Talk:Digital audio/Archive 1

Subjective evaluation
I think that this section should be revised. Placing proper controls in subjective tests makes the results repeatable which is essential in any scientific measurement. It should be made clear that subjective values given like detail, body, etc. can be measured in controlled subjective tests. This can take the form of a rating given across a numerical scale. For example detail or tonal quality might have extremes of too bright or too dull. These evaluations are useful because of their repeatability and the fact that the results can be analysed quantitatively, using, for instance, statistical methods. —The preceding unsigned comment was added by 217.205.242.230 (talk • contribs).


 * Indeed. I wrote the bulk of this article for similar reasons as why this section needed revising. Cburnett 20:49, 3 December 2006 (UTC)

I'm thinking of adding some further information on the common subjective tests. These are the double-blind tests like ABX and open tests which are often used in the audio press. I'll explain the advantages and disadvantages of both methods. Floyd Toole of Harman International has written on this subject.

In The Loudspeaker and Headphone Handbook, Floyd Toole states that objective measurements of loudspeaker performance, particularly amplitude response, are a good indicator of probable evaluation of subjective performance. I think that this link, in broader terms, is also true of other parts of the reproduction chain.

The point made in the second paragraph of the 'Subjective evaluation' section -


 * Audio can be measured and analyzed to more exacting measures than can be done by ear, but what this technical measurement and analysis lacks is the ability to determine if it sounds "good" or "bad" to any given listener

is true, but only in the sense that (objective) measurements won't necessarily correspond to the listener's enjoyment (subjective rating) of a particular performance. This is different because whether or not a listener enjoys a particular performance or not depends on many things, like the production of the recording, and the listener's state of mind. One of the advantages of double-blind testing is that psychological controls attempt to reduce the influence of unrelated factors - unrelated in the sense that we are only interested in the performance of the reproduction equipment, and not the emotional/psychological state of the listener which is quite variable independently. There is also the adaptation of the senses to consider. This alters a person's perceptions of a stimulus over time. To counteract the effect of adaptation, double-blind tests are usually conducted over short time periods. A disadvantage of double-blind testing is the difficulty in getting high-quality data which are able to differentiate high-performance equipment. --Enescot 12:59, 16 December 2006 (UTC)


 * I would recommend reading over Analog sound vs. digital sound and going from there. Cburnett 22:35, 16 December 2006 (UTC)

→I'm having trouble with this subjective portion. What you think sounds "good" generally depends on what you've listened to in the past. For example, if you grew up listening to classical music you're going to expect a huge dynamic range, while people growing up listening to punk will expect a very compressed sound. It's just what you're used to. Things such as recording media, amplifiers, and speakers, can all affect these sorts of parameters. So systems that have some weird compression might sound "good" to a hard rocker, but "unnatural" to a classical lover. The classical lover will think a more linear system sounds better, regardless of what music play through it. The same goes for the analog vs digital media argument. 137.71.23.54 17:05, 8 February 2007 (UTC)Brett

Hype
I love this medium, but:


 * The key advantage of digital audio is that the quality of audio signal being decoded is no longer directly dependant upon the quality of the recording medium. The ability to detect, and then to correct errors present in the recorded digital signal is abstracted to a mathematical problem instead of being a physical engineering problem.  With the birth of cheap digital electronics, this has also made it easier and cheaper to copy and transmit digital signals.

This combines love of the abstruse with a subjective assessment. Let's just dive in to what digital audio *is*, first. --Uncle Ed 02:13, 25 February 2007 (UTC)

Hi. I added the first two sentences above. I think they are a good explanation of why digital audio has been widely adopted. I'd like to add them back to the main page, if you agree - I can live without the third one though... Is there anything fundamentally incorrect about the first two? I can find references for them in Watkinson - art of digital audio if that helps.. --Tomhannen 17:19, 25 February 2007 (UTC)

Then how about this:


 * Digital audio has been widely adopted because ...

Otherwise, no objections, and thanks for your effort and attention. --Uncle Ed 01:24, 26 February 2007 (UTC)

Hey everyone
Begun Restructure of digital audio introductory definition, use, and influence on the recording industry. I will continue this effort piece by piece when time allows. I plan to revise/rephrase, and aim for these additions to supplement some good content already written by others, any help, comments, suggestions, encouraged. I think the article was a little scattered and not structured well enough, but can be with a little effort from all of us.

I don't mean to sound cheesy, but it is what it is.

