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Re: VP9 Bitstream finalization update

Paul Wilkins Jun 12, 2013 9:29 AM
Posted in group: WebM Discussion

Here is the latest VP9 status update.


As of last night the VP9 (profile 0) bitstream is FINAL and the process of validating it on multiple platforms and in different build environments and testing for submission into Chrome is under way.


The last few days have been pretty hectic as we had to make several last minute changes. As always seems to be the case, these were more complex than we had hoped and I want to thank the whole team for working long hours to bring about closure. I also want to thank partners and hardware vendors who have submitted comments and suggestions over the past few weeks.


Details of the final issues resolved over the last 7 days are as follows:-


Changes to the loop filter. Changes to make the loop filter more HW friendly had to go through several iterations and gave rise to a couple of late bugs. As is often the case, initial attempts to make it more hardware friendly turned out to make things more difficult in SIMD software implementations. Hopefully the final solution is a comfortable compromise for both.


Changes to the way compound prediction modes are coded in the bitstream. Though not conceptually complex and necessary to correctly constrain the allowable compound prediction modes, this change touched a lot of files and getting it done on time and debugged was a Herculean effort by those involved.


Definition and implementation of behaviour at the edge of images. This relates to what prediction modes/sizes and transforms are allowed near the edge of an image that does not break down nicely into 64x64 blocks. I mentioned this at the summit and while it sounds simple, like all the simplest changes, it was actually quite hard to get right. Again a big thank you to all involved in working through the issues.


Some minor changes to the frame header (E.g. coding of frame size not needed for all frames)


Some minor changes to the entropy coding of some symbols and some updates to the default tables.


Paul Wilkins