[FFmpeg-devel] vp8: decoder rewrite, spec cleanup

[Ronald S. Bultje]

Hi,

On Fri, May 28, 2010 at 2:56 PM, Diego Biurrun <diego at biurrun.de> wrote:
> On Fri, May 28, 2010 at 01:47:38PM -0400, John Koleszar wrote:
>> Also, if you have any other ideas on how we could work with the open
>> source video community, I'd love to hear them. The webm-discuss@ list
>> is a good place for these topics, technical topics should remain on
>> codec-devel at . We want to work with everybody and be good citizens, but
>> please bear with us; we're new to working in the open source
>> environment and it will take some time to come up to speed.
>
> Another thing I would suggest is looking into releasing the other On2
> codecs into the open. ?We are not only interested in VP8, we want free
> implementations of everything (VP4, VP5, VP6, VP7, AVC audio).

I've +1'ed this before and would like to again. Even if it's old
broken code that doesn't compile anymore, anything is better than
having to RE it.

Spec-wise:
- chapter 17.1 and 17.2 are very oddly split. Note how 17.2, the
second half is completely unrelated to the first half (and occurs in a
completely separate part of the bitstream), and 17.2 first-half
basically completes 17.1.
- for chapter 18, it's not immediately clear how to handle MVs
pointing outside the visible range (this is discussed in other parts
of the spec, but not here, a reference would be handy)

Libvpx-wise, vp8_dx_iface.c, vp8_peek_si():
         * First 3 byte header including version, frame type and an offset
         * Next 3 bytes are image sizewith 12 bit each for width and height
That comment is clearly wrong.

Regards,
Ronald