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VS1005 VSOS A
UDIO
S
UBSYSTEM
VS1005g
13
Audio Decoders
Library audiodec automatically chooses between many Audio Decoders when presented
an audio file. The libraries, their respective decode audio formats, and their clock rate
requirements, are presented below.
NOTE: The clock speeds have been tested with a Class 4 SD card and “typical test
files”. While VLSI believes the information to be accurate, clock rates should still be
interpreted as estimations. The estimations are fiven for a system with a typical inter-
rupt load and with a 8 KiW audio output buffer. An example alternative configuration
file that sets the system up for best playback audio performance is provided in file con-
fig_audio_decoders.txt in the
VSOS Root and Libraries Source Code
package.
Audio Decoders
LibName
Format
Description
decaac
AAC
AAC in ADTS and MP4 containers (.aac, .m4a, .mp4, .3gpp)
decaiff
AIFF
Apple uncompressed PCM format
decalac
ALAC
Apple lossless in MP4 (.mp4, .m4a) or CAFF (.caf) container
decdsd
DSD
DSD bitstream files in .DSF and .DFF container, LSb first only
decflac
FLAC
Free Lossless Audio Codec
decmp3
MP3
MPEG audio layer 3
decvorb
Ogg Vorbis
Vorbis audio in Ogg container
decwav
RIFF WAV
Many RIFF WAV subformats
decwma
WMA
Windows Media Audio
mp4file
-
Determines if MP4 file contains ALAC or AAC
NOTE: For formats where there may be more than 2 audio channels, only files up to 2
audio channels are supported.
Library decaac subformats and clock requirements
Clock
Description
30 MHz
AAC up to 48 kHz, 280 kbit/s
Library decaiff subformats and clock requirements
Clock
Description
12 MHz
AIFF up to 96 kHz 16-bit
18 MHz
AIFF up to 96 kHz 24-bit
37 MHz
AIFF up to 192 kHz 24-bit
61 MHz
AIFF up to 352 kHz 24-bit
Library decalac subformats and clock requirements
Clock
Description
37 MHz
Apple lossless up to 48 kHz 16-bit
74 MHz
Apple lossless up to 96 kHz 24-bit
Rev. 3.57
2019-04-10
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