Tips and tricks

If you've read the last page, I think we're ready to look at some examples! Note that MOST of the compressed files you would spot are going to look like the MP3 128 and 320 examples on the previous page, and plenty easy to notice if you've skimmed this guide and watched them once. This page is examples of tricker examples, which have been chosen carefully out of my collection of 25,000+ WAV's. The idea here is so you that you don't make mistakes seeing things that look bad but are normal, and vice versa.

Old CD recordings

What you see below is normal. It's not lossy. Sometimes something like this is caused by audio encoded at 48000Hz (something studios and producers use) down to 44100Hz (what's used on a CD). It also might be due to the music being transfered from analog reel-to-reel tapes unable to retain high frequencies. Note that the drop isn't as vertical as the actual mp3s, and that it doesn't really ever move to the left or right. This is an example of the type of recording Audiochecker may identify as lossy when it's actually OK. The clip below is Madonna's "Holiday" taken from the You Can Dance single edits promo, pressed a few years before audio compression existed:

Elements sampled from lossy sources

Sometimes, remixers are provided remix tools in lossy formats. Why anyone would do this I don't understand, but it happens. See below... notice how the graph doesn't look "funny" unless Beyonce is singing, and even at those times the missing high end doesn't drop below a certain level. The instrumental ending looks completely normal.

It's not just vocals that can be sampled this way. Producers today sample drum loops and effects and occasionally even synth lines from other recordings, and of course they are often from lossy sources. Here's what it looks like when there's some compressed drum loops and FX, but the rest is normal. See how everything looks good during the quieter, almost acapella section. The second video is another example.

Really weird mastering

I'm not sure what the mastering house did here, but it's not audio compression, the drowning out of the highs is much too gradual to be MP3 compression. It's just some weird EQ. It's not anything the producers did as all the tracks on this CD are like this. It's hard to tell from the recording below, but these do sound quite drowned out.

Exampls of lossy files

This one may look like simply compressed vocals at first, especially during the quiet section shown below, but notice how the upper end (around and above 19k) actually lowers as he says "still gettin it". This shouldn't happen on a lossless file. Notice how this doesn't happen on the Beyonce example above.

This may look like the result of 48k to 44.1k dithering, but notice how the high drop-off doesn't quite stay in the same place. There are occasional dips of the very top right "corner" in the graph lines, those aren't normal.

Sometimes the signs are just very subtle. This one is probably 256 or 320AAC. The high end drops are very subtle, and there isn't really a good quiet part of the song to examine. The surest sign is that the few times the very high end drops don't really seem to follow the music at all. It's interesting to note that there isn't actually any sign of anything compression at the very end, which is usually one of the best places to look!

I don't even know what on Earth is going on in this one, but it sure doesn't look good... all the tracks on this particular EP graph similarly:

If you have any questions, or even if you want me to check some files for you, don't hesitate to contact me!