Re: How good is HD supposed to be?

[Christopher Woods]

Yes, I could have been clearer. This depends on the deintelacing algorithm.

Aside from the very first frame of a 50p video, which can only ever be the 
first two fields (...well, that or black), every frame after that is 
effectively taking two adjacent fields and saying 'make a frame out of 
those', so each field is a part of one frame but it doesn't just go 1+2, 
3+4 etc.


IF you're making a full resolution frame 1, you'd use field 1 and field 2. 
For frame 2, field 2 and field 3. For frame 3, field 3 and field 4 etc.


Otherwise, it's black and field 1 for frame 1, field 1 and 2 for frame 2, etc.

I think of the process of capturing interlaced video as a constantly 
shuffling (up-down) grill which alternately covers even, then odd, lines of 
the CCD (just for conceptualising, not how it actually works). As you're 
freezeframing that point in time for half of your frame, the next field 
will be slightly advanced in time by microseconds so it's not the same as  
'taking a picture' every 25th of a second.


You're actually taking 50 shots per second and immediately discarding half 
the resolution, relying on persistence of vision and the inherent 
properties of the TV to mask this. The two half-resolution images 
interleave neatly and produce a full resolution image, and do so rapidly 
enough that everything works. You get pseudo-50fps as a happy by-product.


http://www.100fps.com has a good explanation and screenshots of various 
scenarios if you're interested in what raw interlaced video looks like and 
the problems you can have working with it.


(I hate interlaced video.)

200, no, 300 fps 4K video for all! It divides nicely with 25 and 29.97 fps 
standards, it's got the temporal and dimensional resolution, what's not to 
like... Except the transmission and storage costs... But H.265 will solve 
all of that ;)


Chris


On 2 May 2016 8:52:25 p.m. "Dave Liquorice"  wrote:


On Sat, 30 Apr 2016 22:49:01 +0100, Christopher Woods wrote:


The deinterlacing algorithm is doing no resizing - it's interpolating
between the frames and then 'printing' that to 50 progressive frames. The
resulting image will have slightly lower definition due to the bob
artifacts as it's reconstructing the frame from two sequentially
interlaced fields, but it hasn't changed resolution.


Sorry, I'm still missing what is actually going on but I think I'm getting
there.

Is the first reference to "frames" refering to a frame constructed from the
two fields designed to be shown at 25 fps? Lets call this F1.

At 50 fps we need twice as many frames so an F1 and an F2. F2 doesn't exist
and is created by interpolation between the current F1 and the next F1.

--
Cheers
Dave.



___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer




___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

Re: How good is HD supposed to be?

[Christopher Woods]

Replied inadvertently to some of this in my other response, but everyone 
may find this interesting if they've not read before:


http://www.bbc.co.uk/rd/blog/2015-07-the-development-of-new-video-factory-profiles-for-bbc-iplayer

There's an 8 mbit 1080i created which I strongly suspect is what's 
delivered to Sky for their on-demand iPlayer offerings, certainly from 
watching some stuff on my Sky+ box. The DOG was smaller and "1080 crisp" 
(as was the picture content) on my panel which it never is using the web 
iPlayer.



From the R blog:


"The [encoding] profiles were designed to be encoded with a 3.84 second 
chunk size. This enables video and audio access units to be aligned for 
HTTP Live Streaming (HLS), where audio and video frames are multiplexed 
together within a single MPEG-2 transport stream, thereby helping some 
decoders have a clean switch between profiles. During subjective evaluation 
done within R, we identified that large screen devices such as TVs 
benefited more from higher frame rates than small screen devices such as 
tablets, where spatial resolution is of greater importance. In addition 
higher framerate 50Hz television streams still exhibit motion artefacts on 
most mobile, tablet and desktop devices due to their 60Hz screen refresh 
rate. So separate profile sets were developed for the two classes of devices."



On 30 April 2016 22:36:51 Tony Quinn  wrote:


On 30-Apr-16 9:15 PM, Dave Liquorice wrote:


But does a frame have the same number of lines as a field? It doesn't
in the analog world. 625 line frame, comprising two 312.5 line fields.
Frame rate 25 per second, field rate 50 per second but half the
vertical resolution. If a digital field only has half the vertical
resolution, which I think it must have or you can't interlace them,
then to create true 50 *frames* per second each field needs to be
upscaled and the missing lines interpolated from the existing ones. If
you just construct a frame from the two fields you have to repeat that
frame or playback at double speed... I missing something but don't
know what.


