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Archived:MIDIControl.setChannelVolume may panic if MIDI channel volume changes independently at the same time (Known Issue)

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Article Metadata
CompatibilityArticle
Created: User:Technical writer 1 (22 Feb 2007)
Last edited: hamishwillee (16 Aug 2013)

Description

If MIDIControl.setChannelVolume() is used when the MIDI engine is started (e.g., the MIDI file player is started or a player using device://midi is prefetched or started), a panic may occur if the volume of any MIDI channel changes independently at the same time as MIDIControl.setChannelVolume() is called. This might happen if the MIDI file contains events for changing channel volumes, or if a set channel volume event is sent manually using the MIDIControl.shortMidiEvent() method.

How to reproduce

  1. Start the MIDI player (MIDI file player or device://midi player)
  2. Get MIDIControl from the player and manually change a channel volume with:
    MIDIControl.shortMidiEvent( MIDIControl.CONTROL_CHANGE | 0, 0x07, 80 );
  3. Immediately call MIDIControl.setChannelVolume: MIDIControl.setChannelVolume( 0, 0 );

Solution

Use the following call instead of MIDIControl.setChannelVolume() to change channel volumes when playback is on:

MIDIControl.shortMidiEvent( MIDIControl.CONTROL_CHANGE | a, ;0x07, b); where 'a' is MIDI channel number and 'b' is desired MIDI channel volume. MIDIControl.setChannelVolume() can be used when the MIDI engine is started (e.g., when the MIDI file player is prefetched but not started), but for convenience it is always safe to use the MIDIControl.shortMidiEvent() method.

This issue has been fixed in S60 3rd Edition FP1.

This page was last modified on 16 August 2013, at 06:03.
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