newcoleco
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Posts posted by newcoleco
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From my presentation about my recent work on Coleco graphics tools; Coleco ADAM users annual convention ADAMCon 29, July 20-23, 2017, in Guelph, Ontario.
The following text is about data compression obtained by using popular LZ variants for 8-bit systems, including my own named Dan, applied on several bitmap pictures for 8-bit systems.
These pictures include formats Coleco .PC, MSX .SC2, and ZX Spectrum .SCR. The pictures are limited to PATTERN and COLOR tables only (no sprites allowed).Table showing results with MIN, MAX, and AVERAGE for each cathebory.
Please note : Exomizer needs extra RAM prior to decompress data, and RLE (Run Length Encoding) is not a LZ variant.
- 3822.74 <- Exomizer
- 3930.13 <- Dan3
- 3931.65 <- Dan4
- 3939.92 <- Dan1
- 3940.85 <- Dan2
- 3944.20 <- PuCrunch
- 4044.70 <- MegaLZ
- 4059.60 <- Pletter , BitBuster
- 4063.13 <- ZX7
- 4077.10 <- ApLib aka APack
- 5899.67 <- RLE
Table 1 - Average compression in bytes obtained on 95 Graphic Mode 2 bitmap pictures of 12K bytes each.
- 4797.03 <- Exomizer
- 4928.53 <- Dan4
- 4930.37 <- PuCrunch
- 4940.84 <- Dan3
- 4958.74 <- MegaLZ
- 4961.80 <- Pletter , BitBuster
- 4963.39 <- ZX7
- 4986.14 <- ApLib aka APack
- 4992.42 <- Dan2
- 4996.06 <- Dan1
- 6059.89 <- RLE
Table 2 - Average compression in bytes on 1115 ZX Spectrum .SCR complex pixel art of 6912 bytes each.
- 2714.56 <- Exomizer
- 2828.22 <- Dan3
- 2832.77 <- Dan4
- 2863.85 <- Pletter , BitBuster
- 2865.63 <- MegaLZ
- 2866.14 <- PuCrunch
- 2867.64 <- ApLib aka APack
- 2867.65 <- ZX7
- 2875.06 <- Dan2
- 2890.77 <- Dan1
- 4264.42 <- RLE
Table 3 - Average compression in bytes on 615 ZX Spectrum .SCR simple pixel art of 6912 bytes each.
DAN3 and DAN4 data compression
DAN3 is a lossless data compression based on the idea to compress relevant data with some patterns more than optimizing patches of emptiness, using the best ideas of LZ77-LZSS variants DAN1 and DAN2 data compression, but changed how doublets ( size and relative index values ) are encoded; using Golomb Gamma instead of Elias Gamma, limited the size of sequences, and simplified the binary tree to decode offset values.
DAN4 is an attempt to improve DAN3. First, the modified k=1 Exp-Golomg values reads bytes instead of bits for large values which improves the decompression speed. Second, the two (2) supported modes, one optimized for simple data and one for complex data such as detailed pixel-arts and heavily dithered graphics.
Of course, DAN3 and DAN4 are not miracle solutions.Because of its nature, DAN3 struggle to do better compression ratio results for pictures with lots of spaces like the following one.
And sometimes, DAN1 is better than DAN3 for bitmap with dithering like the following one by 66 bytes.
So how to decide which data compression to use for our projects? Trial and error? Perhaps, or simply use the data compression tools you are most comfortable with.