Later, James —The preceding unsigned comment was added by TheRecordingGuru (talk • contribs) 01:12, 20 July 2007 (UTC)


 * Hey James. I reverted your changes to this article as well, for some of the same reasons as on the recording studio article. Here's the link to your last-edited version. Some of my comments there apply here as well. One good resource to consult on and coordinate improvements would probably be the professional sound production WikiProject. I'll leave a welcome message on your user talk page with some other helpful links. Good luck! Dancter 01:45, 20 July 2007 (UTC)

Image copyright problem with Image:Quantization noise.ogg
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Advantages of Digital Audio
Perhaps this should be expanded to include some other things such as: Increased processing capability (some effects, including various kinds of delays, filters, modulation, and psycho-acoustic enhancement, are either very expensive, difficult, or impossible to implement with analog components... but can easily be implemented in DSP); Non-destructive editing and processing; Immunity to noise and distortion while in the digital state (although we all know D->A and A->D conversion has these problems); Project sharing among different studios; Error Correction in case of media corruption, etc. These are all very objective and certainly non-biased advantages of digital audio. 137.71.23.54 17:05, 8 February 2007 (UTC)Brett

The biggest advantage of any digitial system is the ability to store, retrieve and transmit signals without any loss of quality. The current wording doesn't really emphasise this. Also important is the fact that it was driven by a need to introduce digital audio into broadcasting systems in order to minimise degredation from long and complex signal chains.

Some of the advantages that you mention are true of course, but I think they would be better categorised as "applications" as they cloud the main factor which leads to all of those things. For example, DSP was not a motivating factor and proponents of analogue will disagree that digital processing really offers anything of value - the majority of effects used will have analogue counterparts. Error correction is not an advantage, it's an absolute necessity e.g. Reed–Solomon on CD.

I know it's mentioned later but maybe it should be noted that by its nature, digital audio inherently represents a less than perfect view of the original analogue signal.

Basically, I think this section should also answer the question "why not stick with analogue?".--Subtractive 22:32, 13 February 2007 (UTC)


 * That depends on what assumptions you place on the analog signal. No analog system can carry an infinite bandwidth signal and at some point the signal will hit the noise floor and you've effectively found your upper frequency. :)  "Perfect" is a misnomer anyway.


 * I think with regards to DSP having an advantage is that it's software. Being able to reflash a new algorithm to give you a completely different function has an incredible value/advantage over doing it in hardware.  I don't think this point is really that contentious either.  How many of people do you know use punch cards to interace with a computer?  Cburnett 22:48, 13 February 2007 (UTC)


 * I found the first sentence of this section useful and included it in the intro. Thanks to whomever contributed it. --Kvng (talk) 05:33, 3 May 2010 (UTC)

More rewrite needed
This page needs some significant re-writes. The stuff about the history is wrong in places - no mention of Sound In Syncs from the BBC in the late 60s. No mention of Nyquist except as a link at the bottom. Needs a separate section on the audio chain. Needs more examples of channel codes, and emphasis on the engineering benefits of digital systems, being careful not to imply that digital systems sound more/less pleasing than analogue systems. Needs some diagrams. Needs more of an engineering outlook.--Tomhannen 00:35, 7 February 2007 (UTC)


 * By all means: WP:BB. :) Cburnett 02:59, 7 February 2007 (UTC)

I agree as well, this "History of digital audio use in commercial recording" section is written by someone who doesn't know anything about the topic, barely understand the topic, or even the language he is attempting to write in.

This section shows it, "...George Martin, felt that the multitrack digital recording technology of the early 1980s had not reached the sophistication of analogue systems. Martin used digital mixing,[citation needed] however, to reduce the distortion and noise that an analogue master tape would introduce (thus ADD). An early example of an analogue recording that was digitally mixed is Fleetwood Mac's 1979 release Tusk.

Mixing? It would have been completely impossible to digitally mix ANY digital multitrack recording before 1985 or so, when the Neve DSP digital mixing console (two were made that year, six in later years). Whoever wrote that doesn't know what mixing means. Ever mix cement? Mix epoxy? Mix eggs and milk? None of them mean "record to". Beware of any claims made by the AMS/Neve website or those that copy from it, Neve lies. When someone at Neve has an idea, or later said they had an idea long ago, they backdate their "world's first ever" product to that date, even if wasn't manufactured then and didn't have a single working prototype for years after! —Preceding unsigned comment added by 208.127.100.145 (talk) 23:23, 12 July 2009 (UTC)

Post note: This went unfixed for a long time, so I went ahead and deleted the part of this paragraph that was unsourced, didn't make sense, and made false claims about a Fleetwood Mac album (claiming it was digitally mixed 7+ years before the existence of any digital mixer). —Preceding unsigned comment added by 208.127.100.174 (talk) 06:01, 6 September 2009 (UTC)


 * I believe I found an authoritative source (Fine) and have reworked most of this section. I did not find any outright errors but I beleive it is now a more comprehensive account. --Kvng (talk) 05:33, 3 May 2010 (UTC)

