Jump to content

Mp3 compression rate

Rate this topic


Guest Anonymous

Recommended Posts

Guest Anonymous

Gentlemen,

I have some radio programs that I recorded onto 80 minute discs in LP4 mode.

I am going to record the audio from my MD to my PC.

I want the entire MD( ~ 5.3 hours) to fit onto one 700 MB CD-R.

What MP3 compression rate should I use to

1. Utilize the highest rate and

2. Fill the CD-R as much as possible (refraining from going over 700 MB)?

Thanks - Ramblin' Man

P.S. This is for an archive - I am not concerned too much about sound quality but I want it to be as good as possible.

Thanks again smile.gif

Link to comment
Share on other sites

I would to a couple of test runs with different bit rates and stuff. They don't need to be long, just enough that you can pick out the differences. Once you have a couple of different versions, compare them (get someone to give you a blind test if possible) and make the decision.

Also, do a recording using a low bitrate PCM encoded .wav file.

Link to comment
Share on other sites

Guest Anonymous

To fit 320 minutes of music onto a 74 minute CD you obviously need to compress by a factor of 320/74, or 4.32. The bit rate of uncompressed CD-quality PCM stereo is 1411200bps. Dividing by 4.32 gives you a maximum bit rate of around 320kbps.

Learn the math, it's not that hard.

Link to comment
Share on other sites

Guest Anonymous

Andy,

Thanks for your suggestions. I will try them this weekend.

Guest,

I was looking for a quick and simple answer as I assumed that there would be people here who had performed similar tasks.

Thanks for your suggestion that I should learn the math. I'm sorry for being naive, but I only got as far as Calculus II in college. Perhaps you should brush up on your reading comprehension skills as I said a 700 MB CD-R which would be 80 minutes, not 74.

Link to comment
Share on other sites

Guest Anonymous

Wow, 320/80, that's even harder. A shame your classes didn'tteach you how to think for yourself.

I travel quite frequently. What part of the country do you live in? Perhaps we can meet and talk about these compression rates.

Link to comment
Share on other sites

To fit 320 minutes of music onto a 74 minute CD you obviously need to compress by a factor of 320/74, or 4.32. The bit rate of uncompressed CD-quality PCM stereo is 1411200bps.  Dividing by 4.32 gives you a maximum bit rate of around 320kbps.

Learn the math, it's not that hard.

74mins CD = 650Mb

80mins CD = 700Mb

320mins = 5:20hours @ 320Kbps = 768Mb

I would suggest you to improve your maths tongue.gif

256kbps would fit better, ending up with 614.4Mb

If you want, you can try 291kbps (VBR) = 698.4Mb 8)

Link to comment
Share on other sites

Note that a 74min pure music CD actually holds much more than 650MB.

At 1411200bps = 176400Bps, and 74 min * 60 seconds, you get an actual capacity of 783,216,000bytes. There's about a 13% per-sector overhead when writing data sectors vs audio sectors, which is why 74min CDRs are only spec'd at 650MB for data use. This is also why you can't simply divide the raw audio capacity by a compression ratio to yield an equivalent MP3 size; you have to factor in the data vs audio overhead.

Link to comment
Share on other sites

Note that a 74min pure music CD actually holds much more than 650MB.

At 1411200bps = 176400Bps, and 74 min * 60 seconds, you get an actual capacity of 783,216,000bytes. There's about a 13% per-sector overhead when writing data sectors vs audio sectors, which is why 74min CDRs are only spec'd at 650MB for data use. This is also why you can't simply divide the raw audio capacity by a compression ratio to yield an equivalent MP3 size; you have to factor in the data vs audio overhead.

TOC + Error correction :shock:

Link to comment
Share on other sites

Guest Anonymous

Ok I have another question.

Generally when I transfer my MD audio to my PC, I simply put my MD into my Sony MDS-JE510 which is connected to my C03 box which in turn is connected to my digital soundcard.

In the case of a MDLP disc, I connect my 505 to the MDS-JE510 with Monster cables and go that route.

I know I can connect the 505 directly to the soundcard and record, but my computer is electrically noisy and my recordings have a higher amount of hiss when I record 505 > PC.

When I let my MDS-JE510 act as an external D/A converter my recordings sound much better.

The thing is that in order for me to get a digital signal to the computer from the MDS-JE510, I need to put a MD in the unit and press PAUSE on the unit.

My question is = Could my MDS-JE510 be harmed in any way by being on pause for 5.2 hours while I play a MDLP disc on my 505 through it?

My MDS-JE510 is getting on in years and I want it to last as long as possible.

Thanks,

Ramblin Man

Link to comment
Share on other sites

Offtopic: STFU = Shut The Fridge Up - I'm not too sure about the 'fridge' though. I've heard it spoken, and it sounded like a word I'd never heard before. Possibly a different language smile.gif

On topic: Your unit should be able to handle a pause for long periods of time anyway. But as you've discovered, you can do it without having a disc in there smile.gif

Also, you can get some really good results from internal soundcards. Just they have to be really good internal soundcards smile.gif. I know that some pro gear is going from external to internal because it is no longer effected by the noisy PC (I'm not sure why - possibly better shielding, possibly something else). The other option which can work really well is using an external CD burner with an audio in. This will do the trick and you can minimise the number of devices your signal has to go through (thus minimising noise), unfortunately, it is a little bit slower (and more expensive)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...