Audio CD 700 Mo

[sirt]

Hi to everybody,

Well I have reflected the whole day and I still can't understand something by myself. Imagine I plan to burn an audio CD-R. To simplify, we will assume its full capacity is 700 Mo = 700 MB which is equal to 700 000 000 o. Of course this is totally different from 700 Mbits because 1 o = 8 bits and then you can immediately find the corresponding value in octet by using a simple rule of three.

I have read almost everywhere 700 Mo are equivalent to 74 - 80 minutes of datas. I know this is based on the fact common uncompressed files are : 16 bit (quantification) / 44100 Hz but I don't understand how you deduce the value in minutes. Could you explain me how ? Detmek gave me a track in another thread but I don't manage to apply his formula there.

Then, in this case it means only length matters when you plan to burn an audio CD-R. Imagine I have several MP3 / 10 Mo whose length is 10 minutes for each one . To my mind, it means I will only be able to burn 7 or 8 on a 700 Mo CD-R (max 8*10=80 minutes). Am I correct ? Moreover, if you imagine I also have several WAV / 50 Mo whose length is the same, I think I will also be able to burn 7 or 8 FLAC. I am not sure if that is true, but in the case it is, it would mean the size doesn't matter, only lenght. But I am really confused. In this case what would be the point of compressing files to MP3 ? Is this just intended to reduce the amount of data but in any case to enable anyone to burn more music ?

If I would like to burn a data CD-R, I think it would be quite different : 700 Mo offered and several MP3 / 10 Mo -> 70 Mp3 can be burnt ; to the contrary if I use FLAC / 50 Mo -> only 14 FLAC can be burnt according to my examples. Am I also correct ?

[filler56789]

First of all, what is "Mo" ? :confused: :rolleyes:

Anyway:

44100x2(bytes)x2(channels)x60(seconds) = 10584000 bytes per minute

So, an "80-minute CD" can contain up to 10584000x80 bytes.

BUT, when the CD is used for storing data (instead of RedBook Audio (http://en.wikipedia.org/wiki/Compact_Disc_Digital_Audio)), around 100MB are reserved for error-correction, so that only 703MB can be effectively-used for data storage.

Read: http://en.wikipedia.org/wiki/ISO_9660#Specifications

http://en.wikipedia.org/wiki/CD-ROM#Extensions

HTH :)

[detmek]

Hi to everybody,

Well I have reflected the whole day and I still can't understand something by myself. Imagine I plan to burn an audio CD-R. To simplify, we will assume its full capacity is 700 Mo = 700 MB which is equal to 700 000 000 o. Of course this is totally different from 700 Mbits because 1 o = 8 bits and then you can immediately find the corresponding value in octet by using a simple rule of three.

I have read almost everywhere 700 Mo are equivalent to 74 - 80 minutes of datas. I know this is based on the fact common uncompressed files are : 16 bit (quantification) / 44100 Hz but I don't understand how you deduce the value in minutes. Could you explain me how ? Detmek gave me a track in another thread but I don't manage to apply his formula there.

Then, in this case it means only length matters when you plan to burn an audio CD-R. Imagine I have several MP3 / 10 Mo whose length is 10 minutes for each one . To my mind, it means I will only be able to burn 7 or 8 on a 700 Mo CD-R (max 8*10=80 minutes). Am I correct ? Moreover, if you imagine I also have several WAV / 50 Mo whose length is the same, I think I will also be able to burn 7 or 8 FLAC. I am not sure if that is true, but in the case it is, it would mean the size doesn't matter, only lenght. But I am really confused. In this case what would be the point of compressing files to MP3 ? Is this just intended to reduce the amount of data but in any case to enable anyone to burn more music ?

If I would like to burn a data CD-R, I think it would be quite different : 700 Mo offered and several MP3 / 10 Mo -> 70 Mp3 can be burnt ; to the contrary if I use FLAC / 50 Mo -> only 14 FLAC can be burnt according to my examples. Am I also correct ?
When you burn Audio CD every file is decompressed to 44100kHz/16-bits PCM stereo. Also, audio data on Audio CD is stored differently compared to data CD, so you can skip the math. Only total length of files matters.

