Setting and Retrieving Global Parameters
By using the IDirectMusicPerformance8::SetGlobalParam and IDirectMusicPerformance8::GetGlobalParam methods, you can set and retrieve parameters that affect the entire performance rather than a single track.
The parameter to be set or retrieved is identified by a GUID in the rguidType parameter of the method. Each parameter is associated with a particular data type, whose size is given in the dwSize parameter. The predefined GUIDs and their data types are shown in the following table.
| Parameter type GUID (rguidType) |
Data (*pParam) |
Description |
| GUID_PerfAutoDownload | BOOL | This parameter controls whether instruments are automatically downloaded when a segment is played. By default, it is off. See Downloading and Unloading Bands. |
| GUID_PerfMasterGrooveLevel | char | The master groove level is a value that is always added to the groove level established by the command track. The resulting value is adjusted, if necessary, to fall within the range from 1 through 100. |
| GUID_PerfMasterTempo | float | The master tempo is a scaling factor applied to the tempo by the final output tool. By default, it is 1. A value of 0.5 would halve the tempo, and a value of 2.0 would double it. This value can be set in the range from DMUS_MASTERTEMPO_MIN through DMUS_MASTERTEMPO_MAX. |
| GUID_PerfMasterVolume | long | The master volume is an amplification or attenuation factor, in hundredths of a decibel, applied to the default volume of the entire performance and any other performances using the same synthesizer. The range of permitted values is determined by the port. For the default software synthesizer, the allowed range is +20db to -200dB, but the useful range is +10db to -100db. Hardware MIDI ports do not support changing master volume. Setting this parameter is equivalent to calling IKsControl::KsProperty for the GUID_DMUS_PROP_Volume property set on every port in the performance. |
Applications can also use custom types of global parameters. To create a new type, establish a GUID and a data type for it.
Note All parameters have to be set before they can be retrieved. When a parameter is set, the performance allocates memory for the data in a linked list of items that are identified by GUID. If SetGlobalParam has never been called on the parameter, it does not appear in this linked list, and GetGlobalParam fails.