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[-] Carnelian@lemmy.world 124 points 1 day ago

lol. They can’t hear the difference even with the most expensive equipment. The resultant signal from decompressing a FLAC phase cancels with the original signal if you invert it. Meaning they are indeed 100% identical. Lossless, dare I say.

Literally all it does as a file format is merge data that is identical in the left and right channel, so as not to store that information twice. You can see this for yourself by trying to compress tracks that have totally different/identical L and R channels, and seeing how much they compress if at all

[-] circuitfarmer 2 points 15 hours ago

Interesting. It must do more than that though -- for example, FLAC offers different compression "levels", which you choose when encoding. To my knowledge all of them are lossless, but what do the levels do if it is only merging identical channel data?

[-] Carnelian@lemmy.world 4 points 12 hours ago

You’re absolutely right about that. My use of “literally all it does” was employed poorly, and is a pretty extreme oversimplification

There’s a whole mathematical thing happening with FLAC generally, regardless of L/R channels, where it replaces your original waveform with a polynomial approximation of it + the differences between that approximation and the actual. When played back together, those two things always result in a perfect recreation of the original.

The various compression levels you can choose from essentially control presets relating to how sophisticated those approximations can be, thus cutting down on the amount of differences that need to be stored.

The reason you may want to play with these settings is somewhat outdated now. But a higher level takes more time to encode, results in a slightly smaller file size, and also takes slightly more processing power to decode. Any modern piece of equipment can handle the maximum setting with no issues.

But yeah, as a result of these processes (rather than as the prime goal explicitly, if that makes sense), it does joint-encoding and merges anything from the L and R channels that can be merged. This enables it to pull “identical” sounds from L and R even when the data itself is totally different, which is actually more common than not in music due to the use of multi-channel effects such as reverb.

In the end, a massive amount of the space saved as a result of the compression in typical music comes from removing duplicate information from the stereo field. But all sorts of funky stuff would happen if you opened up a DAW and started contriving different situations for it to compress

[-] AdrianTheFrog@lemmy.world 1 points 8 hours ago

polynomial approximation seems like a weird choice for audio, is it really more efficient than a frequency based encoding?

also, it seems like audio compression formats have seen a lot less development in recent years than images have. I want to try encoding audio as a lossless jpeg xl now just to see how it does, I think it should be possible as jpeg xl supports extremely large image dimensions

[-] Carnelian@lemmy.world 1 points 4 hours ago

It’s fairly well optimized for audio. Waveforms are usually continuous and relatively repetitive. The other really important aspect is how easily it can be decoded, so that it remains a usable audio file on potentially underpowered equipment.

Although I wonder if there exist some cases where other formats might do a better job

[-] circuitfarmer 1 points 12 hours ago

Thanks for the detailed explanation!

[-] Darkassassin07@lemmy.ca 42 points 1 day ago

This is like trying to explain to a SovCit, why they need to have a license.

You're wasting your time.

[-] Carnelian@lemmy.world 89 points 1 day ago

No, it’s like explaining FLAC to anyone who happens to be curious about it after seeing this screen shot and wondering how something can be both compressed and lossless at the same time. Many people appreciate this type of information being accessible easily in the comments

[-] murmelade@lemmy.ml 13 points 1 day ago

Certainly do. I learned something neat, thank you!

[-] leftzero@lemmynsfw.com 4 points 1 day ago

how something can be both compressed and lossless at the same time

I assume most people who've used a computer are familiar with lossless compression formats like ZIP files.

Of course, though, it doesn't matter how familiar an audiophile is with digital formats. They'll still believe that more expensive cables sound better, and they'll keep on believing that even if you show to them that they can't tell an expensive cable from a bargain bin one in a blind test.

[-] uranibaba@lemmy.world 6 points 22 hours ago

Imagine zip being lossy.

[-] LodeMike@lemmy.today 31 points 1 day ago

Flac is literally lossless in the mathematical sense.

[-] Valmond@lemmy.world 7 points 20 hours ago

Yeah but my ears don't care about mathematics.

Some audiophile, probably...

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[-] Kraiden@kbin.earth 6 points 1 day ago

do you know if anyone has tried this with a flac and an mp3 file? Theoretically all that should be left is the "loss" right? what would that sound like?

eta: I'd try myself but I'm not an audiophile and wouldn't even know where to get a flac file (legally) and doubt my crappy $20 in ears would be capable of playing it back if I did

[-] GreatAlbatross@feddit.uk 4 points 22 hours ago

I did it once a few years ago (IIRC with a copy of Falling Down by Muse, not for any particular reason), and compared V0 320 with FLAC.

