Re: [time-nuts] New Years Eve TV countdown
TV doesn't seem to care about time sync much these days. It also depends a lot on the path getting to you, I get most of my TV via satellite (Dish network). The receiver I have also can get OTA. I have happened to notice, once, that I had a local channel on two TVs. One was receiving the local via satellite and one was tuned to OTA local broadcast. The satellite was many seconds (at least 5, probably more) behind the OTA. I walked from one room to the other and had a brief period of deja vu. Hmm, just occurred to me, an earphone on the early one while watching the later one with friends would make you a living room Jeopardy game show super star. But that satellite delay all makes sense. One thing annoys me though. Many channels don't care much about start and stop times. If I program something to record using the schedule, often I miss the end of it. They frequently go over the half-hour or hour mark by a minute or two. Occasionally they complicate it more by starting a show a little early too. That irks me. But for New Years, I didn't try to measure anything exactly, but I know they were off by about 3 hrs. I live in California. I was watching New York's events on my TV and the ball dropped at about midnight local time. I am enough of a time nut to know that should have happened at 9 PM local time. See, you just can't trust the media for accuracy these days. On 12/31/2014 11:23 PM, David J Taylor wrote: The local ABC network affiliate WJLA in Washington DC was approximately 4 seconds behind WWV in their on-screen countdown clock for New Year's eve. The local NBC affiliate's clock was about 8 seconds late when I checked them at two minutes before midnight. Happy New Year! Dan Schultz N8FGV Dan, I think you just illustrated the delays in digital TV transmission. When watching events from abroad (e.g. F1 races) where precise timing is available, I typically see a delay of 7-8-9-10 seconds, depending on the location. That is likely a delay to the studio, and then delay through Sky satellite TV. The BBC here no longer shows a clock, perhaps partially for that reason. At least there was no leap -second to confuse things! Happy New Year! 73, David GM8ARV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Years Eve TV countdown
It is not that they don't care about time sync, it is that they have to follow the rules of causality. Because the whole digitization, broadcast, and display process of digital TV processes seconds to minutes of material at a time, You cannot make an event show at an exact time unless the event was pre-staged... How do you pre-stage a live event that must happen at a specific time, such as the ringing in of the new year? In the old days of analog TV, the problem was similar, but the smallest unit of data was a screen, which took about 1/30th of a second... added to the un avoidable transport delays... fiber, microwave, or satellite hop. -Chuck Harris Rex wrote: TV doesn't seem to care about time sync much these days. It also depends a lot on the path getting to you, I get most of my TV via satellite (Dish network). The receiver I have also can get OTA. I have happened to notice, once, that I had a local channel on two TVs. One was receiving the local via satellite and one was tuned to OTA local broadcast. The satellite was many seconds (at least 5, probably more) behind the OTA. I walked from one room to the other and had a brief period of deja vu. Hmm, just occurred to me, an earphone on the early one while watching the later one with friends would make you a living room Jeopardy game show super star. But that satellite delay all makes sense. One thing annoys me though. Many channels don't care much about start and stop times. If I program something to record using the schedule, often I miss the end of it. They frequently go over the half-hour or hour mark by a minute or two. Occasionally they complicate it more by starting a show a little early too. That irks me. But for New Years, I didn't try to measure anything exactly, but I know they were off by about 3 hrs. I live in California. I was watching New York's events on my TV and the ball dropped at about midnight local time. I am enough of a time nut to know that should have happened at 9 PM local time. See, you just can't trust the media for accuracy these days. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Years Eve TV countdown
On Thu, 01 Jan 2015 02:08:04 -0800 Rex r...@sonic.net wrote: TV doesn't seem to care about time sync much these days. It also depends a lot on the path getting to you, Oh, they do. Just ask Magnus :-) The thing is, that video delay in digital systems is hard to keep down with all the intermediate processing steps. Video is processed in groups of pictures (GOP) that can be anything from a single frame to several hundred. AFAIK DVB based systems are around 8 to 30 or so. Which makes already up to a second delay at the recording point. And every time you need to process a complete GOP at once, it adds another second. One thing annoys me though. Many channels don't care much about start and stop times. If I program something to record using the schedule, often I miss the end of it. They frequently go over the half-hour or hour mark by a minute or two. Occasionally they complicate it more by starting a show a little early too. That irks me. That's what we have VPS for, or PDC for digital systems[1]. [1] http://en.wikipedia.org/wiki/Programme_Delivery_Control Attila Kinali -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Years Eve TV countdown
That delay might be intentional in case someone says something that has to be bleeped out. http://en.wikipedia.org/wiki/Broadcast_delay Dave -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of David J Taylor Sent: Wednesday, December 31, 2014 23:23 To: time-nuts@febo.com Subject: Re: [time-nuts] New Years Eve TV countdown The local ABC network affiliate WJLA in Washington DC was approximately 4 seconds behind WWV in their on-screen countdown clock for New Year's eve. The local NBC affiliate's clock was about 8 seconds late when I checked them at two minutes before midnight. Happy New Year! Dan Schultz N8FGV Dan, I think you just illustrated the delays in digital TV transmission. When watching events from abroad (e.g. F1 races) where precise timing is available, I typically see a delay of 7-8-9-10 seconds, depending on the location. That is likely a delay to the studio, and then delay through Sky satellite TV. The BBC here no longer shows a clock, perhaps partially for that reason. At least there was no leap -second to confuse things! Happy New Year! 73, David GM8ARV -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Years Eve TV countdown
We have Brighthouse cable here in Central FL and the delay is horrendous. When setting up the DVR recorder integrated in the cable box we have to adjust the start and stop times -/+ 1 minute respectively on a regular basis. The delay is less than a minute, but the adjustment resolution is 1 minute. This means the tuners (two of them) are often busy during the overlap preventing recording and viewing some programs that follow others. Does anyone know if the clock in the cable box, (likely NTP derived) can be adjusted by a knowledgeable user? One thing annoys me though. Many channels don't care much about start and stop times. If I program something to record using the schedule, often I miss the end of it. They frequently go over the half-hour or hour mark by a minute or two. Occasionally they complicate it more by starting a show a little early too. That irks me. -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida jleik...@leikhim.com 407-982-0446 WWW.LEIKHIM.COM ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Years Eve TV countdown
Hi On Jan 1, 2015, at 12:39 PM, Richard (Rick) Karlquist rich...@karlquist.com wrote: We have DirecTV with some receivers standard definition and others High Definition. The delay is considerably greater on the HD version. Even OTA HD is delayed considerably, as noted if you try to listen to a football game on the radio while watching. Sometimes you hear “touchdown Once upon a time I lived close enough to make that observation on analog TV. In those days, the analog signal could make it to New York and back to me quicker than the sound from the stadium. This of course was many decades before the whole “delay to catch stuff” controversy. Bob before the ball is even snapped on TV. Rick ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Years Eve TV countdown
Hi Here in central PA, ABC was almost exactly 10 seconds slow. That’s about 2 seconds longer than the delay in past years. Even with digital and a direct network feed, there are a variable number of buffers in the chain. Bob On Jan 1, 2015, at 12:17 AM, Daniel Schultz n8...@usa.net wrote: The local ABC network affiliate WJLA in Washington DC was approximately 4 seconds behind WWV in their on-screen countdown clock for New Year's eve. The local NBC affiliate's clock was about 8 seconds late when I checked them at two minutes before midnight. Happy New Year! Dan Schultz N8FGV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Years Eve TV countdown
We have DirecTV with some receivers standard definition and others High Definition. The delay is considerably greater on the HD version. Even OTA HD is delayed considerably, as noted if you try to listen to a football game on the radio while watching. Sometimes you hear touchdown before the ball is even snapped on TV. Rick ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Years Eve TV countdown