1080p50 (720p50) is exactly what it says, 50 full 1920x1080 (1280x720)
progressively scanned frames per second (naturally this generates twice
as much information as 25p (although 720p50 is the same raw data rate as
1080p25)).

Going back to an earlier comment on the thread regarding eastenders
being available at 720p50, given that EE is originated at at 1080
resolution, is the implication that it is being shot at 1080p50 and down
converted to 720p50 or that interpolation is being carries out to
generate a 720p50 stream?

FWIW, in interlaced origination (for example 625i50) temporal resolution
is increased at the cost of spatial resolution (twice as many images
with half the vertical resolution). Also bear in mind that (in the 625
analogue world) only 575 lines actually contain picture information


___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer




___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

Re: How good is HD supposed to be?

[Christopher Woods]

Indeed, half the vertical resolution per field but they're composited to 
make one whole frame. Yes, the field resolution is half a frame - It's 
basically analogue compression. And although 625 lines per frame, there's 
timing, blanking and audio lines too - picture content gets 576 lines, 288 
lines per field.


The fact analogue TVs essentially gave you some free motion interpolation 
from interlacing is a fortunate, quirky byproduct of the old mechanical 
process. Even with the quick scanning process (both on capture and 
reproduction) you were always capturing that microsecond in time for each 
line, then the electron gun scanned at the same rate so you actually see 
more of a 'fluid' representation of the light as captured. In practice your 
eyes can't keep up with microsecond shifts in picture position between 
lines, but they can easily see 25 vs 50 pictures per second.



The deinterlacing algorithm is doing no resizing - it's interpolating 
between the frames and then 'printing' that to 50 progressive frames. The 
resulting image will have slightly lower definition due to the bob 
artifacts as it's reconstructing the frame from two sequentially interlaced 
fields, but it hasn't changed resolution.


Downsizing to 720p50 gives you a resolution saving which can be put into 
the higher fps with less of a net cost on bandwidth and disk space. Losing 
absolute 1080 pixel definition but getting smoother motion is a win for me!



25i analogue video never has quite the per-frame definition of 25p video, 
but it wins for motion accuracy and suited the constrained bandwidth 
environment of analogue telly.


The bandwidth savings translate to the digital domain, so it "costs" a 
little less to transmit interlaced. IMO it's a pain to work with and is 
computationally more complex to decode and foremost.


Why they didn't just ditch interlaced encoding in the DVB-T standard and 
let the boxes interlace for old TVs is a bone of contention for me! I think 
it almost was the case that interlacing was almost dropped from the DVB 
spec until fairly late in the day too... Trying to recall a discussion with 
a fellow engineer from many months ago but struggling now...



On 30 April 2016 21:19:35 "Dave Liquorice"  wrote:


On Fri, 29 Apr 2016 20:42:06 +0100, Christopher Woods wrote:


"Upscaling" is a misnomer in this context. That implies a change of
picture resolution, ...


Agreed.


... when there's no resizing going on.


Not convinced.


25 interlaced frames per second yields 50 interlaced fields per second
(due to odd and even line scanning),


But does a frame have the same number of lines as a field? It doesn't in the
analog world. 625 line frame, comprising two 312.5 line fields. Frame rate
25 per second, field rate 50 per second but half the vertical resolution.

If a digital field only has half the vertical resolution, which I think it
must have or you can't interlace them, then to create true 50 *frames* per
second each field needs to be upscaled and the missing lines interpolated
from the existing ones. If you just construct a frame from the two fields
you have to repeat that frame or playback at double speed...

I missing something but don't know what.

--
Cheers
Dave.



___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer




___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

Re: How good is HD supposed to be?

[Dave Liquorice]

On Fri, 29 Apr 2016 20:42:06 +0100, Christopher Woods wrote:

> "Upscaling" is a misnomer in this context. That implies a change of 
> picture resolution, ...

Agreed. 

