Slashdot Mirror

The hum that helps to fight crime (ENF) Electrical Network Frequency analysis

"For the last seven years, at the Metropolitan Police forensic lab in south London, audio specialists have been continuously recording the sound of mains electricity.

It is an all pervasive hum that we normally cannot hear. But boost it a little, and a metallic and not very pleasant buzz fills the air. ...

"The power is sent out over the national grid to factories, shops and of course our homes. Normally this frequency, known as the mains frequency, is about 50Hz," explains Dr Alan Cooper, a senior digital forensic practitioner at the Met Police.

Any digital recording made anywhere near an electrical power source, be it plug socket, light or pylon, will pick up this noise and it will be embedded throughout the audio.

This buzz is an annoyance for sound engineers trying to make the highest quality recordings. But for forensic experts, it has turned out to be an invaluable tool in the fight against crime.

While the frequency of the electricity supplied by the national grid is about 50Hz, if you look at it over time, you can see minute fluctuations. ...

Comparing the unique pattern of the frequencies on an audio recording with a database that has been logging these changes for 24 hours a day, 365 days a year provides a digital watermark: a date and time stamp on the recording.

Philip Harrison, from JP French Associates, another forensic audio laboratory that has been logging the hum for several years, says: "Even if [the hum] is picked up at a very low level that you cannot hear, we can extract this information."

It is a technique known as Electric Network Frequency (ENF) analysis, and it is helping forensic scientists to separate genuine, unedited recordings from those that have been tampered with."

- http://www.bbc.co.uk/news/scie...
- http://cryptogon.com/?p=32789

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Met lab claims 'biggest breakthrough since Watergate'
Power lines act as police informers

- http://www.theregister.co.uk/2...

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Noisy, muffled, incoherent recordings are an audio engineerâ(TM)s worst nightmare, but all too often they contain vital evidence in criminal trials. Itâ(TM)s the job of the forensic audio specialist to extract that evidence.

- http://www.soundonsound.com/so...

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(discussion forum) Electrical network frequency analysis, Mains frequency variations detectable in digital audio recordings?

- http://www.hydrogenaudio.org/f...

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Met Police use electrical 'hum' to solve crimes

The Metropolitan Police is using the "hum" of background noise produced by mains electricity to help solve crimes, it has been disclosed.

- http://www.telegraph.co.uk/new...

#

Related Research
- http://www.ece.umd.edu/~ravig/...

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Engineers Use Electrical Hum To Fight Crime

- http://science.slashdot.org/st...

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Howâ(TM)s the 60Hz coming from your wall?

- http://hackaday.com/2012/07/24...

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Detecting Edited Audio

- https://www.schneier.com/blog/...

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Dating Recordings by Power Line Fluctuations

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http://www.hydrogenaudio.org/f...

http://www.hydrogenaudio.org/forums/index.php?showtopic=54933

It may not have been designed for audio files, but it's pretty damn good at them anyway - the hydrogen audio chaps rate is as equivalent to AAC and vorbis at the same bitrate, as well as having excellent quality at low bitrates along with low algorithmic delay. It appears to be a "cake and eat it" codec at present.

See here for their take on this very promising codec: http://wiki.hydrogenaudio.org/index.php?title=Opus

Now the problem that#s always plagued vorbis... will we see widespread hardware support for it? If it's already being deployed for Skype and WebRTC usage then I hope a few SoC manufacturers are going to support it.

True. However, FLAC is extremely CPU efficient for playback (decoding).
You can find some comparisons where it performs even better than MP3 in terms of CPU usage
http://www.hydrogenaudio.org/forums/index.php?showtopic=92235

It's also more efficient than any other compressed lossless codec (note: WAV/PCM is not compressed):
http://www.hydrogenaudio.org/forums/index.php?showtopic=98665

True. However, FLAC is extremely CPU efficient for playback (decoding).
You can find some comparisons where it performs even better than MP3 in terms of CPU usage
http://www.hydrogenaudio.org/forums/index.php?showtopic=92235

It's also more efficient than any other compressed lossless codec (note: WAV/PCM is not compressed):
http://www.hydrogenaudio.org/forums/index.php?showtopic=98665

I can't help but to think how digital sampling is the exact opposite problem. Taking a good quality analog source with smooth curves and then making it digital with a jagged curve.

Digital waveforms are not "jagged" - this is a common misunderstanding of how sampling works. Usually the waveform is drawn with either a horizontal line between samples ("staircase") or a straight line from sample value to sample value ("zigzag"). Neither is representative of the source waveform; there is actually nothing "between samples." Samples are discrete.

Here are a couple links to explain why the waveform you get from a DAC is smooth:

https://wiki.xiph.org/Videos/Digital_Show_and_Tell

http://www.hydrogenaudio.org/forums/index.php?showtopic=93496

No audiophile has ever heard the difference between FLAC and 320Kbps mp3 audio in an ABX test at a statistical rate that is better than guessing.

That's a bold claim. You're going to be really disappointed with this thread.
http://www.hydrogenaudio.org/forums/index.php?showtopic=70598&start=0

Some people think a 320kbps mp3 is perfect, but its not.

Yes, sometimes it is possible to achieve transparency with mp3, but not with complex samples, especially those involving percussion in high frequencies. It is a format limitation, and can not be fixed without abandoning mp3.

Other lossy formats such as vorbis, are not limited in this regard; so if a passage (sample) is too complex, it can simply bump the bitrate as much as it needs until transparency is achieved. Of course, this needs extensive encoder tuning, but the format is no longer a limiting factor.

