CS6150 Amphion Semiconductor Ltd., CS6150 Datasheet - Page 2

• Manufacturer Part Number: CS6150
• Description: Motion JPEG Decoder
• Manufacturer: Amphion Semiconductor Ltd.

2
The CS6150 ASVC
ous data flow – one image sample per clock cycle – the CS6150 can address the most demanding frame-based video decompres-
sion applications. In addition, fully synchronous operation and zero-power standby make it ideal for low power applications.
The highly autonomous design extracts all relevant information (quantization and Huffman tables and parameter information)
from the JPEG bitstream and requires no software overhead. The CS6150 is a powerful and flexible JPEG decoding solution.
This unit parses and checks the JPEG input stream, automati-
cally detecting and processing all the JPEG marker segments
without the need for a processor and signalling any detected
errors. If an error is found the parser stops reading the JPEG
stream and waits to be reset. After identifying the segments it
re-directs the data to the appropriate units in the decoder to
be stored or processed. In addition the JPEG file header
information and marker segments can be output on the
masked JPEG output port (DecJpg) in accordance with the
value set on the JPEG mask control port.
The variable length decoding unit (VLD) consists of both the
Huffman decoder (HUFF) and run length decoding unit
(RLD). Huffman decoding techniques are first applied to the
stream of parsed data to regenerate the Run-Size data pairs.
The decoder detects the uniquely identifiable Huffman codes
and converts them to corresponding Run-Size pairs read
from a look-up table stored in the Huffman Table memory
(HTMem). The CS6150 can store four user-defined Huffman
tables, two for DC coefficients and two for AC coefficients,
the DC and AC coefficients being Huffman decoded sepa-
rately. The Run-Size data pairs output from the Huffman
decoder are then buffered in the Run-Length Memory
(RLMem) and loaded into the run length decoder unit.
The RLD decompresses the data stream by converting the
Run-Size data pairs into 8x8 blocks of quantized DCT
coefficient data. The decompression produced by the VLD
is data dependent and thus latency can vary.
CS6150
VARIABLE LENGTH DECODER
is a highly integrated JPEG decoder suitable for a wide range of imaging applications. Designed for continu-
PARSER
M o t i o n J P E G D e c o d e r
CS6150 FUNCTIONAL DESCRIPTION
The coefficient dequantization (DQT) unit multiplies each
of the 64 DCT coefficients in an image block by the values
specified in one of the four quantization tables. The purpose
of the dequantization process is to rescale the DCT coeffi-
cients and restore their original magnitude. Up to four user
programmable quantization tables can be stored in the quan-
tization table memory (QTMem). The 11-bit DCT data is
loaded into DQT directly from the VLD. The DQT unit quan-
tizes one sample per clock cycle with a latency between the
first sample in and first sample out of 2 clock cycles. The 11-
bit dequantized DCT coefficients are then output from the
DQT unit for direct input to the inverse frequency transform.
The inverse frequency transform (IFT) unit accepts 64-byte
(8 x 8) blocks of frequency coefficients and converts these to
8 x 8 blocks of image sample data in raster format using a 2D
inverse discrete cosine transform (IDCT) architecture. This is
implemented as two, 1-D IDCT operations, with the interme-
diate results being stored in the dual-port transpose memory
(TRMem) buffer. The architecture of the IFT unit allows for
continuous one sample per cycle operation with a latency
between first sample in and first coefficient out of 83 clock
cycles. The 8-bit decoded image sample data is streamed out
from the IFT unit via the output pixel interface of the core.
The controller unit consists of a code control state machine
(DecCtrl) that manages the operation of the CS6150. It is
used to build the control parameters for decoding from the
input JPEG stream and for detecting illegal and corrupted
markers within the stream.
INVERSE FREQUENCY TRANSFORM
COEFFICIENT DEQUANTIZATION
CONTROLLER