[time-nuts] New Years Eve TV countdown
w1ksz at earthlink.net
Thu Jan 1 18:07:23 EST 2015
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:
> 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.
> 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.
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