Samples with their data compression results:
NewColeco Presents ROM File Edition- 837 < Exomizer
- 845 < Dan2
- 845 < Dan1
- 858 < Dan4
- 863 < PuCrunch
- 895 < ZX7
- 895 < ApLib
- 898 < Pletter
- 908 < Dan3
- 969 < MegaLZ
- 1478 < RLE
Smurf Challenge
- 1140 < Exomizer
- 1162 < Dan2
- 1164 < Dan1
- 1170 < PuCrunch
- 1185 < Dan4
- 1188 < Dan3
- 1229 < ApLib
- 1233 < Pletter
- 1237 < ZX7
- 1245 < MegaLZ
- 1705 < RLE
Bejeweled Title Screen
- 1306 < Exomizer
- 1358 < Dan2
- 1359 < Dan1
- 1372 < Dan4
- 1376 < Dan3
- 1380 < PuCrunch
- 1424 < ApLib
- 1427 < Pletter
- 1427 < ZX7
- 1463 < MegaLZ
- 2711 < RLE
Robee Blaster
- 1937 < Exomizer
- 2005 < PuCrunch
- 2016 < Dan3
- 2023 < Dan4
- 2024 < Dan2
- 2047 < Dan1
- 2050 < ZX7
- 2054 < Pletter
- 2098 < ApLib
- 2101 < MegaLZ
- 8752 < RLE
Maze Maniac
- 2433 < Exomizer
- 2504 < PuCrunch
- 2522 < Dan3
- 2551 < Dan4
- 2554 < Dan2
- 2570 < Dan1
- 2620 < Pletter
- 2621 < ZX7
- 2650 < MegaLZ
- 2671 < ApLib
- 4609 < RLE
Anniversary Cake Demo
- 2947 < Exomizer
- 2993 < PuCrunch
- 3020 < Dan2
- 3025 < Dan3
- 3028 < Dan1
- 3058 < Dan4
- 3108 < ApLib
- 3123 < MegaLZ
- 3126 < ZX7
- 3130 < Pletter
- 4048 < RLE
F1SPP
- 3913 < Exomizer
- 4013 < Dan3
- 4028 < Dan2
- 4033 < Dan4
- 4045 < Dan1
- 4096 < PuCrunch
- 4107 < MegaLZ
- 4170 < Pletter
- 4170 < ZX7
- 4208 < ApLib
- 6770 < RLE
Lena aka Lenna (used a lot in papers about imaging)
- 8595 < Exomizer
- 8812 < Dan4
- 8840 < Dan3
- 8873 < Dan1
- 8897 < Dan2
- 8925 < PuCrunch
- 8962 < MegaLZ
- 9084 < ZX7
- 9085 < Pletter
- 9141 < ApLib
- 11958 < RLE
UPDATES : November 17, 2017. Added informations about DAN4 results developped during October-November 2017.
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Sorry. I ordered flora from them, but have not heard or received anything in a month. I have found AdamCon is now being ran by Adam News Network rather than adamcon.org. Dale has not posted here for a year and emails get bounced back as unavailable. I think he's retired, but left the store website up that still takes payments, unfortunately. Anyhow, just checked Gooddealgames and they have it back in stock (a little pricier, as usual), so I am ordering from them and getting a refund from PayPal. Took some investigating, but didn't really need to bother you once I figured all this out. Thanks though. BTW, PM doesn't work, if not intentional.
You're not bothering me, and thank you for making me aware of the issue.
I really should clean up my mailbox to get messages directed to me personally.
I've sent an email to Dale Wick about the situation and you should hear from him soon.
Sorry for the inconveniences
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removed.
You went to the ADAMCon website to buy Flora game and there is no answer? Try contact Dale Wick, he is the admin of the website.
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I might be naive but I refuse to be angry toward anybody going to an event like this one; my anger is focussed to the ones abusing us, trying to ruin our hobby and friendly community.
Hello, I am the guy with the ticket but am unable to make it to the event. I asked for a refund but got no response. My name is Jason and I post regularly about retro games, mostly ColecoVision & Intellivision, under the name Golden Galaxies Gaming on Facebook & Instagram. I follow the Atari Age Facebook page but don't post here. Someone from a ColecoVision fan page on Facebook sent me the link to this thread. I'm not even sure if someone else can use my ticket since it has my name on it. Can I do that? Thanks ☺
I wish there is/was a way to refund your ticket or able to give to someone else... any information about terms and conditions about such ticket?
We are better than a certain person strong-arming ColecoVision fans. We are here to enjoy and remember ColecoVision. Let's not turn against each others.
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Subforum would be nice!
I agree.
I do think, and have suggested in the past, that Team Pixelboy should have their own sub-forum and all his old message threads moved into it. Pixelboy could just post a message in the main forum as well.
Back then, I've not reacted when you suggested sub-forum either because I've missed the post or I was thinking there was no real benifit to do so. Today, I can see the reasons and it feels you were right all along, making it now a long over due decision.
