hard to have it reproduced, seems to happen randomly after loading many games. And it's not game related, it seems to be a bug from the recent changes I made to get ride of sound skipping issues in interlaced modes.

This is enforced by the fact it disappears when resetting audio (which occurs when you hard reset a game, change region or audio or video settings...).

I'd need to know if it ever happens when HQ FM is disabled and if Render mode (original vs interlaced) has any influence on that.

[Former user]

Comment # 7 originally posted by Darkone180 on 2010-09-12T01:11:06.000Z:

Sound Settings: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ V V High-Quilty Fm:on Fm-rolloff:99.50% Fm Resolution:Max Fm Volume:1.00 Psg Volume:1.50 Psg Noise Boost:on Filtering:on Low Pass Rate:50%

Video Settings: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ V V Display:original Tv Mode: 60 Hz Gx Bilinear:off VI Trap:on VI Gamma:1.0 Ntsc:off Borders:V-Only Aspect:Original(4:3) Position:+05,-5

System Settings: \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ V V Console Region:Usa System Lockups:on 68K:on Tmss:on Lock-on:off Swap:off

same results still occurring

[Former user]

Comment # 8 originally posted by Darkone180 on 2010-09-12T02:45:30.000Z:

oh and hq was on the same steps to fix it work,i tried with it off and it still occurs i think

[Former user]

Comment # 9 originally posted by ekeeke31 on 2010-09-13T10:33:05.000Z:

Would also be useful if you could figure on which revision it started happening.

[Former user]

Comment # 10 originally posted by Darkone180 on 2010-09-13T14:56:27.000Z:

R501

[Former user]

Comment # 11 originally posted by Darkone180 on 2010-09-13T14:59:11.000Z:

it may have started on earlier revs but i dont know for sure,the most recent rev i have used is the r501

[Former user]

Comment # 12 originally posted by gora.patrick on 2010-09-13T15:56:43.000Z:

it didnt happen with the revision with the fixed audio crackling in 60Hz interlaced/progressive mode in the topic i started. i didnt use any other revisions between that one and r501.

[Former user]

Comment # 13 originally posted by ekeeke31 on 2010-09-13T17:02:54.000Z:

someone should test r493 then r494, I personally can verify myself at the time being.

[Former user]

Comment # 14 originally posted by ekeeke31 on 2010-09-15T21:51:35.000Z:

I figured the issue, it is caused by corrupted FM table on initialization, which is itself caused by the pow() function implemntation in devkitPPC newlib sometimes returning incorrect results.

I should be fixing this by using a precalculated static table since the values are constant but this is still quite annoying we can't rely on mathematic functions integrity :-/

[Former user]

Comment # 15 originally posted by svin83 on 2010-09-16T02:44:08.000Z:

So fixing it in genplus-gx is realy just a workaround then :P

I don't know, but maybe it isn't that much more work to fix in newlib svn and commit a patch :P

Just so you won't run into this error again.

[Former user]

Comment # 16 originally posted by ekeeke31 on 2010-09-16T06:27:59.000Z:

Exactly, also the pow() function is used elsewhere in the code.

[Former user]

Comment # 17 originally posted by ekeeke31 on 2010-09-16T11:39:57.000Z:

Should now be fixed in r502.

Workaround was to disable interrupts when executing the initialisation code that calls pow()function in a loop, thanks to shagkur for the idea.

[Former user]

Comment # 18 originally posted by ekeeke31 on 2010-09-16T11:40:37.000Z:

[Former user]

Comment # 19 originally posted by ekeeke31 on 2010-09-25T17:13:29.000Z: