Re: [backstage] Is it just me, or is some stereo audio on BBC chans (Freeview) out of phase?
On 06/03/2008, Steve Jolly <[EMAIL PROTECTED]> wrote: > > 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. I'm using a Vista Media Center with a double DTT card, and no matter which card I use this always happens: http://www.youtube.com/watch?v=hZr-588a5A8 There's a glitch at -27:00 - and the thing is that it's there every hour. It matters not which DVB card I use (I've used Black Gold, a generic one and the Hauupagge one I use now). I've never complained about it because it doesn't happen on standard Freeview boxes. The wierd this is that when I record it and covert it to MPEG to put on YouTube, it's there. The sequence has changed many times and every time it does the audio and video corrupt at -27:00. Wired that. Also, can we have the stereo back on News 24. The music is great, but you can't hear it properly. I've got a fully digital-to-the-amp thing going on with studio monitor speakers... I want to hear David Lowe. 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. Perhaps it could be bad decoding of the mono sound? 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 > > - > Sent via the backstage.bbc.co.uk discussion group. To unsubscribe, please > visit http://backstage.bbc.co.uk/archives/2005/01/mailing_list.html. > Unofficial > list archive: http://www.mail-archive.com/backstage@lists.bbc.co.uk/ > -- Please email me back if you need any more help. Brian Butterworth http://www.ukfree.tv
Re: [backstage] Is it just me, or is some stereo audio on BBC chans (Freeview) out of phase?
Quoting Martin Deutsch <[EMAIL PROTECTED]>: I've been emailing Christopher off-list about this - I suspect it may well be a reciever issue. Most of the services on mux 1 are coded in London, and are the same across much of the country on DTT -- and I'm not seeing any phase issues on our monitoring here, with a couple of different set-top-boxes. I've suggested that Christopher tries another reciever, or moves the aerial to somewhere with better signal strength. (I don't know that much about how the decoding process works, but perhaps someone more fluent in DVB will know - is it possible that error correction and recovery could be doing odd things to the sound in the event of low signal strength?) - martin This doesn't sound like an interference issue. For interference to only affect the MPEG-Audio PES, the interference would have to be spread correctly across the approx. 2k carriers with the interference occurring at exactly the right time so that once the data had transited a symbol de-interleaver, a bit de-interleaver, a Vitterbi decoder and a Reed-Solomon Decoder only the MPEG-Audio PES packet headers are effected. This could be checked by using something like dvbsnoop/tzap or TSReaderLite to look to see if any error messages are being generated. Other possible errors include an error in the Broadcaster Mix - but this hasn't been apparent to anyone else - or an error in installation or manufacture. --- ST [EMAIL PROTECTED] - Sent via the backstage.bbc.co.uk discussion group. To unsubscribe, please visit http://backstage.bbc.co.uk/archives/2005/01/mailing_list.html. Unofficial list archive: http://www.mail-archive.com/backstage@lists.bbc.co.uk/
RE: [backstage] Is it just me, or is some stereo audio on BBC chans (Freeview) out of phase?
> Martin Deutsch wrote: > > I've suggested that Christopher tries another reciever, or > moves the > > aerial to somewhere with better signal strength. (I don't know that > > much about how the decoding process works, but perhaps someone more > > fluent in DVB will know - is it possible that error correction and > > recovery could be doing odd things to the sound in the event of low > > signal strength?) > > I wouldn't describe myself as an expert, but from what I know > of DVB, I think that it would be very unlikely that a > receiver could end up with an audio phase error and no other > symptoms as a consequence of reception difficulties. Well guys, thank you all for humouring me on this (thanks in particular to Steve Jolly and Martin Deutsch) - I guess I'm just going crazy in my old twenty-two years of age. :( My brain's got to be playing tricks on me... In the years that I used the same receiver at my parents' house before moving to Brum for uni, I never once thought twice about how it sounded. It was just something, when I tuned in again here, that made me think "that sounds wrong, hmm..." The most frustrating thing is that to me, it still doesn't sound quite right, but my theories and observations have been roundly (and reassuringly comprehensively) disproved here! Never mind... I'm going to take these ears back to the shop on Monday morning, they've obviously outlived their usefulness. ;) Might get a new brain too (I'll get a lot for my brain because, as a drummer, it's never been used.) One thing that can't be denied is the encoding bitrate on News 24 as opposed to BBC One... When BBC One simulcasts N24 overnight, the difference is immediately noticeable - and it's only a difference of 192kbps on N24 versus 256kbps on BBC One! - Sent via the backstage.bbc.co.uk discussion group. To unsubscribe, please visit http://backstage.bbc.co.uk/archives/2005/01/mailing_list.html. Unofficial list archive: http://www.mail-archive.com/backstage@lists.bbc.co.uk/
Re: [backstage] Is it just me, or is some stereo audio on BBC chans (Freeview) out of phase?
Martin Deutsch wrote: I've suggested that Christopher tries another reciever, or moves the aerial to somewhere with better signal strength. (I don't know that much about how the decoding process works, but perhaps someone more fluent in DVB will know - is it possible that error correction and recovery could be doing odd things to the sound in the event of low signal strength?) I wouldn't describe myself as an expert, but from what I know of DVB, I think that it would be very unlikely that a receiver could end up with an audio phase error and no other symptoms as a consequence of reception difficulties. S - Sent via the backstage.bbc.co.uk discussion group. To unsubscribe, please visit http://backstage.bbc.co.uk/archives/2005/01/mailing_list.html. Unofficial list archive: http://www.mail-archive.com/backstage@lists.bbc.co.uk/
Re: [backstage] Is it just me, or is some stereo audio on BBC chans (Freeview) out of phase?
