----- HDTV Magazine Tips List -----
Robert,
It is until now I have the chance to respond to your note about your exchanges with this person
about 1080i converted back to 1080p giving the same results as 1080p all thru.
This issue of 1080p to 1080i to 1080p again is a not as simple to explain so hang in there:
The main problem is not that much the i to p, you will see.
----------- The player's game ---------------------
The film is already stored in the disc as a telecine video transfer of 1080p 24Fps "in half frames"
(like fields) with flags to rebuild the frames by just putting them together. Sometimes the flags
are not there and the video processor has to detect the cadence of the video to know if a rebuild
step to p frames is necessary (or not, if dealing with a 1080i video recorded at 30Fps of 60 fields,
not coming from film).
Regardless if people has 1080p sets or not the player's manufacturer has to offer the option of
outputting the 1080i version out of that cadence (component and HDMI/DVI), and 480i version of it
(S-video, RCA video out), they call that backward compatibility.
Since both (480i and 1080i) are at 60 fields x sec there has to be a 2:3 pulldown to output that
signal if the user chooses that output on the player's menu. In other words, the 48 half frames of
24Fps film frames end up as 60 fields by repeating some fields, 12 fields to be exact.
All that is done in the digital domain in the HiDef DVD player, almost identical as what happened
with DVD players with 480i over the last 10 years, the issue was and still is the missing 12 fields,
so regular 480i TVs and newer 1080i HDTVs can sync at their standard 60 fields per sec.
It is easy to assume that the minute we start adding fields (12) merged on the cadence (48) the
processing is going to create some artifacts, so some magic has to occur, but not everyone has the
hands and art of David Copperfield.
First problem: if the player does not have 1080p outputs the processing above has to happen to been
able to output interlaced 1080i and 480i, so most TVs can sync to it.
Second problem: how good the player does that ?, and once it is done, the signal is not the clean
original 24fps anymore.
---------------------------
------------ The transport of the signal ----------------
When we had analog connections (VGA, component YPbPr, etc) the player wraps up the job by converting
the resulting signal above from digital to analog to send it out to another piece of equipment,
typically an HDTV. The TV in turn does the opposite to video process in the digital domain. In
other words both pieces of equipment work in digital but they talked to each other in analog.
Third problem: D/A and A/D conversions harm the quality of a signal, even if it is untouched 1080p.
We now have DVI and HDMI connections and one can assume that because the D/A and A/D conversions and
not needed the signal should be transported as clean as it could be.
Fourth problem: That is not case in some circumstances, sometimes wires themselves or HDMI chip hand
shakes do not work well, but if they works the theory is that the digital signal will departure and
arrive with less disruption than with analog conversions.
--------------------------
------------- The displaying of the signal --------------------------
1080i arrives to the 1080p display device as 60 fields per second interlaced, now the set has to do
its magic make the images progressive to display them as 1080x1920 p frames every 60th of a second.
There are many TV manufacturers that do a decent job at it, but also many that do a pitiful job.
All of them might claim they are the Holy Grail of 1080p.
Fifth problem: The magic of deinterlacing is also an art and if done incorrectly the resultant 60 p
frames could be a product mix of a mediocre 2:3 pulldown plus a later deinterlacing, stages done by
player and TV respectively, which could end up not even close to what the original 24fps could have
been if simply evenly repeated to a higher multiple scan rate, like 72fps or 120fps, a la cinema
projector opening the shooter twice for every celluloid frame, at 48, sufficient to smooth out the
presentation.
Pioneer Elite plasmas do 3:3 to take 24fps media and display it as 72fps, clean as it should be, no
interlacing games.
Players that output at 24fps to TV sets that could accept 24fps and repeat frames to at least 3
times its speed without performing unneeded interlaced processing should produce less artifacts, but
how many of that kind of sets are there?
In other words, even when a HiDef DVD player would have 1080p output (of 1080p60) chances are that
to obtain the 60 frames x second from the 24 original stored in the disc the player would do first
3:2 pull-down to get to 30fps (60 fields) and later deinterlace those 60 fields to make 60 frames
for the output, so a 1080p TV accepting 1080p could read it.
