From 7b0bc2352b3e7d0a979bebfe40d855cf1c61dc48 Mon Sep 17 00:00:00 2001 From: James Zern Date: Tue, 26 Mar 2024 13:00:35 -0700 Subject: [PATCH] man/cwebp.1: add more detail to -partition_limit -m and -q can also affect the encoder's ability to satisfy the partition limit. Bug: webp:634 Change-Id: I89ea2b037c0cf1e109c251f45c09378ce501862b --- man/cwebp.1 | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/man/cwebp.1 b/man/cwebp.1 index 07b575cc..f8d88143 100644 --- a/man/cwebp.1 +++ b/man/cwebp.1 @@ -1,5 +1,5 @@ .\" Hey, EMACS: -*- nroff -*- -.TH CWEBP 1 "March 14, 2024" +.TH CWEBP 1 "March 26, 2024" .SH NAME cwebp \- compress an image file to a WebP file .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, 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. -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 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 @@ -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. 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. -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 These options control the level of output: