
1136
6437E–ATARM–23-Apr-13
SAM9M11
Notes:
1. Step size in the start and end coordinates depends on the output picture format and the width
of the data bus.
2. Usable in stand-alone post-processing mode only.
48.3.2
Decoder Data Flow, Hardware Performs Entropy Decoding (VLC Mode)
The decoder software starts decoding the first picture by parsing the stream headers (1). Soft-
ware then setups the hardware control registers (picture size, stream start address etc.) and
enables the hardware (2).
In JPEG case, software parses VLC and QP tables from the stream and writes them to a contig-
uous memory area. In VC-1 case, software parses bitplane macroblock control from the stream
and writes it to memory.
Hardware decodes the picture by reading stream, VLC and QP tables for JPEG (3), and the ref-
erence pictures (4) (required for inter picture decoding) from the external memory. Hardware
writes the decoded output picture to memory (5) one macroblock at a time. When the picture has
been fully decoded, or the hardware has run out of stream data, it gives an interrupt with a
proper status flag and provides stream end address for software to continue and returns to initial
state.
In case the hardware detects erroneous stream during decoding, it will return an error interrupt,
and software will start concealing errors for the current picture. Depending on the selected con-
cealment method, software may re-initialize the hardware in the SW entropy decode mode. The
pictures following the corrupted one are decoded in the normal mode until the next error is
detected.
If post-processing is enabled, one or two additional image transfer operations will take place. If
the decoded images are in display order (i.e. no picture re-ordering has been made when
encoding the sequence), and rotation is not used, PP will process the pictures in pipeline with
the decoder. Otherwise, it will first have to read the decoded image that is to be displayed next
from the memory (6), and then write back the processed image (7).
RGB image color
saturation adjustment
Linear
De-blocking filter for
MPEG-4 simple
profile/H.263
Using a modified H.264 in-loop filter as a post-processing filter. Filtering
has to be performed in combined mode.
Image cropping /digital
zoom
User definable start position, height and width. Can be used with scaling
to perform digital zoom. Usable only for JPEG or standalone mode.
Picture in picture
Output image can be written to any location inside video memory
(1)Supported display size for
picture in picture
Up to 1280 x 720
Output image masking
Output image writing can be prevented on two rectangular areas in the
image (1). The masking feature is exclusive with alpha blending however it
is possible to have one masking area and one blending area.
Rotation 90, 180 or 270 degrees
Horizontal flip
Vertical flip
Table 48-6.
Postprocessing Features (Continued)