2/24/2008 9T6WP
Preliminary Hardware Data Module
BCM7405
06/29/07
Functional Description
Bro a d c o m Co rp o r a ti o n
Document
7405-1HDM00-R
Video and Graphics Display Page 1-43
D
IGITAL
N
OISE
R
EDUCTION
DNR reduces MPEG coding artifacts including block noise and mosquito noise.
DNR is a BVN ready-accept block and is expected to operate immediately after the MPEG feeder(s.) To be effective, DNR
must operate before any scaling or deinterlacing.
Figure 3-9: DNR Position in BVN
DNR requires information about the current picture. The host (or other processor) is expected to provide information about
the picture, user settings, and some quantization information from the video decoder.
DNR Operations
Block noise is an MPEG artifact caused by quantization of low-frequency information. Block noise appears as edges on 8x8
blocks and gives the appearance of a mosaic, or tiles. Mosquito Noise refers to the MPEG artifacts caused by quantization
of high-frequency components. It is also called “ringing” or “Gibb’s effect.”
For block noise, vertical block noise reduction (VBNR) and horizontal block noise reduction (HBNR) are used.
For mosquito noise, Mosquito Noise Reduction (MNR) is used. Extreme filter can be used when input is very noisy. The BNR
and MNR results are ignored in this case.
D
IGITAL
C
ONTOUR
R
EMOVAL
In 8-bit systems, 1-bit quantization levels are visible and can appear as contours on smooth gradients. The source can come
from MPEG video, AVC video, or analog video. DCR will detect and filter regions with 1-bit out of 8-bit digital contours (with
extra internal precision bits) then halftone back to 8-bit output.
MPEG Feeder
DNR
Scaling,
deinterlacing, etc.
BVB
BVB
Video Decoder
Host CPU
Qp
Threshold settings
Top/Bottom
Interlace/Progressive
Picture Width
User Controls
BVB
