Creates a sample stream from a MIDI file.

    BOOL mem,
    void *file,
    QWORD offset,
    QWORD length,
    DWORD flags,
    DWORD freq


memTRUE = stream the file from memory.
fileFilename (mem = FALSE) or a memory location (mem = TRUE).
offsetFile offset to begin streaming from (only used if mem = FALSE).
lengthData length... 0 = use all data up to the end of the file (if mem = FALSE).
flagsA combination of these flags.
BASS_SAMPLE_8BITSUse 8-bit resolution. If neither this or the BASS_SAMPLE_FLOAT flags are specified, then the sample data will be 16-bit.
BASS_SAMPLE_FLOATUse 32-bit floating-point sample data. See Floating-point channels for more info.
BASS_SAMPLE_MONODecode/play the MIDI in mono (uses less CPU than stereo). This flag is automatically applied if BASS_DEVICE_MONO was specified when calling BASS_Init.
BASS_SAMPLE_SOFTWAREForce the stream to not use hardware mixing.
BASS_SAMPLE_3DEnable 3D functionality. This requires that the BASS_DEVICE_3D flag was specified when calling BASS_Init. 3D channels must also be mono, so BASS_SAMPLE_MONO is automatically applied. The SPEAKER flags cannot be used together with this flag.
BASS_SAMPLE_LOOPLoop the file. This flag can be toggled at any time using BASS_ChannelFlags.
BASS_SAMPLE_FXEnable the old implementation of DirectX 8 effects. See the DX8 effect implementations section for details. Use BASS_ChannelSetFX to add effects to the stream.
BASS_STREAM_AUTOFREEAutomatically free the stream when playback ends.
BASS_STREAM_DECODEDecode/render the sample data, without playing it. Use BASS_ChannelGetData to retrieve decoded sample data. The BASS_SAMPLE_3D, BASS_STREAM_AUTOFREE and SPEAKER flags cannot be used together with this flag. The BASS_SAMPLE_SOFTWARE and BASS_SAMPLE_FX flags are also ignored.
BASS_SPEAKER_xxxSpeaker assignment flags. The BASS_SAMPLE_MONO flag is automatically applied when using a mono speaker assignment flag.
BASS_MIDI_DECAYENDLet the sound decay naturally (including reverb) instead of stopping abruptly at the end of the file, including when looping. This flag can be toggled at any time using BASS_ChannelFlags.
BASS_MIDI_DECAYSEEKLet the old sound decay naturally (including reverb) when changing the position, including looping. This flag can be toggled at any time using BASS_ChannelFlags, but it should generally only be used in BASS_ChannelSetPosition calls to have it applied to particular position changes, eg. custom loops.
BASS_MIDI_NOCROPDo not remove empty space (containing no events) from the end of the file.
BASS_MIDI_NOFXDisable reverb and chorus processing, saving some CPU time. This flag can be toggled at any time using BASS_ChannelFlags.
BASS_MIDI_NOSYSRESETIgnore system reset events (MIDI_EVENT_SYSTEM) when the system mode is unchanged. This flag can be toggled at any time using BASS_ChannelFlags.
BASS_MIDI_NOTEOFF1Only release the oldest instance upon a note off event (MIDI_EVENT_NOTE with velocity=0) when there are overlapping instances of the note. Otherwise all instances are released. This flag can be toggled at any time using BASS_ChannelFlags.
BASS_MIDI_SINCINTERUse sinc interpolated sample mixing. This increases the sound quality, but also requires more CPU. Otherwise linear interpolation is used. The sinc interpolation uses 8 points by default, but 16 point sinc interpolation is also available via the BASS_ATTRIB_MIDI_SRC attribute.
BASS_UNICODEfile is in UTF-16 form. Otherwise it is ANSI on Windows or Windows CE, and UTF-8 on other platforms.
freqSample rate to render/play the MIDI stream at... 0 = the rate specified in the BASS_Init call, 1 = the device's current output rate (or the BASS_Init rate if that is not available).

Return value

If successful, the new stream's handle is returned, else 0 is returned. Use BASS_ErrorGetCode to get the error code.

