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uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions.

TV system conversion



 
 
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  #11  
Old March 18th 17, 07:27 PM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Posts: 1,906
Default TV system conversion

On Sat, 18 Mar 2017 16:16:46 -0000, "NY" wrote:

I think the biggest technological advances are in size of cameras. I still
find it hard to get my head round the fact that you can use a camera that is
little bigger than a matchbox to record HD pictures for several hours onto a
wafer about the size of your little fingernail. Shame that all the ones of
that size (GoPro, SJCAM 5000, various dashcams) can only record in
US-standard 30 fps, and aren't switchable to 25 fps for the European market,
which means you have to endure jerky movement if you try to blend footage
from one of those cameras with footage from a proper 25 fps camcorder, as
every 5th frame of the 30 fps is dropped (Adobe Premiere doesn't do anything
fancy with interpolation!). I wonder if it's true 30 fps or 29.97 fps?


I wonder how important the output frame rate really is nowadays, as
just about anything with a screen seems capable of displaying any
frame rate and any resolution, switching seamlessly between them
whenever necessary. My TV screen has to display the outputs of a
couple of Freeview PVRs, a Bluray player, a computer and an Amazon
box, and briefly shows some numbers indicating these technical
parameters whenever a new source is selected. I've seen 60, 50 and 24
flash up in the corner of the screen depending on what I'm watching,
but the rest of the time I can't even tell which it is. There would
only be a problem combining material from different sources, but
anyone making a video production would presumably ensure that all
their own material was to the same standards, so it could be edited
together without any discontinuities. As long any given programme was
consistent within itself, I doubt if anybody would notice.

Rod.

---
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  #12  
Old March 18th 17, 07:55 PM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Posts: 1,906
Default TV system conversion

On Sat, 18 Mar 2017 14:58:56 -0000, "NY" wrote:

Does SECAM use the same gamma and black level as PAL, or do you get the same
problems as with NTSC where their pictures look very artificial and
plasticky.


As far as I know, they're the same. The Sony cameras I remember
working with had plug-in boards for the different sections, the last
one being the encoder. Different boards were available for different
countries, but between the countries that used 625/50 I think the
encoder was the only board that needed to be changed, the rest of the
camera being the same.

For 525/60 the two line delay in the aperture corrector would need to
be different so that board would need to be a different one, but for a
tube camera the rest of it would be very similar. I think the video
processor board, which included things like gamma correction and white
clipping, was always the same.

I never encountered a chip camera that was switchable between 525 and
625, so some of the digital stuff must have been different, but I
think they used the same colour separating prisms, so must have used
essentially the same video processing.

Rod.

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  #13  
Old March 18th 17, 10:08 PM posted to uk.tech.digital-tv
NY
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Posts: 934
Default TV system conversion

"Roderick Stewart" wrote in message
...
On Sat, 18 Mar 2017 16:16:46 -0000, "NY" wrote:

I think the biggest technological advances are in size of cameras. I still
find it hard to get my head round the fact that you can use a camera that
is
little bigger than a matchbox to record HD pictures for several hours onto
a
wafer about the size of your little fingernail. Shame that all the ones of
that size (GoPro, SJCAM 5000, various dashcams) can only record in
US-standard 30 fps, and aren't switchable to 25 fps for the European
market,
which means you have to endure jerky movement if you try to blend footage
from one of those cameras with footage from a proper 25 fps camcorder, as
every 5th frame of the 30 fps is dropped (Adobe Premiere doesn't do
anything
fancy with interpolation!). I wonder if it's true 30 fps or 29.97 fps?


I wonder how important the output frame rate really is nowadays, as
just about anything with a screen seems capable of displaying any
frame rate and any resolution, switching seamlessly between them
whenever necessary. My TV screen has to display the outputs of a
couple of Freeview PVRs, a Bluray player, a computer and an Amazon
box, and briefly shows some numbers indicating these technical
parameters whenever a new source is selected. I've seen 60, 50 and 24
flash up in the corner of the screen depending on what I'm watching,
but the rest of the time I can't even tell which it is. There would
only be a problem combining material from different sources, but
anyone making a video production would presumably ensure that all
their own material was to the same standards, so it could be edited
together without any discontinuities. As long any given programme was
consistent within itself, I doubt if anybody would notice.


Frame rate is less important until you try to mix shots of 25 and 30 fps -
unless you have software and a file format which allows change of frame rate
during a programme. Otherwise some conversion has to take place, and 30 to
25 or 25 to 30 is not pretty, even when it is done well, and it rarely is by
consumer software.

As you say, the ideal is to use the same standard throughout, which is why
the ability to run mini cameras at 25 as an alternative to 30 would be
great. I presume 25 fps cameras are available for broadcast use, but not at
consumer-affordable prices.

  #14  
Old March 19th 17, 01:36 PM posted to uk.tech.digital-tv
Wolfgang Schwanke
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Default TV system conversion

The author has marked this message not to be archived. This post will be deleted on March 26, 2017.

Graham. wrote in
:

https://www.youtube.com/watch?v=T2oNculjoQc


+1

--
John Peel is not enough

http://www.wschwanke.de/ http://www.fotos-aus-der-luft.de/
usenet_20031215 (AT) wschwanke (DOT) de
  #15  
Old March 19th 17, 01:39 PM posted to uk.tech.digital-tv
Wolfgang Schwanke
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Posts: 285
Default TV system conversion

The author has marked this message not to be archived. This post will be deleted on March 26, 2017.