Unfortunately with mp3 you can't put frames above 320kbps, and the samples that fail, will fail and 320kbps cbr can't help you, so if you use mp3 you might as well use a more cost effective vbr choice such as lame -V2; otherwise you are simply wasting space and not achieving transparency anyway.

Furthermore, different lossy formats have different properties, and some can actually achieve transparency, given enough tuning a lots of abx testing and data gathering.

While lossless might be wasting some space compared to a perfectly tuned lossy, it allows you to have a safe, clean source to test all those existing and emerging formats to begin with. Think of it as archival quality; from which you can then lossy compress in whatever you need.

Also you should not transcode something already lossy compressed into another lossy format, every time you do this you introduce artifacts and reduce quality.

Those deeply interested in the subject should visit: http://www.hydrogenaudio.org/ and read the many years of quality discussion archived there.

Pychoacoustics (used to tune lossy encoders) introduce another factor. Aside from different people having different hearing abilities; you are supposed to equalize your listening environment for a "flat" response. People not only rarely ever do this, they bump the settings to make it sound how "they like"; ie lots of bass or treble getting away from the average perceptual "flat" eq curve; which is what lossy encoders strive to keep; resulting in poor perception. Raw/lossless has more data able to help this real time audio modification. Ie, a lossy encoder discarded something you would have normally never listened to, but with your misuse of eq, you were expecting to hear.

Note: its not actually flat, but "Equal loudness contour" which is an average of how humans actually perceive tones.

Can you hear the different when using an ABX test? http://www.hydrogenaudio.org/forums/index.php?showtopic=16295

Archived @:
http://slexy.org/view/s21UWKzafS
http://hpaste.org/79175
https://paste.debian.net/plain/216145
======
The hum that helps to fight crime (ENF) Electrical Network Frequency analysis

"For the last seven years, at the Metropolitan Police forensic lab in south London, audio specialists have been continuously recording the sound of mains electricity.

It is an all pervasive hum that we normally cannot hear. But boost it a little, and a metallic and not very pleasant buzz fills the air. ...

"The power is sent out over the national grid to factories, shops and of course our homes. Normally this frequency, known as the mains frequency, is about 50Hz," explains Dr Alan Cooper, a senior digital forensic practitioner at the Met Police.

Any digital recording made anywhere near an electrical power source, be it plug socket, light or pylon, will pick up this noise and it will be embedded throughout the audio.

This buzz is an annoyance for sound engineers trying to make the highest quality recordings. But for forensic experts, it has turned out to be an invaluable tool in the fight against crime.

While the frequency of the electricity supplied by the national grid is about 50Hz, if you look at it over time, you can see minute fluctuations. ...

Comparing the unique pattern of the frequencies on an audio recording with a database that has been logging these changes for 24 hours a day, 365 days a year provides a digital watermark: a date and time stamp on the recording.

Philip Harrison, from JP French Associates, another forensic audio laboratory that has been logging the hum for several years, says: "Even if [the hum] is picked up at a very low level that you cannot hear, we can extract this information."

It is a technique known as Electric Network Frequency (ENF) analysis, and it is helping forensic scientists to separate genuine, unedited recordings from those that have been tampered with."

- http://www.bbc.co.uk/news/science-environment-20629671
- http://cryptogon.com/?p=32789

#

Met lab claims 'biggest breakthrough since Watergate'
Power lines act as police informers

- http://www.theregister.co.uk/2010/06/01/enf_met_police/

#

Noisy, muffled, incoherent recordings are an audio engineerâ(TM)s worst nightmare, but all too often they contain vital evidence in criminal trials. Itâ(TM)s the job of the forensic audio specialist to extract that evidence.

- http://www.soundonsound.com/sos/jan10/articles/forensics.htm

#

(discussion forum) Electrical network frequency analysis, Mains frequency variations detectable in digital audio recordings?

- http://www.hydrogenaudio.org/forums/index.php?showtopic=81346

#

Met Police use electrical 'hum' to solve crimes

The Metropolitan Police is using the "hum" of background noise produced by mains electricity to help solve crimes, it has been disclosed.

- http://www.telegraph.co.uk/news/uknews/crime/9739037/Met-Police-use-electrical-hum-to-solve-crimes.html

#

Related Research
- http://www.ece.umd.edu/~ravig/Research.html

#

Engineers Use Electrical Hum To Fight Crime

- http://science.slashdot.org/story/12/12/12/1331243/engine

Archived @:
http://slexy.org/view/s21UWKzafS
http://hpaste.org/79175
https://paste.debian.net/plain/216145
==
The hum that helps to fight crime (ENF) Electrical Network Frequency analysis

"For the last seven years, at the Metropolitan Police forensic lab in south London, audio specialists have been continuously recording the sound of mains electricity.

It is an all pervasive hum that we normally cannot hear. But boost it a little, and a metallic and not very pleasant buzz fills the air. ...

"The power is sent out over the national grid to factories, shops and of course our homes. Normally this frequency, known as the mains frequency, is about 50Hz," explains Dr Alan Cooper, a senior digital forensic practitioner at the Met Police.

Any digital recording made anywhere near an electrical power source, be it plug socket, light or pylon, will pick up this noise and it will be embedded throughout the audio.

This buzz is an annoyance for sound engineers trying to make the highest quality recordings. But for forensic experts, it has turned out to be an invaluable tool in the fight against crime.

While the frequency of the electricity supplied by the national grid is about 50Hz, if you look at it over time, you can see minute fluctuations. ...

Comparing the unique pattern of the frequencies on an audio recording with a database that has been logging these changes for 24 hours a day, 365 days a year provides a digital watermark: a date and time stamp on the recording.

Philip Harrison, from JP French Associates, another forensic audio laboratory that has been logging the hum for several years, says: "Even if [the hum] is picked up at a very low level that you cannot hear, we can extract this information."

It is a technique known as Electric Network Frequency (ENF) analysis, and it is helping forensic scientists to separate genuine, unedited recordings from those that have been tampered with."

- http://www.bbc.co.uk/news/science-environment-20629671
- http://cryptogon.com/?p=32789

#

Met lab claims 'biggest breakthrough since Watergate'
Power lines act as police informers

- http://www.theregister.co.uk/2010/06/01/enf_met_police/

#

Noisy, muffled, incoherent recordings are an audio engineerâ(TM)s worst nightmare, but all too often they contain vital evidence in criminal trials. Itâ(TM)s the job of the forensic audio specialist to extract that evidence.

- http://www.soundonsound.com/sos/jan10/articles/forensics.htm

#

(discussion forum) Electrical network frequency analysis, Mains frequency variations detectable in digital audio recordings?

- http://www.hydrogenaudio.org/forums/index.php?showtopic=81346

#

Met Police use electrical 'hum' to solve crimes

The Metropolitan Police is using the "hum" of background noise produced by mains electricity to help solve crimes, it has been disclosed.

- http://www.telegraph.co.uk/news/uknews/crime/9739037/Met-Police-use-electrical-hum-to-solve-crimes.html

#

Related Research
- http://www.ece.umd.edu/~ravig/Research.html

#

Engineers Use Electrical Hum To Fight Crime

- http://science.slashdot.org/story/12/12/12/1331243/engineers-

There is Rubyripper that has secure mode.

That's why audiophiles prefer vinyl, because it captures more sound from thestudio recording.

Audiophiles prefer vinyl because of ignorance mostly.
Here is a nice little post from SoAnIs on HydrogenAudio

24-bit precision gives you about 16.77 million values. Assuming a total groove width of 50 x 10^-6m, the maximum movement of the cutter is physically bounded at about half that. Much more and the cutter will be in the space for an adjacent groove. Thus, 50 microns width divided by 16.77 million gives us about 3 x 10^-12m, i.e. ~0.03 angstroms.

The diameter of a hydrogen atom is 1.0 angstroms (1 x 10^-10m). That would make the resolution of a 24-bit digital signal equivalent to an analog cutter whose resolution is just about 1/30 the width of a hydrogen atom. Sadly, this seems to be physically impossible, as none of the particles smaller than atoms are stable enough to be used in records.

Of course, records aren't made of hydrogen, they're made of the polymer pvc. One molecule of pvc is about 100,000 angstroms. This means that, if the cutters were actually removing single pvc molecules the vinyl records would have about 11 bits of resolution. Sadly, they don't get even that precise, though I'm not sure the actual precision. To get down to a record made of hydrogen atoms (possible under very low temp/very high pressure I suppose) one would need 19 bits. Anything beyond that is useless as long as the laws of physics hold.

Therefore, all other things being equal, digital is superior to vinyl. That said, mastering on CDs is often terrible while the mastering on records is often made somewhat better. This varies from CD to CD and record to record, and CDs are technologically far superior to records.

Joe P also posted a nice table on pink fish media
Here again the equivalent bit depth of vinyl is estimated to somewhere between 8.3 and 12.5 bits.

It's not rubbish at all. You've fallen for audiophile myth..

This should be modded funny, if anything. It is a description of hipsters calling themselves audiophiles. Real audiophiles embrace digital technology but are also skeptical of $100 stereo cables and other fancy sounding junk. Check out the Hydrogen Audio forums and The Audio Critic

The VLC framework and GStreamer piss all over Quicktime.

As for music players and library management, foobar2000, MediaMonkey, Songbird and VLC Media Player, amongst others, are so far ahead of iTunes in performance, supported formats, features, plugins and/or customizations as to be ridiculous to even make a comparison.

I use a heavily customized fb2k with support for pretty much *every* audio file type, from various FM synth formats (ROL, CMS, CMF, Silents, etc.), tracker formats (Protracker, 669, Screamtracker, Impulse Tracker, XM, etc.), console/arcade audio formats (NSF, VGM, SPC, PSF, USF, QSF, PSF2, etc.), MIDI via FluidSynth (GM, GS, XMI, XMF, etc.) to the more common digital audio formats (MP3, Vorbis, FLAC, APE, WAV, AAC, WavPack, etc.). It also has ASIO support, direct kernel streaming, loads of chainable DSP effects, a UPnP server, ReplayGain, scriptable mass-tagger, automatic timestamped lyrics download, automatic artist information download from multiple sources, a waveform seekbar and a completely custom UI. And that is just what I have configured on my own copy. There are tons of other components available that add an almost unimaginable amount of features and extensibility. By comparison, iTunes looks like absolutely pathetic.

Oh and by the way, I have a 40K+ library loaded up and foobar2000 is currently using ~170MB RAM and ~0.75% CPU. So as I said before, iTunes is garbage.

http://www.hydrogenaudio.org/forums/index.php?showforum=59

I find head-fi to be more religious.