History - PCM not invented by Bell
The history of pulse code modulation was wrong, so I have changed it. It wasn't invented by Bell, but by British scientist Alec Reeves. Very interesting 15 min BBC Radio 4 programme on the invention yesterday - cn be heard here. 86.134.116.168 (talk) 07:11, 28 March 2011 (UTC)

New references
History of digital audio. --Kvng (talk) 19:27, 30 November 2011 (UTC)

New lead paragraphs?
Hello, I have some updates for the lead paragraphs, which have been marked as needing improvement. Are there any objects to making the following changes?
 * Digital audio refers to technology that records, stores, and reproduces sound by encoding an audio signal in digital form instead of analog form. The typical method of encoding sound as a digital signal is pulse-code modulation. Audio compression  algorithms are frequently used to reduce the size of the resulting digital data stream. Two essential components of digital audio recording and reproduction are the analog-to-digital conversion (ADC) component and the digital-to-analog conversion (DAC) component. Digital audio systems can also make use of digital storage, processing and transmission components. Benefits of digital audio include reduced noise and distortion, and convenience of storage, transmission and retrieval. The advent of digital distribution has enabled the commercial innovation of selling songs as data files via on-line stores rather than on physical media such as audio cassette tapes or compact discs. Bremand (talk) 13:52, 17 August 2012 (UTC)


 * Definitely an improvement so I support copying it to the article. A couple of nits: Best to avoid back-to-back wikilinks (Audio compression algorithms). The last sentence is not supported in the article body. I'm personally not too sticky about this for articles under development. --Kvng (talk) 12:51, 19 August 2012 (UTC)


 * Ok, I will remove the link on 'algorithms' and delete the last sentence until a paragraph can be put in to support it. Bremand (talk) 19:11, 22 August 2012 (UTC)

MIDI and digital audio
In the "Digital audio interfaces" section of this article, it lists MIDI, and states it as "low-bandwidth interconnect for carrying instrument data; cannot carry sound". Now, if I'm not mistaken, this is not exactly true, since MIDI can carry digital sound via SYSEX dumps, no? Such wouldn't really be totally legit though, I would assume, due to the SYSEX capabilities of MIDI varying from manufacturer to manufacturer to carry any kind of binary data (hence it's name, SYStem EXclusive)... misternuvistor 14:09, 1 October 2006 (UTC)


 * Little of that is correct. SysEx dumps don't carry real-time audio, they're a file-transfer mechanism. There is no playback capability in the process. You're correct that SysEx capabilities vary from manufacturer to manufacturer, but some SysEx capabilities have been standardized, and the SysEx dump is one of those. That feature is not commonly implemented these days, because it's very slow, and is the kind of thing that is only used because nothing better is available. SysEx dumps weren't used for very long before they were replaced by SCSI drives, and those too have long since been replaced. Dementia13 (talk) 16:50, 12 September 2012 (UTC)

Sysex carrying Audio
Whereas it is true that audio can be sent via MIDI Sysex, it is certainly not able to do this in real time. A single CD quality monophonic audio stream will run 16 bits at 44,100 samples per second. That translates to 88,200 bytes per second or 705,600 bits per second. Sysex sends data in packets, maximum bit depth of 7 bits. Since MIDI is running at 33,100 bits per second, and each packet consists of a start bit, a flag bit, seven data bits, and a stop bit, the maximum audio transmission will be .7 * 33,100 bps, or 23,170 bps. Thus it will take a minimum of 30.5 (rounded) seconds to transmit a single second of monophonic CD quality sound. Stereo doubles this, and therefore we get the working value of about 1 minute of data transmission per second of audio.

Obviously one can transmit audio data in many different formats: one could stack pennies in head=0 tail=1, then roll them up and carry them across town. However, I would not recommend this as a mode of transmission! Davidbrucesmith 02:54, 24 October 2006 (UTC)


 * I agree, I think that it's a stretchy, cheating definition to include MIDI in that list. It's only used for file transfer and was replaced for that purpose by SCSI. If SCSI were put into that list, it would get laughed right off. Dementia13 (talk) 18:13, 12 September 2012 (UTC)

Copy edit comments
When I do a copy edit, I may see ways that an article can be improved that aren't directly related to the copy edit, so I point them out on the talk page. I need to explain some of my deletions, because I know that there are a lot of opinions flying around about relative quality of digital and analog audio. I'm not taking a side, but I'm finding some statements about advantages of digital audio that are more about the ideal than about what happens in real life. For instance, to say that analog audio is noisier than digital audio is theoretically true, but in the real world, there are some very noisy digital systems and some very quiet analog systems. It's not that I think the statement shouldn't be there, it's that it needs more information and detail. As stands, it's so overgeneralized as to be untrue. Feel free to add back a clarified and expanded version that includes references.

