#291 dualopl2: addressed as a single OPL2, right channel is muted

sound (27)
XviD User

The dualopl2 (sbpro1) sound emulation mode doesn't seem to work for the game "Rise of the Dragon". There is only sound on the left channel, the right cheannel is completely silent. The opl2 & opl3 modes work fine (in mono).

This game supports stereo OPL2 sound effects, such as a helicopter flying by from left to right (at the first screen after starting a new game). That is the reason why I would like to run it using the sbpro1/dualopl2 mode. I know this because I played this game originally on a 286 & SB Pro.

The game can be downloaded for free here:

Run install.exe to configure sound to "Sound Blaster".
The game must be started with CPU Cycles to 7500 or less (at least on my PC) for the sound blaster detection to work properly, otherwise only the OPL music works and not the OPL sound effects and sampled sound effects.


  • c2woody

    c2woody - 2007-05-27

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    The dual opl mode has been tested and works.
    Are you sure that those version you pointed to
    have dual opl support? If so, maybe there's
    something required to enable it?
    They never write to the left/right wired ports
    so the only thing that could be wrong is the
    game setting, or the sb dual opl detection
    fails under dosbox.

  • XviD User

    XviD User - 2007-05-29

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    I'm sure it has working stereo sound on the SB Pro, as I played in with a real SB Pro (1) at the time.
    Also, even if it wouldn't support stereo OPL2 sound on the SB Pro, then using a SB Pro should still result in normal mono OPL2 sound, right?

    In the mean while, if tried some other games with the sbpro1 setting:
    Civilization (1) - Works fine, music is in stereo, as I remember it was.
    Wing Commander (1) - Same problem as in Rise of the Dragon: only sound is heard from the left channel, while it worked fine with a real SB Pro (1) (although I can't remember if the music was actually in stereo, but I think it was).

  • c2woody

    c2woody - 2007-05-30

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    Well i believe you that you had stereo FM
    with this game. The question is just if the
    versions you're referencing are exactly the
    same as the one you had. At the moment i
    don't see any way how this version could
    produce any stereo FM.

    There is at least one other official version
    of the game, EGA/CGA only. This (or a different
    VGA release) might have additional sound
    drivers or a different sound system at all.

    About the left-channel only: this is a bug,
    when the dualopl2 is addressed in mono mode
    it forwards data only to the left channel.
    No real problem as for those games opl2
    works just fine and they don't have stereo
    output anyways.
    This has nothing to do with the problem
    (or "not" problem) here. Even if it was fixed
    the Rise of the Dragon wouldn't be stereo.

  • XviD User

    XviD User - 2007-05-30

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    I have to admit that I originally played the EGA version of Rise of the Dragon and this is the VGA version.
    Theoretically, it could be that the EGA version was released slightly later than the VGA version and that SoundBlaster Pro support was added.

    Anyhow, it's good to know that the dualopl2 mode is bugged, which explains why there is only sound on the left channel.
    I reported this bug, since I wasn't aware of this.
    The fact that I got Civilization working in stereo, proves that the dualopl2 mode indeed works (if addressed in stereo).

    I've changed summary of this bug, so that it really describes what is wrong with the sbpro1/dualopl2 mode. Other people running into this problem will be able to find the bug here and its workaround (simply select another SB/OPL mode).


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