Creates a sample stream from an MP3, MP2, MP1, OGG, WAV, AIFF or plugin supported file on the internet, optionally receiving the downloaded data in a callback function.

    char *url,
    DWORD offset,
    DWORD flags,
    void *user


urlURL of the file to stream. Should begin with "http://" or "https://" or "ftp://", or another add-on supported protocol. The URL can be followed by custom HTTP request headers to be sent to the server; the URL and each header should be terminated with a carriage return and line feed ("\r\n").
offsetFile position to start streaming from. This is ignored by some servers, specifically when the length is unknown/undefined.
flagsA combination of these flags.
BASS_SAMPLE_FLOATUse 32-bit floating-point sample data. See Floating-point channels for info.
BASS_SAMPLE_MONODecode/play the stream (MP3/MP2/MP1 only) in mono, reducing the CPU usage (if it was originally 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, and the stream must be mono. 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. This flag is ignored when streaming in blocks (BASS_STREAM_BLOCK).
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_RESTRATERestrict the download rate of the file to the rate required to sustain playback. If this flag is not used, then the file will be downloaded as quickly as the user's internet connection allows.
BASS_STREAM_BLOCKDownload and play the file in smaller chunks, instead of downloading the entire file to memory. Uses a lot less memory than otherwise, but it is not possible to seek or loop the stream; once it has ended, the file must be opened again to play it again. This flag will automatically be applied when the file length is unknown, for example with Shout/Icecast streams. This flag also has the effect of restricting the download rate.
BASS_STREAM_STATUSPass status info (HTTP/ICY tags) from the server to the DOWNLOADPROC callback during connection. This can be useful to determine the reason for a failure.
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_UNICODEurl is in UTF-16 form. Otherwise it is ANSI on Windows or Windows CE, and UTF-8 on other platforms.
procCallback function to receive the file as it is downloaded... NULL = no callback.
userUser instance data to pass to the callback function.

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_NONETNo internet connection could be opened. Can be caused by a bad proxy setting.
BASS_ERROR_ILLPARAMurl is not a valid URL.
BASS_ERROR_SSLSSL/HTTPS support is not available.
BASS_ERROR_TIMEOUTThe server did not respond to the request within the timeout period, as set with the BASS_CONFIG_NET_TIMEOUT config option.
BASS_ERROR_FILEOPENThe file could not be opened.
BASS_ERROR_FILEFORMThe file's format is not recognised/supported.
BASS_ERROR_CODECThe file uses a codec that is not available/supported. This can apply to WAV and AIFF files, and also MP3 files when using the "MP3-free" BASS version.
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 insufficient memory.
BASS_ERROR_NO3DCould not initialize 3D support.
BASS_ERROR_UNKNOWNSome other mystery problem!


Use BASS_ChannelGetInfo to retrieve information on the format (sample rate, resolution, channels) of the stream. The playback length of the stream can be retrieved using BASS_ChannelGetLength.

When playing the stream, BASS will stall the playback if there is insufficient data to continue playing. Playback will automatically be resumed when sufficient data has been downloaded. BASS_ChannelIsActive can be used to check if the playback is stalled, and the progress of the file download can be checked with BASS_StreamGetFilePosition.

When streaming in blocks (BASS_STREAM_BLOCK flag), be careful not to stop/pause the stream for too long, otherwise the connection may timeout due to there being no activity and the stream will end prematurely.

When streaming from Shoutcast servers, metadata (track titles) may be sent by the server. The data can be retrieved with BASS_ChannelGetTags. A BASS_SYNC_META sync can also be set via BASS_ChannelSetSync to be informed when metadata is received. A BASS_SYNC_OGG_CHANGE sync can be used to be informed of when a new logical bitstream begins in an Icecast/OGG stream.

When using an offset, the file length returned by BASS_StreamGetFilePosition can be used to check that it was successful by comparing it with the original file length. Another way to check is to inspect the HTTP headers retrieved with BASS_ChannelGetTags.

Custom HTTP request headers may be ignored by some plugins, notably BASSWMA.


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 Windows and Windows CE, ACM codecs are supported with compressed WAV files. Media Foundation codecs are also supported on Windows 7 and updated versions of Vista, including support for AAC and WMA. On iOS and OSX, CoreAudio codecs are supported, including support for AAC and ALAC. Media Foundation and CoreAudio codecs are only tried after the built-in decoders and any plugins have rejected the file. Built-in support for IMA and Microsoft ADPCM WAV files is provided on Linux/Android/Windows CE, while they are supported via ACM and CoreAudio codecs on Windows and OSX/iOS.


Stream an MP3 file.
HSTREAM stream=BASS_StreamCreateURL("", 0, 0, NULL, 0);

Stream an MP3 file with a cookie sent to the server.

HSTREAM stream=BASS_StreamCreateURL("\r\nCookie: mycookie=blah\r\n", 0, 0, NULL, 0);

See also