VIP Deinterlacer in Motion Adaptive Mode Questions

Hello,

The algorithm you suggest is reasonable but this is not what Altera's deinterlacer is doing at the moment:

1) each incoming field is stored in memory

2) to produce one progressive output frame, the core has to read back 4 fields (including the current field)

For reference purpose here is how to compute the bandwidth requirements for the 9.0 motion adaptive deinterlacer for 1080i60 RGB (24-bits) -> 1080p RGB (24-bits) with double-buffering assuming that the data port with of the memory masters is 256 bits.

1) data sample packing efficiency:

the Avalon MM master interfaces pack 10 pixels per 256-bit words (10 x 24 = 240 bits) which means 1.6 bits are wasted for each 24 bit pixel

2) bandwidth required to write the 1080i60 input to memory:

1920 x 540 x (24+1.6 bits) x 60 fields/s = 1.593 Gbit/s

3a) bandwidth required to read 4 fields from memory to output 1080p30 (input frame rate = output frame rate)

1920 x 540 x 4 x (24+1.6 bits) x 30 frame/s = 3.185 Gbit/s

3b) bandwidth required to read 4 fields from memory to output 1080p60 (input field rate = output frame rate, smoother algorithm but may cause shimmering)

1920 x 540 x 4 x (24+1.6 bits) x 60 frame/s = 6.37 Gbit/s

Total for 1080p30: 1.593 + 3.185 = 4.778 Gbit/s

Total for 1080p60: 1.593 + 6.37 = 7.963 Gbit/s

Motion values are stored and read back from external memory if motion bleed is on. This will add:

4) motion sample packing efficiency

the Avalon MM master interfaces pack 32 motion values per 256-bit words (32 x 8 = 256 bits) which means there is no waste

5a) bandwidth required to write a motion field AND read a motion field assuming a 1080p30 output:

2 x 1920 x 540 x (8 bits) x 30 frame/s = 0.498 Gbit/s

5b) bandwidth required to write a motion field AND read a motion field assuming a 1080p60 output:

2 x 1920 x 540 x (8 bits) x 60 frame/s = 0.996 Gbit/s

Total for 1080p30 with motion bleed: 4.778 + 0.498 = 5.276 Gbit/s

Total for 1080p60 with motion bleed: 7.963 + 0. 996 = 8.959 Gbit/s

> This is about a 13% margin. Is this safe?

It is recommended to plan designs with a 25% margin and to use long bursts (32 or 64) but it seems your margin is much better than necessary.

> Does the de-interlacer work equally well for YUV (4:4:4) and RGB (4:4:4)

Yes, the algorithm would give slightly different results but this would be difficult to spot.

Kind regards,

vgs

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edit: corrected bandwitch computation for the motion bleed