L64105 LSI Logic Corporation, L64105 Datasheet - Page 339

• Manufacturer Part Number: L64105
• Description: Mpeg-2 Audio/video Decoder
• Manufacturer: LSI Logic Corporation

10.3.2 Audio Decoder Start/Stop
The host can determine the decoder mode at any time by reading the
Audio Decoder Play Mode Status bits in Register 354
two bits are encoded identically to the play mode bits.
The Audio Decoder Start/Stop bit in Register 355
control both the selected audio decoder and its channel buffer read
pointer. When the Audio Decoder Start/Stop bit is set, the Audio Decoder
operates according to the play mode setting described in the previous
section. When the start/stop bit is cleared, the Audio Decoder is stopped
at the end of the current frame and the audio read pointer in the Audio
ES Channel Buffer is reset to the write pointer location. Any unread audio
data is lost to the decoder. The S/P DIF read pointer is not affected, so
the formatter can still run.
Decoding Flow Control
guarantee that the channel read pointer will stop at the end of a
frame, decoder resynchronization is required when the mode is
changed again.
A prolonged audio pause will cause the Audio ES Channel Buffer to
overflow and the system parser to deassert the channel request
signals, stopping video as well as audio.
0b01 - Normal Play. The decoder is playing at normal speed. When
the PCM output buffer or S/P DIF output buffer empties and the next
output signal is requested by the audio DAC or S/P DIF decoder, the
last pair of output samples is repeated.
0b10 - Fast Play. The MPEG Decoder skips one out of every 16 pairs
of samples and plays at 16/15 normal speed. The Linear PCM
Decoder performs fast play at 8/7 normal speed. When the Linear
PCM bitstream is at 48 kHz, every eighth pair of PCM samples is
skipped. When it is 96 kHz, every fifteenth and sixteenth pair of PCM
samples and every eighth pair of S/P DIF samples are skipped.
0b11 - Slow Play. The MPEG Decoder repeats every sixteenth pair
of samples and plays at 16/17 normal speed. The Linear PCM
Decoder runs at 8/9 normal speed in Slow Play Mode. When the
Linear PCM bitstream is at 48 kHz, every eighth pair of PCM
samples is played twice. When Fs is 96 kHz, every fifteenth and
sixteenth pairs of PCM samples and every eighth of S/P DIF samples
are played twice.
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