> ... when there's no resizing going on. 

Not convinced.

> 25 interlaced frames per second yields 50 interlaced fields per second 
> (due to odd and even line scanning), 

But does a frame have the same number of lines as a field? It doesn't in the 
analog world. 625 line frame, comprising two 312.5 line fields. Frame rate 
25 per second, field rate 50 per second but half the vertical resolution.

If a digital field only has half the vertical resolution, which I think it 
must have or you can't interlace them, then to create true 50 *frames* per 
second each field needs to be upscaled and the missing lines interpolated 
from the existing ones. If you just construct a frame from the two fields 
you have to repeat that frame or playback at double speed...

I missing something but don't know what.

-- 
Cheers
Dave.



___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

RE: How good is HD supposed to be?

[Christopher Woods]

Vieras are nice. Perhaps your panel is doing frame rate interpolation, 
where it upconverts low frame rate source material to high frame rate for 
display. This is something panels which can operate at higher refresh rates 
offer (100 Hz, 120 Hz, 200 Hz etc).


This is also something I immediately turn off if I'm ever setting up a 
screen, because it makes everything look like a soap opera and annoys me 
after a while (unless it's true high frame rate source material, like The 
Hobbit HFR).


Check in your options for something like 'True Motion', 'Cinema Smoother', 
Motion Estimation / Motion Compensation... And turn it off. Manufacturers 
call it various nonsense marketing names including 'Truemotion Plus', 'Auto 
Motion Plus', 'ClearFrame' etc. Essentially it's pulldown, and it's not the 
original picture, and I don't like it. ;)


Often the chipset doesn't get it quite right, or it gets confused with 
picture content, and you can end up with the option smoothing suddenly 
stopping - or kicking in - midway through a camera pan or actor moving 
slowly in a scene, which is incredibly jarring.


Also (depending on your panel options) set local dimming off, turn 
brightness down to about halfway, turn contrast to about 3/4 and set your 
colour balance or screen temperature to 'warm' or 'warm 1' (usually much 
closer to the calibrated D65 reference white used in broadcast). Almost 
every TV I've ever seen is FAR too blue out of the box on its defaults. Set 
Sharpness to as low as possible, on almost all screens this is ADDITIONAL 
sharpness and makes everything look foul. Your eyes will thank you!


Cheers
Chris


On 30 April 2016 2:23:40 p.m. "Simon Morgan" <s.mor...@skm.org.uk> wrote:


Thanks for your helpful explanation. Demystified a few points for me. I have
a new Panasonic Viera (is this "high end"?) and I find the 25fps from my GiP
downloads more than adequate - perhaps because I know no better!
RGds
Simon Morgan

-Original Message-
From: get_iplayer [mailto:get_iplayer-boun...@lists.infradead.org] On Behalf
Of Christopher Woods
Sent: 29 April 2016 20:42
To: Dave Lambley; Dave Liquorice
Cc: Get_iplayer List
Subject: Re: How good is HD supposed to be?

"Upscaling" is a misnomer in this context. That implies a change of picture
resolution, when there's no resizing going on. What iPlayer does for the 50p
streams is double frame rate deinterlacing, using what looks like a bob
deinterlace technique.

If you watch content originated in 25i, you will (once the stream steps up
to 720p50) see the deinterlaced 50p content and you'll notice immediately
how fluidic motion is - "just like TV", because that's exactly what CRTs
used to do.

25 interlaced frames per second yields 50 interlaced fields per second (due
to odd and even line scanning), with the resultant persistence of vision
effect inducing a pseudo 50 frames per second on viewing as each field's
worth of capture by the camera sensor 'sees' a slightly different point in
time. This renders as smoother motion, with a slight loss of sharpness due
to the low overall temporal resolution, but as it overall appears more
lifelike the eye prefers it.

25psf (progressive segmented frames) is the "filmic" look, where there's
only 25 distinct 'captures' of motion per second; the video simply
'transported' as interlaced. Each field 'sees' its half of the same source
frame. When decoded properly, you get 100% progressive output. However as
this gives you half the temporal resolution, motion is visibly less fluid.

