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A Fictional Compression Metric Moves Into the Real World
Tekla Perry (3034735) writes The 'Weissman Score' — created for HBO's "Silicon Valley" to add dramatic flair to the show's race to build the best compression algorithm — creates a single score by considering both the compression ratio and the compression speed. While it was created for a TV show, it does really work, and it's quickly migrating into academia. Computer science and engineering students will begin to encounter the Weissman Score in the classroom this fall."
A "combined score" for speed and ratio is useless, as that relation is not linear.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
The so-called Weissman score is just proportional to (compression ratio)/log(time to compress).
I guess the idea is that twice as much compression is always twice as good, while increases in time become less significant if you're already taking a long time. For example, taking a day to compress is much worse than taking an hour, but taking 24 days to compress is only somewhat worse than taking one day since you're talking offline/parallel processing anyway.
The log() seems kind of an arbitrary choice, but whatever. It's no better or worse than any other made-up metric, as long as you're not taking it too seriously.
"They were pure niggers." – Noam Chomsky
They're talking about the Score, not the compression algorithm. And your link doesn't mention anything about the Score.
it's for lossless compression only.
anyway, you can just add a term representing the lost information and throw it into this "score". hey, why not? just figure out how important the lossiness is relative to compression rate. if it's very important, take the exp() of the loss metric; if it's unimportant (like time is), take the log(); finally, if it's just kind of important, leave it linear, or maybe square or square root. whatever.
seriously, just make some shit up and throw it in. you won't compromise anything. it's already just made-up shit.
"They were pure niggers." – Noam Chomsky
In the TV show only lossless compression was being considered, so MP3 would fail.
The reason the Score is utter bullshit is that the scale is completely arbitrary and useless. It says that 2:1 compression that takes 1 second should have the same score as 4:1 compression that takes log(2) seconds, or 1 million to 1 compression that takes log(1 million) seconds.
WHY? State why log time is a better measure than straight time, or time squared, or square root of time. And look at the units of the ratio: reciprocal log seconds. What the hell is the significance of that? It also conveniently sidesteps the variability with different architectures. Maybe SSE helps algorithm A much more than it does algorithm B. Or B outperforms A on AMD, but not on Intel. Or maybe it is strongly dependent on size of source (there is an implicit assumption that all algorithms scale linearly with size of source; maybe in actual fact some are not linear and others are).
In real life, for some compression jobs you don't CARE how long it takes, and for other jobs you care very much. Or imagine an algorithm that compresses half as fast but decompresses 1000 times faster. That doesn't even register in the score.
It's bullshit.
And Jerry Gibson, a professor at the University of California at Santa Barbara, says he's going to introduce the metric into two classes this year. For a winter quarter class on information theory, he will ask students to use the score to evaluate lossless compression algorithms. In a spring quarter class on multimedia compression, he will use the score in a similar way, but in this case, because the Weissman Score doesn't consider distortion introduced in lossy compression, he will expect the students to weight that factor as well.
The scoring method as stated is only useful for evaluating lossless compression. One could also take into account the resemblance of the output to the input to allow a modified version of the score to evaluate lossy compression.
It is pitch black. You are likely to be eaten by a grue.
From the article:
Misra came up with a formula
So, now Jar Jar Binks does C.S.? Shit...