GPxSound

The GPxSound extension consists of sound related features.

3D sound

GP3 by itself only produces 2D sound. This extension adds 3D sound for the engine sounds of other cars and for a pit siren. 3D engine sound means that you can hear another car driving past you and also on which side. If you have a 4D sound system you can also hear if the car is in front or behind you. When the speed difference is big you'll hear a doppler effect, meaning the pitch of the sound is higher when the car is approaching you and lower when it drives away from you. The distance between you and the other car also has an effect on the volume of course.

Besides adding realism to the game, the advantage of adding opponent car sound is that it's easier to locate your opponent, instead of only having the rear mirrors to look at. After a bit of practice it should be possible to hear when you're past the other car so you can safely enter a corner. Another advantage is that you can hear other cars approaching after you've left the track and you want to get back on again, so you can avoid a crash.

The 3D pit siren sound is located 15 meters after the start of the pit lane, and 5 meters sideways towards the track (can be changed in gpxsound.ini). It will be triggered when a car is at the start of the pit lane (where the pit speed limiter is turned on).

The 3D sound was implemented using DirectSound. If you have an appropriate soundcard it will be hardware accelerated and have no effect on the PO. Even using software mixing (like on my own system) the PO is not much affected. If you notice a large PO increase on your system you might need to upgrade your sound drivers, or else fiddle with the settings like voice management and max. distance.

Although GP3-2000 has its own 3D sound, this feature will still be enabled if you choose to have the default GP3 sound within the game (in the game's sound options). GP4 has good 3D sound, but if you want to use GPxSound instead, it's possible to turn off 3D sound in GP4. If you want to keep the EAX effects (like tunnels), only turn off GP4's engine sounds by setting the 'other cars' sound volume to 0 in the game's advanced sound settings menu. It's possible that it interferes with GPxSound though.

There are still a few unresolved issues that might be corrected in next versions:

Event sounds

It is possible to associate sounds with events. GPxSound can load so called sound sets that specify which .wav files should be played at which events. GPxSound doesn't include any sounds by default, so you'll have to specify them yourself or download pre-made sound sets from the internet.

Below is a list of all possible events:

A default soundset.ini file can be found in the gpxpdata\snd folder. The names of the events speak for themselves. The path of a sound is relative to the snd directory. Specifying an absolute path might not work (the multimedia api of Windows doesn't seem to like it, strangely).

Sounds starting at RaceLastLap are pit communication sounds, and are mutually exclusive. This means these sounds cannot be played at the same time.

Configuration options

The following options are available for GPxSound (clearing a numeric value will reset it to the default):
  • Doppler factor. Specifies how much doppler effect is applied. It can range from 0.0 (no doppler effect) to 10.0. A value of 1.0 means the effect is realistic.
  • Rolloff factor. Specifies how much the volume is affected by the distance between the sound and the listener. It can range from 0.0 (no rolloff) to 10.0. A value of 1.0 means the effect is realistic.
  • Distance factor. Specifies how much meter is in one unit. It can range from 0.0 to 10.0. A value of 1.0 means the effect is realistic. This parameter should normally be left alone. Better is to adjust the doppler factor instead.
  • Use voice management. Will use DirectX voice management, which means the location of the sound buffers (hardware or software mixing) will be determined when the sounds are actually played (each frame in this case). If no hardware buffers are available for a sound, the sound that is furthest away from the listener will be moved to a software buffer. Uncheck this feature if you notice more slow down than without it, or if you don't have a good soundcard (e.g. a simple onboard sound chip).
  • 3D algorithm. Selects the 3D algorithm to use for software mixing. It's adviced to use "Default", but maybe other options are better for your particular system.
  • Enable 2D event sounds. Uncheck to disable this feature.
  • Global volume. This specifies the volume in percentage for all event sounds.
  • Event sound set. Specifies the file that contains a list of .wav files to be played at each event. By default, this file is located in the gpxpdata\snd directory and has no sounds associated to any event. Pressing the "Edit" button will launch Notepad in which you can specify the sounds (sorry, no better interface for now). For new sound sets that will be released on the internet it is recommended that these are completely located in a subdirectory under gpxpdata\snd, with the subdirectory named after the author.

    • Advanced options

    Some options can only be specified in gpxsound.ini:
    SectionOptionValuesDefaultDescription
    [Siren]XOffsetmeters5 X component of the distance of the pit siren from the pit lane start. For tracks with a pit lane on the left this value is negated, so a positive value means towards the track.
    [Siren]YOffsetmeters15 Y component of the distance of the pit siren from the pit lane start. A positive value means it's within the pit lane.

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