[sirt]

Thanks guys for the clarification.

detmek, then imagine I have one MP3 / 900 MB whose length is exactly 80 minutes. Then I deduce it could be burnt ; what if this MP3 is 1 000 000 MB but 80 minutes length ? I know the size doesn't matter but they are some limits, aren't they ?

[detmek]

In your example limit is maximum bitrate for MP3 standard. 900MB MP3 would have 1536kbs which is not possible by standard.

For Audio CD limit is total length of 80 minuts. Again, it doesn't matter what bitrate, samplerate or bitdepth have the source.

But, for the sake of discussion lets say it is possible. Then yes, you could burn that mp3 as Audio CD because, I repeat, every file MUST BE decoded (and converted), internaly or manualy, to 44100kHz/16-bit PCM stereo file before you burn it as Audio CD.

Another example, if you want to burn 384kHz/24-bit 7.1 FLAC file to Audio CD, the file must be downconverted and downsampled to 44100kHz/16-bit/2.0 PCM audio before software starts to burn it as Audio CD.

[pandy]

Before starting this thread first you should read this:
http://www.cdmediaworld.com/hardware/cdrom/cd_oversize.shtml
http://www.cdmediaworld.com/hardware/cdrom/cd_cd-r80.shtml
http://www.cdmediaworld.com/hardware/cdrom/cd_cd-r99.shtml

old articles but still applicable

also there is very short answer

http://wiki.answers.com/Q/What_is_the_maximum_storage_capacity_of_a_CD

[pandy]

Another example, if you want to burn 384kHz/24-bit 7.1 FLAC file to Audio CD, the file must be downconverted and downsampled to 44100kHz/16-bit/2.0 PCM audio before software starts to burn it as Audio CD.

Nope - if you can put FLAC in container with CBR 1,411.2kbps then CD player should be able to output such audio to external decoder without problems (same situation as for DTS and AC-3).

[detmek]

Yes, but it is not a true Audio CD, right? You can not play that Audio CD on every Audio CD capable player. Plus, I am not sure that it is possible to create 384kHz/24-bit/7.1 FLAC that can fit into 1411,2kbs limit, unless most of the content is digital silence.

BTW, text in links you posted states that most of those formats are not CD Red-Book compliant.

[sirt]

Sorry for my ignorance but what is exactly 384 khz/24-bit/7.1 FLAC (in simple words) ? According to the quantification used and the high sampling rate, I deduce it is far better than any CD audio track. But what "7.1" refers to ? Moreover is such an audio available somewhere ?

[detmek]

Well, it is FLAC file with samplerate of 384kHz, bitdepth of 24 bits and it has 8(7+1) audio channels. Is it bettet then Audio CD? Yes, but mostly to the presence of surround channels, not so much because of higher sampling rate or bitdepth.
I don't khow if you can find such audio on internet. There are DTS-HD MA tracks with 96kHz/24-bit/7.1 which you could upsample to 384kHz and encode it to FLAC. You won't get better quality from upsampling but you will have an audio track to experiment with.

[pandy]

Yes, but it is not a true Audio CD, right? You can not play that Audio CD on every Audio CD capable player. Plus, I am not sure that it is possible to create 384kHz/24-bit/7.1 FLAC that can fit into 1411,2kbs limit, unless most of the content is digital silence.

BTW, text in links you posted states that most of those formats are not CD Red-Book compliant.

This is visible for CD player as valid Audio CD however external decoder is required to produce audible audio not noise.

I agree that 80 and 99 minutes are not red book complaint but question was related to capacity and there is nice background.

(honestly not understand why 384ksps/24 bit/7.1? - with 384 ksps 16 bit or even 8 bit with noiseshaping and dither will more than enough - DSD stream is sampled less than 8 times more but with 1 bit and provide accordingly to some goldenears guys better sound than DVD-Audio)

[Ghitulescu]

Golden ears are usually found more in hifi magazines, show rooms and sales departments, rather than in universities, industry or academic reunions :)

But I still do not understand the problem the OP faces. Frankly it escapes my understanding ....
CD-Audio is CBR, that means that an 80 minutes CDR will hold EXACTLY 80 minutes of music or any other sound (take or give a few seconds), like an E-180 VHS tape will hold 180 minutes of video, irrespective whether it's black-and-white or colour. Unlike VHS there is no LP mode ....

