Quote:
Originally Posted by Katsunami
It could have been something like undetectable low or high frequency tones at the beginning or ending of the book, or in the "silences" for example. You should have opened it up with an audio-editor, and run a high and low pass filter over it  |
I don't know anything about it either except what that developer told me, and since it was so long ago I don't recall much about that. What I do remember was that it was information embedded in the file in such a way that it looked like music but produced no effect on the sound and that any compressor would see as important. I have no idea how that might work. I've read some descriptions of how MP3 compressors do what they do but I didn't really see how this could fit in with that.
I do remember that developer was very impressed with this technique. It was developed by a 3rd party and Audible licensed it, as I recall, and he was amazed at how cleverly it was designed. I don't recall his giving me any descriptions of that design although as a retired programmer I probably asked.
Barry