Modern Science at it's best ... Some years ago, before the days of Digital TV, I used to compare an OTA NFL broadcast of a certain game with the cable broadcast of the same game. The difference was striking. So, they improved things, now it's all lousy !! 73 es HNY, Dick, W1KSZ On 1/1/2015 12:15 PM, Magnus Danielson wrote: Chuck, In digital times, the main reason for creating delays is due to the temporal compression of MPEG-2 and MPEG-4. Production quality is either not compressed or JPEG-2000 compressed. If you do not compress at all, delay structure can be similar to that of analog video days. JPEG-2000 typically requires the full frame to be grabbed before serious crunching can be done, due to the 2D wavelet processing. There exists low-delay compression schemes which is in the handful of lines (about 16) of delay. MPEG-2 requires a re-arraning of transmission order in order for the IBBBPBBBP... sequence requires the I (or preceeding P) and following P be sent before the B frames interpolating between them. Add that many buffer management systems is horrible, especially when going over IP. Doing long distance (22500 km) 4K uncompressed video has been done with only 750 ms delay. That delay is probably trimable if you really need to. The one feature you have with digital video, is that you can create delays by mistake so easy, and that is gravely misused feature to this day. Let's say that most systems does not impress me. Cheers, Magnus On 01/01/2015 04:31 PM, Chuck Harris wrote: It is not that they don't care about time sync, it is that they have to follow the rules of causality. Because the whole digitization, broadcast, and display process of digital TV processes seconds to minutes of material at a time, You cannot make an event show at an exact time unless the event was pre-staged... How do you pre-stage a live event that must happen at a specific time, such as the ringing in of the new year? In the old days of analog TV, the problem was similar, but the smallest unit of data was a screen, which took about 1/30th of a second... added to the un avoidable transport delays... fiber, microwave, or satellite hop. -Chuck Harris Rex wrote: TV doesn't seem to care about time sync much these days. It also depends a lot on the path getting to you, I get most of my TV via satellite (Dish network). The receiver I have also can get OTA. I have happened to notice, once, that I had a local channel on two TVs. One was receiving the local via satellite and one was tuned to OTA local broadcast. The satellite was many seconds (at least 5, probably more) behind the OTA. I walked from one room to the other and had a brief period of deja vu. Hmm, just occurred to me, an earphone on the early one while watching the later one with friends would make you a living room Jeopardy game show super star. But that satellite delay all makes sense. One thing annoys me though. Many channels don't care much about start and stop times. If I program something to record using the schedule, often I miss the end of it. They frequently go over the half-hour or hour mark by a minute or two. Occasionally they complicate it more by starting a show a little early too. That irks me. But for New Years, I didn't try to measure anything exactly, but I know they were off by about 3 hrs. I live in California. I was watching New York's events on my TV and the ball dropped at about midnight local time. I am enough of a time nut to know that should have happened at 9 PM local time. See, you just can't trust the media for accuracy these days. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Years Eve TV countdown
Chuck, In digital times, the main reason for creating delays is due to the temporal compression of MPEG-2 and MPEG-4. Production quality is either not compressed or JPEG-2000 compressed. If you do not compress at all, delay structure can be similar to that of analog video days. JPEG-2000 typically requires the full frame to be grabbed before serious crunching can be done, due to the 2D wavelet processing. There exists low-delay compression schemes which is in the handful of lines (about 16) of delay. MPEG-2 requires a re-arraning of transmission order in order for the IBBBPBBBP... sequence requires the I (or preceeding P) and following P be sent before the B frames interpolating between them. Add that many buffer management systems is horrible, especially when going over IP. Doing long distance (22500 km) 4K uncompressed video has been done with only 750 ms delay. That delay is probably trimable if you really need to. The one feature you have with digital video, is that you can create delays by mistake so easy, and that is gravely misused feature to this day. Let's say that most systems does not impress me. Cheers, Magnus On 01/01/2015 04:31 PM, Chuck Harris wrote: It is not that they don't care about time sync, it is that they have to follow the rules of causality. Because the whole digitization, broadcast, and display process of digital TV processes seconds to minutes of material at a time, You cannot make an event show at an exact time unless the event was pre-staged... How do you pre-stage a live event that must happen at a specific time, such