— RU.COMPRESS
From : Eugene D. Shelwien 2:5020/400 18 Feb 03 20:41:29
To : Maxim Smirnov
Subj : Re: ëó÷øèå àðèôìåòèêè äå-ôàêòî
From: "Eugene D. Shelwien" <shelwien@thermosyn.com>
Hi!
> >> Ó÷åáíûé êîìïðåññîð DummyPPM.cpp ("DummyPPM coder (method D), íàïå÷àòàí
> >> Ì.Ñìèðíîâûì â 2000ã) èñïîëüçóåò "arith.c by Michael Schindler, Feb. 1997"
> >> ñ ïîìåòêîé "Public domain ñ ó÷åòîì gnu'ñíîñòè arith"
>
> EDS> ×åñòíî ñêàçàòü, íå âèæó ñìûñëà åãî (îðèãèíàëüíûé rangecoder)
> EDS> èñïîëüçîâàòü. Hàïèñàí î÷åíü çàïóòàííî è íåýôôåêòèâíî.
> EDS>
>
> Çàïóòàííî -- ôàêò.
> Håýôôåêòèâíî -- ñïîðíî.
_Hàïèñàí_ íåýôôåêòèâíî ;)
Ò.å. òîò æå àëãîðèòì áóäåò ðàáîòàòü áûñòðåé â íîðìàëüíîé ðåàëèçàöèè.
> Ïî ñæàòèþ îí ÷óòîê îáñòàâëÿåò ïðî÷èå èññëåäîâàííûå ìíîþ ðåàëèçàöèè.
> Ðàáîòàåò ïðàêòè÷åñêè íîçäðÿ â íîçäðþ ñ q-êîäåðîì.
Ó íåãî MaxFreq íà îäèí áèò ìåíüøå. Äëÿ ppmy ýòî èìååò çíà÷åíèå.
> Maxim
Ñ÷àñòëèâî!
- Øåëâèí
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* Origin: Shadow Research Center (2:5020/400)
— RU.COMPRESS
From : Bulat Ziganshin 2:5093/4.126 18 Feb 03 21:14:36
To : All
Subj :
* Originally in RU.COMPRESS
Ïðèÿòíîãî òåáå äíÿ è íåçàáûâàåìîé íî÷è, All!
÷èòàþ âàñ è ÷óâñòâóþ ñåáÿ ïàïóàñîì ñ çåðêàëüöåì. ëàäíî, çàâòðà ïîñòàðàþñü âíåñò
è ñâîé ïîñèëüíûé âêëàä ;)
Bulat, mailto:bulatz-AT-fort.tatarstan.ru, ICQ: work 15872722, home 11849833
... Èíîãäà äëÿ òîãî, ÷òîáû èçìåíèòü ñâîå âîñïðèÿòèå ìèðà,
... ëþäè ïûòàþòñÿ èçìåíèòü ñàì ìèð
--- GoldED+/W32 1.1.2
* Origin: ×óáàéñ - ïîâåëèòåëü Òüìû (2:5093/4.126)
— RU.COMPRESS
From : Dmitry Subbotin 2:5020/400 19 Feb 03 01:10:55
To : Eugene D. Shelwien
Subj : Re: ëó÷øèå àðèôìåòèêè äå-ôàêòî
From: "Dmitry Subbotin" <morf@nline.ru>
Tue Feb 18 2003 20:32, Eugene D. Shelwien wrote to Dmitry Subbotin:
>> 1. Îáû÷íûå àðèôìåòè÷åñêèå êîäåðû. Îáåñïå÷èâàþò êîäèðîâàíèå äàííûõ ñ
>> ðàçìåðîì âûõîäà áëèçêîãî ê îïòèìàëüíîìó.
EDS> Håñêîëüêî íàïîìèíàåò èçâåñòíóþ ðåêëàìó ;).
EDS> Êàêèå êîíêðåòíî "îáû÷íûå" êîäåðû èìåþòñÿ â âèäó?
Hó êàê îíè îïèñàíû âî âñåõ ñòàðûõ ñòàòüÿõ. Âñåì, êòî èõ ÷èòàë, ýòî äîëæíî áûòü
èçâåñòíî. ;)
EDS> Ïîñìîòðè, pls, ìîè ìîäèôèêàöèè øèíäëåðîâñêîãî êîäåðà â
EDS> Ðàñïðîñòðàíÿþòñÿ ëè íà íèõ øèíäëåðîâñêèå ïðàâà?
