Issue 225 in webp: Lossless spec does not specify uint8 to int8 conversion

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pascal.m… via monorail

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Sep 5, 2016, 2:01:40 PM9/5/16
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Owner: jy...@google.com
Status: Accepted

Comment #2 on issue 225 by pascal.m...@gmail.com: Lossless spec does not specify uint8 to int8 conversion
https://bugs.chromium.org/p/webp/issues/detail?id=225#c2

thanks for spotting the missing description.
8b two's complement was indeed implied.
I uploaded a patch[1] to make an explicit mention of it.

[1] https://chromium-review.googlesource.com/#/c/380558/

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bugdro… via monorail

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Sep 7, 2016, 1:53:52 AM9/7/16
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Comment #3 on issue 225 by bugd...@chromium.org: Lossless spec does not specify uint8 to int8 conversion
https://bugs.chromium.org/p/webp/issues/detail?id=225#c3

The following revision refers to this bug:
https://chromium.googlesource.com/webm/libwebp/+/13ae011e4cd540088dfc80ee2f303811f5c51389

commit 13ae011e4cd540088dfc80ee2f303811f5c51389
Author: Pascal Massimino
Date: Mon Sep 05 17:57:56 2016

doc: use two's complement explicitly for uint8->int8 conversion

BUG=webp:225

Change-Id: I6bad131e275dbd992484e95a1b834010121281b8

[modify] https://crrev.com/13ae011e4cd540088dfc80ee2f303811f5c51389/doc/webp-lossless-bitstream-spec.txt

pascal.m… via monorail

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Sep 9, 2016, 6:11:50 AM9/9/16
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Status: Done

Comment #4 on issue 225 by pascal.m...@gmail.com: Lossless spec does not specify uint8 to int8 conversion
https://bugs.chromium.org/p/webp/issues/detail?id=225#c4

change will be reflected on the web site soon.
thanks for the report!

jyrki.al… via monorail

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Sep 12, 2016, 10:49:27 AM9/12/16
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Comment #5 on issue 225 by jyrki.al...@gmail.com: Lossless spec does not specify uint8 to int8 conversion
https://bugs.chromium.org/p/webp/issues/detail?id=225#c5

Lukas, would you be fine leaving this unchanged? It seems to me that all major computers designed after 1965 use two's complement for signed integers. We could add a text that int8 is two's complement, but adding more weight and detail to the spec does not necessarily make it easier to read.

bugdro… via monorail

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Dec 9, 2016, 10:00:29 PM12/9/16
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Labels: merge-merged-0.5.2

Comment #6 on issue 225 by bugd...@chromium.org: Lossless spec does not specify uint8 to int8 conversion
https://bugs.chromium.org/p/webp/issues/detail?id=225#c6


The following revision refers to this bug:

Author: Pascal Massimino
Date: Mon Sep 05 17:57:56 2016

doc: use two's complement explicitly for uint8->int8 conversion

BUG=webp:225

Change-Id: I6bad131e275dbd992484e95a1b834010121281b8
(cherry picked from commit 13ae011e4cd540088dfc80ee2f303811f5c51389)

[modify] https://crrev.com/76e190735b07adce29b86b47c75f82315ffcd8fd/doc/webp-lossless-bitstream-spec.txt
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