TL7231MD Datasheet, PDF (29/37 Pages) Samsung semiconductor – FULL LAYER-III ISO/IEC 11172-3 AUDIO DECODER

TL7231MD
Voice Record/Playback Function
TL7231MD records voice data from ADC in 8kHz sampling rate. There are three compression
modes according to bit rates of compressed data: high quality (32Kbps), medium quality
(24Kbps) and low quality (16Kbps). In high quality mode, relatively large bits are allocated for
compressed data to achieve high quality of the sound. In low quality mode, smaller bits are
allocated to record much more samples in the same size of storage media. Medium quality
mode gives tradeoff between high and low quality modes. Compressed codes are byte-aligned
and transmitted to host MCU through the serial port.
In playback the codes are uncompressed to PCM samples, with the compression mode in
recording, and then oversampled to 32 kHz and output to DAC. Compressed codes are
transmitted from host MCU through the serial interface.
Table 9 is the summary of the relation between compression modes and code size.
Table 9. Summary of Three Voice Compression Modes
COMPRESSION MODES CODE LENGTH
RECORDING TIME
(BIT)
FOR 32MB STORAGE MEDIA
High Quality (32Kbps)
4
140 min.
Medium Quality (24Kbps)
3
186 min.
Low Quality (16Kbps)
2
280 min.
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