Bug 122257

Summary:	LO Impress: Estimated and final sizes differ in Presentation minimizer
Product:	LibreOffice	Reporter:	Vera Blagoveschenskaya <vercha>
Component:	Impress	Assignee:	Not Assigned <libreoffice-bugs>
Status:	NEW ---
Severity:	enhancement	CC:	thb, vasily.melenchuk
Priority:	medium
Version:	6.2.0.0.beta1+
Hardware:	All
OS:	All
See Also:	https://bugs.documentfoundation.org/show_bug.cgi?id=43715
Whiteboard:
Crash report or crash signature:		Regression By:
Bug Depends on:
Bug Blocks:	113354
Attachments:	screen presentation to test

Description Vera Blagoveschenskaya 2018-12-21 13:03:29 UTC

Description:
Estimated and final size differ in Presentation minimizer

Steps to Reproduce:
1. Open some presentation via LO Impress
2. Tools -> Minimize presentation
3. Go through the wizard to the last page. Look at the size estimated
In my case size will be reduced from 16.0 Mb to 8.3 Mb
4. Perform minimization physically
5. Look at the size in the final message

Actual Results:
Final size differs from estimated size (see screenshot)

Expected Results:
The same sizes


Reproducible: Always


User Profile Reset: No



Additional Info:
Reproduced for 

Version: 6.2.0.1
Build ID: 0412ee99e862f384c1106d0841a950c4cfaa9df1
CPU threads: 1; OS: Linux 4.14; UI render: default; VCL: kde5; 
Locale: ru-RU (ru_RU.UTF-8); UI-Language: en-US
Calc: threaded

Version: 6.2.0.1
Build ID: 0412ee99e862f384c1106d0841a950c4cfaa9df1
CPU threads: 1; OS: Linux 4.14; UI render: default; VCL: gtk3; 
Locale: ru-RU (ru_RU.UTF-8); UI-Language: en-US
Calc: threaded

Comment 1 Vera Blagoveschenskaya 2018-12-21 13:05:55 UTC

Created attachment 147741 [details]
screen

Comment 2 Vera Blagoveschenskaya 2018-12-21 13:58:48 UTC

Created attachment 147744 [details]
presentation to test

Comment 3 Durgapriyanka 2018-12-21 20:38:17 UTC

Thank you for reporting the bug. I can confirm that the bug is present in

Version: 6.3.0.0.alpha0+
Build ID: 3c964980da07892a02d5ac721d80558c459532d0
CPU threads: 2; OS: Windows 6.1; UI render: default; VCL: win; 
TinderBox: Win-x86@42, Branch:master, Time: 2018-12-12_02:07:45
Locale: en-US (en_US); UI-Language: en-US
Calc: threaded

Comment 4 Thorsten Behrens (allotropia) 2018-12-22 14:20:40 UTC

Unclear if that is doable - Cc Vasily who was looking into that code recently.

Especially for images, relationship between compression paramaters and actual file size can be rather complex.

Comment 5 Vasily Melenchuk (CIB) 2018-12-22 16:11:10 UTC

Current implementation (see https://opengrok.libreoffice.org/xref/core/sdext/source/minimizer/optimizerdialogcontrols.cxx#791-806) is making very rough calculation based only on desired JPG compression and resolution. This approach gives very rough estimation even for JPEG images, but here are many factors not taken into account, like removing hidden slides, cropping images, etc.

Theoretically, I see no limitations to provide more precise filesize estimation.