"NY" wrote in
:

think that UK news teams would be able to get a clean copy without any
SECAM-to-PAL artefacts like speckle and streaks on the edges of
saturated colours.


That's not a conversion artefact but a defect of SECAM. You get (sorry
used to get) those streaks with native SECAM reception. Of course
conversion can't remove them.

Does SECAM use the same gamma and black level as PAL


I think so

--
John Peel is not enough

http://www.wschwanke.de/ http://www.fotos-aus-der-luft.de/
usenet_20031215 (AT) wschwanke (DOT) de
  #16  
Old March 19th 17, 01:40 PM posted to uk.tech.digital-tv
NY
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Posts: 934
Default TV system conversion

"Wolfgang Schwanke" wrote in message
...
"NY" wrote in
:

think that UK news teams would be able to get a clean copy without any
SECAM-to-PAL artefacts like speckle and streaks on the edges of
saturated colours.


That's not a conversion artefact but a defect of SECAM. You get (sorry
used to get) those streaks with native SECAM reception. Of course
conversion can't remove them.


I knew about crosshatch patterning but not about streaks.

I suppose if BBC/ITN did a deal with a French/Russian station they'd have
access to the original in-studio PAL before conversion to SECAM for
broadcast, but if they had to use an off-air signal (maybe cheekily
"acquiring" the footage without permission!) then they'd get SECAM
artefacts.

  #17  
Old March 19th 17, 05:18 PM posted to uk.tech.digital-tv
Wolfgang Schwanke
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Posts: 285
Default TV system conversion

The author has marked this message not to be archived. This post will be deleted on March 26, 2017.

"NY" wrote in
:

That's not a conversion artefact but a defect of SECAM. You get (sorry
used to get) those streaks with native SECAM reception. Of course
conversion can't remove them.


I knew about crosshatch patterning but not about streaks.


By crosshatch pattern do you mean cross luminance? Yes that's slightly
worse with SECAM as well, but not badly. The typical "SECAM fire" I was
talking about consists of blue/red/magenta streaks to the right of
sharp edges.

Exaggerated examples caused by bad reception:

https://www.youtube.com/watch?v=KcaQaAVQQmU

http://www.scheida.at/scheida/TV_SEI...standardRF.jpg

In real life with good reception it wasn't nearly as bad, but it was
always there.

I suppose if BBC/ITN did a deal with a French/Russian station they'd have
access to the original in-studio PAL before conversion to SECAM for
broadcast,


That's assuming the studio worked in PAL. That wasn't the case in the
early days, and even later not in all places.

--
John Peel is not enough

http://www.wschwanke.de/ http://www.fotos-aus-der-luft.de/
usenet_20031215 (AT) wschwanke (DOT) de
  #18  
Old March 19th 17, 05:27 PM posted to uk.tech.digital-tv
Wolfgang Schwanke
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Posts: 285
Default TV system conversion

The author has marked this message not to be archived. This post will be deleted on March 26, 2017.

PS

In real life with good reception it wasn't nearly as bad, but it was
always there.


Here's a clip that shows SECAM fire under more typical conditions. It
has blue/red streaks on bright spots almost throughout, but not in a
disturbing way.

https://www.youtube.com/watch?v=HkyqVuIyuP4

--
John Peel is not enough

http://www.wschwanke.de/ http://www.fotos-aus-der-luft.de/
usenet_20031215 (AT) wschwanke (DOT) de
  #19  
Old March 19th 17, 06:05 PM posted to uk.tech.digital-tv
Mark Carver
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Posts: 7,524
Default TV system conversion

On 18/03/2017 14:58, NY wrote:

Does SECAM use the same gamma and black level as PAL,


Yes

or do you get the
same problems as with NTSC where their pictures look very artificial and
plasticky.


You are talking in the present, none of this is relevant any more, and
from the mid 80s, the only place in France you'd find a SECAM coder in
use, (in the Tx chain) was the transmitter site.

The French in recent decades did everything before the transmitter as
PAL, then from the early nineties as component video (just as we did,
with our PAL encoders way downstream too) (BBC regional studios
excepted)

Mind you, even on NTSC tellies, US pictures look odd, in a
way that is difficult to define - something to do with contrast and
tonal range.


Not any more, it's a digital component world, contemporary American TV
pictures are as good European ones. Better you might argue, coz they are
running at 30 frames/Sec not 25.


--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #20  
Old March 19th 17, 06:37 PM posted to uk.tech.digital-tv
Alan White[_3_]
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Posts: 60
Default TV system conversion

On Sat, 18 Mar 2017 16:16:46 -0000, "NY" wrote:

I think the biggest technological advances are in size of cameras. I still
find it hard to get my head round the fact that you can use a camera that is
little bigger than a matchbox to record HD pictures for several hours onto a
wafer about the size of your little fingernail. Shame that all the ones of
that size (GoPro, SJCAM 5000, various dashcams) can only record in
US-standard 30 fps, and aren't switchable to 25 fps for the European market,
which means you have to endure jerky movement if you try to blend footage
from one of those cameras with footage from a proper 25 fps camcorder, as
every 5th frame of the 30 fps is dropped (Adobe Premiere doesn't do anything
fancy with interpolation!). I wonder if it's true 30 fps or 29.97 fps?


The GoPro Hero4 Silver and the GoPro Hero5 both record 1080/50.

--
Alan White
Mozilla Firefox and Forte Agent.
By Loch Long, twenty-eight miles NW of Glasgow, Scotland.
Webcam and weather:- http://windycroft.co.uk/weather
 




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