From dc7687340632b9b96d8c0725613c8a92a412806c Mon Sep 17 00:00:00 2001
From: Martijn Laan <1092369+martijnlaan@users.noreply.github.com>
Date: Thu, 10 Oct 2024 07:58:17 +0200
Subject: [PATCH] Explain effect of LZMA2_DIC_SIZE_FROM_PRO, also mentioned in
lzma-specification.txt from the SDK, and seen in test (especially when
compressing).
---
ISHelp/isetup.xml | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/ISHelp/isetup.xml b/ISHelp/isetup.xml
index 66f6612cf..0a96ac3be 100644
--- a/ISHelp/isetup.xml
+++ b/ISHelp/isetup.xml
@@ -4454,7 +4454,7 @@ Name: portablemode; Description: "Portable Mode"
The compression memory requirements are approximately 60% of the above when LZMAMatchFinder is set to HC at the expense of compression ratio.
-
lzma2 is the method of compression employed by the 7-Zip LZMA2 compressor. LZMA2 is a modified version of LZMA that offers a better compression ratio for incompressible data (random data expands about 0.005%, compared to 1.35% with original LZMA), and optionally can compress multiple parts of large files in parallel, greatly increasing compression speed but with a possible reduction in compression ratio (see LZMANumBlockThreads). Like LZMA, it can consume a lot of memory; see the above table. If a compression level isn't specified, it defaults to max.
+
lzma2 is the method of compression employed by the 7-Zip LZMA2 compressor. LZMA2 is a modified version of LZMA that offers a better compression ratio for incompressible data (random data expands about 0.005%, compared to 1.35% with original LZMA), and optionally can compress multiple parts of large files in parallel, greatly increasing compression speed but with a possible reduction in compression ratio (see LZMANumBlockThreads). If a compression level isn't specified, it defaults to max. Like LZMA, LZMA2 can consume a lot of memory; see the above table. Do note: LZMA2 only supports a limited number of dictionary sizes and other sizes will be rounded up to the next supported size. Supported sizes are powers of two starting at 4 (4, 8, 16, 32, etc., up to 1048576) and the midway points between them (6, 12, 24, etc., up to 786432). For instance, a dictionary size of 524289 (512 MB + 1 byte) has the same memory requirements as one of 786432 (768 MB).