The following are precautions for playback using this library.
(1) Notes on creating an application
- This library uses CPU DMA and timer. Do not use CPU DMA and timer when operating this library.
The frequency of calling - PCM_Task should be at least the frequency of V blank interrupt (1 time / 16ms) or more.
If the same sound occurs twice, it is possible that PCM_Task is called less frequently.
(2) Relationship with other libraries
- This library uses a file system, stream system, DMA library, and ADPCM decompression library. Please link these libraries.
(3) How to remove buffer
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Ensure the following size.
Work buffer: Size of the work structure.
Ring buffer: Minimum (sector size) * 10 [byte]. An integer multiple of the sector size.
1 sector = 2324 bytes for CD-ROM XA Audio playback.
* 1. Otherwise, 1 sector = 2048 bytes.
PCM buffer: 4096 * 2 to 4096 * 4 [sample / 1ch].
Pause processing work: Minimum 4096 [sample]. The same size as the PCM buffer is optimal.
(4) Seamless branch
When seamless branching is performed with - PCM_EntryNext, the PCM volume and PAN will be the same as the previous handle.
When seamless branching with - PCM_EntryNext, continuous playback is possible for up to 60 minutes. Further continuous playback is not possible.
- For seamless branching, pre-read the file with an application program.
When using the - file system, the seamless branch function cannot be used.
- Seamless branch can only be performed during single playback. Cannot be executed during multi playback.
(5) Multi playback
- Set the PCM stream playback number to a different number for multi playback.
To play multiple files on the - CD at the same time, perform file interleaving or channel interleaving. In that case, use the stream system.
- Multiple playback of the same file is not possible. Please specify a different file.
- Multiple playback can be performed up to four at the same time.
- Only one ADPCM compressed data can be played.