libZPlayDelphi.TCallbackMessage Enumeration

Callback messages.

Pascal

TCallbackMessage = (
  MsgStopAsync = 1,
  MsgPlayAsync = 2,
  MsgEnterLoopAsync = 4,
  MsgExitLoopAsync = 8,
  MsgEnterVolumeSlideAsync = 16,
  MsgExitVolumeSlideAsync = 32,
  MsgStreamBufferDoneAsync = 64,
  MsgStreamNeedMoreDataAsync = 128,
  MsgNextSongAsync = 256,
  MsgStop = 65536,
  MsgPlay = 131072,
  MsgEnterLoop = 262144,
  MsgExitLoop = 524288,
  MsgEnterVolumeSlide = 1048576,
  MsgExitVolumeSlide = 2097152,
  MsgStreamBufferDone = 4194304,
  MsgStreamNeedMoreData = 8388608,
  MsgNextSong = 16777216,
  MsgWaveBuffer = 33554432,
  MsgAll = -1,
  MsgAllAsync = 65535,
  MsgAllSync = -65536
);

File

libZPlay

Parameters

Parameters	Description
MsgStopAsync	Send this message after song stops playing. Wave device is closed and decoding thread is ending. param1: not used, always is 0 param2: not used, always is 0 return: not used
MsgPlayAsync	Send this message when decoding thread starts and playing is about to start. Wave device is not open yet, but decoding thread is created. param1: not used, always is 0 param2: not used, always is 0 return: not used
MsgEnterLoopAsync	Send this message when decoding thread enters loop processing. param1: not used, always is 0 param2: not used, always is 0 return: not used
MsgExitLoopAsync	Send this message when decoding thread exits loop processing. param1: not used, always is 0 param2: not used, always is 0 return: not used
MsgEnterVolumeSlideAsync	Send this message when decoding thread enters volume slide processing. param1: not used, always is 0 param2: not used, always is 0 return: not used
MsgExitVolumeSlideAsync	Send this message when decoding thread exits volume slide processing. param1: not used, always is 0 param2: not used, always is 0 return: not used
MsgStreamBufferDoneAsync	Send this message when one buffer is done and removed from dynamic stream. param1: number of buffers remaining in dynamic stream param2: number of bytes remaining in dynamic stream return: not used
MsgStreamNeedMoreDataAsync	Send this message when dynamic stream needs more data. param1: not used, always is 0 param2: not used, always is 0 return: not used
MsgNextSongAsync	Send this message when decoding thread starts playing next song from gapless queue. param1: index of playing song param2: number of songs remaining in gapless queue return: not used
MsgStop	Send this message after song stops playing. param1: not used, always is 0 param2: not used, always is 0 return: not used
MsgPlay	Send this message when decoding thread starts and playing is about to start. param1: not used, always is 0 param2: not used, always is 0 return: 0 continue playing, 1 break decoding thread and don't play anything
MsgEnterLoop	Send this message when decoding thread enters loop processing. param1: not used, always is 0 param2: not used, always is 0 return: not used
MsgExitLoop	Send this message when decoding thread exits loop processing. param1: not used, always is 0 param2: not used, always is 0 return: not used
MsgEnterVolumeSlide	Send this message when decoding thread enters volume slide processing. param1: not used, always is 0 param2: not used, always is 0 return: 0 continue volume slide processing, 1 don't even start volume slide processing
MsgExitVolumeSlide	Send this message when decoding thread exits fade processing. param1: not used, always is 0 param2: not used, always is 0 return: not used
MsgStreamBufferDone	Send this message when one buffer is done and removed from dynamic stream. param1: number of buffers remaining in dynamic stream param2: number of bytes remaining in dynamic stream return: not used
MsgStreamNeedMoreData	Send this message when dynamic stream needs more data. param1: not used, always is 0 param2: not used, always is 0 return: 0 wait for new data, 1 stop playing, 2 don't wait, try again
MsgNextSong	Send this message when decoding thread starts playing next song from gapless queue. param1: index of playing song param2: number of songs remaining in gapless queue return: not used
MsgWaveBuffer	Send this message when decoding thread is ready to send data to soundcard. param1: pointer to memory PCM data buffer param2: number of bytes in PCM data buffer return: 0 send data to soundcard, 1 skip sending data to soundcard, 2 stop playing Note: PCM data buffer always contains 16 bit per sample, 2 channel PCM data. Even if input data is 1 channel (mono), output data are always 16 bit per sample, 2 channel.

Remarks

There are 2 types of messages. Sync (blocking) and async (non blocking) messages.

Sync message is sent from decoding thread and thread is waiting until callback function returns, so thread is blocked until user process sync message. Return value from sync message can be used to control decoding thread.

Note: DON'T CALL other interface functions from sync message because this will block decoding thread and calling thread.

Async message is sent from another thread and this message is not blocking, decoding thread continues to play. Return value from async message is not used.