1) Never listen to any music you buy from Apple or same. They compress the music until it's shit and no, their ALAC isn't worth a damn:

http://wiki.hydrogenaudio.org/index.php?title=Lossless_comparison#Comparison_Table

  No really, you don't have to have golden ears to hear the difference. Either take the time to burn tracks from CDs into a totally loss-less format like FLAC or do what I do and screw digital music for now, it's not ready for prime time- buy used CDs they're literally sonically perfect, (even too perfect for some vinyl lovers).

Bullshit. ALAC and FLAC are both exactly the same. *Exactly* the same. There is no difference between one format and another except for what devices/software is capable of decoding it. Most modern hardware audio decoders can decode ALAC, while most cannot decode FLAC, which gives ALAC a slight edge in practicality.

Audio CD is not "sonically perfect". Actually they sound pretty shit compared to what ALAC and FLAC are capable of.

And if you want to compare quality between an Audio CD and a "mastered for iTunes" track, then you will only notice the difference with a really good "DAC". Because it doesn't matter how good your digital source is, unless you have good hardware to convert a digital signal into analogue sound waves, there really is no point wasting your time trying to get a good digital version of the song.

If you are going to discuss high quality audio and %6,000 speakers, first take the effort to actually *learn how the fucking things work*.

My home stereo is worth many tens of thousands of dollars, but I still buy MP3's online - because most of the time I'm not listening to music in my lounge room.

If you want to have a full blown no holds barred freaking audiophile experience worthy of a 10,000 home set up, walking down the street here's how you do it:

1) Never listen to any music you buy from Apple or same. They compress the music until it's shit and no, their ALAC isn't worth a damn:

http://wiki.hydrogenaudio.org/index.php?title=Lossless_comparison#Comparison_Table

No really, you don't have to have golden ears to hear the difference. Either take the time to burn tracks from CDs into a totally loss-less format like FLAC or do what I do and screw digital music for now, it's not ready for prime time- buy used CDs they're literally sonically perfect, (even too perfect for some vinyl lovers).

Get yourself a portable, skipless CD player (which are sadly getting hard to get in decent quality anymore) and pair it with the most expensive version of this headphone you can afford, new or used,

http://www.gradolabs.com/page_headphones.php

disregarding entirely the in-ear variety because you said you want something *really* good.

I own the SR325is and it blows everything else away including the highest end Bose (junk) Sennheisers etc etc etc.

The separation of the sound and incredible detail is nothing you're going to experience this side of $6,000-a -pair home speakers. If you've been listening to digital audio, you've never even HEARD whole parts of the recording.. literally you'll hear things in the music, like, percussion parts, you didn't even know were there

. Not to mention the actual quality and timbre of the vocalist's voice.

This is the way to roll.

112dB? Ha! Hilarious.

You're lucky to get 70dB out of audiophile grade vinyl. See http://wiki.hydrogenaudio.org/index.php?title=Vinyl_Myths

There's also an interesting discussion of the dynamic range of both vinyl and 16-bit/44kHz digital audio here:

http://www.hydrogenaudio.org/forums/index.php?showtopic=47827&st=0&p=425794&#entry425794

The dynamic range of vinyl does vary by frequency. For example, in that thread a poster notes he measured 84dB at 300Hz for vinyl. A 300Hz tone recorded to a 16-bit wave file with noise shaped dither exhibited a dynamic rage of 151dB!

Vinyl has extremely limited dynamic range in the bass - something like 30dB at 20Hz. The needle would pop out of the groove if you tried to record more than that. Vinyl also suffers from constant negative signal to noise ratio incidents, when impulse noise (clicks and pops from scratches, dust and defects in the groove, static discharge) completely drowns out the signal. Unacceptable, in any format.

See also this recent article, which, while skewering the distribution of 24-bit/192kHz audio, notes that 16-bit digital audio has an overall dynamic range of 120dB with dither:

http://people.xiph.org/~xiphmont/demo/neil-young.html

Vinyl's a shitty format for reasons apart from its inferior dynamic range, but that's not terribly surprising since it's like 100 years old, mechanical, and prone to a plethora of issues - rumble, wow and flutter, phase issues caused by the RIAA equalization / de-equalization process, scads of unwanted harmonics and harmonic distortion, ultrasonic noise, preamp hum, static clicks, etc., etc., etc.

Probably should have been replaced by some other analog disc-based format by the early '70s - maybe something based on RCA's capacitance discs, which wound up being used for video, and had scads of bandwidth - more than enough for near-flawless reproduction of the original studio master tapes. But at the time most industry attention was focused on the emerging lo-fi but convenient tape formats, first 8-track then cassette, as well as the failed competing quad systems. And then by the middle of the decade everybody knew a digital format was coming, with Sony and Philips working first separately, and then by '79 or so together on what would become the Compact Disc.

112dB? Ha! Hilarious.

You're lucky to get 70dB out of audiophile grade vinyl. See http://wiki.hydrogenaudio.org/index.php?title=Vinyl_Myths

There's also an interesting discussion of the dynamic range of both vinyl and 16-bit/44kHz digital audio here:

http://www.hydrogenaudio.org/forums/index.php?showtopic=47827&st=0&p=425794&#entry425794

The dynamic range of vinyl does vary by frequency. For example, in that thread a poster notes he measured 84dB at 300Hz for vinyl. A 300Hz tone recorded to a 16-bit wave file with noise shaped dither exhibited a dynamic rage of 151dB!

