Closed GoogleCodeExporter closed 9 years ago
thanks for the report!
i can confirm some values are badly compressed on the alpha plane.
See attached the Y/U/V/A planes for a 00.tga compressed with 0.4.2 vs HEAD.
Investigating...
Original comment by pascal.m...@gmail.com
on 22 Jan 2015 at 2:55
Attachments:
looks like the regression was introduced by
https://gerrit.chromium.org/gerrit/#/c/72101/1/src/enc/vp8l.c
with a bad interaction between references tokens and increased color_cache bits.
I will submit an "emergency fix" to shut this new feature off until the problem
is figured out.
-> https://gerrit.chromium.org/gerrit/73565
btw: attaching the good 00_HEAD_bad.png this time, for future reference.
Original comment by pascal.m...@gmail.com
on 22 Jan 2015 at 6:15
Attachments:
v0.3.1 appears to be correct, so using that as a base this bisects to:
64c844863ab0d13e8dd51a59001ab55fbe64065e is the first bad commit
commit 64c844863ab0d13e8dd51a59001ab55fbe64065e
Author: Urvang Joshi <urvang@google.com>
Date: Mon May 13 16:24:49 2013 -0700
Further reduce memory to decode lossy+alpha images
Earlier such images were using roughly 9 * width * height bytes for
decoding. Now, they take 6 * width * height memory.
Change-Id: Ie4a681ca5074d96d64f30b2597fafdca648dd8f7
:040000 040000 da89ac00cb7fa3ca1bd34073037c38d58f5cf420
8a8f8f98f2e1854a47a5eadf606e9809a9fd89ad M src
Original comment by jz...@chromium.org
on 22 Jan 2015 at 9:11
strange, 0.4.2 is correct here. The error seemed to have been introduced
since...
Original comment by pascal.m...@gmail.com
on 22 Jan 2015 at 9:51
[deleted comment]
As discussed offline, the regression James found was fixed in:
https://gerrit.chromium.org/gerrit/#/c/58842/, and the image decodes fine at
that point.
So, I reran bisect from that commit, and here's what I got.
a4d5f59d9e0869009433103818e87d131a56270d is the first bad commit
commit a4d5f59d9e0869009433103818e87d131a56270d
Author: skal <pascal.massimino@gmail.com>
Date: Mon Jun 24 09:34:30 2013 +0200
Faster lossless decoding
Specialize and simplify the alpha-decoding case, which is used when:
- no color-cache is use
- all red/blue/alpha values are the same (and hence their Huffman tree has
only 1 symbol. We don't need to consume any bits for reading these).
+ revamped the loop to use size_t and offsets instead of pointers.
~2-3% faster on Unix (gcc) but up to 25% faster lossy+alpha decoding
on Mac (llvm) and ARM.
Change-Id: I43c9688d1e4811cab0ecf0108a5b8f45781083e6
:040000 040000 3f13501c31f3b1e28d9023d7336f16a8a8d03279
7504e82c2f23ca486a377eb4a6d93b1e342a8aea M src
Original comment by urv...@google.com
on 22 Jan 2015 at 9:58
I ended up at the same point, earlier I was bisecting across 2 working branches
with a merge in between which may have caused the difference. When I check from
that merge (30e77d0 Merge branch '0.3.0') I hit the same commit.
Original comment by jz...@google.com
on 22 Jan 2015 at 10:24
Pascal, try to directly decode the alpha plane of the image encoded with HEAD.
This works fine before the commit a4d5f59d9e0869009433103818e87d131a56270d I
mentioned above, but not anytime after. (0.4.2 is bad as well).
Original comment by urv...@google.com
on 22 Jan 2015 at 10:25
This seems to be related to a change in DecodeImageData() from the earlier
macro implementation:
- if (src < src_end) {
\
- htree_group = GetHtreeGroupForPos(hdr, col, row);
\
+ if (src < src_last) {
+ if (col & mask) htree_group = GetHtreeGroupForPos(hdr, col, row);
specifically the if condition, reverting that to src_end works here where (row,
col, last_row)==(40, 40, 40); I haven't looked more closely at the logic
itself...
Original comment by jz...@google.com
on 22 Jan 2015 at 11:55
Indeed, that is the problem.
In fact, no if condition is needed, as src <= src_end is implied at that point.
Sending a patch shortly.
Original comment by urv...@google.com
on 23 Jan 2015 at 1:13
i think "if (src < src_end) { ... }" is indeed correctly fixing the issue
Original comment by pascal.m...@gmail.com
on 23 Jan 2015 at 7:16
Fixed here: https://gerrit.chromium.org/gerrit/#/c/73580/
Thanks again for the report!
Original comment by urv...@google.com
on 23 Jan 2015 at 9:56
Original issue reported on code.google.com by
shekh.an...@gmail.com
on 22 Jan 2015 at 1:24Attachments: