Creates a sample stream from an Opus file.

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


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_FLOATUse 32-bit floating-point sample data. See Floating-point channels for info. If this flag is not specified, then the stream is 16-bit.
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, and the stream must be mono. The SPEAKER flags can not 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_PRESCANPre-scan the file for seek points and accurate length reading in chained Opus files (has no effect on normal Opus files). This can significantly increase the time taken to create the stream, particularly with a large file.
BASS_STREAM_AUTOFREEAutomatically free the stream when playback ends.
BASS_STREAM_DECODEDecode 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. These flags have no effect when the stream is more than stereo.
BASS_ASYNCFILERead the file asynchronously. When enabled, the file is read and buffered in parallel with the decoding, to reduce the chances of the decoder being affected by I/O delays. This can be particularly useful with slow storage media and/or low latency output. The size of the file buffer is determined by the BASS_CONFIG_ASYNCFILE_BUFFER config option. This flag is ignored when streaming from memory (mem = TRUE).
BASS_UNICODEfile is in UTF-16 form. Otherwise it is ANSI on Windows or Windows CE, and UTF-8 on other platforms.

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, they are attempting to assign a stereo stream to a mono speaker or 3D functionality is enabled.
BASS_ERROR_MEMThere is insufficent memory.
BASS_ERROR_NO3DCould not initialize 3D support.
BASS_ERROR_UNKNOWNSome other mystery problem!


Use BASS_ChannelGetInfo to retrieve information on the format of the stream. Opus always has a sample rate of 48000 Hz, but the source material may have had a different sample rate, which is available via the BASS_ATTRIB_OPUS_ORIGFREQ attribute. The playback length of the stream can be retrieved using BASS_ChannelGetLength.

The Opus file format is Ogg-based, so the standard BASS_TAG_OGG and BASS_TAG_VENDOR tag types apply to Opus too, via BASS_ChannelGetTags.

Chained Opus files containing multiple logical bitstreams are supported, but seeking within them is only fully supported if the BASS_STREAM_PRESCAN flag is used (or the BASS_CONFIG_OGG_PRESCAN option is enabled) to have them pre-scanned. Without pre-scanning, seeking will only be possible back to the start. The BASS_POS_OGG "mode" can be used with BASS_ChannelGetLength to get the number of bitstreams and with BASS_ChannelSetPosition to seek to a particular one. A BASS_SYNC_OGG_CHANGE sync can be set via BASS_ChannelSetSync to be informed of when a new bitstream begins during decoding/playback.

To stream a file from the internet, use BASS_OPUS_StreamCreateURL. To stream from other locations, see BASS_OPUS_StreamCreateFileUser.


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.


Create a stream of an Opus file.
HSTREAM stream=BASS_OPUS_StreamCreateFile(FALSE, "afile.opus", 0, 0, 0);

See also

BASS_OPUS_StreamCreateFileUser, BASS_OPUS_StreamCreateURL

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