Vinyl has extremely limited dynamic range in the bass - something like 30dB at 20Hz. The needle would pop out of the groove if you tried to record more than that. Vinyl also suffers from constant negative signal to noise ratio incidents, when impulse noise (clicks and pops from scratches, dust and defects in the groove, static discharge) completely drowns out the signal. Unacceptable, in any format.

See also this recent article, which, while skewering the distribution of 24-bit/192kHz audio, notes that 16-bit digital audio has an overall dynamic range of 120dB with dither:

http://people.xiph.org/~xiphmont/demo/neil-young.html

Vinyl's a shitty format for reasons apart from its inferior dynamic range, but that's not terribly surprising since it's like 100 years old, mechanical, and prone to a plethora of issues - rumble, wow and flutter, phase issues caused by the RIAA equalization / de-equalization process, scads of unwanted harmonics and harmonic distortion, ultrasonic noise, preamp hum, static clicks, etc., etc., etc.

Probably should have been replaced by some other analog disc-based format by the early '70s - maybe something based on RCA's capacitance discs, which wound up being used for video, and had scads of bandwidth - more than enough for near-flawless reproduction of the original studio master tapes. But at the time most industry attention was focused on the emerging lo-fi but convenient tape formats, first 8-track then cassette, as well as the failed competing quad systems. And then by the middle of the decade everybody knew a digital format was coming, with Sony and Philips working first separately, and then by '79 or so together on what would become the Compact Disc.

The only real comparison we've made with Vorbis and AAC was a 64 kb/s test comparing Opus to Vorbis and HE-AAC (v1). See the results and the analysis. At higher rate, we definitely reach a point where Opus is transparent for everything, but the exact rate depends on the content and the listener.

As for Microsoft, they've actually updated their covenant to something which is nicer than what Skype originally had and (IMO but IANAL) totally acceptable.

mp4 is a container. not an audio codec.

did you mean AAC?
which AAC, quicktime, faac, nero?

doesn't really matter. aotuv tuned vorbis beats or at worst ties any flavor of aac down to and including 96kbps.
http://wiki.hydrogenaudio.org/index.php?title=Listening_Tests#Multiformat_Tests

doesn't truly matter anyway. aside from "killer samples", all modern codecs, including MP3, reach perceptual transparency by about 192kbps or so.

It seems like FLAC has a slight compression edge

Not according to this table.
http://wiki.hydrogenaudio.org/index.php?title=Lossless_comparison

Note for the compression ratio, smaller percentage is better. ALAC is slightly better than FLAC. But it's so marginal it makes no difference.

Then again, the table also said that compression ratios are determined by the codec's default settings, and that flac scored "very good" in flexibility whereas apple scored "bad" (flexibility being defined as number of options given to the user). It could be that you could tweak flac's settings for slower encoding / decoing speed and better compression ratio.

And yes, they're close enough that it doesn't matter, so the point is moot.

Also,

* FLAC is less compute-intensive for decode

1
2
3

Means longer battery life and/or lower power processors.

Actually the OP got it wrong. ALACs compression is marginally better than FLAC. Though not enough to be concerned about.
http://wiki.hydrogenaudio.org/index.php?title=Lossless_comparison

It seems like FLAC has a slight compression edge

Not according to this table.
http://wiki.hydrogenaudio.org/index.php?title=Lossless_comparison

Note for the compression ratio, smaller percentage is better. ALAC is slightly better than FLAC. But it's so marginal it makes no difference.

You could try here...
http://wiki.hydrogenaudio.org/index.php?title=Lossless_comparison

It doesn't include results from this open sourced version - if there's any different at all to the tested version - though.

From that table, it seems FLAC compresses about as well (depends on the exact track) while being much faster.

But as others have pointed out, most of the technicalities may be moot if your target device is an iPod, iPhone or iPad - in which case ALAC is practically your only option.

The same applies to FLAC, really. Looks like there's a few formats that are superior to FLAC in one way or another - but if your Archos device or Android phone doesn't know what to do with the format, there's little point in using it.

Compare it to JPEG2000 vs JPEG, for example - licensing issues have hindered JPEG2000 adoption and JPEG is 'good enough' for web needs (with PNG and GIF filling some voids) so while it might make sense to compress processed RAW images to lossless JPEG2000 for archival, there's little point in doing so when publishing to the web.. most people wouldn't be able to view it.

Decay isn't what you should be worrying about, you should be worrying about what you're going to be able to verify regularly. It doesn't matter if it's a reliable medium if you have to spend 6 hours every few months verifying that the data hasn't gotten corrupted and then figuring out how to restore the files.

A better solution is to just use an external HDD which is backed up to an external location. I personally like to use SFV to provide the verification function. It takes a bit of time on large collections, but is automatic once started and will give me a list of files that have gone south if there are any.

For large important files I'll sometimes use PAR and for discs I'll generally use DVDisaster to store parity information on disk. I'll generally also store an image of the disc, which is why I only do that for DVDs and CDROMs that I buy as it's more unwieldy than just using SFV on a number of smaller files.

For audio CDs, I'll, generally rip those discs to HDD using these instructions. http://www.hydrogenaudio.org/forums/index.php?showtopic=23019&st=0 and combine that with SFVs for verification and a proper off site back up.

So some people will say Codec A sounds best. Some will say Codec B sounds best. Some will say that Codecs A and B suck donkey shit and Codec C sounds best. What exactly does this prove?

You're commenting on something you have no knowledge about.

This is a blind ABX listening test. You can go read about what that is here.

This is the program being used in this test.