When you enter the CV&ADAM Forum, all of the sub-forums contained in it are listed first and are highlighted when there are new messages posted. It's pretty simple in my mind.
So VectorGamer, how do you follow the CollectorVision and Opcode Games sub-forums?
Anyway, heck of a lot easier and "logical" to have all the Team Pixelboy related posts organnized together in a sub-forum for easy access... especially for newbies.
It is logicial, and the keyword "organized". It's simply a way to be organized in this melting pot of messages.
Personnally, i tend to read sub-forums a lot less than the main colecovision forum. ...
Since Collectorvision has his subforums, i'm almost not aware of what they are doing!
But i never miss a bulletin news of Teampixelboy.
We're all checking exclusively the forums and sub-forums based on our interests, and even more the ones that we can contribute to, and it's normal. And missing some messages either in the main or sub forums happens all the time.
Maybe it's simply the way we see the forums as the main part do get the most attention and therefor it's where important messages should be... but the content that should be together is diluted in the list of messages.
The other thing we can do is follow these sub-forums to receive email notifications of new posts.
I've not used email notification yet for (sub)forums threads. I am intrigued how to set it up.
I view new messages by going to "View New Content"
...
"View New Content" filters on the forums I have selected. If a new forum is added, and there's no annoucement posted, I won't know about it and therefore not see the content.
...
I would think that posting a thread in the Web site Announcements forum to let people know of new forums would be the solution.
I've not used this option yet, thanks for showing how to do it.
We learn new things every day, great when it's good things like this.
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Good writeup Mr Me. The fact that seven Tetromino pieces (3 symmetric plus two chiral pairs) exist as a mathematical superset, along with two possible triominoes (I and L, both symmetric), 18 possible pentominoes (6 symmetrical and 6 chiral pairs), and a bunch of hexominoes (I attempted to catalog all of them once on graph paper; I forget the exact count but I nearly filled the page...) seems to indicate the lack of "artistry" considering all seven possible combinations of tetrominoes are used with a pseudo-random generator.
I remember a number of Win9x homebrew shareware apps proporting to be Tetris back in the 90s. Most got shut down except the officially licensed Microsoft port originally distributed on Floppy disks for Win3.1. I distinctly remember a rather fun Qbasic Tetris port called "Didris" which had a number of simple bgm tunes played on the PC speaker. It had bombs that you could drop on the pile as well as paratroopers who fell from the sky, whom you could "smash with the blocks. Occasionally, a heliocopter would come down and rescue the stranded troopers. If the heliocopter succeeded, you lost 50 points. The game also had a "body count" in addition to the main score, and I always attempted to maximize my body count rather than generate a high score. I used a Qbasic compiler to compile the game into a DOS EXE and probably have it somewhere. I really need to install DOSbox and play it again. That and I also had a really neat Mario.exe which was a fairly nice completely free unauthorized port of Super Mario Bros for DOS.
Fun times...
Sorry this may be off topic but just wanted to react...
I do remember that time with shareware and such. I think I do have one shareware we can't find on any site today.
I used QuickBASIC 4.5 for years. I've coded DOS games and tools including VOIROM (my hex editor) and ICVGM (my graphics editor) both written in QB4.5
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If I can pick the ones I would love to play right now non-stop for an hour or more because I do enjoy these games...
Here's my 25 favorites arcade ports from the original ColecoVision arcade ports library.
(alphabetical order)- Bump 'n' Jump
- BurgerTime
- Centipede
- Donkey Kong
- Donkey Kong Jr.
- Frenzy
- Frogger
- Galaxian
- Gorf
- Gyruss
- Lady Bug
- Looping
- Mr. Do!
- Omega Race
- Pepper II
- Popeye
- Q*bert
- Roc 'N Rope
- Slither
- Space Fury
- Tapper
- Time Pilot
- Turbo
- Venture
- Zaxxon
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Everyone here is a adult and doesn't care what anyone buy's or don't buy's
including attending XXX Expo or not.
So I doubt anyone here will treat anyone differently over it
We sure are adults... or I'm in hot water with some of us for saying that I'm curious to see images of it.
We sure didn't need the coleco drama in our lives, almost ruin the passions and the vacations for some.
