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section 3.8.1.2 needs to define get_rac #230

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mcr opened this issue Sep 22, 2020 · 8 comments
Closed

section 3.8.1.2 needs to define get_rac #230

mcr opened this issue Sep 22, 2020 · 8 comments

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@mcr
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mcr commented Sep 22, 2020

As per Barry Lieba review, the section 3.8.1.2 says:

 "get_rac" returns a boolean, computed from the bytestream as
 described in Section 3.8.1.1. 

but it is not defined, and likely relates to the decode process.

@mcr
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mcr commented Sep 22, 2020

https://github.com/dwbuiten/go-ffv1/blob/master/ffv1/rangecoder/range.go
also change reference from 3.8.1.1 to cite figure 9.

@mcr
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mcr commented Sep 22, 2020

@dericed

@michaelni michaelni changed the title section 3.8.1.2 needs to define getrac section 3.8.1.2 needs to define get_rac Sep 22, 2020
@dwbuiten
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Worth noting here that when I implemented go-ffv1, it was with an older revision of the spec, and it seems the figure numbers have since changed... I'll update the comments.

(Also worth noting that go-ffv1 is not an official reference decoder.)

@dericed
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dericed commented Sep 23, 2020

Hi @dwbuiten, you could contextualize your comments to the version of the draft such as "draft-ietf-cellar-ffv1-17", although as the document is in "IESG Evaluation" status the RFC number may be soon.

@dwbuiten
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Yes, I'll do that when I update them.

michaelni pushed a commit that referenced this issue Oct 5, 2020
Addresses #230 and #231.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
Github: Closes #242
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
@dericed
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dericed commented Oct 6, 2020

@dwbuiten, @michaelni, are you able to assist with the get_rac piece of Barry's review. The quote from the review is

— Section 3.8.1.2 —

   "get_rac" returns a boolean, computed from the bytestream as
   described in Section 3.8.1.1.

I see nothing in Section 3.8.1.1 that describes get_rac.

I understand that get_rac refers to figure 9; however a narrative could help. For instance does rac mean RAnge Coded binary value? If figure 9 is read as the i-th range coded binary value equals, then what is the R_i of the formula mean?

This was referenced Oct 6, 2020
@michaelni
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I understand that get_rac refers to figure 9; however a narrative could help. For instance does rac mean RAnge Coded binary value?

IIRC get_rac() was named for consistancy with get_cabac(), it returns a single bit coded using the range coder. Not sure if the 3 letters can be matched to grammatically 100% fitting words

@JeromeMartinez
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It looks like this issue can be closed (#230 and #241 are merged).

@mcr mcr closed this as completed Mar 23, 2021
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