cl-permutation
opus
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cl-permutation | opus | |
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4 | 26 | |
47 | 2,103 | |
- | 4.1% | |
3.5 | 9.6 | |
10 months ago | 3 days ago | |
Common Lisp | C | |
BSD 3-clause "New" or "Revised" License | GNU General Public License v3.0 or later |
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cl-permutation
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Permutation Iteration and Random Access
Here is Lisp code [1] that maps all sorts of combinatorial objects—permutations, bit sets, base-B integers, multi-set permutations, etc.—perfectly into the smallest set of integers [0, n-1] and back. (In a sense, it's a perfect hash.) This is used to efficiently solve combinatorial puzzles.
[1] https://github.com/stylewarning/cl-permutation/blob/master/s...
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Can a Rubik's Cube be brute-forced?
Note that in the unlikely event anyone wants to run the code in the post, the algorithm presented is still in an open PR, APIs change until merged, etc.
- Favorite Lisp project? Shameless plugs welcome & encouraged!
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Is Fisher-Yates Shuffle (aka Knuth Shuffle) implemented in some vetted CL library?
CL-PERMUTATION has random-perm to produce a random permutation of even, odd, or any parity.
opus
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TSAC: Low Bitrate Audio Compression
Opus doesn't support 44.1 kHz because compatibility and effort/benefit ratio:
https://github.com/xiph/opus/issues/43
The browser audio limitation is presumably a workaround to some bug or performance limitation that was relevant at some point in history (the site was created in 2014).
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Permutation Iteration and Random Access
There is a pattern here (that also goes with the author's prior article on inverting gauss' sum formula): Generally if if you can make a formula that counts the combination of things you can convert that into a code to encode and decode those combinations into indexes.
So for example the opus audio codec needs to encode/decode vectors of dimension n whos absolute values sum to k. https://github.com/xiph/opus/blob/master/celt/cwrs.c#L74
Or this rolling cuckoo filter that optimally encode/decode four sorted numbers in a range 0..2N with the constraint that the they span a range of N. https://github.com/sipa/bitcoin/blob/202006_cuckoo_filter/sr...
If you're lucky there will be closed form expressions for the encoding and decoding equations. (There for both of the above, at least for some parameters, but in both those examples the implementations use small tables because for the ranges involved the tables end up being faster than sqrts).
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A CPU in Sunvox
Too bad 10Hz is a too slow to generate audio-rate bitops music.
(e.g. https://github.com/xiph/opus/blob/master/tests/test_opus_enc... )
- L’avenir de la loi Hadopi suspendu à une décision de la justice européenne
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Global Underground Disk Images
Could anyone help me get a disk image files for older Global Underground CDs? I encoded my old CDs into subpar mp3 files, and I'd now like to have high-quality Opus encodings and experiment across various bitrates.
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Which is better Opus or AC3?
Presumably, OP is referring to the Opus audio codec versus Dolby's AC3 codec.
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HD: Opus?
Indeed. https://opus-codec.org/
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Multiple tags with the same name in metadata
If there are multiple tags with the same name, Ffmpeg will only use the last tag. If you really need to have multiple tags with the same name in your OPUS files, use opusenc instead (https://opus-codec.org/). Beware that some playback software does not display multiple artists gracefully.
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I built a Zoom clone 100% IN RUST
AFAIK ogg isn't really suitable for low latency audio streaming. Consider the Opus codec instead.
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ffmpeg libopus producing larger file size for the same bitrate as compared to vorbis
I have asked on GitHub also https://github.com/xiph/opus/issues/263 in anyone wants to respond there.
What are some alternatives?
sly - Sylvester the Cat's Common Lisp IDE
libvorbis - Haskell binding for libvorbis, for decoding Ogg Vorbis audio files
ultralisp - The software behind a Ultralisp.org Common Lisp repository
go-m3u8 - Parse and generate m3u8 playlists for Apple HTTP Live Streaming (HLS) in Golang (ported from gem https://github.com/sethdeckard/m3u8)
shan - A declarative wrapper around your favourite system-wide package manager
argos-translate - Open-source offline translation library written in Python
phel-lang - Phel is a functional programming language that transpiles to PHP. A Lisp dialect inspired by Clojure and Janet.
vorbis - Reference implementation of the Ogg Vorbis audio format.
doc - Flexible documentation generator for Common Lisp projects.
vgmstream - vgmstream - A library for playback of various streamed audio formats used in video games.
weblocks - This fork was created to experiment with some refactorings. They are collected in branch "reblocks".
libopenaptx - Open Source implementation of Audio Processing Technology codec (aptX)