Displaying 60p fps (frames per second)

[hollowman]

(I'm sure this topic rec'd gotten prev. attn., so apologies in advance for waste of bandwidth; I have admittedly not been exhaustive in my research!)

For PC- (HTPC-)based playing(viewing)/editing, how do I properly configure my Win-7-based system to CORRECTLY display 60p (or even 72p) fps? I use a fairly high-quality LCD monitor, which can handle high refresh rates (tho' I've heard this is not really related to high-frame-rate displaying).

I'm not interested in high-frame-rate for video games; rather using one of the better HD camcorders to display 60p fps (which model does this best?) to achieve Showscan-like results

Resources:
http://www.100fps.com/frame_interlacing_is_not_display_interlacing.htm

[jagabo]

For smoothest playback you want to set your graphics card to an integer multiple of the videos frame rate. Set your graphics card to 60 Hz output for 30 or 60 Hz sources, 72 Hz output for 24 or 72 Hz sources (where are you getting 72 Hz video files?), 50 or 75 Hz for 25 Hz sources, etc.

You also need to be sure you have a CPU that can play your sources fast enough (1080p60 and 720p60 is too strenuous for older processors) or use a graphics card that supports hardware decoding (h.264, MPEG2, WMV) at those rates. Very few camcorders capture 1080p60.

[hollowman]

For smoothest playback you want to set your graphics card to an integer multiple of the videos frame rate. Set your graphics card to 60 Hz output for 30 or 60 Hz sources, 72 Hz output for 24 or 72 Hz sources (where are you getting 72 Hz video files?), 50 or 75 Hz for 25 Hz sources, etc.

You also need to be sure you have a CPU that can play your sources fast enough (1080p60 and 720p60 is too strenuous for older processors) or use a graphics card that supports hardware decoding (h.264, MPEG2, WMV) at those rates. Very few camcorders capture 1080p60.

Thx for the feedback!
Some of my PCs are older, and you're right about the CPU (even with newer/faster video-cards). But I have a 6-month-old mid-range Dell laptop which can display properly.
Not 72hz but 72p (it is hyperlinked in the OP, and you can read more on it as necessary.) Also, you seem to be confusing refresh rates for frame rates, which are not the same thing (on that issue, I have some links in the OP)
I'm also not sure about your comment "Very few camcorders capture 1080p60." Even very basic/inexpensive modern units can do 720p60. And the Panasonic HDC-TM700 ($900) can do 1080p60.

[jagabo]

Not 72hz but 72p

It's the same thing.

Also, you seem to be confusing refresh rates for frame rates, which are not the same thing

Not at all. To display a 60p video as 60p you need to have your monitor set to 60 Hz refresh, or an integer multiple thereof. To display 24p video smoothly have have to have your monitor's refresh rate set to an integer multiple of 24 Hz. At 60 Hz the 24p video will be displayed alternately for 2 and 3 times (2/60 second and 3/60 second), leading to judder. At 72 Hz each frame is displayed 3 times (3/72 second) eliminating the judder.

I'm also not sure about your comment "Very few camcorders capture 1080p60." Even very basic/inexpensive modern units can do 720p60.

720p60 is not 1080p60.

And the Panasonic HDC-TM700 ($900) can do 1080p60.

I didn't say NO camcorders shoot 1080p60. I said very few. The Flip Mino can also shoot 1080p60.

[hollowman]

To display a 60p video as 60p you need to have your monitor set to 60 Hz refresh, or an integer multiple thereof. To display 24p video smoothly have have to have your monitor's refresh rate set to an integer multiple of 24 Hz. At 60 Hz the 24p video will be displayed alternately for 2 and 3 times (2/60 second and 3/60 second), leading to judder. At 72 Hz each frame is displayed 3 times (3/72 second) eliminating the judder.

Doesn't the player (software or hardware) and/or operating system automagically optimize the display (e.g., monitor) for the best rate/ratio based on source's native FR?

[jagabo]

Doesn't the player (software or hardware) and/or operating system automagically optimize the display (e.g., monitor) for the best rate/ratio based on source's native FR?

Most players don't.

[edDV]

Most AVCHD/HDV camcorders shoot 1080i/29.97 (aka 60i) or 1280x720/29.97 (aka 30p). In both cases the software player needs to convert to 59.94 LCD display. Many display drivers allow refresh choices of 59 or 60 Hz. Use 59Hz (actually 59.94).

Conversion consists of a smart bob deinterlace for 1080i to 1080p or a frame doubling for 720p/29.97 to720p/59.94.

Some prosumer camcorder models shoot 1080p/59.94 or 720p/59.94 which need no conversion.

Some camcorders shoot 23.976p. In that cast the player must frame repeat in a 2323 pattern to 59.94.

[jagabo]

Oh, sorry, it's not the Flip Mino (~US100) that shoots 1080p60. It's some of the Sanyo Xacti line. Like the FH1 and HD2000 (~US$500).

[hollowman]

I think the "best" refresh rate may be 120Hz, as it is an even multiple of both 30 fps and 24 fps. Also, and only if your monitor/video-card/electronics/firmware can handle it (i.e., all else held equal), it is less "flickery" due to higher freq.

[edDV]

I think the "best" refresh rate may be 120Hz, as it is an even multiple of both 30 fps and 24 fps. Also, and only if your monitor/video-card/electronics/firmware can handle it (i.e., all else held equal), it is less "flickery" due to higher freq.

Yes but you were talking about a computer monitor. Better to use an HDTV for video.

[jagabo]

At 120 Hz he'll still wont get perfect playback of PAL sources. Though I doubt most people could tell the difference with most material.