Modern flat panels all deinterlace all interlaced source material to display
a progressive image, but only the higher end panels do quality deinterlacing
(Yadif or similar) Cheaper screens will usually bob deinterlace
(computationally less demanding) and porbably convert to 60p as their panels
and processing will be running internally at 60Hz.

You can even spot some cheap screens doing this as they'll add or duplicate
frames periodically to equal 60 fps from 50 fps source material, or they'll
do weird interpolation which can result in jumpy credits or news ticker
scrolling artifacts.

For an example of 720p50 iPlayer content, watch any episode of EastEnders
(be sure to enable HD), full screen it and wait for the bandwidth to step up
to max - you'll need 5 megabits per second minimum to stream (... Or just dl
it with gip).

For an example of progressive scan material, just about any documentary
(e.g. Horizon) or episode of Click will do. The latest Horizon about dating
is 25 PsF: you can see the deinterlacing 'interline twitter' on high
contrast edges during the programme - an example being the leaves of the pot
plant moving on the windowsill at around 22 minute mark.


On 29 April 2016 12:44:31 p.m. Dave Lambley <d...@lambley.me.uk> wrote:


On 29 April 2016 at 00:57, Dave Liquorice <allso...@howhill.com> wrote:

On Thu, 28 Apr 2016 07:07:33 -0500, artisticforge . wrote:

RE: How good is HD supposed to be?

[Simon Morgan]

Thanks for your helpful explanation. Demystified a few points for me. I have
a new Panasonic Viera (is this "high end"?) and I find the 25fps from my GiP
downloads more than adequate - perhaps because I know no better!
RGds
Simon Morgan

-Original Message-
From: get_iplayer [mailto:get_iplayer-boun...@lists.infradead.org] On Behalf
Of Christopher Woods
Sent: 29 April 2016 20:42
To: Dave Lambley; Dave Liquorice
Cc: Get_iplayer List
Subject: Re: How good is HD supposed to be?

"Upscaling" is a misnomer in this context. That implies a change of picture
resolution, when there's no resizing going on. What iPlayer does for the 50p
streams is double frame rate deinterlacing, using what looks like a bob
deinterlace technique.

If you watch content originated in 25i, you will (once the stream steps up
to 720p50) see the deinterlaced 50p content and you'll notice immediately
how fluidic motion is - "just like TV", because that's exactly what CRTs
used to do.

25 interlaced frames per second yields 50 interlaced fields per second (due
to odd and even line scanning), with the resultant persistence of vision
effect inducing a pseudo 50 frames per second on viewing as each field's
worth of capture by the camera sensor 'sees' a slightly different point in
time. This renders as smoother motion, with a slight loss of sharpness due
to the low overall temporal resolution, but as it overall appears more
lifelike the eye prefers it.

25psf (progressive segmented frames) is the "filmic" look, where there's
only 25 distinct 'captures' of motion per second; the video simply
'transported' as interlaced. Each field 'sees' its half of the same source
frame. When decoded properly, you get 100% progressive output. However as
this gives you half the temporal resolution, motion is visibly less fluid.

Modern flat panels all deinterlace all interlaced source material to display
a progressive image, but only the higher end panels do quality deinterlacing
(Yadif or similar) Cheaper screens will usually bob deinterlace
(computationally less demanding) and porbably convert to 60p as their panels
and processing will be running internally at 60Hz.

You can even spot some cheap screens doing this as they'll add or duplicate
frames periodically to equal 60 fps from 50 fps source material, or they'll
do weird interpolation which can result in jumpy credits or news ticker
scrolling artifacts.

For an example of 720p50 iPlayer content, watch any episode of EastEnders
(be sure to enable HD), full screen it and wait for the bandwidth to step up
to max - you'll need 5 megabits per second minimum to stream (... Or just dl
it with gip).

For an example of progressive scan material, just about any documentary
(e.g. Horizon) or episode of Click will do. The latest Horizon about dating
is 25 PsF: you can see the deinterlacing 'interline twitter' on high
contrast edges during the programme - an example being the leaves of the pot
plant moving on the windowsill at around 22 minute mark.