Äóìàþ, íåò. Ïðàâà Øèíäëåðà ðàñïðîñòðàíÿþòñÿ íà êîä, íî íå íà ñàìó èäåþ
rangecoder'à.
>> 3. Carryless rangecoder èì. ìåíÿ (îí æå "ðóññêèé íàðîäíûé"). Ïðåäñòàâëÿåò
>> ñîáîé ìîäèôèêàöèþ rangecoder'à, ñèëüíî óïðîùåííóþ çà ñ÷åò ïðèìåíåíèÿ
>> àëüòåðíàòèâíîé ñõåìû îáðàáîòêè ïåðåíîñîâ. Håìíîãî áûñòðåå îáû÷íîãî
>> rangecoder'a (íåñóùåñòâåííî äëÿ PPM),
EDS> Hî äåêîäèðîâàíèå ìåäëåííåé.
Äà, âîò ýòî ÿ íàâðàë, ïðèçíàþ. Ðåàëüíî ïî òåñòàì ðàçíèöû ïî÷òè íèêàêîé.
>> 4. Rangecoder'û îò Å.Øåëâèíà. Hàñêîëüêî ÿ çíàþ, ÿâëÿþòñÿ âàðèàíòîì
>> carryless'à, â êîòîðîì ñíÿòî îãðàíè÷åíèå íà TotalFreq ïóòåì èñïîëüçîâàíèÿ
>> áîëüøèõ ÷èñåë.
EDS> Äàëåêî íå òîëüêî. Åùå åñòü íåñêîëüêî âàðèàöèé íà òåìó øèíäëåðîâñêîãî
EDS> rangecoder'à (çíà÷èòåëüíî óïðîùåííûõ ñðàâíèòåëüíî ñ îðèãèíàëîì), åùå
EDS> áîëåå êîìïàêòíàÿ âåðñèÿ carryless (CLR), à òàêæå ðåàëèçàöèÿ
EDS> ñîâåðøåííî äðóãîãî ìåòîäà èçáåæàíèÿ ïåðåíîñà (CLRF).
Ïîñìîòðåë. CLRF - ýòî ïîòåíöèàëüíûé ãëþêîäðîì. CLR - íàòóðàëüíûé âàðèàíò
carryless'à, â êîòîðîì ñíÿòî îãðíè÷åíèå íà TotalFreq. ;) Âðîäå äîëæåí
ðàáîòàòü.
EDS> Hå ãîâîðÿ óæå î ïàðàëëåëüíîé (parcoder.rar) è ìóëüòèàëôàâèòíîé
EDS> (marcdemo.rar) âåðñèÿõ rangecoder'à.
Òóò ïðèçíàþ ÷òî íå âîçäàë äîëæíîå òâîèì òðóäàì.
>>  öåëîì ìîæíî ñêàçàòü, ÷òî ñ òî÷êè çðåíèÿ ñæàòèÿ áîëüøîé ðàçíèöû ìåæäó
>> ðàçíûìè êîäåðàìè ïî÷òè íåò (êðîìå ñëó÷àÿ 5 è îòäåëüíûõ óáëþäî÷íûõ
>> èìïëåìåíòàöèé).
EDS> Ïðè ïîïûòêàõ êîäèðîâàíèÿ ñîáûòèé ñ âåðîÿòíîñòüþ ìåíüøå 1/64k, ê
EDS> ñîæàëåíèþ, òàêîâàÿ îáúÿâëÿåòñÿ.
Hó òîæå ïîæàëóé ïðàâèëüíî.
2 Ðîìàí: êîðî÷å ãîâîðÿ, ìîæíî áðàòü øåëâèíñêèé CLR êàê ïîäõîäÿùèé ïî âñåì
ñòàòüÿì êîäåð. Îãðàíè÷åíèå íà TotalFreq â 2^24 òåáÿ íàâåðíîå óñòðîèò.
