jaysung;237765 Wrote: > I am not sure if you are right to view 16bit integer values as a > fraction of 1. Since the biggest number you can write in 16bit is 32767 > the end is open to the sky theoretically. You just don't use the numbers > above... On the other hand if you have 1 devided by something you have a > situation where you assume a definite limit which can not be assumed for > loudness. In fact, PCM digital audio, as the industry has defined it, *does* have a definite upper limit, 0 dBFS; actual audio levels are specified, for example, as -10 dBFS, etc. The fact that additional resolution gets added on at the bottom and not the top is a matter of industry definition, not theory. This is done so that a signal with 8 bits, 16 bits and 24 bits of resolution can all express the same maximum loudness, however more resolution can give a more accurate representation of a low-level signal. If this was not done, one would have to turn up the volume big-time when switching from 8-bit playback to 16-bit playback, or from 16-bit playback to 24-bit playback.
There are special cases however, where extra bits of resolution do get added on at the top. One example is HDCD, which defines that besides adding resolution the normal way at the bottom, it has a peak companding mode that adds exactly one extra bit at the top. In HDCD playback hardware, normal audio that is not HDCD encoded is attenuated by 6 dB (1 bit) so it will better approximate the percieved loudness of material encoded with HDCD peak extension. One of our members here has posted an HDCD decoder program for WAV files, and indeed it does just this if given a non-HDCD file, reduce the level by 1 bit. In practice, it also reduces the average level of most encoded discs by close to 6 dB also, because, when HDCD is used properly, the audio signal doesn't spend a lot of time in the "peak extension" companding region. Sorry for the "topic creep". -- Timothy Stockman ------------------------------------------------------------------------ Timothy Stockman's Profile: http://forums.slimdevices.com/member.php?userid=8867 View this thread: http://forums.slimdevices.com/showthread.php?t=39611 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