I've been emailing Christopher off-list about this - I suspect it may well be a reciever issue. Most of the services on mux 1 are coded in London, and are the same across much of the country on DTT -- and I'm not seeing any phase issues on our monitoring here, with a couple of different set-top-boxes. I've suggested that Christopher tries another reciever, or moves the aerial to somewhere with better signal strength. (I don't know that much about how the decoding process works, but perhaps someone more fluent in DVB will know - is it possible that error correction and recovery could be doing odd things to the sound in the event of low signal strength?) - martin On 3/6/08, Matt Barber <[EMAIL PROTECTED]> wrote: > Have you tried two different freeview receivers? Could it be something > strange going on in hardware, or delay introduced on speaker setup / > processing? > > > > On Thu, Mar 6, 2008 at 1:08 PM, Steve Jolly <[EMAIL PROTECTED]> wrote: > > > > 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 > > > > - > > Sent via the backstage.bbc.co.uk discussion group. To unsubscribe, please > visit > http://backstage.bbc.co.uk/archives/2005/01/mailing_list.html. > Unofficial list archive: > http://www.mail-archive.com/backstage@lists.bbc.co.uk/ > > > > - Sent via the backstage.bbc.co.uk discussion group. To unsubscribe, please visit http://backstage.bbc.co.uk/archives/2005/01/mailing_list.html. Unofficial list archive: http://www.mail-archive.com/backstage@lists.bbc.co.uk/
Re: [backstage] Is it just me, or is some stereo audio on BBC chans (Freeview) out of phase?
Have you tried two different freeview receivers? Could it be something strange going on in hardware, or delay introduced on speaker setup / processing? On Thu, Mar 6, 2008 at 1:08 PM, Steve Jolly <[EMAIL PROTECTED]> wrote: > 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 > > - > Sent via the backstage.bbc.co.uk discussion group. To unsubscribe, please > visit http://backstage.bbc.co.uk/archives/2005/01/mailing_list.html. > Unofficial list archive: > http://www.mail-archive.com/backstage@lists.bbc.co.uk/ >
Re: [backstage] Is it just me, or is some stereo audio on BBC chans (Freeview) out of phase?
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 - Sent via the backstage.bbc.co.uk discussion group. To unsubscribe, please visit http://backstage.bbc.co.uk/archives/2005/01/mailing_list.html. Unofficial list archive: http://www.mail-archive.com/backstage@lists.bbc.co.uk/
RE: [backstage] Is it just me, or is some stereo audio on BBC chans (Freeview) out of phase?
> 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). - Sent via the backstage.bbc.co.uk discussion group. To unsubscribe, please visit http://backstage.bbc.co.uk/archives/2005/01/mailing_list.html. Unofficial list archive: http://www.mail-archive.com/backstage@lists.bbc.co.uk/
Re: [backstage] Is it just me, or is some stereo audio on BBC chans (Freeview) out of phase?
Christopher Woods wrote: Not used my USB Freeview receiver for a while, hooked it up because I dug out an amplified aerial and thought 'heck, why not.' In essense, audio seems to be varying degrees out of phase - measurably 90 degrees out of phase on BBC Three and N24. I observed this phenomenon tonight on BBC Three, BBCs One and Two but most noticeable on News 24. Speech is fine (which is generally monaural, so yeah) and on other channels it's a bit noticeable in places, but it's most obvious on N24 and BBC Three where there's stereo music... The top of the hour buffer (with the countdown) on News 24 is totally out of phase for its duration. Can you give an exact channel, date and time when you observed the phenomenon? (03:59 GMT last night on N24, perhaps?) S - Sent via the backstage.bbc.co.uk discussion group. To unsubscribe, please visit http://backstage.bbc.co.uk/archives/2005/01/mailing_list.html. Unofficial list archive: http://www.mail-archive.com/backstage@lists.bbc.co.uk/
[backstage] Is it just me, or is some stereo audio on BBC chans (Freeview) out of phase?
Not used my USB Freeview receiver for a while, hooked it up because I dug out an amplified aerial and thought 'heck, why not.' In essense, audio seems to be varying degrees out of phase - measurably 90 degrees out of phase on BBC Three and N24. I observed this phenomenon tonight on BBC Three, BBCs One and Two but most noticeable on News 24. Speech is fine (which is generally monaural, so yeah) and on other channels it's a bit noticeable in places, but it's most obvious on N24 and BBC Three where there's stereo music... The top of the hour buffer (with the countdown) on News 24 is totally out of phase for its duration. I'm sure I've not noticed this before, or if I have it's not been that bad, so I've not really thought too much of it... But with a reference studio setup I've gotten very used to out of phase audio (I do a lot of mixing and production for my uni course) and it sounds really odd. Elephant Diaries' stereo incidental music is also very out of phase. Is this something anybody else has noticed, or is it just me with this particular setup? I've got AC3Filter playing back audio at the moment, but it's doing nothing fancy, just matrixing the audio to a simple L/R config (stereo in, stereo out). I've got recordings from years ago (Glastonbury recordings, music recordings etc) and they never sounded wrong... This has me wondering if it's something to do with my particular setup, or whether some funky psychoacoustic processing has been applied to any stereo audio. Mono sound and speech remains perfectly in phase, dead on the axis Ambient background from in-shot stereo mics sounds like it has a very wide stereo image (binaural or T-bar mic on the camera?) but it's still pretty much in phase Background incidental music and trailers / buffers (N24 etc) sound totally out of phase I can see the phase in Audition as I watch a channel, so I have a good realtime, visual representation - and it tallies with what my ears can hear. Can anybody else hear what I'm on about? It's been a long time since I had a good chance to properly listen to the sound on Freeview, but I need a sanity check on this, because to me, something sounds different. Help! Cheers Christopher