In order to make an LP CDR :), eg using the MP3 algorithm, this is no longer an audio CD, is a data CD, and as such it doesn't play in a CD player, unless it has support for MP3. The bitrate, irrespective of its format (MP3, FLAC or even WAV), defines the duration of music - lower bitrate = more music, higher bitrate = less music.

All these informations are freely available, eg in Wikipedia.

[Groucho2004]

But I still do not understand the problem the OP faces.
<rant>
Simple - If one lacks the very basic understanding of a given subject, in this case it's Audio data formats, redbook standard, etc., he/she will not understand anything, no matter how well explained.
This goes for pretty much every thread/subject the OP brought up.

The weird thing is that nowadays one does not even have to go to the library and rent or buy books (like I did many years ago). The information is just a few mouse clicks away but apparently even that is too much hassle. Just open a thread and pester the experienced forum members until they spill all the links and information necessary.
</rant>

[SeeMoreDigital]

I agree that 80 and 99 minutes are not red book complaint but question was related to capacity and there is nice background.Quite a few years ago I managed to back-up Pink Floyd The Wall (81min 9secs), from it's original two disc's onto one 800MB CD-R, I even added 'Text' data.

And my Philips 101 CD player, which I bought way back on the 4 June 1984 can play it perfectly....

[filler56789]

I agree that 80 and 99 minutes are not red book compliant

Maybe you're right about the 99-minute CDs, but regarding the 80-minute (700MB) CDs,
this is the only type of CD-R/CD-RW available at the shops since many years ago
( I live in a 5th-World country :o :mad: :D , therefore things can be quite different in the First World :) ).

[sirt]

Golden ears are usually found more in hifi magazines, show rooms and sales departments, rather than in universities, industry or academic reunions :)

But I still do not understand the problem the OP faces. Frankly it escapes my understanding ....
CD-Audio is CBR, that means that an 80 minutes CDR will hold EXACTLY 80 minutes of music or any other sound (take or give a few seconds), like an E-180 VHS tape will hold 180 minutes of video, irrespective whether it's black-and-white or colour. Unlike VHS there is no LP mode ....

In order to make an LP CDR :), eg using the MP3 algorithm, this is no longer an audio CD, is a data CD, and as such it doesn't play in a CD player, unless it has support for MP3. The bitrate, irrespective of its format (MP3, FLAC or even WAV), defines the duration of music - lower bitrate = more music, higher bitrate = less music.

All these informations are freely available, eg in Wikipedia.

Ghitulescu, if you don't "understand" my questions, then why do you bother to reply back ? On the other hand, I am not sure to understand what you mean by "lower bitrate = more music and higher bitrate = less music". As I discussed with detmek on another thread, only length matters when you burn an Audio CD-R. Then whatever if I use FLAC or MP3, it appears I will only be able to burn same number of tracks. So the bitrate doesn't interfer in this case, Am I wrong ?


<rant>
Simple - If one lacks the very basic understanding of a given subject, in this case it's Audio data formats, redbook standard, etc., he/she will not understand anything, no matter how well explained.
This goes for pretty much every thread/subject the OP brought up.

The weird thing is that nowadays one does not even have to go to the library and rent or buy books (like I did many years ago). The information is just a few mouse clicks away but apparently even that is too much hassle. Just open a thread and pester the experienced forum members until they spill all the links and information necessary.
</rant>

Groucho204, it is good for you if you don't "lack" the basic understanding and so on as much as you read many books. Then, in this case you should have been able to answer each basic (or advanced) questions I asked but that was not the case or you repudiated to answer. Why the hell would you like me or anybody else to open a thread ? I or someone else precisely do that to obtain an answer on some specifical issue. Did you just wonder one second that I may encounter problems while doing a "few mouse cliks" in order to find an information ? It is possible I've read and I stil don't understand. It is also possible I haven't read what I should have had to.

