NNSSndStrmCallback

Syntax

#include <nnsys/snd.h>

typedef void (*NNSSndStrmCallback)(
        NNSSndStrmCallbackStatus status,
        int numChannles,
        void* buffer[],
        u32 len,
        NNSSndStrmFormat format,
        void* arg );

Arguments

`status`	The callback state.
`numChannles`	The number of channels.
`buffer`	The array of the top address of the buffer for every channel.
`len`	The byte length of the buffer for each channel.
`format`	The sample data format.
`arg`	The user argument.

Return Values

None.

Description

The callback function called when waveform data must be supplied during stream play.

This callback function is registered by the NNS_SndStrmSetup, NNS_SndArcStrmStartEx2, and the NNS_SndArcStrmPrepareEx2 functions.

Callback functions registered with the NNS_SndStrmSetup function are responsible for supplying the waveform data for the passed buffer. Callback functions registered with the NNS_SndArcStrmStartEx2 or NNS_SndArcStrmPrepareEx2 functions are called after waveform data is supplied by the sound archive stream library, so they are not responsible for supplying waveform data. However, they can process waveform data.

The callback function is called at two possible different points. One point to call it is before starting stream play, in order to pass waveform data in advance to all stream buffers. At this time, NNS_SND_STRM_CALLBACK_SETUP is passed in the callback state status. The other point to call the callback is during stream play. Here it is called in order to supply the continuation of the waveform data to the buffer, which has been consumed by playback. At this time, NNS_SND_STRM_CALLBACK_INTERVAL is passed in the callback state status.

The number of channels used for stream play is passed in numChannles. The number of elements in the array buffer, which holds the top addresses of the buffers, is the same as the value of numChannles. The buffer size for each channel is len bytes.

The sample data format format is one of the following values.

Table: NNSSndStrmFormat

Label	Description
NNS_SND_STRM_FORMAT_PCM8	8-bit PCM.
NNS_SND_STRM_FORMAT_PCM16	16-bit PCM.

Note

After supplying and/or processing the waveform data, call the DC_FlushRange function or a similar function to ensure that it is written to main memory.

Note: Be aware that the callback functions registered with the NNS_SndStrmSetup function are called while interrupts are prohibited. On the other hand, be aware that callback functions registered with the NNS_SndArcStrmStartEx2 or the NNS_SndArcStrmPrepareEx2 functions are called from the stream thread.

It is not always necessary to finish supplying the waveform data within the callback function. However, the supplying of this data must be complete before that region is next played. Otherwise the proper audio will not be output.

Revision History

2004/11/26 Extracted from description of the NNS_SndStrmSetup function.