Datasheet

VS1053b Datasheet
9 OPERATION
0000 52 49 46 46 34 2e 99 00 57 41 56 45 66 6d 74 20 |RIFF4...WAVEfmt |
0010 14 00 00 00 11 00 02 00 44 ac 00 00 a7 ae 00 00 |........D.......|
0020 00 02 04 00 02 00 f9 01 66 61 63 74 04 00 00 00 |........fact....|
0030 14 15 97 00 64 61 74 61 00 2e 99 00 |....data....|
9.8.5 Playing ADPCM Data
In order to play back your PCM / IMA ADPCM recordings, you have to have a file with a header
as described in Chapter 9.8.3 or Chapter 9.8.4. If this is the case, all you need to do is to
provide the ADPCM file through SDI as you would with any audio file.
9.8.6 Sample Rate Considerations
VS10xx chips that support IMA ADPCM playback are capable of playing back ADPCM files with
any sample rate. However, some other programs may expect IMA ADPCM files to have some
exact sample rates, like 8000 or 11025 Hz. Also, some programs or systems do not support
sample rates below 8000 Hz.
If you want better quality with the expense of increased data rate, you can use higher sample
rates, for example 16 kHz.
9.8.7 Record Monitoring Volume
In VS1053b writing to the SCI_VOL register during IMA ADPCM encoding does not change the
volume. You need to set a suitable volume before activating the IMA ADPCM mode, or you can
use the VS1053 hardware volume control register DAC_VOL directly.
For example:
WriteVS10xxRegister(SCI_WRAMADDR, 0xc045); /*DAC_VOL*/
WriteVS10xxRegister(SCI_WRAM, 0x0101); /*-6.0 dB*/
The hardware volume control DAC_VOL (address 0xc045) allows 0.5 dB steps for both left (high
8 bits) and right channel (low 8 bits). The low 4 bits of both 8-bit values set the attenuation in
6 dB steps, the high 4 bits in 0.5 dB steps.
Version: 1.13, 2011-05-27 55