I wish a good time to everyone!
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I managed to save the Discovery on skill level 4 only once, back when I was a kid, and I didn't use HAL because I didn't know how at the time (because I didn't have the manual). Let me tell you I was screaming with joy when I saw the discovery achieve escape altitude!
2010 is really my favorite CV game among all of them.
Lucky, you!
I am able to play Level 3 after many tries, but Level 4 is just too much. I've video on Youtube done on emulator. -
power cable was lose.
When that happened to me, I noticed the issue was related to the power cable, if put in a certain way the issue was occuring often. I've thrown away multiple power supplies in the garbage years ago because I didn't know how to fix it beside just trying another power supply that seems to not have that defect.
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Meh. I've gone without a sub-forum all these years, and I really don't see the point of it now. I'd rather see my news bulletins appear in the main ColecoVision sub-forum anyhow.
True, but I think you are too modest.
It helps to have everything together, easier to find and read about... you should consider it.
Beside your name is wellknown now, and represent many products and years of being in service.
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I would love to see it, but I can't be there. Surely, someone will post pictures and videos of this event, right?
And beware of evil adult content games!
Have a great time!
Regards,
Daniel -
Here's what I sent them in 2008.
Again, the original (and only) Coleco portable I made was in 2005, by commission for a customer who was not associated with RWB.
And yes as some have mentioned it was a heavily modded original Colecovision, not a new machine. And by looking at the dates on these provided logo files, RWB contacted me over 2 year after I built the one-off.
It really looks like Brock Bold font except for the spacing and the missing curve at the bottom of the E. I remember modifying this font more than a decade ago based on the ColecoVision logo it worked just fine. I've tried to share the font file online, but somehow it's nowhere to be found. I remember using it in a pdf file, so maybe the font is embedded in a pdf file near you.
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Thanks! ^_^ I've listen to it and I think you missed the last minute of the music, you cut the ending, it's not a looping song.
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Sorry, that wasn't very well written. What I intended to say was that sound effect for key#1 was soft compared to the rainbow brite music. But I think it it is more of a babbling brook or electric hum sound compared to the alarm and firing sounds of the others.
Ah! I see!
Well, these sound effects are from my game Flora and the Ghost Mirror. That's what we call "place holders" to test and also have fun to try playing sound effects while the music play, which is a good way to see if it sounds good, if it works as background music for a game. Remember that the sound chip has only 3 TONE channels.
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That's pretty cool. Its like guess the retro game sound effect with the nostalgia trip: What was I doing in 1982 when I heard that sound effect. I think one was a little hard to hear, but could just be my hearing.
I assure you that the sequences shared by both musics are played at the same volume.
The music has nuances, softer parts within louder parts, which is more exposed in the extended version.
Playing a softer music part right after a normal or louder part tends to make it sounds quieter than it is, which is an illusion, it seems "difficult to hear".
I can see 2 reasons to put nuances like this in a music: it gives a break to our ears in long music pieces, and it tricks our mind to think that the next part is louder than it is which is often used to put emphasis on the upcoming ending, grand finale.
There is that and also with time we lose the capacity to hear high pitch notes which removes some sounds to be heard fully, missing some richer sounds in a music piece.
The original material I've listen to make the extended version is the "French Rainbow Brite Theme Song" from the Multimedia section of this Rainbow Brite web site. If you listen to it, you will notice the nuances of softer parts within normal/loud parts.
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Good morning everyone!
No, this is not clickbait... it's real.
To celebrate the 35th anniversary of the ColecoVision game system
To show my music composing talent
And to show how I don't care about drama, about being imposed restrictions in my hobby.
LADIES AND GENTLEMEN
RAINBOW BRITEtm JUKEBOX MUSIC FOR THE ADAM COMPUTER, COLECOVISION AND COMPATIBLE SYSTEMS
BY NEWCOLECO AKA DANIEL BIENVENU
Please leave a like and comment!
Enjoy!
ROM FILE : RAINBOW BRITE JUKEBOX 2017.zip
SOURCE FILE : RAINBOW BRITE JUKEBOX 2017 (SRC FILES).zip
FAQ
Q: Software to make the music?
A: My own software CVSoundGen.zip and 2 days of patience and listening the theme song in chunks with Audacity.
