67 votes
Accepted

Why was video, audio and picture compression the poorest when storage space was the costliest?

TL;DR Computer processing power/speed/cost and storage density/cost have been moving at roughly the same pace for 50+ years. There are of course variants, where either CPU speed has increased much ...
manassehkatz-Moving 2 Codidact's user avatar
47 votes
Accepted

When did HTTP start compressing text?

Compression of document bodies is negotiated between clients and servers (and proxies), using notably the Accept-Encoding header: the client indicates which compression algorithms it supports, and the ...
Stephen Kitt's user avatar
44 votes

Disk compression risks in MS-DOS

The dangerous part was that your disk contents would be compressed. i.e., you have data that can only be read by the compression engine. If the compression engine was buggy, no data for you. If other ...
dave's user avatar
  • 35.2k
42 votes

Why was video, audio and picture compression the poorest when storage space was the costliest?

You mean beside that all these algorithms had to be designed, implemented, rolled out and accepted first? Which of course would only happen as a need was developed to use them? Well, that may leave ...
Raffzahn's user avatar
  • 219k
39 votes
Accepted

How did the Sega CD decompress video?

We used to have to write our own video playback system, so each game did it differently. I worked on Microcosm for the SegaCD and if I recall we used a 16 colour palette for the video playback and had ...
Martin Linklater's user avatar
39 votes

Disk compression risks in MS-DOS

The main problem was that DOS drive compression programs such as DriveSpace, Stacker, or SuperStor created a virtual drive and stored its contents in a large file on the original drive. This created ...
Stephen Kitt's user avatar
34 votes
Accepted

Why does MP3 audio decoding overwhelm retro CPU's?

What's lacking is mostly raw number-crunching ability. The MP3 format is relatively lightweight, and can be implemented using only fixed-point math (no FPU required), but it still takes a fair amount ...
Mark's user avatar
  • 8,547
28 votes

How well known and how commonly used was Huffman coding in 1979?

According to Google Scholar, Huffman’s 1952 paper had 326 citations by 1979, which given the volume of publication at the time means it was well-known, as far as can be determined now. Most ...
Stephen Kitt's user avatar
25 votes
Accepted

How well known and how commonly used was Huffman coding in 1979?

Well, in fact, a closely related question has been asked (and answered) few years ago: What is the history of data compression tools on personal computers? From that question, and its answer, it ...
introspec's user avatar
  • 4,152
23 votes

Why was video, audio and picture compression the poorest when storage space was the costliest?

Compression == Expensive To get an idea of what was considered an acceptable cost for compression, you should take a look at the PCX format, which was common for games and graphics programs of the DOS ...
Lawnmower Man's user avatar
20 votes
Accepted

What type(s) of compressed files was the MS-DOS EXPAND command able to decompress?

EXPAND.EXE is a tool specifically created for installation of Microsoft products. Its file format is a proprietary Microsoft definition, not following any existing standard. It is only good to expand ...
Raffzahn's user avatar
  • 219k
19 votes
Accepted

Compression techniques used in old ZX Spectrum tapes

I don't recall any mass-market commercial software for the Spectrum using the term "decrunching" - I'd associate that more with the demo and cracking scenes of central and eastern Europe, ...
gasman's user avatar
  • 1,341
19 votes

How did the Sega CD decompress video?

Playback of compressed digital video is handled entirely in software on the Sega CD which is why FMV games on it play with the video taking less than the full screen and at relatively low frames per ...
mnem's user avatar
  • 4,527
17 votes
Accepted

How to convert Amiga DMS to ADF?

From some quick research, WinUAE (a popular Amiga emulator) supports reading a DMS file just like an ADF. So you could probably mount it and then save it back as ADF. Also, according to the ADF Opus ...
Thraka's user avatar
  • 2,913
14 votes

Disk compression risks in MS-DOS

In addition to the compatibility problems and the data recovery problems mentioned in the other answers, there is one inherent problem with the disk compression schemes: They are sometimes quite off ...
fraxinus's user avatar
  • 1,324
13 votes

Compression techniques used in old ZX Spectrum tapes

As far as I know, there were two main approaches to compress the data. The first one, more common, was to load the whole code and "de-crunch" it. It uses RLE or simple vocabulary algorithm (...
Martin Maly's user avatar
  • 5,515
13 votes

How well known and how commonly used was Huffman coding in 1979?

