[ssamadhi97]

Originally Posted by kuba

How can you tell a difference between ATRAC and MP3 sourced material just by looking at spectral analysis?? I mean, not every MP3 file is cut right above "xy" kHz, there are various encoders and bitrates, so it can be easily cut at "xy+2" or "xy+3.756" kHz... Do you see my point?

On file format and encoder "fingerprints":

There are several characteristics that can be used to tell which lossy format (sometimes even which encoder, when it comes to mp3) was used to process an audio file.


Here are the (in my opinion!) most important things you can look for:

• The cutoff frequency: an obvious tendency to cut off 16kHz usually equals mp3 (as explained in my previous post).
• the "shape" of the cutoff
• "blocking": pretty much all lossy formats require that samples are processed in blocks of a certain length. Most formats use only one or two different block lengths, so-called short blocks and long blocks. The length of these differs between formats. On a close-up screenshot of a spectrum you can estimate the block lengths and thereby identify formats.
• stray blocks due to different decisions on which block to encode with which degree of detail

I'll fill in some blanks in this post next time I feel like it. To be continued...