More VP8 Documentation Items
Mike Melanson
Stylistic matter: search for every occurrence of the phrase "of course"
(there are 19) and strike entirely. Similarly, the phrase "taken up"
should me replaced with something liked "described".
Overall, I'd like to see a solid bitstream reference. Its confusing to
see a concise table of literals that will appear in the bitstream
following by a paragraph describing more flags and literals that will
appear. That paragraph should be in a tabular form.
7.3: Back on the matter of the bool decoder, it's debatable whether the
spec should include copy & pasted C functions implemented. However, the
copy & pasted functions don't match the reference decoder which has some
small tweaks. For example, in the value maintenance code, range and
value are shifted by a constant 1. In the reference decoder, the shifted
value comes from a table.
9.4: MAX_REF_LF_DELTAS and MAX_MODE_LF_DELTAS are used but not defined
anywhere in the spec (both are 4).
9.7: I don't understand this sentence: "Whether golden frame is
refreshed ( 0 complete. This flag does not occur for no, 1 for yes)."
9.8: On the matter of refreshing the last frame buffer, this sentence
left me confused: "VP8 uses one bit, L(1) , to indicate if the last
frame reference buffer is refreshed using the constructed
current frame. On key frame this bit is overridden, and the last frame
buffer is always refreshed."
So, is it supposed to be present on keyframes? Present, but will always
be set to 1? Present, but should be disregarded by the decoder?
Reference decoder seems to indicate that the bit is missing on keyframes.
11.2: bmode_tree data structure is missing a comma after the number 16.
13.2: I'm having trouble with this sentence: "This makes use of the fact
that in any block last non zero coefficient before the end of the block
is not 0 , therefore no dct_eob follows a DCT_0 coefficient in any block."
Another stylistic matter: In describing how the intraframe prediction,
here's a more visual approach I've used to describe the same thing:
http://wiki.multimedia.cx/index.php?title=H.264_Prediction
Something like that might be preferable to copy & pasted C code.
--
-Mike Melanson
Paul Wilkins
I am trying to keep a record of comments and will get someone to do a
run through make a batch of changes in the near future.
Lou Quillio
> Thanks Mike,
>
> I am trying to keep a record of comments and will get someone to do a
> run through make a batch of changes in the near future.
I'm tracking these, too. We were talking today about starting a
project in the git forest just for the bitstream spec -- which is
pretty easy to do since it's sourced in text and already in a git
repo. Just have to make sure it's clear how to work with the source,
mostly because of the MathML, and partly because of the Markdown and
PrinceXML transforms.
LQ
--
Lou Quillio
Tech Writer
WebMProject.org
+1 518.285.0003 <= Mobile (gV)
+1 518.881.4256 <= Office
Yaowu Xu
James
Does anyone know where I can obtain or down load a copy of the VP8/
WEBM standard?
Thanks in advance.
-- James
On 6月2日, 上午10时17分, Yaowu Xu <ya...@google.com> wrote:
> I think it is a good idea to have a text version that changes can be easily
> tracked and reviewed. We may use a review process similar to the one for
> source code patches to incorporate corrections and additions.
>
> Yaowu
>
>
>
> > On Tue, Jun 1, 2010 at 9:33 AM, Paul Wilkins <paulwilk...@google.com>
> > > Thanks Mike,
>
> > > I am trying to keep a record of comments and will get someone to do a
> > > run through make a batch of changes in the near future.
>
> > I'm tracking these, too. We were talking today about starting a
> > project in the git forest just for the bitstream spec -- which is
> > pretty easy to do since it's sourced in text and already in a git
> > repo. Just have to make sure it's clear how to work with the source,
> > mostly because of the MathML, and partly because of the Markdown and
> > PrinceXML transforms.
>
> > LQ
>
> > --
> > Lou Quillio
> > Tech Writer
> > WebMProject.org
> > +1 518.285.0003 <= Mobile (gV)
>
> - 显示引用的文字 -
Mike Melanson
> Hi Mike,
>
> Do you know where I can get a copy of vp8/webm stardard?
http://www.webmproject.org/media/pdf/vp8_bitstream.pdf
--
-Mike Melanson
Lou Quillio
> James wrote:
>> Hi Mike,
>>
>> Do you know where I can get a copy of vp8/webm stardard?
>
> http://www.webmproject.org/media/pdf/vp8_bitstream.pdf
Hi James,
The above is correct. For reference, what you're looking for is
linked from this page:
http://www.webmproject.org/code/specs/
Lou Quillio
> We were talking today about starting a
> project in the git forest just for the bitstream spec -- which is
> pretty easy to do since it's sourced in text and already in a git
> repo.
Here it is:
https://review.webmproject.org/gitweb?p=bitstream-guide.git;a=summary
As stated in the README, this has been a practical-minded document
heretofore, with a very small audience, and has had no ambitions of
becoming a "specification." It may not necessarily have those
ambitions now.
Nevertheless, the world turned a bit in the last month. All
submissions welcome.