Mp3 Compression
I often argue with people about the audibility quality of music. I prefer when possible to listen to stuff at cd quality, when its not possible i have my ipod music at 320kbps mp3.( By comparison cd is around about 1140 kbps :) ) People often ask why i bother with cds at all. A large collection of music at a low bit rate seems to be the norm for most of my non-musical friends.
For this post i have taken a 15 second sample recording of a piece of music i recorded last year and have converted into many mp3 bit rates ranging from 8-320 kbps. For simplicity they have all been put into a single soundcloud file. The "obvious edits" are where the next sample starts, i did the chop together in logic fairly quickly :L
Analysis:
Its clear from the very first sample that it sounds shit, A bit of geeky analysis is needed.
Geeky Analysis:
As the bit rate drops the sample rate does also, the direct result of this is less high frequency response. Because the lowest bit rates of 8 & 16 only have a re-sample rate of 8khz, any thing above 4 khz will be UN-audible. The fluttering is audio being rapped around. (see the nyquist theory! )
As the bit rate increases, we start to hear more high frequencies still sounds a bit like a 50s sci-fi film. though pay close attention as the cymbals will sound washy for a while yet.
As 50 seconds rolls around the sample rate changes and suddenly we hear some guitar. There is still what sounds like a low pass filter going on.
At 1:36 another clear jump can be heard, the audio is now at around 56kbps.
2:54 the audio is now at 128 kbps, this is a common format for most mp3s. This would have been the norm for older iTunes downloads and what spotify streams at when on a basic account.
The second from last sample is what iTunes music is at. (256 kbps ) though that is using a different audio format (aac).
As the bit rate increases, we start to hear more high frequencies still sounds a bit like a 50s sci-fi film. though pay close attention as the cymbals will sound washy for a while yet.
As 50 seconds rolls around the sample rate changes and suddenly we hear some guitar. There is still what sounds like a low pass filter going on.
At 1:36 another clear jump can be heard, the audio is now at around 56kbps.
2:54 the audio is now at 128 kbps, this is a common format for most mp3s. This would have been the norm for older iTunes downloads and what spotify streams at when on a basic account.
The second from last sample is what iTunes music is at. (256 kbps ) though that is using a different audio format (aac).
Finally the last sample is at 320kbps mp3, the only format i like to use :L hahaha.
Feel free to comment on either soundcloud or this blog should you notice anything you wish to mention.
Thats it for now folks!
No comments:
Post a Comment