_MEMSOUND

The _MEMSOUND function returns a _MEM value referring to a sound's raw data in memory using a designated sound handle created by the _SNDOPEN or _SNDNEW function.

Syntax

soundBlock = _MEMSOUND(soundHandle&[, channel&])

Parameters

• The soundBlock _MEM type variable holds the read-only elements .OFFSET, .SIZE, .ELEMENTSIZE, .TYPE and .SOUND.
  • .OFFSET is the starting memory address of the sound sample data.
  • .SIZE is the size of the sample data in bytes
  • .ELEMENTSIZE will contain the number of bytes-per-sample the audio contains.
    • Can return 1 (8-bit mono), 2 (8-bit stereo), 2 (16-bit mono), 4 (16-bit stereo), 4 (32-bit mono) or 8 (32-bit stereo).
    • Use .TYPE to determine the data type of the sample data.
  • .TYPE will contain the data type of the sample data. See _MEM for details.
  • .SOUND will contain the same handle value as returned by the _SNDOPEN function.
• The second parameter channel& is optional and deprecated. This was used to specify the sound channel. In QB64-PE v3.1.0 and above stereo data is always interleaved. You must use .ELEMENTSIZE and .TYPE to determine the type of audio data you are dealing with.

Description

• Use this function to obtain a pointer to the raw sound data in memory for direct access.
• Even if the memory pointer obtained by this fuction was already freed again using _MEMFREE, the respective Sound handle itself must still be freed using _SNDCLOSE when no longer required.
• If .SIZE returns 0, that means the data could not be accessed. It may happen if you try to access the right channel in a mono file or the format simply does not support accessing raw PCM samples.
• channel& - 1 (left channel/mono) or 2 (right channel; for stereo files) was supported on the old OpenAL backend. For the new miniaudio backend, this must be 0.
• _MEMSOUND does not work for sounds loaded with _SNDOPEN when using the STREAM or NODECODE flags.

Availability

• 

  v1.5

• 

  all

• 
• 

  yes

• 

  yes

• 

  yes

Examples

Example 1

Checking that a sound file is stereo.

OPTION _EXPLICIT CONST FILE_FILTER = "*.wav|*.aiff|*.aifc|*.flac|*.ogg|*.mp3|*.it|*.xm|*.s3m|*.mod|*.rad|*.ahx|*.hvl|*.mus|*.hmi|*.hmp|*.hmq|*.kar|*.lds|*.mds|*.mids|*.rcp|*.r36|*.g18|*.g36|*.rmi|*.mid|*.midi|*.xfm|*.xmi|*.qoa" PRINT "Loading..."; DIM Song AS LONG Song = _SNDOPEN(_OPENFILEDIALOG$("Open audio file", , FILE_FILTER)) IF Song < 1 THEN PRINT "Failed to load sound!" END END IF PRINT "Done!" DIM channels AS _UNSIGNED _BYTE: channels = SndChannels(Song) IF channels THEN PRINT "This sound data has"; channels; "channels." ELSE PRINT "An error occurred." END IF _SNDCLOSE Song END ' This function returns the number of sound channels for a valid sound handle FUNCTION SndChannels~%% (handle AS LONG) DECLARE LIBRARY ' This is needed to convert _OFFSET to LONG / _INTEGER64 $IF 32BIT THEN FUNCTION SndChannels.CLngPtr~& ALIAS "uintptr_t" (BYVAL o AS _UNSIGNED _OFFSET) $ELSE FUNCTION SndChannels.CLngPtr~&& ALIAS "uintptr_t" (BYVAL o AS _UNSIGNED _OFFSET) $END IF END DECLARE DIM soundData AS _MEM: soundData = _MEMSOUND(handle) IF soundData.SIZE THEN ' See https://qb64phoenix.com/qb64wiki/index.php/MEM for details SELECT CASE soundData.TYPE CASE 260 ' 32-bit floating point SndChannels = SndChannels.CLngPtr(soundData.ELEMENTSIZE) \ _SIZE_OF_SINGLE CASE 132 ' 32-bit signed integer SndChannels = SndChannels.CLngPtr(soundData.ELEMENTSIZE) \ _SIZE_OF_LONG CASE 130 ' 16-bit signed integer SndChannels = SndChannels.CLngPtr(soundData.ELEMENTSIZE) \ _SIZE_OF_INTEGER CASE 1153 ' 8-bit unsigned integer SndChannels = SndChannels.CLngPtr(soundData.ELEMENTSIZE) \ _SIZE_OF_BYTE CASE ELSE ' unknown format SndChannels = 1 END SELECT END IF IF soundData.SOUND = handle THEN _MEMFREE soundData END FUNCTION

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Example 2

Plotting a sound's waves.

OPTION _EXPLICIT CONST FILE_FILTER = "*.wav|*.aiff|*.aifc|*.flac|*.ogg|*.mp3|*.it|*.xm|*.s3m|*.mod|*.rad|*.ahx|*.hvl|*.mus|*.hmi|*.hmp|*.hmq|*.kar|*.lds|*.mds|*.mids|*.rcp|*.r36|*.g18|*.g36|*.rmi|*.mid|*.midi|*.xfm|*.xmi|*.qoa" DECLARE LIBRARY ' This is needed to convert _OFFSET to LONG / _INTEGER64 $IF 32BIT THEN FUNCTION CLngPtr~& ALIAS "uintptr_t" (BYVAL o AS _UNSIGNED _OFFSET) $ELSE FUNCTION CLngPtr~&& ALIAS "uintptr_t" (BYVAL o AS _UNSIGNED _OFFSET) $END IF END DECLARE SCREEN _NEWIMAGE(800, 327, 32) PRINT "Loading..."; DIM Song AS LONG Song = _SNDOPEN(_OPENFILEDIALOG$("Open audio file", , FILE_FILTER)) IF Song < 1 THEN PRINT "Failed to load sound!" END END IF PRINT "Done!" _SNDPLAY Song DIM soundData AS _MEM: soundData = _MEMSOUND(Song, 0) IF soundData.SIZE = 0 THEN PRINT "Failed to access sound sample data." END END IF DIM sz AS _UNSIGNED _INTEGER64: sz = CLngPtr(soundData.ELEMENTSIZE) DIM x AS LONG, i AS _UNSIGNED _INTEGER64 DO UNTIL _KEYHIT = 27 OR NOT _SNDPLAYING(Song) OR i + (_WIDTH * sz) > soundData.SIZE CLS LOCATE 1, 1: PRINT i; "/"; soundData.SIZE, "Frame Size ="; sz, "Data Type ="; soundData.TYPE ' See https://qb64phoenix.com/qb64wiki/index.php/MEM for details SELECT CASE soundData.TYPE CASE 130 ' integer stereo or mono FOR x = 0 TO _WIDTH - 1 DIM si AS INTEGER: si = _MEMGET(soundData, soundData.OFFSET + i + x * sz, INTEGER) ' get sound data LINE (x, _HEIGHT \ 2)-STEP(0, 300! * si / 32768!), _RGB32(0, 111, 0) 'plot wave NEXT CASE 132 ' long stereo or mono FOR x = 0 TO _WIDTH - 1 DIM sl AS LONG: sl = _MEMGET(soundData, soundData.OFFSET + i + x * sz, LONG) ' get sound data LINE (x, _HEIGHT \ 2)-STEP(0, 300! * sl / 2147483648!), _RGB32(0, 111, 0) 'plot wave NEXT CASE 260 ' floating point stereo or mono FOR x = 0 TO _WIDTH - 1 DIM sf AS SINGLE: sf = _MEMGET(soundData, soundData.OFFSET + i + x * sz, SINGLE) ' get sound data LINE (x, _HEIGHT \ 2)-STEP(0, sf * 300!), _RGB32(0, 111, 0) 'plot wave NEXT CASE 1153 ' unsigned byte stereo or mono FOR x = 0 TO _WIDTH - 1 DIM sb AS _BYTE: sb = _MEMGET(soundData, soundData.OFFSET + i + x * sz, _UNSIGNED _BYTE) XOR &H80 ' get sound data and convert to signed LINE (x, _HEIGHT \ 2)-STEP(0, 300! * sb / 128!), _RGB32(0, 111, 0) ' plot wave NEXT END SELECT _DISPLAY _LIMIT 60 i = FIX(_SNDGETPOS(Song) * _SNDRATE) * sz ' calculate the new sample frame position LOOP _SNDCLOSE Song _AUTODISPLAY END

See also

• _MEM, _MEMFREE
• _MEMPUT, _MEMGET, _MEMGET (function)
• _SNDOPEN, _SNDNEW, _SNDCLOSE, _SNDRAW
• _SNDRATE

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