It proves whether or not a statistically significant difference in perceived audio quality can be found between the various codecs by the group of testers. It is valid and scientific. If it wasn't, you wouldn't see the Hydrogen Audio forum associated with it, because they're actually interested in the real deal, and it's against their forum rules to make claims without evidence. (See here. Rule #8.) That would also be why many encoder and codec designers/developers are active in the forum, because it's where they get real empirical feedback.

So some people will say Codec A sounds best. Some will say Codec B sounds best. Some will say that Codecs A and B suck donkey shit and Codec C sounds best. What exactly does this prove?

You're commenting on something you have no knowledge about.

This is a blind ABX listening test. You can go read about what that is here.

This is the program being used in this test.

It proves whether or not a statistically significant difference in perceived audio quality can be found between the various codecs by the group of testers. It is valid and scientific. If it wasn't, you wouldn't see the Hydrogen Audio forum associated with it, because they're actually interested in the real deal, and it's against their forum rules to make claims without evidence. (See here. Rule #8.) That would also be why many encoder and codec designers/developers are active in the forum, because it's where they get real empirical feedback.

The Hydrogen Audio Forums tests have traditionally used a sound methodology, it would probably be worth reading up on it before you comment, lest you make a fool out of yourself.

They will not be trying to measure how 'good' each codec sounds, they are trying to measure how close it is to the source material, with a 'perfect score' being statistically indistinguishable.

many people can tell the difference between 128kkps mp3 and flac

"Many" might be not the best word, it might be too many, for modern mp3 encoders (well, lame...) at ~128kbps, if proper listening tests are any indication. Their encodings have gone a long way; basically, many people would need to train themselves to have any chance of reliably hearing the difference (and what would be the point of that, anyway?)

You don't use 320kbps VBR (I corrected the K for you), it's either 320kbps orVBR. The only way to get a completely 320kbps file is to encode it CBR and force it to be 320kbps. 320k is wasteful enough that a utility like mp3packer can easily and losslessly reallocate the frames to under 300k.

Anyway, It is speculative to even think evil media could make a case against a user. When the gestapo raids your house based on the digital audio files that the RIAA claims they've found, they'd need both evidence (the ripped audio files and proof they are the copyright holder) and lack of evidence (no original media, no record of purchasing) to even start. I might have all those CDs in a storage shed that I will bring in as surprise evidence.

The lack of original media is an underwhelming argument though, the 1992 audio home recording act specifically clarifies that fair use includes home taping and copying a friend's CDs, even if the destination is digitally encoded. If the OP has guilt, he should look at the thousands he already spent on music to fund lawyers, and for any unknown audio tracks, imagine that all your friends on the internet personally sent you a 'digital tape' of their CDs.

There is no such thing as a "direct digital rip". The CD standard doesn't provide one, there are no boundaries on the CD for one to work against, and as stated rip jitter is inevitable. The only question is how the software and hardware involved handle it. The post you were objecting to talks about one of the pieces of the magic used to help with this fundamental problem that you're not aware of, and there are some others too.

Drives that support what's called AccurateStream will guarantee you that they always pick the same spot every time you ask it to seek somewhere, which is the first part of the problem. If you drive doesn't do that, you end up needing to do the overlapping read shuffle described above to figure that out. See EAC Drive Options for more about all that.

Even if you have AccurateStream, there's a second problem: the spot will be the same every time, but exactly where that is can't be guaranteed--it varies based on the drive model. The way AccurateRip copes with this problem to collect a database of CD Drive Offsets. If your drive isn't in their database, what you can do is use a known music CD that AccurateRip has good data on, then calibrate your drive using it to figure out how much you're off by. People submitting those test results is how they compiled the database.

If you have AccurateStream hardware, and you know your drive offset, you can get the same rip every time and match against the checksums that AccurateRip provides. But this is only happening because several pieces of the chain know how to compensate for the limitations of audio CDs encoding, there is no way to get digital data straight off of them usefully.

Well, I don't know who thought it was a good idea to duplicate info like IP and port, but I've been using SIP for my own phone service for years, and G.711 works fine, so there's actually no need to use G.729. I'm sure there are some people on 56k or something where it actually makes a difference, but for your average broadband user, G.711 is fine. There's also Codec 2, Opus, which had outstanding performance on what looks like a pretty rigorous listening test, and of course, Speex, but uptake is an issue for those, of course, since both ends have to support the codec.

according to http://wiki.hydrogenaudio.org/index.php?title=Lossless_comparison#Comparison_Table wavpack is faster to compress and offers marginally better compression but flac has wider support from both hardware and software.

IMO the difference between 58.7% and 58.0% compression is negligible and for a store wider support is more important than faster compression.

Yes we geeks have no trouble rigging up a script to convert anything to anything (though preserving tagging can be trickier) but we are a tiny minority of the market.

I was amazed at how good the headphones that came with my BlackBerry Bold 9000 are, as well as the quality of the output of the phone.

I doubt that they use more than 12bit dacs anyway.

SoAnIs from hydrogenaudio also gives an interesting perspective on the 24-bit thingy.

I did some digging and it looks like the Bold 9000 uses the Texas Instruments TLV320AIC3106 stereo audio DAC rated at 102 dBa S/N, 16,20,24,32-bit data, and 8 kHz - 96 kHz sample rates. I don't pretend to know if the Bold actually outputs at the full capability of the chip, but why bother using such a chip if you're not going to make the features available?