On 29 April 2016 12:44:31 p.m. Dave Lambley <d...@lambley.me.uk> wrote:

> On 29 April 2016 at 00:57, Dave Liquorice <allso...@howhill.com> wrote:
>> On Thu, 28 Apr 2016 07:07:33 -0500, artisticforge . wrote:
>>
>>
>>>>> NB hvfhd DOES NOT OFFER HIGHER RESOLUTION (CLARITY), only doubled 
>>>>> framerate (25FPS x2), which results in smoother scenes where 
>>>>> motion is involved!
>>>>
>>>> How does repeating frames improve smoothness of movement? Or does 
>>>> this encode upscale each field(*) and encode that to increase the 
>>>> temporal resolution?
>>>
>>> It is the frames per second that provide the human eye with the 
>>> persistence of vision, the illusion of motion.
>>
>> I could show you 100 fps but if there where only 4 different images 
>> displayed the illusion of motion would be no smoother than 25 fps. 
>> You only get smoother movement by increasing the number of different 
>> images displayed.
>>
>> So if this hvfhd only repeats each frame to get a higher frame there 
>> is no increase in smoothness. How ever if they take each field, 
>> upscale it and encode as a frame that would inrease the smoothness.
>
> I believe the frame repeating idea is a red herring. Real 50 frame/s 
> computer video is a thing which exists. If your browser's up to it you 
> can see for yourself here, https://www.youtube.com/watch?v=PmNapQdWFKg
>
> You'll need to choose one of the "p50" resolutions on the Quality menu.
>
> Dave
>
> ___
> get_iplayer mailing list
> get_iplayer@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/get_iplayer



___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer


___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

Re: How good is HD supposed to be?

[Christopher Woods]

"Upscaling" is a misnomer in this context. That implies a change of picture 
resolution, when there's no resizing going on. What iPlayer does for the 
50p streams is double frame rate deinterlacing, using what looks like a bob 
deinterlace technique.


If you watch content originated in 25i, you will (once the stream steps up 
to 720p50) see the deinterlaced 50p content and you'll notice immediately 
how fluidic motion is - "just like TV", because that's exactly what CRTs 
used to do.


25 interlaced frames per second yields 50 interlaced fields per second (due 
to odd and even line scanning), with the resultant persistence of vision 
effect inducing a pseudo 50 frames per second on viewing as each field's 
worth of capture by the camera sensor 'sees' a slightly different point in 
time. This renders as smoother motion, with a slight loss of sharpness due 
to the low overall temporal resolution, but as it overall appears more 
lifelike the eye prefers it.


25psf (progressive segmented frames) is the "filmic" look, where there's 
only 25 distinct 'captures' of motion per second; the video simply 
'transported' as interlaced. Each field 'sees' its half of the same source 
frame. When decoded properly, you get 100% progressive output. However as 
this gives you half the temporal resolution, motion is visibly less fluid.


Modern flat panels all deinterlace all interlaced source material to 
display a progressive image, but only the higher end panels do quality 
deinterlacing (Yadif or similar) Cheaper screens will usually bob 
deinterlace (computationally less demanding) and porbably convert to 60p as 
their panels and processing will be running internally at 60Hz.


You can even spot some cheap screens doing this as they'll add or duplicate 
frames periodically to equal 60 fps from 50 fps source material, or they'll 
do weird interpolation which can result in jumpy credits or news ticker 
scrolling artifacts.


For an example of 720p50 iPlayer content, watch any episode of EastEnders 
(be sure to enable HD), full screen it and wait for the bandwidth to step 
up to max - you'll need 5 megabits per second minimum to stream (... Or 
just dl it with gip).


For an example of progressive scan material, just about any documentary 
(e.g. Horizon) or episode of Click will do. The latest Horizon about dating 
is 25 PsF: you can see the deinterlacing 'interline twitter' on high 
contrast edges during the programme - an example being the leaves of the 
pot plant moving on the windowsill at around 22 minute mark.



On 29 April 2016 12:44:31 p.m. Dave Lambley  wrote:


On 29 April 2016 at 00:57, Dave Liquorice  wrote:

On Thu, 28 Apr 2016 07:07:33 -0500, artisticforge . wrote:



NB hvfhd DOES NOT OFFER HIGHER RESOLUTION (CLARITY), only doubled
framerate (25FPS x2), which results in smoother scenes where motion is
involved!


