John, I do not know much about what you describe, but you could answer the frequency issue by recording the sound into Audacity on the laptop. (Assuming you do not have a 'scope.)
Is there a chance that the connections which produce the hum include two different AC powered devices with a (not quite) common ground? -Denis On Mon, Jun 19, 2017 at 10:33 PM, John Jason Jordan <[email protected]> wrote: > You can't play Blu-ray movies on Linux, right? Wrong. You can if you > give $50 for a license for MakeMKV. Not only will MakeMKV for Linux rip > and encode a Blu-ray movie to a .mkv file, if you follow the > instructions in their forums you can get VLC to play the discs > directly. > > I did this successfully on my laptop first, as that is my usual > platform for making .mkv files. It works perfectly. But I use my > desktop for viewing movies, so that was my next step. Both machines are > Xubuntu 14.04. The desktop installation went perfectly and MakeMKV sees > and will rip and encode a Blu-ray movie. (Both machines have Blu-ray > drives.) I followed the same instructions on the desktop as I did on the > laptop for getting VLC to play a Blu-ray movie, and it does so, but > there is a loud hum, loud enough to drown out the audio in the movie. I > would say it is a 60-Herz hum, except that it seems just a bit higher. > This is strange because the desktop spends all day streaming internet > radio stations to my stereo, and the output is beautiful - no hum. And > the laptop play the same Blu-ray movie without hum. > > There is a difference in the source of the audio signal, of course. For > internet radio Banshee is connecting to the stream and sending the > audio signal to the stereo. For the movie the source is the Blu-ray > drive, although I don't know how it is processed into the signal that > goes to the stereo. Note that the same Blu-ray drive on the desktop > plays DVD movies without the hum. (I currently own only one Blu-ray > movie.) It also plays television over the air through my HDHomeRun > tuner, which uses VLC, also without issue. > > I poked around in Pulseaudio volume control on the desktop and failed > to resolve the problem. > > I need some clues. > _______________________________________________ > PLUG mailing list > [email protected] > http://lists.pdxlinux.org/mailman/listinfo/plug > _______________________________________________ PLUG mailing list [email protected] http://lists.pdxlinux.org/mailman/listinfo/plug