Sixth Problem: No matter how we look at it, unless done as the Pioneer Elite plasmas above, someone
in the signal chain will have to do those stages, all on the player, split it between the player and
the TV with HDMI in between, all in the TV if output as 24fps, all in the digital domain.
Having 1080p outputs on players and 1080p inputs on TVs, in addition to 1080i inputs/outputs, opens
the opportunity of improvement of the processing by choosing the processing that works best, and
also the chance to add a separate video processor in between if it becomes totally necessary for the
function to be out of the player/set pair for image improvement.
To take this to a practical experience most of us went thru, let us go back in time.
Remember back in 1998/9, 480i DVD players, HDTVs deinterlacing it to 480p, a first hand opportunity
for many early adopters to see what movies look like in the HDTVs, 24fps movies stored as 480i half
frames to be exact (fields if you may).
The first generation deinterlacers on TV were horrible, but what else to do? adding a scaler? might
be, but the problem was that there were only a few and expensive. A bit later progressive DVD
players arrived, the whole 3:2 pull-down and deinterlacing jobs to 480p done within the player, all
in the digital domain, the HDTV with 480p inputs, big difference.
What happened? we replaced one piece of the puzzle, the deinterlacer of the TV was not doing a good
job working over a 480i signal converted twice to be transported as analog, the only connection back
then.
My message is clear: film at 24fps would not be displayed perfectly if going to the 60i world to get
to the 60p world of the last stage of 1080p TVs, but even TVs with 1080p inputs would not do the
perfect solution either. But offering 1080p input/output options for a piece meal approach could
improve the scenario: try the player as 1080i and let the TV do the p, try the player as 1080p60 and
let the TV just map, try a scaler in between to do the deinterlacing of 1080i to p, some of these
options would not be possible if the player does not have a 1080p output and the HDTV neither.
Regarding your wobulation issue, that guy sounds like he has the thermometer on his hand but does
not want to get pregnant.
I will address that later.
Hope this was not too long.
Best Regards,
Rodolfo La Maestra
-----Original Message-----
From: HDTV Magazine On Behalf Of
Dr Robert A Fowkes
Sent: Sunday, May 14, 2006 1:10 AM
To: HDTV Magazine
Subject: Re: A first volley in an absurd DVD war
----- HDTV Magazine Tips List -----
At 03:22 PM 5/13/2006 -0400, you wrote:
>Having said that I will see you this Sunday at Tweeter, we waited
>long enough, just kidding.
Rodolfo,
My sentiments, exactly! Let's each buy two!
Seriously, thank you for the excellent follow up to my somewhat
nostalgic, sometimes rambling thoughts on the current state of
affairs regarding the first generation HD-DVD players. We are
definitely on the same page here (and have been for some time.) Yes,
I realize that the HD-DVDs are encoded at 1080p even though the first
generation players only output 1080i. I've been having a somewhat
heated discussion over on the HTF regarding my insistence that I wait
for 1080p output to feed my 1080p input compliant HD MD5880n. One
guy is suggesting that the difference between 1080i and 1080p is
minimal at best so it's not a "valid reason" (his words) to wait
until 1080p output is available. He doesn't seem to understand that
1080p fed into a 1080p display with no processing is better than
1080p content --> 1080i output --> 1080i input --> 1080p display. He
then goes on to say that "wobulation" is not 1080p "in his
book." Actually, he's wrong there. Wobulation is 1080p in the
vertical direction: it's the 1920 spec that comes from wobulating 960
units twice. And since the effect takes place faster than the human
eye can register the net effect is that one always sees a full
1920x1080p image. In fact, the wobulation takes the edge off the
pixels a bit so the resultant image appears to be smoother in some
respects to "native" 1920x1080p. I also pointed out to him that he
was using both sides of an argument to prove his points. First 1080i
is "indistinguishable" from 1080p so 1080p output isn't
critical. Then "wobulation" isn't as good as "real" 1080p. See what
I mean? <g>
Yes, I will have some HD disc players shortly (probably one of each)
but not this weekend. And yes, I will get a 1080p FP to complement
my 1080p RP for Big Screen presentations (when the price comes down a
bit more). But for a change I'm not the first kid on the block.
Take care.
-- RAF
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Robert,
It is until now I have the chance to respond to your note about your exchanges with this person
about 1080i converted back to 1080p giving the same results as 1080p all thru.