After amplifying the tiny, tiny wiggle of a sound that was left, I was left with very slight thin echoes, mostly well above 10k.
The sort of stuff you really wouldn't worry about, unless you 100% wanted bit-perfect reproduction, or wanted to justify a £2000 pair of headphones.

Funnily enough, that was the point I stopped bothering to load FLAC onto my DAC, and just mirror everything into V0 for portable use.

[-] prole@lemmy.blahaj.zone 1 points 17 hours ago* (last edited 17 hours ago)

Yeah, I think the difference between a FLAC and v0/320kbps is negligible.

However, the difference between a 128kbps mp3 and a v0/320kbps mp3 is massive and absolutely noticeable (and yes, it becomes more noticeable on higher quality equipment). Anything under 192kbps (or maybe 160), and you start to get noticeable degredation imo.

If anyone wants to claim that one cannot tell the difference between 128kbps and 320kbps, I'd take a blind listening test right now.

[-] LostXOR@fedia.io 11 points 1 day ago

Not a FLAC, but I tried it on this video by reencoding to an mp3 at 320 kbps, then subtracting the original, amplified it a bit, and got this. The song is definitely recognizable, but heavily distorted.

[-] sangriaferret@sh.itjust.works 9 points 1 day ago

The end result sounds awesome. I would totally listen to that on its own.

[-] WolfLink@sh.itjust.works 5 points 1 day ago

If you want free, legal FLAC files just to play with, this Zelda fan music album is free and legal to download in FLAC format (you do need to torrent the FLAC version, yes legal torrents exist).

It also has some good tracks in it IMO.

[-] mayhair@discuss.tchncs.de 4 points 23 hours ago* (last edited 23 hours ago)
[-] prole@lemmy.blahaj.zone 3 points 17 hours ago

If you own the music, you are allowed to own a backup of it in FLAC (or any format).

[-] kinsnik@lemmy.world 7 points 1 day ago

you wouldn't need a flac file, you can use any wav file, the audio of both is identical.

regadring your question, you can think mp3 as the jpeg of music. both mp3 and jpeg use fourier transforms*. so, to image what mp3 is doing to the audio, you can see what jpeg does to images (spoiler alert, unless you are aggressively compressing it, it is not noticable)

(*jpeg actually use discrete cosine transform instead of fft, but it is similiar enough)

[-] prole@lemmy.blahaj.zone 2 points 17 hours ago

This is why I always use PNG

[-] sxan@midwest.social 6 points 1 day ago

Another place is bandcamp. When you buy music from there you can choose the encoding.

I generally download FLACs when I can; after building an mp3 library, then adding oggs, and most recently opus, I value having a source that I can transcode into whatever new, improved codec takes the lead every few years. However, you have to be prepared for the size requirements. FLACs are still pretty big: I recently bought Heilung's "Drif", and the FLAC archive was nearly 650MB. Granted, it's bigger than usual; the average album comes in around 400MB, but still... you have to commit to find sizeable long-term storage if you keep those sources, and off-site, cloud backup can get pricey. Or, you can trust that where you buy it from will provide downloads of your purchases indefinitely.

[-] WolfLink@sh.itjust.works 3 points 1 day ago* (last edited 1 day ago)

Theoretically all that should be left is the "loss" right? what would that sound like?

Like noise, more or less, but at frequencies that are hard to hear.

wouldn't even know where to get a flac file (legally)

BandCamp offers FLAC downloads. There are some other sites that do too, like Quobuz and I think some Japanese ones. Soundtracks I’ve bought via Steam sometimes come in FLAC too.

You can also rip a CD.

[-] entropicdrift 4 points 1 day ago

HDTracks.com sells DRM free albums in FLAC format

[-] Player2@lemm.ee 3 points 1 day ago

Bandcamp too sometimes

[-] black0ut@pawb.social 4 points 1 day ago

I've tried myself, and the "loss" is really not that much. You can see it if you zoom, but if you listen to it you can't make out the track it comes from. It sounds more like noise. That was at least on the track I tried this with, maybe in a less compressable track there is more of a difference.

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this post was submitted on 15 Dec 2024
294 points (98.0% liked)

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