Christopher Woods wrote:
Can you give an exact channel, date and time when you
observed the phenomenon? (03:59 GMT last night on N24, perhaps?)
Definitely. Observable on BBC2 last night/this morning (05/03/2008) during
the intro for "Spin" (03:44am). Also observable during the 60second
countdown buffer for N24 top of the hour (4am). I can send MPEG2 files if
you want (direct streamrip, advantage of having USB DTV receiver).
I have access to DTT stream recordings. :-) I took a look at the N24
music you mentioned. Listening to it, there's a very clear difference
in the stereo characteristic of the sound between the (virtually mono)
talking head segments on either side of the music, and a lesser
difference between the music at the end of the special report and the
N24 countdown in question.
Converting the stereo to mid/side encoding and listening to the new
channels separately, the side channel contains virtually no LF
component, whereas the mid-channel contains plenty - you'd expect them
to contain roughly the same amount if the signal had been subjected to a
90 degree phase offset, and you'd expect all the low frequencies to be
concentrated in the side channel in the case of a 180 degree phase
inversion.
So at the moment, I don't see any evidence for an overall phase error,
I'm afraid - at least for the one section of audio I've had a look at.
:-) The difference in the characteristic of the sound that I can hear
could simply be due to the transition between dead-centre mono speech
and a very complex bit of music with a broad sound stage.
S
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