There is no doubt in my mind that 24-bit and higher is better than anything analog, but I guess I'm old enough that someone will have to prove to me that CD's can be better than reel-to-reel. I'll also add that there is simply no comparison between reel-to-reel and vinyl. Have you ever listened to a good quality reel-to-reel? One roughly the size of a 24" CRT (ca. 1995)? They really do sound quite good,not that I'd ever buy one.

Wow, lots more commenters than moderators on this thread. I'll add my voice to the din. Sound quality articles catch my interest, from coat hangers to codecs, but I haven't paid much attention to this particular topic. Here's a short list of 24-bit FAQs for end users.

Existing sites like HDtracks.com, linnrecords.com, naimlabel.com, and Society of Sound offer 24-bit files with sample rates ranging from 44.1 KHz to 192 KHz, with 96 KHz being the most popular. Popular formats (in decreasing order of popularity) include FLAC, Apple lossless (ALAC), and WMA lossless.

FLAC seems to have more diverse support, but ALAC has arguably broader support, including iTunes and iPods. WMA appears to compress better than FLAC, which appears to compress better than ALAC. (FLAC's compression levels don't seem to change the ratio much, except at the lowest/fastest levels.) FLAC seems to have the fastest decoder, but ALAC has the handy property that you can simply discard the eight low-order bits (as iPods apparently do). [Sources: Hydrogenaudio Knowledgebase, hvdh at inter.nl.net, and FLAC comparison.]

I also came across some discussion of high-definition compatible digital (HDCD), a patented mastering fad from the late 90s that encodes about twenty bits on a CD, subsequently bought and buried by Microsoft. Apparently there are only two models of machines in the world that can encode HDCD, and they're both discontinued, with replacement parts in jeopardy as well.

Scrounging through CDs in the attic, I found some HDCD CDs from Capitol, High Street (Windham Hill), Red House, Sony, and Warner Bros. Goodwin's High End has an extensive list. As a quick test, I ripped Deana Carter's "Strawberry Wine" to a 16-bit WAV (51.4 MB) with XLD, converted to a 24-bit WAV (77.1 MB) with hdcd.exe (Windows only, but seems to work in WINE), then converted to 24-bit ALAC (56.4 MB) with XLD. I don't have the time or gear for an ABX test right now. The HDCD conversion is noticably quieter, for what it's worth.

Another quick way to try this at home is to torrent the 24/96 FLACs of the The Slip from nin.com (email registration required).

It's not naive, it's a documented fact. Most companies that bothered to release SACD or DVD-A did a much better job mixing and mastering them then they did on the CD. Here is just one example, but for the most part it's very rare to find a DVD-A that uses the same master as the CD.

The main problems with those formats was the fact that not enough albums are released in that format, and they are overpriced. Neither of these will change unless more people buy them, although if they did become mainstream there will probably be more companies that release the CD master on that format.

I was amazed at how good the headphones that came with my BlackBerry Bold 9000 are, as well as the quality of the output of the phone.

I doubt that they use more than 12bit dacs anyway.

SoAnIs from hydrogenaudio also gives an interesting perspective on the 24-bit thingy.

24-bit precision gives you about 16.77 million values. Assuming a total groove width of 50 x 10^-6m, the maximum movement of the cutter is physically bounded at about half that. Much more and the cutter will be in the space for an adjacent groove. Thus, 50 microns width divided by 16.77 million gives us about 3 x 10^-12m, i.e. ~0.03 angstroms.

The diameter of a hydrogen atom is 1.0 angstroms (1 x 10^-10m). That would make the resolution of a 24-bit digital signal equivalent to an analog cutter whose resolution is just about 1/30 the width of a hydrogen atom. Sadly, this seems to be physically impossible, as none of the particles smaller than atoms are stable enough to be used in records.

Of course, records aren't made of hydrogen, they're made of the polymer pvc. One molecule of pvc is about 100,000 angstroms. This means that, if the cutters were actually removing single pvc molecules the vinyl records would have about 11 bits of resolution. Sadly, they don't get even that precise, though I'm not sure the actual precision. To get down to a record made of hydrogen atoms (possible under very low temp/very high pressure I suppose) one would need 19 bits. Anything beyond that is useless as long as the laws of physics hold.

Therefore, all other things being equal, digital is superior to vinyl. That said, mastering on CDs is often terrible while the mastering on records is often made somewhat better. This varies from CD to CD and record to record, and CDs are technologically far superior to records.

Well I learned something new. Perhaps "liberated" would be a better term since the software, like Seamonkey, Songbird, OpenOffice.org, have been liberated from the clutches of single companies (i.e. Microsoft).

Google also has a WebP standard based on VP8, to replace GIFs/JPEGs, but it seems like it's reached a deadend. So WebM is the container.
--- VP8 is the video
--- Vorbis is the audio
Versus h.264:
--- MPEG4 AVC for video
--- plus some audio codec, like MP3 or AAC or HE-AAC

MPEG4/h264 vs. VP8 comparison (h264 slightly better - specially on low bitrate connections):
        - http://compression.ru/video/codec_comparison/h264_2010/vp8_vs_h264.html
HE-AACplus vs. Vorbis (HE-AAC wins):
        - http://listening-tests.hydrogenaudio.org/sebastian/mf-48-1/results.htm
JPEG vs. WebP (WebP wins):
        - http://englishhard.com/2010/10/01/real-world-analysis-of-googles-webp-versus-jpg/

So let's see: WebM is the container.
--- VP8 is the video
--- Vorbis is the audio

Google also has a WebP standard based on VP8, to replace GIFs/JPEGs - wonder why they're not pushing that too? Ya know: Remove image support from their Chrome. (shrug)

