BASS

BASS_StreamCreateFileUser

Creates a sample stream from an MP3, MP2, MP1, OGG, WAV, AIFF or plugin supported file via user callback functions.

HSTREAM BASS_StreamCreateFileUser(
    DWORD system,
    DWORD flags,
    BASS_FILEPROCS *procs,
    void *user
);

Parameters

system

File system to use, one of the following.

STREAMFILE_NOBUFFER	Unbuffered.
STREAMFILE_BUFFER	Buffered.
STREAMFILE_BUFFERPUSH	Buffered, with the data pushed to BASS via BASS_StreamPutFileData.

flags

A combination of these flags.

BASS_SAMPLE_FLOAT	Use 32-bit floating-point sample data. See Floating-point channels for info.
BASS_SAMPLE_MONO	Decode/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_SOFTWARE	Force the stream to not use hardware mixing.
BASS_SAMPLE_3D	Enable 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_LOOP	Loop 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_FX	Enable 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_PRESCAN	Pre-scan the file for accurate seek points and length reading in MP3/MP2/MP1 files and chained OGG files (has no effect on normal OGG files). This can significantly increase the time taken to create the stream, particularly with a large file and/or slow storage media. This flag only applies when using the STREAMFILE_NOBUFFER system.
BASS_STREAM_RESTRATE	Restrict 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 possible. This flag only has effect when using the STREAMFILE_BUFFER system.
BASS_STREAM_BLOCK	Download and play the file in smaller chunks. 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. This flag also has the effect of restricting the download rate. This flag has no effect when using the STREAMFILE_NOBUFFER system.
BASS_STREAM_AUTOFREE	Automatically free the stream when playback ends.
BASS_STREAM_DECODE	Decode 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_xxx	Speaker assignment flags. These flags have no effect when the stream is more than stereo.
BASS_ASYNCFILE	Read 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 only applies when using the STREAMFILE_NOBUFFER system.

procs

The user defined file functions.

user

User instance data to pass to the callback functions.

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_INIT	BASS_Init has not been successfully called.
BASS_ERROR_NOTAVAIL	Only 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_ILLPARAM	system is not valid.
BASS_ERROR_FILEFORM	The file's format is not recognised/supported.
BASS_ERROR_CODEC	The 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_FORMAT	The 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_SPEAKER	The 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_MEM	There is insufficient memory.
BASS_ERROR_NO3D	Could not initialize 3D support.
BASS_ERROR_UNKNOWN	Some other mystery problem!

Remarks

The buffered file system (STREAMFILE_BUFFER) is what is used by BASS_StreamCreateURL. As the name suggests, data from the file is buffered so that it is readily available for decoding; BASS creates a thread dedicated to "downloading" the data. This is ideal for when the data is coming from a source that has high latency, like the internet. It is not possible to seek in buffered file streams, until the download has reached the requested position; it is not possible to seek at all if it is being streamed in blocks.

The push buffered file system (STREAMFILE_BUFFERPUSH) is the same, except that instead of the file data being pulled from the FILEREADPROC function in a "download" thread, the data is pushed to the stream via BASS_StreamPutFileData. A FILEREADPROC function is still required, to get the initial data used in the creation of the stream.

The unbuffered file system (STREAMFILE_NOBUFFER) is what is used by BASS_StreamCreateFile. In this system, BASS does not do any intermediate buffering; it simply requests data from the file as and when it needs it. This means that reading (FILEREADPROC) must be quick, otherwise the decoding will be delayed and playback buffer underruns (old data repeated) are a possibility. It is not so important for seeking (FILESEEKPROC) to be fast, as that is generally not required during decoding, except when looping a file.

In all cases, BASS will automatically stall playback of the stream when insufficient data is available, and resume it when enough data does become available.

A copy is made of the procs callback function table, so it does not need to persist beyond this function call.

Platform-specific

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.