Error codes

BASS_ERROR_INITBASS_Init has not been successfully called.
BASS_ERROR_NOTAVAILOnly decoding channels (BASS_STREAM_DECODE) are allowed when using the "no sound" device. The BASS_STREAM_AUTOFREE flag is also unavailable to decoding channels.
BASS_ERROR_ILLPARAMThe length must be specified when streaming from memory.
BASS_ERROR_FILEOPENThe file could not be opened.
BASS_ERROR_FILEFORMThe file's format is not recognised/supported.
BASS_ERROR_FORMATThe sample format is not supported by the device/drivers. If the stream is more than stereo or the BASS_SAMPLE_FLOAT flag is used, it could be that they are not supported.
BASS_ERROR_SPEAKERThe specified SPEAKER flags are invalid. The device/drivers do not support them or 3D functionality is enabled.
BASS_ERROR_MEMThere is insufficient memory.
BASS_ERROR_NO3DCould not initialize 3D support.
BASS_ERROR_UNKNOWNSome other mystery problem!


BASSMIDI supports standard MIDI format 0/1/2 files. In the case of format 2, the tracks are rendered/played one after another. RIFF MIDI (RMID) files are also supported. The General MIDI standard events are supported, as are several Roland GS and Yamaha XG NRPN and SysEx events. A full list of supported MIDI events can be found in the BASS_MIDI_StreamEvent documentation.

Soundfonts provide the sounds that are used to render a MIDI stream. A default soundfont configuration is applied initially to the new MIDI stream, which can subsequently be overridden using BASS_MIDI_StreamSetFonts. By default, with the BASS_CONFIG_MIDI_AUTOFONT config option enabled, BASSMIDI will also check for a soundfont of the same name as the MIDI file. Note that a MIDI stream can have multiple soundfonts stacked, each providing different presets, for example.

As well as the standard byte/time-based positioning, MIDI tick-based positioning is also supported. The BASS_POS_MIDI_TICK "mode" can be used with BASS_ChannelGetLength, BASS_ChannelGetPosition and BASS_ChannelSetPosition to deal in ticks. The BASS_ATTRIB_MIDI_PPQN attribute can be used to translate the position to beats.

Marker, instrument name, cue, text, and lyric events can be retrieved via the BASS_MIDI_StreamGetMark function. Syncs can also be used to be notified of their occurrence.

Other texts of each track (eg. track name) are available via the BASS_TAG_MIDI_TRACK+<track> tag, where track=0 is the first track. A pointer to a series of null-terminated strings is given, the final string ending with a double null. The first text in the first track is generally the title of the MIDI file. RIFF MIDI tags are also available via the standard BASS_TAG_RIFF_INFO tag.

Alongside the events played from the MIDI file, custom MIDI events can be applied via the BASS_MIDI_StreamEvent and BASS_MIDI_StreamEvents functions. The events can be played on the same MIDI channels that are used by the MIDI file, or they can be played on additional channels allocated via the BASS_ATTRIB_MIDI_CHANS attribute.

Unlike with most stream formats, the entire MIDI file is loaded to memory. This means the file can be deleted or moved after calling this function, or the memory can be discarded (mem = TRUE).

To play a MIDI file from the internet, use BASS_MIDI_StreamCreateURL. To play a custom sequence of MIDI events, BASS_MIDI_StreamCreateEvents can be used.


Away from Windows, all mixing is done in software (by BASS), so the BASS_SAMPLE_SOFTWARE flag is unnecessary. The BASS_SAMPLE_FX flag is also ignored. On Android and iOS, sinc interpolation requires a NEON-supporting CPU; the BASS_MIDI_SINCINTER flag will otherwise be ignored. Sinc interpolation is not available on Windows CE.


Create a stream of a MIDI file, with a sample rate of 44100hz.
HSTREAM stream=BASS_MIDI_StreamCreateFile(FALSE, "afile.mid", 0, 0, 0, 44100);

See also


BASS_ChannelGetInfo, BASS_ChannelGetLength, BASS_ChannelGetTags, BASS_ChannelPlay, BASS_ChannelSetAttribute, BASS_ChannelSetDSP, BASS_ChannelSetFX, BASS_ChannelSetLink, BASS_StreamFree