dany/libwebp
1
0
Fork 0
mirror of https://github.com/webmproject/libwebp.git synced 2025-04-05 00:16:50 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity

man/cwebp.1: add more detail to -partition_limit

Browse Source 
-m and -q can also affect the encoder's ability to satisfy the
partition limit.

Bug: webp:634
Change-Id: I89ea2b037c0cf1e109c251f45c09378ce501862b
This commit is contained in:
James Zern 2024-03-26 13:00:35 -07:00
parent 3c0011bbd1
commit 7b0bc2352b
1 changed files with 5 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
man/cwebp.1
View File

@ -1,5 +1,5 @@
.\" Hey, EMACS: -*- nroff -*- .\" Hey, EMACS: -*- nroff -*-
.TH CWEBP 1 "March 14, 2024" .TH CWEBP 1 "March 26, 2024"
.SH NAME .SH NAME
cwebp \- compress an image file to a WebP file cwebp \- compress an image file to a WebP file
.SH SYNOPSIS .SH SYNOPSIS
@ -204,7 +204,8 @@ In the VP8 format, the so\-called control partition has a limit of 512k and
is used to store the following information: whether the macroblock is skipped, is used to store the following information: whether the macroblock is skipped,
which segment it belongs to, whether it is coded as intra 4x4 or intra 16x16 which segment it belongs to, whether it is coded as intra 4x4 or intra 16x16
mode, and finally the prediction modes to use for each of the sub\-blocks. mode, and finally the prediction modes to use for each of the sub\-blocks.
For a very large image, 512k only leaves room to few bits per 16x16 macroblock. For a very large image, 512k only leaves room for a few bits per 16x16
macroblock.
The absolute minimum is 4 bits per macroblock. Skip, segment, and mode The absolute minimum is 4 bits per macroblock. Skip, segment, and mode
information can use up almost all these 4 bits (although the case is unlikely), information can use up almost all these 4 bits (although the case is unlikely),
which is problematic for very large images. The partition_limit factor controls which is problematic for very large images. The partition_limit factor controls
@ -213,7 +214,8 @@ useful in case the 512k limit is reached and the following message is displayed:
\fIError code: 6 (PARTITION0_OVERFLOW: Partition #0 is too big to fit 512k)\fP. \fIError code: 6 (PARTITION0_OVERFLOW: Partition #0 is too big to fit 512k)\fP.
If using \fB\-partition_limit\fP is not enough to meet the 512k constraint, one If using \fB\-partition_limit\fP is not enough to meet the 512k constraint, one
should use less segments in order to save more header bits per macroblock. should use less segments in order to save more header bits per macroblock.
See the \fB\-segments\fP option. See the \fB\-segments\fP option. Note the \fB-m\fP and \fB-q\fP options also
influence the encoder's decisions and ability to hit this limit.
.SS LOGGING OPTIONS .SS LOGGING OPTIONS
These options control the level of output: These options control the level of output: