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.

Availability

• QB64 v1.5 and up
• QB64-PE all versions

Examples

Example 1

Checking that a sound file is stereo.

OPTION _EXPLICIT PRINT "Loading..."; DIM Song AS LONG Song = _SNDOPEN("onward_ride1.flac") ' Replace file name with your sound file IF Song < 1 THEN PRINT "Failed to load sound!" END END IF PRINT "Done!" DIM Channels AS _UNSIGNED _BYTE Channels = SndChannels(Song) IF Channels = 2 THEN PRINT "This file is STEREO" ELSEIF Channels = 1 THEN PRINT "This file is MONO" ELSE PRINT "An error occurred." END IF _SNDCLOSE Song 'closing the sound releases the mem blocks END ' This function returns the number of sound channels for a valid sound "handle" ' 2 = stereo, 1 = mono, 0 = error FUNCTION SndChannels~%% (handle AS LONG) DIM SampleData AS _MEM SndChannels = 0 ' Assume failure ' Check if the sound is valid SampleData = _MEMSOUND(handle, 0) IF SampleData.SIZE = 0 THEN EXIT FUNCTION END IF ' Check the data type and then decide if the sound is stereo or mono IF SampleData.TYPE = 260 THEN ' 32-bit floating point IF SampleData.ELEMENTSIZE = 4 THEN SndChannels = 1 ELSEIF SampleData.ELEMENTSIZE = 8 THEN SndChannels = 2 END IF ELSEIF SampleData.TYPE = 132 THEN ' 32-bit integer IF SampleData.ELEMENTSIZE = 4 THEN SndChannels = 1 ELSEIF SampleData.ELEMENTSIZE = 8 THEN SndChannels = 2 END IF ELSEIF SampleData.TYPE = 130 THEN ' 16-bit integer IF SampleData.ELEMENTSIZE = 2 THEN SndChannels = 1 ELSEIF SampleData.ELEMENTSIZE = 4 THEN SndChannels = 2 END IF ELSEIF SampleData.TYPE = 1153 THEN ' 8-bit unsigned integer IF SampleData.ELEMENTSIZE = 1 THEN SndChannels = 1 ELSEIF SampleData.ELEMENTSIZE = 2 THEN SndChannels = 2 END IF ELSEIF SampleData.TYPE = 0 THEN ' This means this is an OpenAL sound handle DIM RightChannel AS _MEM RightChannel = _MEMSOUND(handle, 2) IF RightChannel.SIZE > 0 THEN SndChannels = 2 ELSE SndChannels = 1 END IF END IF END FUNCTION

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Example 2

Plotting a sound's waves.

OPTION _EXPLICIT DECLARE LIBRARY $IF 32BIT THEN FUNCTION ConvertOffset~& ALIAS "uintptr_t" (BYVAL o AS _UNSIGNED _OFFSET) $ELSE FUNCTION ConvertOffset~&& 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("OPL3 Groove.rad") ' replace this with your ( WAV, AIFF, AIFC, FLAC, OGG, MP3, MID, IT, XM, S3M, MOD, RAD, AHX, HVL) sound file IF Song < 1 THEN PRINT "Failed to load song!" END END IF PRINT "Done!" _SNDPLAY Song DIM SampleData AS _MEM: SampleData = _MEMSOUND(Song, 0) IF SampleData.SIZE = 0 THEN PRINT "Failed to access sound sample data." END END IF DIM sz AS _UNSIGNED _INTEGER64: sz = ConvertOffset(SampleData.ELEMENTSIZE) ' sz is the total size of the sound in bytes DIM x AS LONG, i AS _UNSIGNED _INTEGER64 DO UNTIL _KEYHIT = 27 OR NOT _SNDPLAYING(Song) OR i + (_WIDTH * sz) > SampleData.SIZE CLS LOCATE 1, 1: PRINT i; "/"; SampleData.SIZE, "Frame Size ="; sz, "Data Type ="; SampleData.TYPE $CHECKING:OFF IF SampleData.TYPE = 130 THEN ' 128 OR 2: integer stereo or mono FOR x = 0 TO _WIDTH - 1 DIM si AS INTEGER: si = _MEMGET(SampleData, SampleData.OFFSET + i + x * sz, INTEGER) ' get sound data LINE (x, _HEIGHT / 2)-STEP(0, 300 * si / 32768), _RGB32(0, 111, 0) 'plot wave NEXT ELSEIF SampleData.TYPE = 260 THEN ' 256 OR 4: floating point stereo or mono FOR x = 0 TO _WIDTH - 1 DIM sf AS SINGLE: sf = _MEMGET(SampleData, SampleData.OFFSET + i + x * sz, SINGLE) ' get sound data LINE (x, _HEIGHT / 2)-STEP(0, sf * 300), _RGB32(0, 111, 0) 'plot wave NEXT ELSEIF SampleData.TYPE = 1153 THEN ' 128 OR 1 OR 1024: unsigned byte stereo or mono FOR x = 0 TO _WIDTH - 1 DIM sb AS _BYTE: sb = _MEMGET(SampleData, SampleData.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 IF $CHECKING:ON _DISPLAY _LIMIT 60 i = FIX(_SNDGETPOS(Song) * _SNDRATE) * sz ' calculate the new sample frame position LOOP _SNDCLOSE Song ' closing the sound releases the mem blocks _AUTODISPLAY END

See also

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

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