If you actually look at how the Z-Machine compresses texts, it does the following (from memory, it's been a while): There's a list of frequently appearing words (like "the", "and") which are directly ...
dirkt's user avatar
  • 27k
13 votes
Accepted

Could early nineties PCs access raw CD bitstream?

TL;DR; Yes and yes, but. CD-ROM Mode 2 offers all 2336 bytes of a CD-ROM block for user data. By default all CD-ROM drives can read Mode 2 disks as well Mode 2 CD-ROM have been produced, but it never ...
Raffzahn's user avatar
  • 219k
13 votes

Disk compression risks in MS-DOS

I'll add some context to the good technical answers already given. When the first on-the-fly disk compression software for PCs (Stacker) came out, it had a huge impact. It became prevalent faster than ...
user1172763's user avatar
12 votes

Why does MP3 audio decoding overwhelm retro CPU's?

Mp3 is primarily a lossy compression format for audio. It must be decompressed, and the process needs a lot of CPU time (as for retro computers.) Modern computers both have speeds good two orders of ...
SF.'s user avatar
  • 7,085
12 votes

Compression techniques used in old ZX Spectrum tapes

I wrote the compression routine use by the Multiface on the Spectrum and Amstrad machines. It was a plug in unit that would save all memory to tape and allow you to continue your game where you left ...
Thomas Quillin's user avatar
11 votes

Was there a compression program based on the Mayne-James algorithm?

After browsing the paper, it looks like the idea is to extract common sequences of letters from a given text into a table of a certain size, and then replace those substrings with references to the ...
dirkt's user avatar
  • 27k
11 votes

When did HTTP start compressing text?

http/0.9 didn't have any headers, and so couldn't support compression. On the other hand, http/1.0 (rfc1945, May 1996) already had that support. It was already on draft-00 (as Content-Encoding: x-gzip)...
Ángel's user avatar
  • 221
10 votes
Accepted

What is the history of data compression tools on personal computers?

The story is told in this 1988 usenet post by Paul Homchick: Some time went by and it was a CP/M world, and diskettes were bigger. In 1981 Richard Greenlaw released SQ and USQ, based on Huffman ...
sendmoreinfo's user avatar
9 votes
Accepted

What was the first database to start compressing in situ?

As time goes by, CPU power becomes cheaper and more plentiful, to the point where it makes sense to start spending some of it using more complex storage formats that save disk space and bandwidth, and ...
Raffzahn's user avatar
  • 219k
9 votes

Why does MP3 audio decoding overwhelm retro CPU's?

Like others already answered: old CPUs does not have enough MIPS, and/or they are lacking instructions that would helped in MP3 decoding algorithm (remember that MP3 is standardized in 1995.). Nice ...
Milan Kovac's user avatar
9 votes

What is the difference between DriveSpace and DoubleSpace?

It appears that there are several versions of both DoubleSpace and DriveSpace. Information about each version as I find get it will be posted in this answer. DoubleSpace DoubleSpace uses MRCI, which ...
wizzwizz4's user avatar
  • 18.5k
8 votes

What is the difference between DriveSpace and DoubleSpace?

MS-DOS 6.0 and 6.20 shipped with DoubleSpace. MS-DOS 6.21 removed it due to the Stac lawsuit, and MS-DOS 6.22 replaced it with DriveSpace with an incompatible algorithm and format. Soon after MS-DOS 6....
Yuhong Bao's user avatar
8 votes

Why does MP3 audio decoding overwhelm retro CPU's?

Early 68k processors implemented a multi-cycle multiply instruction (70 cycles per MULx), so the inverse MDCT would likely be the limiting factor in terms of raw CPU time.
hotpaw2's user avatar
  • 8,183
8 votes

Compressing a list of records so it can be uncompressed elementwise

Compression isn't really retrocomputing-related, but I'll give it a crack anyway as there are a few tricks which work on small systems. Essentially, you want to compress a large-ish (100–200) list of ...
pndc's user avatar
  • 10.9k

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