VS1033 Datasheet, PDF (47/70 Pages) List of Unclassifed Manufacturers – MP3/AAC/WMA/MIDI AUDIO CODEC

VLSI
Solution ^y
VS1033a PRELIMINARY
VS1033A
9. OPERATION
9.8.1 Common Parameters
Parameter
chipID
version
jumpPoints[16]
latestJump
seek1
seek2
resync
Address
0x1940/41
0x1942
0x1946-65
0x1966
0x1967
0x1968
0x1969
Usage
Fuse-programmed unique ID (copy)
Structure version – 0x0001
Packet offsets for WMA and AAC
Index to latest jumpPoint
Seek amount in bytes
Seek amount in kilobytes
Automatic resync selector
The fuse-programmed ID is read at startup and copied into the chipID field. The version field can
be used to determine the layout of the rest of the structure. The version number is changed when the
structure is changed.
jumpPoints contain 32-bit file offsets. Each valid (non-zero) entry indicates a start of a packet for
WMA or start of a raw data block for AAC (ADIF, .mp4 / .m4a). latestJump contains the index of
the entry that was updated last. If you only read entry pointed to by latestJump you do not need to
read the entry twice to ensure validity. Jump point information can be used to implement perfect fast
forward and rewind for WMA and AAC (ADIF, .mp4 / .m4a).
seek1 and seek2 fields are used when music data is skipped or inserted. Negative values mean that
data has been added (for example in rewind operation), positive values mean that data has been skipped.
You can use either seek1, which gives the seek amount in bytes, or seek2 which gives the seek amount
in kilobytes, or you can use both. The field value is zeroed when the firmware has detected the seek.
resync field is used to force a resynchronization to the stream for WMA and AAC (ADIF, .mp4 / .m4a).
This field can be used to implement almost perfect fast forward and rewind for WMA and AAC (ADIF,
.mp4 / .m4a). The user should set this field before performing data seeks if they are not in packet or data
block boundaries. The field value tells how many tries are allowed before giving up. The value 32767
gives infinite tries, in which case the user must use SM OUTOFWAV or software reset to end decoding.
In every case remember to use seek1 and/or seek2 fields to indicate the skipped/inserted data.
Note: WMA, ADIF, and .mp4 / .m4a files begin with a metadata section, which must be fully processed
before any fast forward or rewind operation. When the first jumpPoint appears it is safe to perform seeks.
You can also detect the start of decoding from SCI DECODE TIME.
9.8.2 WMA
Parameter Address Usage
curPacketSize 0x196a/6b The size of the packet being processed
packetSize 0x196c/6d The packet size in ASF header
The ASF header packet size is available in packetSize. With this information and a packet start offset
from jumpPoints you can parse the packet headers and skip packets in ASF files.
Version 0.6, 2005-01-05
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