MPEG4/h264 vs. VP8 comparison (h264 slightly better - specially on low bitrate connections):
    - http://compression.ru/video/codec_comparison/h264_2010/vp8_vs_h264.html
HE-AACplus vs. Vorbis (HE-AAC wins):
    - http://listening-tests.hydrogenaudio.org/sebastian/mf-48-1/results.htm
JPEG vs. WebP (WebP wins):
    - http://englishhard.com/2010/10/01/real-world-analysis-of-googles-webp-versus-jpg/

MPEG4/h264 vs. VP8 comparison (h264 slightly better): http://compression.ru/video/codec_comparison/h264_2010/vp8_vs_h264.html

HE-AACplus vs. Vorbis (HEAAC wins): http://listening-tests.hydrogenaudio.org/sebastian/mf-48-1/results.htm

WebP vs. JPEG (WebP wins): http://englishhard.com/2010/10/01/real-world-analysis-of-googles-webp-versus-jpg/

You know.

If they would put out the box sets, more specifically, the MONO remastered box set they did a year or two ago...and put on iTunes in a lossless format, for a reasonable price.

I'd buy them.

Do you even have a clue how good 256kbps AAC sounds?

If you feel like throwing away more than half your storage for audio files (see what I did there?) that not one person in 10,000 could reliably distinguish from the original in blind ABX tests, then by all means go for it.

Meanwhile, the rest of us will already be enjoying the content BEFORE we become too old to hear the difference, waiting for "the perfect version" to be released.

Life is a series of compromises. 256k AAC is a pretty small sonic compromise in the overall scheme of things.

But perhaps for you, what we are REALLY talking about is the compromise your personal mindset would have to go through...

As for the technical side of this, it seems to me something like Replaygain would work well. Especially since commercials are known before hand (no live broadcasting) - the program establishes a baseline sound level that audio is measured against. Depending on track or album gain settings, I think that this would be made to work.

http://wiki.hydrogenaudio.org/index.php?title=Replaygain

As far as congress goes? I'm so glad they can get this bill passed, when everything else is punted down the road until the lame duck session or beyond. Lord knows we don't pay them nearly enough to think about anything harder than freakin' TVs being too loud ...

I stopped reading at 'CDs dont last as long.' Seriously? Vinyl outlasts a pressed CD? What planet are you from? ..or what universe? (jk yes I read your whole comment)

1. people buy cds to listen to music, not to save for college. 'the right places to the right audiophiles'.. You mean the emotional kind who buy into hype over technical realities?

2. in a reasonable environment, cds will outlast just about any other storage medium to date.. By 'reasonable' I mean a typical home environment under the auspices of a careful owner. I do not mean a clean room environment. There is nothing to wear out. The laser is not powerful enough to etch the polycarbonate or reflective layers. The data on it has error correction built into it. Yes, I know it's not very robust, but it's good enough to prevent gradual 'error creep' from careless use. If the cd has been abused to the point where you can hear audible errors, you'll know for sure by the screetching/popping/skipping.

3. Collecting modern vinyl is moot since most of it will be produced with the same studio mix as the CD. Collect old stuff if you want to avoid the loudness war, but this problem will not go away simply by switching formats.

4. What does 'beyond its fidelity' mean? If you mean that good equipment exposes flaws in the recording, I agree. With lossless digital formats, the weak points are the studio engineers and the consumer playback devices, not the format itself. Vinyl is a lossy format. It's just not digital, and that's what everyone raves about even though the term doesn't address its weaknesses. The anti digital crowd's argument boils down to misguided assumptions about signal purity. At sufficient resolution, a PCM approximation of an analog waveform is indistinguishable from the original by ANYONES' ear, especially once it's pumped back through an analog power amplifier and speakers. CDs 16 bit 44100hz rate is sufficient to do this for 99% of all sources. The problem lies in the policies of the recording studio.

Listeners, audiophiles or not, are far more likely to notice the lower dynamic range, rising intermod distortion, cracks/pops/skips, wow/flutter of vinyl as it wears, than they would miss the theoretical ultrasonic sampling rates (say 60Khz and up) it may offer.

More details here
http://wiki.hydrogenaudio.org/index.php?title=Myths_(Vinyl)

http://www.hydrogenaudio.org/forums/index.php?showtopic=35530

Second, and this is by all means a serious question, are current vinyl releases any better than current CD releases? Or are they also compressed to avoid complaints about sounding quieter than the CD version?

Generally the vinyl is not over-compressed. But there are notable exceptions like the recent Metallica album - in that case the vinyl was exactly the same as CD because they were both mixed under the auspices of the same producer - I forget his name, but he's become ever more popular in the business and he brings the loudness war with him to every new project he takes on and this was his first metallica album. What's really interesting about the metallica case is that the guitar hero version was (apparently) mixed by the guitar hero sound engineers and they were not under the control of any of the loudness warriors. The result was that the people who really wanted the best sound quality from that album bootlegged the ripped guitar hero version.

Here's a video comparing CD mix to guitar hero mix - you don't even need headphones to tell the difference.
http://www.youtube.com/watch?v=DRyIACDCc1I

Because the dynamic range of vinyl albums can't be compressed as much as they are on a CD resulting in better sounding music?

The dynamic range of CDs is actually at least three orders higher than that of vinyl (120dB dynamic range for high-end vinyl equipment vs 150dB for CDs). The reason that CDs sound worse is because of the skill (and agenda) of the sound engineers, not the medium.