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CD vs MP3 Quality.

4003 Views 27 Replies 15 Participants Last post by  samurray
In an OTA thread yesterday, several people brought up this issue. Those posts were deleted since they hijacked an OTA thread.

I'd like to start that "debate" again here. (the people who were discussing digital vs analogue cameras in that thread may do the same in a new thread) ;)

If I recall the gist of what people were saying, they were stating that MP3s were better than CDs because 128 is higher than 44.

I believe people have got bitrate and sampling frequency mixed up...
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stampeder said:
Thanks for that! Does anyone know if MP3s can do multi-channel too, such as on an SACD?
No multichannel with MP3.
Here are some approximate numbers to compare.

CD = 44100Hz x 16bps x 2 channels = 1411 kbps
MP3 = 44100Hz x 3.6bps x 2 channels = 320 kbps

Note the 3.6 bits per sample for MP3. Which is an approximation after compression.
57 said:
I use Apple iTunes and it has a lossless encoder. Saves about 50%.
I should have been more accurate.

What I meant to say is that there is no generic means of compressing data losslessly to 2:1 (a la the WINZIP example). Now for a specific context of data (say audio files) you could come up with an encoding scheme that might achieve a better compression ratio, because the data has a fixed context and tends to be more predictable. You mention the iTunes encoder. There is also the FLAC encoder which is actually free.

There is a good comparison of lossless encoders here:

You will see that even these encoders average >50% (except one) although they are all less than 60%. But look at the numbers for specific songs and you can see significant various based on the type of music. For some songs the ratio rises to 60+% whereas for some other songs the ratio drops to as low as 30+%. In fact, from the looks of it, it seems that classical music compresses better than pop music?
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ok so if you take a 320 kbit file and play it on a DVDA player as I have is my player down sampling it to 44.1

I've noticed sometimes my DVDA player does this as my player will read 44.1 ?

But isn't a DVDA suppose to play at a higher frequency? .... (im just learning about my player as you can tell)
stampeder said:
Thanks for that! Does anyone know if MP3s can do multi-channel too, such as on an SACD?
That would be DD (Dolby Digital). The software cost alone would prohibit it.
Just to clarify Filper's remark. MP3s CANNOT contain more than 2 channels. It is not in the spec. I believe WMA can contain more than 2 channels. Though I have never heard one. Not sure about AAC, but I would think it would.

I was using the WinZip as an example of lossless compression. I was not impling that we could use it on WAV files to save space!

As you have said, usng the proper encoder can save 50% without any loss of the digital signal ie APE, FLAC, WMA, etc

Anyone who wants to transfer their CD collection to MP3 (or whatever) should take one or 2 titles, rip them using various bit rates and sit down and decide which is the best for them. I did that and settled on the 320 VBR using the lame decoder. I think "most" people would be happy with that.
A website I'd recommend on this subject is I've been reading this site for years. A thorough comparison of lossless audio encoders can be found here

There's also an excellent audio format guide where (lol) the first section is titled "Why no simple answer?". They cover many of the considerations folks have brought up and provide a framework for making choices.

On a side note, for anyone looking to digitize their CD collection my only advice (and the best decision I personally made) would be to keep a lossless rip of your CDs... it's worth the hard drive space. As codecs improve and change you'll thank yourself as re-encoding is far easier if you've got the lossless files and don't have to feed your CDs through your PC - again!!
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