Q: Development kit?
A: My own kit based on Marcel deKogel's devkit released in 1998 and adapted to work with SDCC compiler.
Q: Can I use this music and sounds for my own projects?
A: No, unless I tell you otherwise.
Q: Will there be a playable game Rainbow Brite for the ColecoVision?
A: Maybe, maybe not.
Q: Why you decided to make a jukebox with the Rainbow Brite theme song?
A: For fun. First time ever I've heard the music and I quite like how catchy and groovy it sounds as a chiptune.
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Here's my chance to react before this thread closes again.
Friends,
This drama caused a rollercoaster of emotions for me. At first, I felt terrible that an amazing fan page was in trouble partially because my video games for adults were mentioned. And then, I felt better with your nice words.
This thread is warning us that: WE are being used, abused, and this has to stop.
It's great to see the massive positive feedback and support from everyone, homebrewers and retro gaming fans together, stronger than ever.
And, like a cherry on top, I've received messages from people interested to know more about my work and programming new games.
It's fun to explore as if the video game crash never happened, and I wish our hobby continue for a long time.
I hope to see you in a convention or gaming expo. At the moment I'm writing this message, you can find me at the ADAMCon 29, July 20-24, 2017; it will be a pleasure to sign boxes and carts of my games.
I will take the "don't be fooled" advice and move on with my life and my passion.
I wish nice summer vacations to Robb and his family, and to all my friends!
Thanks to AtariAge, Albert, for letting us say the last words and not deleting any of this.
Best regards,
Daniel Bienvenu aka NewColeco
Twitter: @DanielBienvenu
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Even after all these days, I see a lot more pages here and my name mentionned again and I think "OMG when it's gonna stop?".
This is a very interesting read: http://nerdlypleasures.blogspot.com/2017/06/the-ownership-of-and-issues-with.html
Thanks for the link.
After a first read, I don't understand it all; legal documents tend to make me feel dizzy and I just click OK when installing software.
I'll read it again later, with more care, not in diagonal.
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We all like to be happy, so do I. And I love sharing my work but this drama made me feel terrible.
- the attention toward these particular games which in my case are refered as more sexual than they are.
- a brand that is part of my childhood memories being now so childish and upset toward the same fans and people that keep the name alive.
- this forums thread is huge, must be a record on AtariAge.
- the rollercoaster of emotions; it made me cry, depressed, questioning if I really want to come back in the active scene in these circonstances.
Seeing homebrewers and fans together, the community is stronger than ever, makes me happy.
I'm confused but I like the spirit of continuing our passion of making videogames so... I'm back.
I know, some of you already told me that I should not feel bad or say sorry. I've let this drama affects me more than it should.
Thanks everyone and let's enjoy videogames
Best regards,
Daniel-
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Hey guys - I had to clean up this thread a bit more.
Great!
Do I understand it well? Please, someone, tell me that I'm wrong!
So, he capitalizes on at least one homebrew game to make a name for himself, without any effort put in it nor making a donation to the homebrew scene, with no apology for DMCA attacking fans.
And on top of that, trying to demonize the homebrew scene who made the Coleco scene alive for 2 decades, and making ColecoVision label the "must not be printed" name.
All this to gain credits and profit for work he never does, and get the attention, visibility, and publicity for his gaming expo and future Coleco products for parents and "true fans".
Isn't it by definition the actions of a "super vilain" in movies? I think so, yes.
At this point to me it is more than clear that Coleco wants one thing and just one thing, to twist my arm to work for them for free in trade of using the ColecoVision logo. And I am not interested in that. So I have found my own solution, and I will using that from now on. I need to focus on my games instead of waste my time in this pointless juvenile fight between Coleco Holdings and the community, though I am sure be watching as they crash and burn just for fun with great interest.
It sure is a way to deal with the situation and I don't see another solution at the moment.
Not printing any trademark word is a way to "be safe" until something else happen.
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It was the original plan, but it was changed to make it possible for most of us to be at the convention this year.Had hopes it would be in New York this year
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There are easter eggs in some my CV games.Wow! What an incredible background for the game! That is truly touching. I doubt few games could match a backstory like that. Thank you for sharing.
