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Discussion Groups | Image Signal Processing | (MPEG4) intra-MBs in P-VOP

Technical Discussions related to Image Processing (image coding, compression, digital effects, mpeg, etc)

  

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(MPEG4) intra-MBs in P-VOP - Dok - Jul 2 7:46:00 2004




Hi, I am a bit confused on why there are intra-coded
MacroBlocks on a P(predicted)-VOPs. I assumed that all
MBs of a P-VOP are inter-MBs. When to code a MB of a
P-VOP as intra-MB?

Thanks,
Dok

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Re: (MPEG4) intra-MBs in P-VOP - Rumit Thakur - Jul 2 15:55:00 2004

Hi Dok,
For error resilience i.e if there are 5 frames then lets say 4th is predicted from 3rd and 3rd from 2nd..
then if there is error(due to transform mismatch ,inaccurate prediction.. )then that error will be propogated.
By having Intra we can have check on that as it predicts from the same frame.
also There is a cost function which decides whether a MB is to be coded as Intra  or P
for P VOPs..The cost function can favour Intra if the bits required are less and the clarity given is more
than P Vop..typically in fast motion areas..
regards
rumit

Typically

Dok wrote:

Hi, I am a bit confused on why there are intra-coded
MacroBlocks on a P(predicted)-VOPs. I assumed that all
MBs of a P-VOP are inter-MBs. When to code a MB of a
P-VOP as intra-MB?

Thanks,
Dok
           
__________________________________

_____________________________________
 . 

-- RUMIT THAKUR




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Re: (MPEG4) intra-MBs in P-VOP - Ganesh Vijayan - Jul 5 4:31:00 2004

Hi Dok,
If the cost of coding a particular MB in inter mode is higher than in intra mode, the MB will be coded as Intra to save bits. Also this can be used as an error-resilience technique.
Hope this helps.
Ganesh
----- Original Message -----
From: Dok
To: i...@yahoogroups.com
Sent: Friday, July 02, 2004 1:16 PM
Subject: [imagedsp] (MPEG4) intra-MBs in P-VOP


Hi, I am a bit confused on why there are intra-coded
MacroBlocks on a P(predicted)-VOPs. I assumed that all
MBs of a P-VOP are inter-MBs. When to code a MB of a
P-VOP as intra-MB?

Thanks,
Dok

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