PRELIMINARY
VS1063a Prog. Guide
7
AUDIO FORMAT SPECIFIC COMMENTS
7
Audio Format Specific Comments
7.1
Encoders
7.1.1
VLSI Solution’s Ogg Vorbis Encoder VSOVE v2.00
VLSI Solution’s Ogg Vorbis Encoder VSOVE v2.00 is a continuation of the proprietary VS1053b
Ogg Vorbis encoder originally published in 2007.
The encoder uses short and long frames as shown in the following table. (Note! A 1024 sample
window in this table corresponds to what the Ogg Vorbis community calls 2048 sample window.)
Ogg Vorbis window lengths as function of samplerate
Nominal Profile / Hz
fs / Hz
Short Win
Long Win
8000
0...9999
64
256
16000
10000...29999
128
512
32000
30000...39999
128
1024
44100
40000...65535
128
1024
Channel coupling is always used for stereo streams. Dual-channel audio is not supported.
For stereo streams, channel coupling is always used (as opposed to MP3, this is a lossless
operation in Ogg Vorbis). However, to save space, part of the audio spectrum is only encoded
as intensity stereo. The frequency threshold for intensity stereo depends on the quality setting.
For quality setting 0, practically all stereo information above 100 Hz is encoded as intensity
stereo. Dual-channel audio like multilingual transmissions using one stereo stream is neither
supported nor recommended.
VSOVE uses VLSI Solution’s proprietary PAMM psycho-acoustic model. PAMM is a non-
iterative, constant-time, processor-time efficient real-time algorithm that is capable of near CD
quality at bitrates averaging around 140 kbit/s.
VSOVE supports only VBR and makes no attempts at equalizing its output bitrate: the output
file size purely depends on the user-chosen quality setting.
7.1.2
VLSI Solution’s MP3 Encoder VSMPE v1.00
VSMPE is VLSI Solution’s proprietary MP3 encoder first time published for the VS1063 in 2011.
VSMPE supports VBR and CBR.
VSMPE only uses long blocks (576 samples per block).
Version: 0.40, 2011-09-02
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