Research & Development 1 High Frame Rate Television Mike Armstrong, Steve Jolly, Richard Salmon BBC...

Research & Development 1

High Frame Rate Television

Mike Armstrong, Steve Jolly, Richard Salmon

BBC R&D

HPA Technical Retreat18 February 2009


Standard frame/field rates

• TV frame/field rates were chosen over 70 years ago.



• TV frame/field rates were chosen over 70 years ago.

• They were chosen to:– exceed the threshold for apparent motion

– avoid visible flicker (on small screens)

– avoid interaction with the mains frequency

– provide a way of showing cinema film



• Current 50/60Hz TV was a match to– standard definition pictures

– and smaller CRT displays



• Current 50/60Hz TV was a match to– standard definition pictures

– and smaller CRT displays

• Problems arise with– larger displays

– increased picture resolution

– sample-and-hold display technology


Loss of detail on moving objects


Motion Portrayal at 50/60Hz

• The portrayal of motion is a trade off between– motion blur (long shutter)

– temporal aliasing (short shutter), leading to jerky motion and spoked wheels running backwards


Motion Portrayal

We need the ball to remain looking like a ball as it moves, without using excessive camera shuttering


Dynamic Resolution at 50/60Hz

• When the camera pans the entire High Definition scene becomes blurred - for example when following the action during a football match


Dynamic Resolution at 50/60Hz

• When the camera pans the entire High Definition scene becomes blurred - for example when following the action during a football match

• As you increase the resolution so the rate of panning has to be reduced to keep the blurring under control


Dynamic Resolution

The dynamic resolution of HDTV is no better than SD


Impact on the Viewer

• Where there is a large difference between the resolution of a static and dynamic picture, this can lead to a feeling of nausea


Impact on the Viewer

• Where there is a large difference between the resolution of a static and dynamic picture, this can lead to a feeling of nausea

• Therefore the higher the static resolution, the higher the dynamic resolution must be for comfortable & lifelike images


Up-converting Displays

• 100/120Hz LCD TVs are becoming common, and 180/200/240Hz models are now being exhibited– These put 50/60Hz signals on the screen

interpolated to higher rates, so solving the problems of flicker and display smearing

– they create intermediate pictures using motion prediction

– it is done to mitigate the problems of sample-and-hold displays



• But this is not High Frame Rate TV– Cannot reduce motion blur captured in camera– Cannot predict complex motion



• But this is not High Frame Rate TV– Cannot reduce motion blur captured in camera– Cannot predict complex motion

• To make motion rendition more lifelike we need higher frame rates – in the camera– for distribution– and in the display.


Higher Frame Rates

• We would suggest that:– if SD is acceptable at 50Hz– then full HDTV needs 150Hz– as resolution increases, we probably want at

least 300Hz


Higher Frame Rates

• We would suggest that:– if SD is acceptable at 50Hz– then full HDTV needs 150Hz– as resolution increases, we probably want at

least 300Hz

• 300Hz is easy to convert to 50 or 60Hz and is compatible with mains frequencies


Potential HFR Issues

• Higher data rates means:– increased storage requirements

– increased bandwidth

• Shorter exposure for each frame

• Interaction with AC lighting

• Loss of “film-look”?


HFR Data Rates

• HFR video should be easier to compress– smaller changes between each picture

– each frame is sharper making the motion is easier to predict

– less temporal aliasing

– could make use of three-dimensional transforms in video compression


HFR and Video Noise

• Shorter exposure times lead to higher noise levels but– gives a clearer separation between image

motion and video noise enabling more effective noise removal

– and at higher display rates random noise is far less visible, c.f. DLP and plasma displays


HFR and lighting

• AC lighting will lead to changes in illumination between pictures– this may make compression more difficult– but will not be noticeable when displayed– use multiple of mains frequency to avoid beating


HFR and lighting

• AC lighting will lead to changes in illumination between pictures– this may make compression more difficult– but will not be noticeable when displayed– use multiple of mains frequency to avoid beating

• It is simpler to filter out temporal lighting problems and flash photography


HFR film-look and other possibilities

• With a higher frame rate shoot you can change the temporal characteristics of the video in post, for example:– add film-look later

– add film-look to only part of the picture

– develop a new range of motion characteristics


HFR Production

• High Frame rate production also gives the possibility of creating higher quality standard rate productions– 300Hz production can be converted equally well

for 50 and 60Hz TV– Better temporal down-sampling can be used to

minimise aliasing and give range of motion portrayal

– a greater range of motion FX can be applied


Demonstration of High Frame Rate TV• At IBC, on the EBU Village

– Video shot 1920 x 1080 at 300fps down converted to display at 1400 x 788 100fps


Demonstration of High Frame Rate TV

50 fps

300 fps


HFR - Further Work

• To understand how well HFR video compresses


HFR - Further Work


• To understand how visibility of noise decreases vs increase in noise with loss of sensitivity


HFR - Further Work



• To understand what bit depth is required as frame rate increases


HFR - Further Work



• To understand what bit depth is required as frame rate increases

• Compromise to choose the optimum frame for a given resolution


HFR Conclusion

• Increasing the static resolution without improving the frame rate makes the TV system less and less suitable for moving pictures


HFR Conclusion

• Increasing the static resolution without improving the frame rate makes the TV system less and less suitable for moving pictures

• We assert that increasing the frame rate for capture and display of television pictures produces a very significant improvement in video quality

Research & Development

Thank you

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