> On Fri, Feb 15, 2002 at 07:36:35AM -0600, I wrote:
>> the video/tv sets are working at 24-25 cycles, and such frequency is
>> sometimes considered the cause of some seizure , similar to a crisis,
>> for being a near multiple of the 12 cycles lightning frequency used for
>> medical detection of epilepsy.
>>> randolph answered:
> This is not so in the USA, where the television frame rate is 30 or 60
> frames/second, depending on how it's counted.
Let me follow:
just a doubt : do you mean that US used NTSC color tv or black and white
system was always and still is based on a rate of 30 images per second when
"reading" or "appearing", instead of the 24 images per second in movies and
25 images per second in european pal/secam television/video ?
I don't understand then the option between 30 and 60 frames per second.
what for ? is 60 including the (more or less)black screen or data "bar"
between each frame? (I studied some 30 years movie/video theory/techniques
and never heard of such 30 frames per second in US television. But then
Europeans cared less about US tv than now...)
meaby we should ask to some oficial/technician from NBC CBS a.s.o. a precise
explanation, or you could give it to Us there ?
> Because of now
> irrelevant technical considerations, television frame rates are half
> the AC power frequency.
but actually you seem quite right: after all, 25 frames in european tv is
also the half of the power source frequency (50 hertz in those places)
but the technical reason is possibly presented so, when actually the frame
rate of 24 in movie and 25 in tv ( european) are based on the minimum speed
necessary to obtain a good quality "vision" of the projected movie.
so I suppose the first equipments looked for a mathematical formula to
simplify the scanning synchronisation, and as the power source frequency was
and still is one of the most stable constant in our modern world, the
technicians used such as a basis to attain a result around 24/25.In europe.
and in the US it became 30 in electronical tv processes. the news of the
day.
But at the world level, movie industry then is still struggling between 24,
25 and 30 frames rates... when showing on our tv screens movies made in the
24 frames rate
>
>> in some animated movies, the picts used to animate the movement are
>> sometimes used with the same 12 cycles frequency,( one pict each two
>> frames) and eventually a kind of crisis is possible like the one who
>> appeared some years ago with the japanese animated film for childrens.
>
but jut wondering now: suppose the 12 cycles frequency is used as a basis of
medical examination of some patient. the doctor starts with some variation
around such frequency. he tries the rate let's say at 1 per sec and goes up
and down with a max of let's say 25 or 50 cycles. If the encephalografic
sensor detects some "trouble" it should be seen at around the 12 cycles.
But not exactly.
So such fact could explain the appearance of problems also if the
frequency is slightly different from the 12 cycles multiple,in some US Tv
programs working at 30 frame rate, and causing eventually a slight or
eventually very strong epilepsylike crisis. Such US tv rate of 30 instead of
24-25 could also start the crisis when seeing some animated films or
special video games. Then the percentage variation between 12, 12.5 and 15
is kept in a range of 20 percent.
> I'll be damned--I didn't know about that.
the good point of some forums/list is the exchange of info. I learn daily...
Didn't know such 30 frames per second rate in US tv. funny. But very higher
and so difficult to combine/modify Video imaging with the traditional 24 per
sec rate of the general movie industry. just wondering if there is another
standard also available.
Such difference is huge. 6 frames per sec to quit/condense/adapt to the
acetate from the magnetic tape ? a very big difference. imagine Pixar
studios animating on Maya let's say the Shreck movie, and having to "cut" in
some way a quart of the work in video/computer imaging, just to make the
movie's color copies ? ( 6 over 24 is a quart, and 6 over 30 is still a
fifth. just to be loosed ?) there must be another way of doing that.Actually
I wonder which...
Do you ?
Patrick
>> the video/tv sets are working at 24-25 cycles, and such frequency is
>> sometimes considered the cause of some seizure , similar to a crisis,
>> for being a near multiple of the 12 cycles lightning frequency used for
>> medical detection of epilepsy.
>>> randolph answered:
> This is not so in the USA, where the television frame rate is 30 or 60
> frames/second, depending on how it's counted.
Let me follow:
just a doubt : do you mean that US used NTSC color tv or black and white
system was always and still is based on a rate of 30 images per second when
"reading" or "appearing", instead of the 24 images per second in movies and
25 images per second in european pal/secam television/video ?
I don't understand then the option between 30 and 60 frames per second.
what for ? is 60 including the (more or less)black screen or data "bar"
between each frame? (I studied some 30 years movie/video theory/techniques
and never heard of such 30 frames per second in US television. But then
Europeans cared less about US tv than now...)
meaby we should ask to some oficial/technician from NBC CBS a.s.o. a precise
explanation, or you could give it to Us there ?
> Because of now
> irrelevant technical considerations, television frame rates are half
> the AC power frequency.
but actually you seem quite right: after all, 25 frames in european tv is
also the half of the power source frequency (50 hertz in those places)
but the technical reason is possibly presented so, when actually the frame
rate of 24 in movie and 25 in tv ( european) are based on the minimum speed
necessary to obtain a good quality "vision" of the projected movie.
so I suppose the first equipments looked for a mathematical formula to
simplify the scanning synchronisation, and as the power source frequency was
and still is one of the most stable constant in our modern world, the
technicians used such as a basis to attain a result around 24/25.In europe.
and in the US it became 30 in electronical tv processes. the news of the
day.
But at the world level, movie industry then is still struggling between 24,
25 and 30 frames rates... when showing on our tv screens movies made in the
24 frames rate
>
>> in some animated movies, the picts used to animate the movement are
>> sometimes used with the same 12 cycles frequency,( one pict each two
>> frames) and eventually a kind of crisis is possible like the one who
>> appeared some years ago with the japanese animated film for childrens.
>
but jut wondering now: suppose the 12 cycles frequency is used as a basis of
medical examination of some patient. the doctor starts with some variation
around such frequency. he tries the rate let's say at 1 per sec and goes up
and down with a max of let's say 25 or 50 cycles. If the encephalografic
sensor detects some "trouble" it should be seen at around the 12 cycles.
But not exactly.
So such fact could explain the appearance of problems also if the
frequency is slightly different from the 12 cycles multiple,in some US Tv
programs working at 30 frame rate, and causing eventually a slight or
eventually very strong epilepsylike crisis. Such US tv rate of 30 instead of
24-25 could also start the crisis when seeing some animated films or
special video games. Then the percentage variation between 12, 12.5 and 15
is kept in a range of 20 percent.
> I'll be damned--I didn't know about that.
the good point of some forums/list is the exchange of info. I learn daily...
Didn't know such 30 frames per second rate in US tv. funny. But very higher
and so difficult to combine/modify Video imaging with the traditional 24 per
sec rate of the general movie industry. just wondering if there is another
standard also available.
Such difference is huge. 6 frames per sec to quit/condense/adapt to the
acetate from the magnetic tape ? a very big difference. imagine Pixar
studios animating on Maya let's say the Shreck movie, and having to "cut" in
some way a quart of the work in video/computer imaging, just to make the
movie's color copies ? ( 6 over 24 is a quart, and 6 over 30 is still a
fifth. just to be loosed ?) there must be another way of doing that.Actually
I wonder which...
Do you ?
Patrick