This issue of 1080p to 1080i to 1080p again is a not as simple to explain so hang in there:
The main problem is not that much the i to p, you will see.
----------- The player's game ---------------------
The film is already stored in the disc as a telecine video transfer of 1080p 24Fps "in half frames"
(like fields) with flags to rebuild the frames by just putting them together. Sometimes the flags
are not there and the video processor has to detect the cadence of the video to know if a rebuild
step to p frames is necessary (or not, if dealing with a 1080i video recorded at 30Fps of 60 fields,
not coming from film).
Regardless if people has 1080p sets or not the player's manufacturer has to offer the option of
outputting the 1080i version out of that cadence (component and HDMI/DVI), and 480i version of it
(S-video, RCA video out), they call that backward compatibility.
Since both (480i and 1080i) are at 60 fields x sec there has to be a 2:3 pulldown to output that
signal if the user chooses that output on the player's menu. In other words, the 48 half frames of
24Fps film frames end up as 60 fields by repeating some fields, 12 fields to be exact.
All that is done in the digital domain in the HiDef DVD player, almost identical as what happened
with DVD players with 480i over the last 10 years, the issue was and still is the missing 12 fields,
so regular 480i TVs and newer 1080i HDTVs can sync at their standard 60 fields per sec.
It is easy to assume that the minute we start adding fields (12) merged on the cadence (48) the
processing is going to create some artifacts, so some magic has to occur, but not everyone has the
hands and art of David Copperfield.
First problem: if the player does not have 1080p outputs the processing above has to happen to been
able to output interlaced 1080i and 480i, so most TVs can sync to it.
Second problem: how good the player does that ?, and once it is done, the signal is not the clean
original 24fps anymore.
---------------------------
------------ The transport of the signal ----------------
When we had analog connections (VGA, component YPbPr, etc) the player wraps up the job by converting
the resulting signal above from digital to analog to send it out to another piece of equipment,
typically an HDTV. The TV in turn does the opposite to video process in the digital domain. In
other words both pieces of equipment work in digital but they talked to each other in analog.
Third problem: D/A and A/D conversions harm the quality of a signal, even if it is untouched 1080p.
We now have DVI and HDMI connections and one can assume that because the D/A and A/D conversions and
not needed the signal should be transported as clean as it could be.
Fourth problem: That is not case in some circumstances, sometimes wires themselves or HDMI chip hand
shakes do not work well, but if they works the theory is that the digital signal will departure and
arrive with less disruption than with analog conversions.
--------------------------
------------- The displaying of the signal --------------------------
1080i arrives to the 1080p display device as 60 fields per second interlaced, now the set has to do
its magic make the images progressive to display them as 1080x1920 p frames every 60th of a second.
There are many TV manufacturers that do a decent job at it, but also many that do a pitiful job.
All of them might claim they are the Holy Grail of 1080p.
Fifth problem: The magic of deinterlacing is also an art and if done incorrectly the resultant 60 p
frames could be a product mix of a mediocre 2:3 pulldown plus a later deinterlacing, stages done by
player and TV respectively, which could end up not even close to what the original 24fps could have
been if simply evenly repeated to a higher multiple scan rate, like 72fps or 120fps, a la cinema
projector opening the shooter twice for every celluloid frame, at 48, sufficient to smooth out the
presentation.
Pioneer Elite plasmas do 3:3 to take 24fps media and display it as 72fps, clean as it should be, no
interlacing games.
Players that output at 24fps to TV sets that could accept 24fps and repeat frames to at least 3
times its speed without performing unneeded interlaced processing should produce less artifacts, but
how many of that kind of sets are there?
In other words, even when a HiDef DVD player would have 1080p output (of 1080p60) chances are that
to obtain the 60 frames x second from the 24 original stored in the disc the player would do first
3:2 pull-down to get to 30fps (60 fields) and later deinterlace those 60 fields to make 60 frames
for the output, so a 1080p TV accepting 1080p could read it.
Sixth Problem: No matter how we look at it, unless done as the Pioneer Elite plasmas above, someone
in the signal chain will have to do those stages, all on the player, split it between the player and
the TV with HDMI in between, all in the TV if output as 24fps, all in the digital domain.