How does repeating frames improve smoothness of movement? Or does this
encode upscale each field(*) and encode that to increase the temporal
resolution?


It is the frames per second that provide the human eye with the
persistence of vision, the illusion of motion.


I could show you 100 fps but if there where only 4 different images
displayed the illusion of motion would be no smoother than 25 fps. You only
get smoother movement by increasing the number of different images
displayed.

So if this hvfhd only repeats each frame to get a higher frame there is no
increase in smoothness. How ever if they take each field, upscale it and
encode as a frame that would inrease the smoothness.


I believe the frame repeating idea is a red herring. Real 50 frame/s
computer video is a thing which exists. If your browser's up to it you
can see for yourself here,
https://www.youtube.com/watch?v=PmNapQdWFKg

You'll need to choose one of the "p50" resolutions on the Quality menu.

Dave

___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer




___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

Re: How good is HD supposed to be?

[Dave Lambley]

On 29 April 2016 at 00:57, Dave Liquorice  wrote:
> On Thu, 28 Apr 2016 07:07:33 -0500, artisticforge . wrote:
>
>
 NB hvfhd DOES NOT OFFER HIGHER RESOLUTION (CLARITY), only doubled
 framerate (25FPS x2), which results in smoother scenes where motion is
 involved!
>>>
>>> How does repeating frames improve smoothness of movement? Or does this
>>> encode upscale each field(*) and encode that to increase the temporal
>>> resolution?
>>
>> It is the frames per second that provide the human eye with the
>> persistence of vision, the illusion of motion.
>
> I could show you 100 fps but if there where only 4 different images
> displayed the illusion of motion would be no smoother than 25 fps. You only
> get smoother movement by increasing the number of different images
> displayed.
>
> So if this hvfhd only repeats each frame to get a higher frame there is no
> increase in smoothness. How ever if they take each field, upscale it and
> encode as a frame that would inrease the smoothness.

I believe the frame repeating idea is a red herring. Real 50 frame/s
computer video is a thing which exists. If your browser's up to it you
can see for yourself here,
https://www.youtube.com/watch?v=PmNapQdWFKg

You'll need to choose one of the "p50" resolutions on the Quality menu.

Dave

___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

Re: How good is HD supposed to be?

[Dave Liquorice]

On Thu, 28 Apr 2016 07:07:33 -0500, artisticforge . wrote:


>>> NB hvfhd DOES NOT OFFER HIGHER RESOLUTION (CLARITY), only doubled
>>> framerate (25FPS x2), which results in smoother scenes where motion is
>>> involved!
>>
>> How does repeating frames improve smoothness of movement? Or does this
>> encode upscale each field(*) and encode that to increase the temporal
>> resolution?
>
> It is the frames per second that provide the human eye with the 
> persistence of vision, the illusion of motion.

I could show you 100 fps but if there where only 4 different images 
displayed the illusion of motion would be no smoother than 25 fps. You only 
get smoother movement by increasing the number of different images 
displayed.

So if this hvfhd only repeats each frame to get a higher frame there is no 
increase in smoothness. How ever if they take each field, upscale it and 
encode as a frame that would inrease the smoothness.

-- 
Cheers
Dave.



___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

Re: How good is HD supposed to be?

[Dave Lambley]

On 28 April 2016 at 10:41, Dave Liquorice  wrote:
>
> On Thu, 28 Apr 2016 03:08:38 +0300, Vangelis forthnet wrote:
>
> >> In addition a high bit-rate (8000kbps) 1920x1080, interlaced at 25fps,
> >> full HD encode is generated, but has not yet been made available.
> >
> > but it has not yet been released publicly...
> > At ca. 8Mps, those will be really huge files!
>
> 3.2 GB/hour roughly. The current 2.5 Mbps (ish) uses about 1 GB/hr.
>
> > NB hvfhd DOES NOT OFFER HIGHER RESOLUTION (CLARITY), only doubled
> > framerate (25FPS x2), which results in smoother scenes where motion is
> > involved!
>
> How does repeating frames improve smoothness of movement? Or does this
> encode upscale each field(*) and encode that to increase the temporal
> resolution?
>
> (*) If good ole 25 frames/50 fields per second has any relevance in the
> digital world.