as the ringing in of the new year? In the old days of analog TV, the problem was similar, but the smallest unit of data was a screen, which took about 1/30th of a second... added to the un avoidable transport delays... fiber, microwave, or satellite hop. -Chuck Harris Rex wrote: TV doesn't seem to care about time sync much these days. It also depends a lot on the path getting to you, I get most of my TV via satellite (Dish network). The receiver I have also can get OTA. I have happened to notice, once, that I had a local channel on two TVs. One was receiving the local via satellite and one was tuned to OTA local broadcast. The satellite was many seconds (at least 5, probably more) behind the OTA. I walked from one room to the other and had a brief period of deja vu. Hmm, just occurred to me, an earphone on the early one while watching the later one with friends would make you a living room Jeopardy game show super star. But that satellite delay all makes sense. One thing annoys me though. Many channels don't care much about start and stop times. If I program something to record using the schedule, often I miss the end of it. They frequently go over the half-hour or hour mark by a minute or two. Occasionally they complicate it more by starting a show a little early too. That irks me. But for New Years, I didn't try to measure anything exactly, but I know they were off by about 3 hrs. I live in California. I was watching New York's events on my TV and the ball dropped at about midnight local time. I am enough of a time nut to know that should have happened at 9 PM local time. See, you just can't trust the media for accuracy these days. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Years Eve TV countdown
Hi Magnus, I strongly suspect that the major cause of time lag in TV programs seen on Digital over-the-air TV is in the TV sets themselves. My evidence for this is observation of simulcast programs that are broadcast in both HD and LD on different channels of the same station. The HD always lags the LD by about 10 seconds on my 2014 vintage Sony TV. It was the same on my 2007 vintage Sony TV, only maybe a little more so. If it ever even once went the other way, I would consider that it might be some anomaly at the broadcast station, but it never does... So, I believe it is related to the processing effort the TV set has to do to process HD over that of LD. The stations can do all the work in the world to minimize their time lags, and perhaps even achieve the 750ms you quote, and it will all be for naught come New Years eve when some time nut notices how the ball drops 8 or 10 seconds after the midnight we measure through other means. Simultaneous was possible in the days of analog TV to within 1 frame plus transport time. Digital TV's are going to have to run a lot faster than they do now just to catch up with what was routine in the past. -Chuck Harris Magnus Danielson wrote: Chuck, In digital times, the main reason for creating delays is due to the temporal compression of MPEG-2 and MPEG-4. Production quality is either not compressed or JPEG-2000 compressed. If you do not compress at all, delay structure can be similar to that of analog video days. JPEG-2000 typically requires the full frame to be grabbed before serious crunching can be done, due to the 2D wavelet processing. There exists low-delay compression schemes which is in the handful of lines (about 16) of delay. MPEG-2 requires a re-arraning of transmission order in order for the IBBBPBBBP... sequence requires the I (or preceeding P) and following P be sent before the B frames interpolating between them. Add that many buffer management systems is horrible, especially when going over IP. Doing long distance (22500 km) 4K uncompressed video has been done with only 750 ms delay. That delay is probably trimable if you really need to. The one feature you have with digital video, is that you can create delays by mistake so easy, and that is gravely misused feature to this day. Let's say that most systems does not impress me. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New Years Eve TV countdown
The local ABC network affiliate WJLA in Washington DC was approximately 4 seconds behind WWV in their on-screen countdown clock for New Year's eve. The local NBC affiliate's clock was about 8 seconds late when I checked them at two minutes before midnight. Happy New Year! Dan Schultz N8FGV Dan, I think you just illustrated the delays in digital TV transmission. When watching events from abroad (e.g. F1 races) where precise timing is available, I typically see a delay of 7-8-9-10 seconds, depending on the location. That is likely a delay to the studio, and then delay through Sky satellite TV. The BBC here no longer shows a clock, perhaps partially for that reason. At least there was no leap -second to confuse things! Happy New Year! 73, David GM8ARV -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