[hollowman]

I think the "best" refresh rate may be 120Hz, as it is an even multiple of both 30 fps and 24 fps. Also, and only if your monitor/video-card/electronics/firmware can handle it (i.e., all else held equal), it is less "flickery" due to higher freq.

Yes but you were talking about a computer monitor. Better to use an HDTV for video.

edDV: confused ... HD DTV is digital; so, in my albeit limited-experience-based-not-so-humble opinion, playback on PC monitor or a late-model "home-theater TV" should be almost processless and, hence, virtually indistinguishable... correct?

;At 120 Hz he'll still wont get perfect playback of PAL sources. Though I doubt most people could tell the difference with most material.

I am your avg. United States of American, for whom the rest of world doesn't exist. And if my attitude upsets you, tell it to our well-fed military. Their upcoming motto will be "Region 1, baby ... or F U" . LOL!!!

[jagabo]

I live in the USA and watch PAL video quite often.

[edDV]

I think the "best" refresh rate may be 120Hz, as it is an even multiple of both 30 fps and 24 fps. Also, and only if your monitor/video-card/electronics/firmware can handle it (i.e., all else held equal), it is less "flickery" due to higher freq.

Yes but you were talking about a computer monitor. Better to use an HDTV for video.

edDV: confused ... HD DTV is digital; so, in my albeit limited-experience-based-not-so-humble opinion, playback on PC monitor or a late-model "home-theater TV" should be almost processless and, hence, virtually indistinguishable... correct?

Incorrect. Frame rate and refresh issues are similar for analog or digital display. The main differences are in display technology e.g. CRT, LCD, Plasma, DLP, etc.

So you don't deal with PAL so we'll leave that part off.

Analog CRT monitors can be run at a wide range of refresh rates and frame sizes. Remember multi-scan? Digital displays tend to optimize at a specific native frame size (e.g. 1920x1080) and are often fixed to a specific refresh rate (e.g. 59.94, 60, 119.88 and other multiples of 59.94).

I think you said you are watching an LCD computer monitor so I will only compare that to a "120Hz" HDTV. LCD computer monitors usually give the option of 60Hz or 59.94Hz refresh. Since NTSC/ASTC video is based on 29.97 or 59.94 frame rates, it makes sense to run the monitor at 59.94.

Issue 1: Interlace vs. Progressive

Most legacy NTSC and digital 480i/1080i ATSC video is interlace at 29.97 fps (59.94 fields per second). LCD monitors are native progressive. Direct display of interlace video on a progressive display will show alternate scan lines at different sample points (offset by 1/59.94 sec) so you get line split during motion. All HDTV sets include smart BOB deinterlacers (quality varies) to convert 59.94 fields per second (half vertical resolution) to 59.94 frames per second (full vertical resolution) to allow progressive LCD display. Computer monitors are dumb displays. Deinterlace is a function of the software video player often working with assist from the display card hardware deinterlacer (quality varies). The player needs to be properly configured to use the display card deinterlacer (e.g. dxva api for Direct Show).

Issue 2: Film rate vs. Video rate.

Most movies are shot at ~24 fps (23.976 if TV display is a goal). Most prime time TV series are also shot at 23.976 fps going back to the 1950's. The remainder (e.g. news, sports, game shows, talk shows, variety) are shot 29.97 fps interlace or 59.94 fps progressive. Traditionally film rate movies and camera elements were telecined to 29.97 fps interlace and edited interlace to a 29.97 fps (480i or 1080i) distribution master. In recent years there has been a slow conversion to 23.976 fps progressive editing and a 23.976 edit master which is then converted to various distribution formats.

Issue 3: Video Player Requirements

A computer video player needs to deal with several video frame rates, telecine, frame size and codec. Typical frame rates (ignoring PAL) are:

- 23.976 progressive (film rate)
- 29.97 interlace (no telecine)
- 29.97 interlace with telecine
- 29.97 progressive (usually from consumer camcorders)
- 59.94 progressive (e.g. direct 720p broadcast)
- 59.94 progressive with 2 3 2 3 frame repeats (film source)

The codec is needed to decode the video to uncompressed. The native frame size is scaled to monitor resolution by the display card in "full screen" or "theater" mode.

Computer video players vary in sophistication when dealing with this variety of input. The poor players will resort to simple resampling with interpolation resulting in spacial and/or motion blur. The better players will optimize to each frame rate, deinterlace or inverse telecine as needed and will closely integrate with the display card hardware.

A classic HDTV limits the input format variety to NTSC/ATSC broadcast standards (all 19 ATSC formats must be supported per FCC mandate) plus DVD. DVD (and consumer camcorders) uses 720x480 for standard def while ATSC uses 704x480.

Modern HDTV sets are adding support for direct 23.976/24 fps Blu-Ray input (no telecine or frame repeats). The TV internally converts to 59.94 or 119.88 display rates. Other HDTV sets are adding support for non-broadcast spec codecs and frame sizes from Ethernet or USB flash drives.

Issue 4: Judder from 23.976 source (or Why 120Hz ?)

Conversion of 23.976 film to interlace 29.97 requires insertion of pad fields to build up the frame rate (aka telecine). This results in judder which is a change in speed for frames with pad fields. Likewise progressive 23.976 to progressive 59.94 conversion requires pad frames in a 2x 3x 2x 3x repeat pattern. This also causes judder.

A 119.88 refresh rate is an exact multiple of 23.976 (5x) , 29.97 (4x)* and 59.94 (2x). Thus display can be achieved by linear frame repeats eliminating judder from film rate source.



* Interlace telecined 29.97 fps source must first be inverse telecined to 23.976p, then frame repeated 5x to 119.88 fps for display. Most HDTV sets offer frame interpolation as an option over simple frame repeat (quality varies). 59.94p film source needs to have the 2x 3x frame repeat pattern to be converted to 5x 5x frame repeat.