I tagged a statement as "dubious", and here's why: to say that digital audio is free of noise and distortion, is to ignore the possibility that further processing may be performed on the audio. If this processing involves mixing or a gain boost, the audio's bit depth can be exceeded, and its waveforms will be chopped. This results in some very nasty sounding distortion. There's also the possibility that its quality may be degraded by a conversion to a lower sample rate or bit depth. So, statements like that need to be expanded and clarified. Use of references would clear up a lot of these problems. Dementia13 (talk) 00:51, 13 September 2012 (UTC)


 * I have expanded on this with text copied from Digital article. Citations are always good but I don't think they are essential here. ---—Kvng 16:49, 14 September 2012 (UTC)


 * My point was that if something is researched, it should reduce or eliminate the kind of errors that come when someone is writing off the cuff. It's not to be anal-retentive about adding references, it's about encouraging better-researched articles. Dementia13 (talk) 16:00, 24 September 2012 (UTC)

Present Uses of Digital Audio
This section seems to have confused digital audio with digital distribution. For instance, one part reads "[i]n 2011, digital music provided 50.3% of all music purchases"; but, in context, 'digital music' refers to downloads, not CD or DAT or the various other types of digital music available. Furthermore, the discussion on piracy is largely irrelevant for an article about the technical attributes of digital audio. This section should either be moved to a more appropriate article, or removed altogether. micronbyte (talk) 00:10, 10 December 2012 (UTC)


 * Here's the section which I just removed, references moved down to show as a list:
 * "With current digital audio technologies, the present uses of digital music have grown immensely. With a trade value of 4.6 billion dollars, the worldwide digital music market is transforming the way society listens to their music. From 2004 to 2010, there was a 1000% increase in the value of the digital music market. This number continues to increase with new ways to purchase digital audio, through digital stores like iTunes and from purchasing playlist premium services such as Spotify and Pandora’s premium options. In 2011, digital music provided 50.3% of all music purchases. Pirating has greatly hindered the economic growth of digital music, while free playlists have slowed the economic development of digital audio as well. Digital music integration with social media has been an innovative driving force for the music industry. With new formats, such as YouTube, Spotify and other Facebook applications, one can share music with their network with ease. The challenge of the music industry is finding how to harness the enthusiasm of social media and digital music to lead to song and album purchases rather than illegal downloads."


 * I think your point is valid that the writer confuses all of "digital audio" with "downloadable digital audio". Until that point is addressed, the text is not quite suited to this article. Binksternet (talk) 03:00, 11 December 2012 (UTC)
 * I think your point is valid that the writer confuses all of "digital audio" with "downloadable digital audio". Until that point is addressed, the text is not quite suited to this article. Binksternet (talk) 03:00, 11 December 2012 (UTC)
 * I think your point is valid that the writer confuses all of "digital audio" with "downloadable digital audio". Until that point is addressed, the text is not quite suited to this article. Binksternet (talk) 03:00, 11 December 2012 (UTC)

Geoff Hill, 1951
The Analog-to-digital timeline article says, "1951, Audio recording: Geoff Hill plays back the first digital audio recording of Colonel Bogey's March."

Is this worthy of inclusion in the "History in commercial recording" section? (And, might want to change the title of that section, because non-commercial efforts are often notable too.) 75.163.140.80 (talk) 18:10, 10 June 2017 (UTC)


 * Analog-to-digital timeline is not in great shape. I have recovered the reference for this claim and it doesn't looks solid. I have changed the section heading. ~Kvng (talk) 14:12, 13 June 2017 (UTC)

Definition of Digital Audio
I think this needs a bit more clarification. It seems many people are still confused, and believe that it is possible to listen to a digital audio signal. It is not. Your eardrum cannot process digital information. It can only hear an analog sound waveform. Digital audio is merely a representation of this analog waveform. I think the article should be more clear in the fact that digital audio is merely a carrier between the original analog sound source (maybe a voice speaking into a microphone) and the analog sound coming out of your speaker hitting your eardrums. kimhi dan


 * You can't hear analog audio either. I have inserted the word representation into the opening sentence. ~Kvng (talk) 13:41, 31 March 2020 (UTC)

Professional audio industry
The professional audio industry is moving to 96 and 192k sampling rates. Another important issue is bit depth, many consumer devices are only 16 bit while professional application are moving to 24 bit depth.

→In response to this I'd say the process has already been completed. Studios running under 192kHz and 24-bit are almost gone at this point. Even though the end media is usually 44.1kHz, 16-bit (standard audio CD), recording in 192-24 dramatically reduces the noise propagated through the system and increases the reproducible frequency range, which can yield a higher quality master, even after downsampling and truncation. 137.71.23.54 17:05, 8 February 2007 (UTC)Brett


 * Some of this is covered at Sampling_(signal_processing) ~Kvng (talk) 13:45, 31 March 2020 (UTC)