The BBC could well have non-interlaced 50 frames/s master copies, and
for when they don't there are de-interlacing algorithms which can give
smooth 50 fields/s output from interlaced 25 frames/s video. (I
believe MPlayer has some.)

Dave

___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

Re: How good is HD supposed to be?

[artisticforge .]

hello

the human eye is still not digital, give them time. By not being
digital the idea
of frames per second still holds. It is the frames per second that
provide the human
eye with the persistence of vision, the illusion of motion.



On Thu, Apr 28, 2016 at 4:41 AM, Dave Liquorice  wrote:
> On Thu, 28 Apr 2016 03:08:38 +0300, Vangelis forthnet wrote:
>
>>> In addition a high bit-rate (8000kbps) 1920x1080, interlaced at 25fps,
>>> full HD encode is generated, but has not yet been made available.
>>
>> but it has not yet been released publicly...
>> At ca. 8Mps, those will be really huge files!
>
> 3.2 GB/hour roughly. The current 2.5 Mbps (ish) uses about 1 GB/hr.
>
>> NB hvfhd DOES NOT OFFER HIGHER RESOLUTION (CLARITY), only doubled
>> framerate (25FPS x2), which results in smoother scenes where motion is
>> involved!
>
> How does repeating frames improve smoothness of movement? Or does this
> encode upscale each field(*) and encode that to increase the temporal
> resolution?
>
> (*) If good ole 25 frames/50 fields per second has any relevance in the
> digital world.
>
>
> --
> Cheers
> Dave.




-- 
terry l. ridder ><>

___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

Re: How good is HD supposed to be?

[Dave Liquorice]

On Thu, 28 Apr 2016 03:08:38 +0300, Vangelis forthnet wrote:

>> In addition a high bit-rate (8000kbps) 1920x1080, interlaced at 25fps, 
>> full HD encode is generated, but has not yet been made available.
> 
> but it has not yet been released publicly...
> At ca. 8Mps, those will be really huge files!

3.2 GB/hour roughly. The current 2.5 Mbps (ish) uses about 1 GB/hr.

> NB hvfhd DOES NOT OFFER HIGHER RESOLUTION (CLARITY), only doubled 
> framerate (25FPS x2), which results in smoother scenes where motion is 
> involved!

How does repeating frames improve smoothness of movement? Or does this 
encode upscale each field(*) and encode that to increase the temporal 
resolution?

(*) If good ole 25 frames/50 fields per second has any relevance in the 
digital world.


-- 
Cheers
Dave.



___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

Re: How good is HD supposed to be?

[Vangelis forthnet]

On Tue Apr 26 23:11:50 BST 2016, Budge wrote:


Is there any way I can get better resolution?
(snip)
What is the best I can expect using GiP
and do I have it already or not?


... As far as resolution itself goes, 720p
is the best that BBC iPlayer offers currently...
There was some talk last July (2015) in the BBC
R & D blog of a full HD 1920x1080i 25FPS encode,

http://www.bbc.co.uk/rd/blog/2015/07/the-development-of-new-video-factory-profiles-for-bbc-iplayer

A series of new profiles were defined to cover representations for all 
devices.
They range from the low bit-rate (sub 64kbps), 192x108 at 6.25 frames per 
second (fps)

through to a HD 1280x720 50fps encode.
In addition a high bit-rate (8000kbps) 1920x1080, interlaced at 25fps, 
full HD encode is generated,

but has not yet been made available.
It can be enabled for TV devices in the future.


but it has not yet been released publicly...
At ca. 8Mps, those will be really huge files!

With GiP 2.94, flashhd1=hlshd1 is the best resolution/quality
you can get.
You may be interested in a recent list thread started by terry:

http://lists.infradead.org/pipermail/get_iplayer/2016-April/008893.html

notably my post here:

http://lists.infradead.org/pipermail/get_iplayer/2016-April/008899.html

and further down the thread Paul Phillips's reply:

http://lists.infradead.org/pipermail/get_iplayer/2016-April/008903.html

To test hvfhd tvmode (1280x720p, ca. 5Mbps @50FPS)
you'd need GiP 2.95dev and (should you wish for an MP4/MKV end file)
your FFmpeg copy should be >= 2.5
NB hvfhd DOES NOT OFFER HIGHER RESOLUTION (CLARITY),
only doubled framerate (25FPS x2), which results in smoother
scenes where motion is involved!