[Groucho2004]

Then, in this case you should have been able to answer each basic (or advanced) questions I asked but that was not the case or you repudiated to answer.
Why should I answer a question that has already been answered?

Why the hell would you like me or anybody else to open a thread ? I or someone else precisely do that to obtain an answer on some specifical issue.
You're completely missing the point.

It is possible I've read and I stil don't understand.
That is indeed possible.

[sirt]

You should answer in sample words. Else, what would be the point of having such a forum ? You claim all the needed information is around and one just needs to read it. But it is not that simple. Look, I am studying maths. I could tell you, for example, prove the density of diagonal matrices inside square matrices of n dimension. You may not have the answer and you will "google" up (as you like saying it). You will find one or several demonstrations. And so what ? What if you simply don't understand or you need further information about such and such notion ? It is logical you will join a forum ans discuss this issue. As you see, we discuss ; it is different from asking you for information as if you were a teacher. Here occurs an exchange. It is not my fault if you are unable to understand that.

Not everything is as easy as "googling" the needed information and that's all.

[Groucho2004]

You should answer in sample words.
:confused:

you will "google" up (as you like saying it).
I never phrased it like this. Anyway, Google is just a tool to find further information, a scientific paper about a given subject for example.

As you see, we discuss ; it is different from asking you for information as if you were a teacher. Here occurs an exchange.
The "exchange" in your case appears to be very one-directional. I don't recall you ever answering a question.

[sirt]

You are simply missing the point as well. By exchange I refer to the existence of this thread and anything else. Here we can simply interact together. Not only this is about solving my questions but it is also the occasion to ask for further information if needed and literally discuss such and such idea, raise other questions, in a word : talk over. Nonetheless, it looks like you don't share my point of view once and for all. It is good for you if google helped you in any cases to find the information you needed. But it is not the same for me : not only I need to read but also to discuss. I am not a "robot".

Then when you refer to exchanging by answering questions, it is another story. As it appears, I am not enough skilled to offer my knownledge so it is perfectly logical I open threads and have various discussions. But telling me "all the information already exists" and that you are enough experienced to answer - but you don't - won't help anybody.

[Guest]

Gents, please take further discussion of this off-topic tangent to PM. Thank you.

[pandy]

Quite a few years ago I managed to back-up Pink Floyd The Wall (81min 9secs), from it's original two disc's onto one 800MB CD-R, I even added 'Text' data.

And my Philips 101 CD player, which I bought way back on the 4 June 1984 can play it perfectly....

Maybe you're right about the 99-minute CDs, but regarding the 80-minute (700MB) CDs,
this is the only type of CD-R/CD-RW available at the shops since many years ago
( I live in a 5th-World country :o :mad: :D , therefore things can be quite different in the First World :) ).



https://en.wikipedia.org/wiki/Compact_Disc_Digital_Audio#Storage_capacity_and_playing_time

http://www.cdrfaq.org/faq03.html#S3-8

"A standard Red Book audio CD or Yellow Book CD-ROM is designed to allow at most 74 minutes of data."

[pandy]

As I discussed with detmek on another thread, only length matters when you burn an Audio CD-R. Then whatever if I use FLAC or MP3, it appears I will only be able to burn same number of tracks. So the bitrate doesn't interfer in this case, Am I wrong ?


Yes - as MP3/FLAC have different bitrate compared to PCM CD audio thus for same capacity you can store more tracks - there is nothing against encapsulate on CD many audio tracks that can be later extracted by external decoder.

No - as CD Audio format is constant and if we consider ONLY PCM data (or any data with same bitrate as audio data) then lenght count not bitrate (which is fixed and equal to: "The undecoded channel-data rate for a Red Book audio CD is 4.3218 Mbit/s, with 2.0338 Mbit/s being the rate of the undecoded audio and subcode." https://en.wikipedia.org/wiki/Compact_Disc_Digital_Audio#Bit_rate )