Quick question on compressed files

Posted by: pjl2 on 05 May 2012

Just a quick question.

 

If a compressed file at, say, 192 kpbs is burnt to a CD and then ripped at say 320 kbps, then will any further compression occur compared to if the CD was ripped as say a WAV file? In other words, do compressed formats continue to compress regardless of the quality of the source file? If the answer is "no" then presumably there would be nothing further lost by ripping at 192kbps?

 

The answer may be obvious to some, but not to me!

 

Thanks,

 

Peter

Posted on: 05 May 2012 by Maxi Me

Once a file has been compressed, other than lossless formats, the information has been lost. Doesn't matter what you do to it after that.

 

Sorry, see what you mean. I assume, but don't know, that even more information would get lost when you re-rip yet again.

Posted on: 06 May 2012 by pjl2

Thanks, I assumed that would be the case.

 

Peter

Posted on: 06 May 2012 by Simon-in-Suffolk

Peter, I think I know what you mean.. Each time you encode as a lossy file type, you are removing information in the transcoding process.

Therefore if you have a 192kbps mp3 bit rate, and then reencode code at 320kbps mp3 bit rate, you will have thrown information away from in the 320kbps mp3 that was there in the 192kbps. 

 

Changing an mp3 to WAV has no subsequent loss, ie the mp3 is 'frozen', but clearly is not a sensible use of resources/file size. But if you ever made another mp3 from that WAV file, you will be throwing more information away.

Simon

 

Posted on: 06 May 2012 by pjl2

Simon,

 

Many thanks for clarifying this for me.

 

Peter

Posted on: 06 May 2012 by totemphile

How about this? There are software tools such as Audio Hijack and iRecordMusic that allow you to record any audio stream delivered over the Internet in just about any codec you require. For example, you can record music stored in SoundCloud even though there is no download option provided as part of the stream. A lot of these streams are 320 kbps at best, yet if you choose to record them as an AIFF file they show up as 1411kbps files in iTunes and sound a lot better than the original stream? What's happening here during the recording process?