Having 1080p outputs on players and 1080p inputs on TVs, in addition to 1080i inputs/outputs, opens
the opportunity of improvement of the processing by choosing the processing that works best, and
also the chance to add a separate video processor in between if it becomes totally necessary for the
function to be out of the player/set pair for image improvement.
To take this to a practical experience most of us went thru, let us go back in time.
Remember back in 1998/9, 480i DVD players, HDTVs deinterlacing it to 480p, a first hand opportunity
for many early adopters to see what movies look like in the HDTVs, 24fps movies stored as 480i half
frames to be exact (fields if you may).
The first generation deinterlacers on TV were horrible, but what else to do? adding a scaler? might
be, but the problem was that there were only a few and expensive. A bit later progressive DVD
players arrived, the whole 3:2 pull-down and deinterlacing jobs to 480p done within the player, all
in the digital domain, the HDTV with 480p inputs, big difference.
What happened? we replaced one piece of the puzzle, the deinterlacer of the TV was not doing a good
job working over a 480i signal converted twice to be transported as analog, the only connection back
then.
My message is clear: film at 24fps would not be displayed perfectly if going to the 60i world to get
to the 60p world of the last stage of 1080p TVs, but even TVs with 1080p inputs would not do the
perfect solution either. But offering 1080p input/output options for a piece meal approach could
improve the scenario: try the player as 1080i and let the TV do the p, try the player as 1080p60 and
let the TV just map, try a scaler in between to do the deinterlacing of 1080i to p, some of these
options would not be possible if the player does not have a 1080p output and the HDTV neither.
Regarding your wobulation issue, that guy sounds like he has the thermometer on his hand but does
not want to get pregnant.
I will address that later.
Hope this was not too long.
Best Regards,
Rodolfo La Maestra
-----Original Message-----
From: HDTV Magazine On Behalf Of
Dr Robert A Fowkes
Sent: Sunday, May 14, 2006 1:10 AM
To: HDTV Magazine
Subject: Re: A first volley in an absurd DVD war
----- HDTV Magazine Tips List -----
At 03:22 PM 5/13/2006 -0400, you wrote:
>Having said that I will see you this Sunday at Tweeter, we waited
>long enough, just kidding.
Rodolfo,
My sentiments, exactly! Let's each buy two!
Seriously, thank you for the excellent follow up to my somewhat
nostalgic, sometimes rambling thoughts on the current state of
affairs regarding the first generation HD-DVD players. We are
definitely on the same page here (and have been for some time.) Yes,
I realize that the HD-DVDs are encoded at 1080p even though the first
generation players only output 1080i. I've been having a somewhat
heated discussion over on the HTF regarding my insistence that I wait
for 1080p output to feed my 1080p input compliant HD MD5880n. One
guy is suggesting that the difference between 1080i and 1080p is
minimal at best so it's not a "valid reason" (his words) to wait
until 1080p output is available. He doesn't seem to understand that
1080p fed into a 1080p display with no processing is better than
1080p content --> 1080i output --> 1080i input --> 1080p display. He
then goes on to say that "wobulation" is not 1080p "in his
book." Actually, he's wrong there. Wobulation is 1080p in the
vertical direction: it's the 1920 spec that comes from wobulating 960
units twice. And since the effect takes place faster than the human
eye can register the net effect is that one always sees a full
1920x1080p image. In fact, the wobulation takes the edge off the
pixels a bit so the resultant image appears to be smoother in some
respects to "native" 1920x1080p. I also pointed out to him that he
was using both sides of an argument to prove his points. First 1080i
is "indistinguishable" from 1080p so 1080p output isn't
critical. Then "wobulation" isn't as good as "real" 1080p. See what
I mean? <g>
Yes, I will have some HD disc players shortly (probably one of each)
but not this weekend. And yes, I will get a 1080p FP to complement
my 1080p RP for Big Screen presentations (when the price comes down a
bit more). But for a change I'm not the first kid on the block.
Take care.
-- RAF
To unsubscribe please click: [email protected]
To receive the digest mode (one email a day made from all posted that same day) send an email to:
[email protected]
To unsubscribe please click: [email protected]
To receive the digest mode (one email a day made from all posted that same day) send an email to:
[email protected]