Does decompressing MP3s affect sound quality?

flac, alac, and wav can be converted back and forth without quality loss.

there should be no loss of quality or change in the actual audio quality whatsoever since the audio portion of the file is never being altered in any of these format changes.

Decompressing lossy formats (MP3) won't improve the sound quality. It's lost irreverisbly during compression. It's like converting BMPs to JPGs with a high compression rate.

Decompressing lossless formats (FLAC) won't improve the sound quality (although some people argue that it does). Nothing is lost during compression. Lossless formats are like zipped BMPs that you can access on the fly without any changes as far as quality goes.

I still actually believe that FLAC and these other "lossless" formats aren't really lossless. They also have bitrates. And some go quite low, seen FLACs going like 500kbps. So if you have the same CD, convert it once to FLAC 1000kbps and again to FLAC 500kbps.... are the two resulting FLAC files really the same?

Mochan: The bit-rate is of the file, not a measure of anything about the music. What matters is the data once the file has been de-compressed.  

If you're still not convinced: Zip a text file, then unzip it.  Does the file change?

No such thing as selecting bitrates for flac. You can only select the compression level. Flac doesn't strip any audible info like lossy codecs do. It's the data that is being compressed similar to a file being compressed by winzip.

Quote:

Originally Posted by Mochan 

I still actually believe that FLAC and these other "lossless" formats aren't really lossless. They also have bitrates. And some go quite low, seen FLACs going like 500kbps. So if you have the same CD, convert it once to FLAC 1000kbps and again to FLAC 500kbps.... are the two resulting FLAC files really the same?

It's like zip files but optimized for audio. . . nothing is misssing.

> I still actually believe that FLAC and these other "lossless" formats aren't really lossless. They also have bitrates. And some go quite low, seen FLACs going like 500kbps. So if you have the same CD, convert it once to FLAC 1000kbps and again to FLAC 500kbps.... are the two resulting FLAC files really the same?

That's not what people mean by "lossless." Lossless in this contexts refers to types of compression where you don't lose anything in the compression. Obviously if you start with a 44.1 KHz sample rate and do lossless compression, you still have only 44,100 samples per second. It's just stored more compactly. It's still the same signal.

If you convert a higher bitrate to a lower bitrate, that's not lossless. They may be stored in a format that has been compressed losslessly. But when you convert between two bitrates you're losing something.

According to the official website:

• Lossless: The encoding of audio (PCM) data incurs no loss of information, and the decoded audio is bit-for-bit identical to what went into the encoder. Each frame contains a 16-bit CRC of the frame data for detecting transmission errors. The integrity of the audio data is further insured by storing an MD5 signature of the original unencoded audio data in the file header, which can be compared against later during decoding or testing.
• Fast: FLAC is asymmetric in favor of decode speed. Decoding requires only integer arithmetic, and is much less compute-intensive than for most perceptual codecs. Real-time decode performance is easily achievable on even modest hardware.

So lower compression rate = quicker encoding, bigger filesize, quicker decoding... I don't see any upsides to this, considering that the encoding/decoding speed and filesize are the only differences between low and high comp FLACs. Encoding doesn't take that much time with today's hardware; if you don't care about disk space, why compress at all?; I highly doubt anyone still owns a PC so old that it wouldn't be able to decode highly compressed FLACs on the fly.

Quote:

Originally Posted by fufula 

 I highly doubt anyone still owns a PC so old that it wouldn't be able to decode highly compressed FLACs on the fly.

Maybe, but PCs arent the only device called on to do this type of decoding. Read the (excellent) review of the QLS QA350 for an example of a device which has the potential to be a giant killer as soon as they find a chip that has the power to decode FLAC. So very, very close IMO.