I wished to see someone figuring out the Easter Eggs in Flora without me telling any. I'm sure at least one had the question: "why clothes has bonus points?" ... well now you know why.
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Warning: the following is my opinion and my opinion only.
Hello again,
I've read the tweets, I've watched Pat's video, and I could not believe my eyes.
I may not word things well enough to express myself fully, but I assure you that I'm giving here my honnest reaction.
...
This situation is mental, beyond surreal, and I won't be surprised to see it eventually get the attention of the mainstream media.
Some may not like Pat's vlog, but perhaps it's not a good idea to go after him and try to censor his free speech. I won't suggest to fill DMCA claims about his video either. Going after a video blog, when you think about it, is overreacting and may cause more reputation damage than anything else.
The only reason why we see the ColecoVision scene active is because WE MADE IT ! We are fans, we have nostalgia, we dreamed about "what if the videogame crash never occured?" and we made it possible. Every talent, resource, and time spent (more than 2 decades) to make all this possible is precious and should be appreciated, cherished, not in peril.
To the world, the ColecoVision market is long dead; the brand has a place in videogame history and in the heart of the fans, and I don't know what the heck the actual brand owner is trying to accomplish.
Wanna use Coleco brand for something new? something big? Go for it! I would love to see a new generation of Coleco products.
I do understand some concerns and legal terms, and the fan page is fair use and should get an apology.
And if you think about it, perhaps it wasn't a good idea for anyone to acquire a brand name refering to a vintage videogame system without any prior research, plan or respect to the fans. Do you realise that some ColecoVision homebrew games refered in the complains were made way before 2005, the year RWB acquired the Coleco brand?
All this could have been avoided easily, and I really hope I'm not the only one to see it.
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To Chris aka "Coleco Holding": You are not, in any way, representing the fans and the company and games that we love. In life, especially in the Internet, we are exposed to positive and negative feedbacks. And the way we react to the feedbacks shows what we are as a person. You can do your expo with any brand name, but you selected this one and try to capitalize on the effort of the homebrew scene while putting it in jeopardy. Please, don't fk with us anymore; you are not giving yourself a favor by doing so. This situation shouldn't have occured and I hope you acknowledge it. Regards, Daniel Bienvenu
...My friends,
We might not like or do the same things but friendship and respect was forged through time in this community, and that's beautiful.
I have my views about what should be done for our beloved vintage game system, and I think I've contributed positively to the games library and the homebrew scene in general, sharing my work for us to enjoy.
It's with regrets that I've decided to stop my ColecoVision activities during this turmoil time. I will focus on the ADAMCon convention (still time to register for it), and my life.
Continue to make our vision the ColecoVision that we want it to be, with our love and dreams!
I'm just a dreamer. I'm tired of this crap, feeling my energy sucked out of me the more I read about this, I'm going to bed.
Thank you so much to keep us informed, I really appreciate it.
Sincerely,
Daniel Bienvenu
aka NewColeco
aka The GodFather Coleco
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Welcome back, Daniel!
Thank you!
Bon retour, Monsieur Daniel !
Merci! Ça fait plaisir d'être de retour!
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Data Compression Benchmark - DAN, PLETTER, ZX7, EXOMIZER, PUCRUNCH, MEGALZ
in ColecoVision Programming
Posted · Edited by newcoleco
SPACE VERSUS SPEED
Especially for the 8-bits and 16-bits homebrew projects, optimization is a constant dilemma between space and speed.
The following table shows the results of DAN1, DAN3, PLETTER and ZX7, all running the same SlideShow demo, all decompressing directly to VRAM (which is very slow), with the size in bytes of each decompression routine, the size in bytes of the ROM file containing decompression routine with the pictures, and the time in seconds for the decompression of the 1st picture.
APPENDIX - Questions and Answers
QUESTION :
WHY PLETTER AND ZX7 OFFER SIMILAR COMPRESSION RESULTS IN THIS BENCHMARK?