Best regards,
Vangelis. 



___
get_iplayer mailing list
get_iplayer@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/get_iplayer

Re: How good is HD supposed to be?

[artisticforge .]

hello

I have found that projection television is always disappointing.
part of it is due to the picture your eyes view is a reflection and
not a light beam as from a CRT Television or LCD/LED Television. The
literal physics of the light is different.

The best results for a projection television are using a screen of the
same type used to show home colour slides and home super 8 movies. I
still have my grandfather's home movie projector, home camera &
screen. A friend used the screen to test out his new projector. the
results were far better than when projected unto a bare plaster wall
or large sheet of white muslin.




On Tue, Apr 26, 2016 at 5:11 PM, Budge  wrote:
> I have been downloading using tv prefs flashhd, flashvhigh and when viewed
> on laptop I have always been satisfied with the picture quality.
>
> I have recently purchased a projector and to test network installation I
> tried projecting a downloaded programme; with rather disappointing results.
> Picture was dimmer than expected with vertical scan lines visible.  (Not yet
> tried Bluray which will be normal source but not set up yet on lan)
>
> Meanwhile Mediainfo gives the following on the file I used:-
>
> General
> Complete name:
> /home/alastair/mastermedia/Videos/The_Night_Manager/The_Night_Manager_-_1._Episode_1_p03g14d5_default.mp4
> Format   : MPEG-4
> Format profile   : Base Media
> Codec ID : isom
> File size: 990 MiB
> Duration : 57mn 30s
> Overall bit rate mode: Variable
> Overall bit rate : 2 406 Kbps
> Season   : 1
> Movie name   : The Night Manager
> Album: The Night Manager
> Album/Performer  : BBC TV
> Part : 1
> Part/Position: 1
> Track name/Position  : 1
> Grouping : Drama,Thriller
> Performer: BBC One
> Composer : BBC iPlayer
> Genre: Drama
> ContentType  : TV Show
> Description  : Hotel night manager Jonathan Pine
> is drawn into the world of arms dealer Richard Roper.
> Recorded date: UTC 2016-02-21 21:00:00
> Tagged date  : UTC 2016-02-22 18:32:55
> Writing application  : Lavf56.40.101
> Copyright: 2016 British Broadcasting
> Corporation, all rights reserved
> Cover: Yes
> Lyrics   : Hotel night manager Jonathan Pine
> receives a plea for help from a well-connected guest. His actions draw him
> into the world of Richard Roper, a businessman and arms dealer. /  / EPISODE
> / http://www.bbc.co.uk/iplayer/episode/p03g14d5 /  / SERIES /
> http://www.bbc.co.uk/programmes/p03g13rt
> Comment  : Hotel night manager Jonathan Pine
> is drawn into the world of arms dealer Richard Roper.
> Part_ID  : s01e01
> TVNetworkName: BBC One
>
> Video
> ID   : 1
> Format   : AVC
> Format/Info  : Advanced Video Codec
> Format profile   : High@L4.1
> Format settings, CABAC   : Yes
> Format settings, ReFrames: 2 frames
> Codec ID : avc1
> Codec ID/Info: Advanced Video Coding
> Duration : 57mn 30s
> Bit rate mode: Variable
> Bit rate : 2 307 Kbps
> Maximum bit rate : 3 500 Kbps
> Width: 1 280 pixels
> Height   : 720 pixels
> Display aspect ratio : 16:9
> Frame rate mode  : Constant
> Frame rate   : 25.000 fps
> Color space  : YUV
> Chroma subsampling   : 4:2:0
> Bit depth: 8 bits
> Scan type: Progressive
> Bits/(Pixel*Frame)   : 0.100
> Stream size  : 949 MiB (96%)
>
> Audio
> ID   : 2
> Format   : AAC
> Format/Info  : Advanced Audio Codec
> Format profile   : LC
> Codec ID : 40
>