CD 80 MIN MAXIMUM OR MB MAX ? RECORDING HELP

Posted: Mon May 12, 2008 10:19 am

Hi
Looks a great forum. I have a bit of an odd question here.Hope someone can help. I have been burning some CDs that have talks lasting just under 80mins. Now the Cds state that they are 80minute audio cds( I think most CDs are the same these days). I have had no problem with them but it has been pointed out by a replication company i am using that the maximum Mb size on a CD is around the 650 mb size. Now the size of the file on some od the cds is around 810 mb. Could anyone let me know what the science is behind this and if i will have problems in the future with these large sizes? Up till now it looks like the cds are ok...
thank you Paul
PS The cd files are stereo. Someone has suggested i make them into a single mono file to reduce the size, but when i had a go it looks like the cd software creates a stereo file anyway so the size is back to 810Mb.Can a cd be burned with a single mono file? Would it play through just one channel ?

Posted: Mon May 12, 2008 9:11 pm

Paul, yes, slightly confusing. Replicated CDs are stamped out much like vinyl was. Replication companies typically adhere to the Redbook standard which was created 25+ years ago. CDs were only 650MB back then which is the replicated standard. Since then, we have been able to obtain a slightly higher capacity recordable CD which are 700MB and that gives you 80 minutes.

All CDs have to adhere to the Redbook audio CD standards which absolutely have to be 16-bit, 44.1kHz sampling, stereo files in ".wav". So yeah, you're half sized mono track becomes a stereo dual mono track which is twice as large. No way around that for audio CDs.

What I can recommend is that, if these are spoken word recordings, many audio softwares, such as Adobe Audition & others have the ability to compress or expand, time, without changing the pitch. (Oh, if we could only do that in real life?!) Typically referred to as " stretch". When dealing with music, this can be a mixed blessing as results can appear that the musicians are more capable than demonstrated. I have frequently utilized this feature for making commercials exactly 28.5/58.5 seconds. In fact I just did that last night for a client. Some software is even designed to sense empty chunks of audio, only time compressing the non-sound containing chunks. That's your only really good option. This feature can only go so far before things get quite comical.

So you really don't have many options when producing an audio CD of any kind. The only exception is the fact that with our recordable CDs, we don't have to precisely follow the Redbook standard. And since inexpensive desktop multiple CD duplicators have become so much lower in price, many folks can offer 700MB/80 minutes " duplicated" CDs as opposed to stamped out " replicated" CDs.

Another possibility is offering MP3 downloads or, on CD ROM. The MP3 standard is broad ranging. For instance, instead of 128 kilobits per second, 44.1kHz stereo sampling at 16-bit, for spoken word, you could run at 11kHz mono sampling at 16-bit. This equates to a frequency response similar to AM radio only extending out to 5kHz frequency response. Totally adequate for spoken word and allows one to create a CD ROM, only playable in players that recognize MP3 CDs but with up to over 70 hours of program content! This is not a CD that can be played in an audio CD player but generally only computers. I did that for a project for some folks at Northrop Grumman here in the DC area. Originally, they had asked me for cassettes! You don't have to be a rocket scientist to know that was goofy? Or maybe you do?

Rocket Roll engineer
Ms. Remy Ann David

Posted: Tue May 13, 2008 4:36 am

Dear Remy thank you for your kind advice. Most informative. Most of my customers are a bit older than the average mp3 buying public so i have not gone down the mp3 route. What does intrigue me is why my audio cds with around 800 mb in size play ok! I just went along with the 80 min max idea , duplicated on my rimage 2000i, and all seems well. Though to help me sleep at nights i don't want to dwell on it all too much!! The cds have gone all over ( about 40 countries) most to the US and since duplicating them over the last 2 years have had very few returns. the Chinese company that have done the replication for me checked the cds and they were very surprised they seemed ok. As you mentioned i guess the red book standard keeps us within those boundaries . I am trying to keep other cds a bit smaller in file size and will certainly try out your stretch idea..update..i just tried it and am surprised how good it still sounds in audition.It now has a file size of 668mb and is 66 mins instead of 79.It does sound a bit faster but i will listen again and see if it can be ok to publish.Thanks again for all your help Remy

SPAM Joined: May 21, 2008 Posts: 3

if these are spoken word recordings, many audio softwares, such as Adobe Audition & others have the ability to compress or expand, time, without changing the pitch. (Oh, if we could only do that in real life?!) Typically referred to as " stretch". When dealing with music, this can be a mixed blessing as results can appear that the musicians are more capable than demonstrated.

Posted: Wed May 21, 2008 8:39 am

This looks like spam. The link points to the same site as the other recent spammers ("Yes! Nice information you have shared with us.").
Anyone agree?

Posted: Wed May 21, 2008 9:37 am

PaulSoffe seems to be on the level. Jackson_Us5 though, yeah. Spammer.

Posted: Wed May 21, 2008 11:43 am

Wasn't meaning to refer to PaulSoffe, sorry about that.

Posted: Tue May 27, 2008 12:50 pm

Thanks for the post PaulSoffe, I was wondering the same thing exactly in regards to my album.

Posted: Tue Jun 03, 2008 10:20 pm

"I have frequently utilized this feature for making commercials exactly 28.5/58.5 seconds. In fact I just did that last night for a client."

lol remy.. i recorded a commercial for a local electronics store that needed to be just under 30 seconds.. the final product was about 33.. for about 5 hours i went back and forth through the edit carving out .03 seconds of silence or even the midsection here and there of a word to get it down the the required length.. then about a month later read about cubases' new time stretching technology and nearly wet myself laughing. if only i had waited a little longer ( i believe it was cubase that intro'd it)

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