Ñ íàèëó÷øèìè,
Äèìà
--- ifmail v.2.15dev5
* Origin: FidoNet Online - http://www.fido-online.com (2:5020/400)
— RU.COMPRESS
From : RIP 2:5093/4.126 19 Feb 03 02:04:15
To : All
Subj : News at ftp://ftp.elf.stuba.sk/pub/pc/pack/
ftp://ftp.elf.stuba.sk/pub/pc/pack/7z230b28.exe
7-ZIP Archiver v2.30 beta 28 - Command line file archiver (1,136,073 bytes)
ftp://ftp.elf.stuba.sk/pub/pc/pack/comprsia.exe
Compressia v1.0 Beta 1 - GUI Archiver for Win32 (235,008 bytes)
--- PktMake.pl
* Origin: PktMake.pl (2:5093/4.126)
— RU.COMPRESS
From : Dmitry Subbotin 2:5020/400 19 Feb 03 11:22:45
To : Eugene D. Shelvein
Subj : Re: ëó÷øèå àðèôìåòèêè äå-ôàêòî
From: "Dmitry Subbotin" <morf@nline.ru>
Wed Feb 19 2003 01:10, Dmitry Subbotin wrote to Eugene D. Shelwien:
DS> CLRF - ýòî ïîòåíöèàëüíûé ãëþêîäðîì.
×åãî-òî ÿ ìåíÿ ñàìîãî ñèëüíî ãëþ÷èò â ïîñëåäíåå âðåìÿ. Ïàðäîí, âñå ñ CLRF
íîðìàëüíî, áóäåò ðàáîòàòü.
Ñ íàèëó÷øèìè,
Äèìà
--- ifmail v.2.15dev5
* Origin: FidoNet Online - http://www.fido-online.com (2:5020/400)
— RU.COMPRESS
From : Dmitry Shkarin 2:5020/400 19 Feb 03 19:47:05
To : Maxim Smirnov
Subj : Re: ëó÷øèå àðèôìåòèêè äå-ôàêòî
From: "Dmitry Shkarin" <dmitry.shkarin@mtu-net.ru>
Hi, Maxim!
> ïðî÷èå èññëåäîâàííûå ìíîþ ðåàëèçàöèè. Ðàáîòàåò ïðàêòè÷åñêè
> íîçäðÿ â íîçäðþ ñ q-êîäåðîì.
q-êîäåð - ýòî ÷òî? Åñëè IBMîâñêèé äâîè÷íûé Q-coder, òî ñðàâíèâàòü èõ
íåêîððåêòíî.
--- ifmail v.2.15dev5
* Origin: home (2:5020/400)
— RU.COMPRESS
From : Maxim Smirnov 2:5020/175.2 20 Feb 03 10:04:43
To : Dmitry Shkarin
Subj : Re: ëó÷øèå àðèôìåòèêè äå-ôàêòî
From: "Maxim Smirnov" <model@iac.spb.ru>
Wed Feb 19 2003 19:47, Dmitry Shkarin wrote to Maxim Smirnov:
DS> From: "Dmitry Shkarin" <dmitry.shkarin@mtu-net.ru>
DS> Hi, Maxim!
>> ïðî÷èå èññëåäîâàííûå ìíîþ ðåàëèçàöèè. Ðàáîòàåò ïðàêòè÷åñêè
>> íîçäðÿ â íîçäðþ ñ q-êîäåðîì.
DS> q-êîäåð - ýòî ÷òî? Åñëè IBMîâñêèé äâîè÷íûé Q-coder, òî ñðàâíèâàòü èõ
DS> íåêîððåêòíî.
íå-à, ibm'èé q-êîäåð -- ýòî íå q-êîäåð, à äâîè÷íûé èáì'îâñêèé
àðèôìåòèê :-)
À âîò q-êîäåðîì îäíîçíà÷íî ÿâëÿåòñÿ
ARITHMETIC CODING FOR DATA COMPRESSION
IAN H. WITTEN, RADFORD M. NEAL, and JOHN G. CLEARY
â ñèëó áîëüøîãî êîëè÷åñòâà q â èñõîäíèêå ;-)
Ïàðäîí çà ïóòàíèöó.
Êñòàòè îá ÈÁÌ. Ñòàòüÿ ïî Qx-êîäåðó:
http://www.research.ibm.com/journal/rd/426/mitchell.html
Maxim
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