Digital Signal Processing Reference
In-Depth Information
Deinterlacer (MA)
DDR2
Figure 20.5. A motion-adaptive deinterlacer requires
ve (master) accesses to the
DDR memory.
So to calculate the memory bandwidth demanded by this
deinterlacer, we will first assume that this is a simple 4:4:4 video
with 10 bits per color plane for each pixel. This means that each
pixel requires 30 bits to be represented. The input format to the
deinterlacer is fields and the output format is frames.
Input format: 1080i, 60 fields/sec, 10-bit color
•
1920
1.866 Gbit/s
Output format: 1080p, 60 frames/sec, 10-bit color
•
1920
1080
30bits
60/2
¼
3.732Gbit/s
Let's also assume that the motion vector calculated is repre-
sented as a 10-bit value. So there will be one motion vector read
and one motion vector write.
Motion format: only use 10 bits for the motion values:
•
1920
1080
30bits
60
¼
0.622 Gbit/s
The total memory access required for the deinterlacer can thus
be calculated as:
1
1080
10 bits
60/2
¼
write at input rate: 1.866 Gbit/s.
1
write at motion rate: 0.622 Gbit/s.
1
read at motion rate: 0.622 Gbit/s.
2
read at output rate: 7.464 Gbit/s.
Total: 10.574 Gbit/s
this is for 4:4:4 video.
Just as an exercise, let's see what happens if we use 4:2:2 video.
The pixels are represented by 20 bits, however the motion vectors
are still at 10 bits.
Input format: 1080i, 60 fields/sec, 10-bit color
•
1920
)
1.24 Gbit/s
Output format: 1080p, 60 frames/sec, 10-bit color
•
1920
1080
20bits
60/2
¼
2.48 Gbit/s
Motion format: Only use 10bits for the motion values
•
1920
1080
20bits
60
¼
1080
10bits
60/2
0.622 Gbit/s
¼
Memory access:
1
write at input rate: 1.24 Gbit/s.
1
write at motion rate: 0.622 Gbit/s.
1
read at motion rate: 0.622 Gbit/s.