ANSWER :
ZX7 and PLETTER are both using two possible sizes to encode offset (relative index) values in their LZ77 encoding. The small size to encode offset values is 7 bits ( 128 ) long for both compressors while the big size is fixed to 11 bits ( 2048 ) long for ZX7 and variable for PLETTER from 9 bits ( 512 ) up to 13 bits ( 8192 ) long. After a first pass scanning data, PLETTER decides the ideal size to encode the big offset values. To get similar results, both PLETTER and ZX7 should use similar sizes to encode offsets, which is 11 bits long. And it happens that the bitmap pictures made of 6K bytes data tables ( PATTERN table for ZX Specatrum screens, PATTERN and COLOR tables for Graphic Mode 2 ) tend to get better results with big offsets encoded as 11 bits values. In sumary, if the data to compress do need 7 bits long offsets and/or 11 bits long offsets to get a good compression result, PLETTER and ZX7 should always give similar results, otherwise PLETTER do provide better compression with its flexibility of various ( from 9 to 13 bits long ) sizes to encode offsets.
CONCLUSION :
PLETTER is similar to ZX7 but provides better compression overall.
QUESTION :
Why DAN3 is better than DAN1 and DAN2 compression in this benchmark?
ANSWER :
In this benchmark, the bitmap pictures may get better compression by using 8 bits ( 256 ) instead of only 7 bits ( 128 ) for the small offset values. Why? Because of the way the graphics are encoded. If you look at ZX Spectrum .SCR bitmap pictures, bytes for the PATTERN table are interlace in a way that bytes 256 away from each others in the data table are one above the other on screen making them more likely to be the same. And Graphic Mode II bitmap pictures are in blocks of 256x8 pixels on screen which makes offsets of 256 bytes in the data tables more likely to find similar bytes than offsets of 128 bytes. Because of this, DAN1, DAN2 and DAN3 do have 8 bits offsets. However, DAN1 and DAN2 do worse than DAN3 to compress ZX Spectrum pictures simply because their smaller offset bit-size is only 4 bits ( 16 ) while it's 5 bits ( 32 ) for DAN3, and offset of 32 is very important: it's 32 bytes long for each line of 256 pixels on screen, and ZX Spectrum COLOR table are rows of 32 bytes. These differences explain the difference in the results. And also, it's 32 x 24 characters on screen for our beloved 8-bit systems (mostly), which again makes 32 a relevant offset value.
CONCLUSION :
Overall, DAN3 is using a better set of possible bit-sizes to encode offsets than DAN1 and DAN2 for graphics like title screens that we need in our projects. Also the 4 bits instead of 5 bits to encode smaller offsets do explain why DAN1 and DAN2 do worse than DAN3 with ZX Spectrum bitmap screens, because extra bits are used to identify in which small size is encoded each offset in the compressed data.
QUESTION :
Shouldn't a flexible set of bit-sizes for offsets be a better solution than making a format with fixed sizes?
ANSWER :
Yes, and that's exactly the reason why Exomizer out-perform all the others compressors. But to achieve this, a table of variable bit-size lengths to encode-decode offsets is needed. This table is encoded very efficiently into the first 52 bytes of the compressed data. The table needs to be decoded into RAM prior to the decompression. The space needed in RAM for this offsets table can be a deal breaker for some vintage systems, for some projects without enough extra memory space available.
CONCLUSION :
A flexible way to encode offsets, like the one used in Exomizer, do perform better than fixed sizes. To achieve this, extra memory space is used for a table of the possible offset sizes which can be significant enough on vintage 8bits computers and consoles like the ColecoVision to be a deal-breaker.
QUESTION :
Is Exomizer 2.0 the best data compression for vintage 8-bits systems?
ANSWER :
It depends what you mean by "best" data compression. For example, Subsizer 0.6 is a data compression tool for the Commodore 64 that gives slightly better results (a few bytes difference) than Exomizer 2.0. After some tests, Subsizer 0.6 crashes while trying to compress some files including 2 of the Graphic Mode II pictures from my benchmark test. Another tool from the Commodore 64 scene is named ALZ64 and uses arithmetic coding instead of Huffman coding to get even better compression at the cost of time and memory space, but it's a packer for Commodore 64 programs, not a data compression tool for raw files like picture, text, and audio files.
CONCLUSION :
There are many data compression tools and some do compress more than Exomizer 2.0.
*UPDATE : December 8, 2017 - Added section SPACE VERSUS SPEED