Roku Developer Program

[RokuJoel]

"EnTerr" wrote:
How much is the refresh rate of Roku though?

The max frame rate is 60 fps and is tied to the vsync of the monitor, so, in UK probably 50fps

- Joel

[EnTerr]

"RokuJoel" wrote:

"EnTerr" wrote:
How much is the refresh rate of Roku though?

The max frame rate is 60 fps and is tied to the vsync of the monitor, so, in UK probably 50fps

Does this mean if i use roScreen with Roku in HDTV mode, i am guaranteed to get either 50Hz or 60Hz?
Any idea where i can read more on this (re Roku choosing output refresh rate)?

[TheEndless]

"EnTerr" wrote:

"RokuJoel" wrote:

"EnTerr" wrote:
How much is the refresh rate of Roku though?

The max frame rate is 60 fps and is tied to the vsync of the monitor, so, in UK probably 50fps

Does this mean if i use roScreen with Roku in HDTV mode, i am guaranteed to get either 50Hz or 60Hz?
Any idea where i can read more on this (re Roku choosing output refresh rate)?

It's not entirely clear what you're asking, but the framerate for roScreen is heavily dependent on what your code needs to do. The max you'll get is 60 fps, but if you're drawing a lot to the screen (particularly text), and doing other processing at the same time, then your framerate is going to suffer. It's much easier to achieve ~60 fps on the Roku 3 than it is on the lower and older models. I believe the legacy Rokus (firmware 3.x) max out at 30 fps.

[EnTerr]

"TheEndless" wrote:

"EnTerr" wrote:
Does this mean if i use roScreen with Roku in HDTV mode, i am guaranteed to get either 50Hz or 60Hz?
Any idea where i can read more on this (re Roku choosing output refresh rate)?

It's not entirely clear what you're asking, but the framerate for roScreen is heavily dependent on what your code needs to do. The max you'll get is 60 fps, but if you're drawing a lot to the screen (particularly text), and doing other processing at the same time, then your framerate is going to suffer. It's much easier to achieve ~60 fps on the Roku 3 than it is on the lower and older models. I believe the legacy Rokus (firmware 3.x) max out at 30 fps.

You misunderstand.
You are thinking Frame_rate#Video_games, whereas i am talking Frame_rate#Digital_video_and_television

The hardware refresh rate with which Roku outputs to HDTV is likely one of the values here: https://en.wikipedia.org/wiki/Hdtv#Stan ... ield_rates - it happens at pre-determined interval, no matter how fast or slow you draw your images. Say hardware refresh rate were 30Hz (30 frames per second) and you draw at 40fps, then every 4th frame you draw does not make it on screen, giving you fine jerks in the motion.

PS. When talking about playing video, in 3 places wiki docs say that only 23.976 fps or 29.97 fps are supported, which is likely connected to the hardware refresh rate.

[TheEndless]

"EnTerr" wrote:

"TheEndless" wrote:

"EnTerr" wrote:
Does this mean if i use roScreen with Roku in HDTV mode, i am guaranteed to get either 50Hz or 60Hz?
Any idea where i can read more on this (re Roku choosing output refresh rate)?

It's not entirely clear what you're asking, but the framerate for roScreen is heavily dependent on what your code needs to do. The max you'll get is 60 fps, but if you're drawing a lot to the screen (particularly text), and doing other processing at the same time, then your framerate is going to suffer. It's much easier to achieve ~60 fps on the Roku 3 than it is on the lower and older models. I believe the legacy Rokus (firmware 3.x) max out at 30 fps.

You misunderstand.
You are thinking Frame_rate#Video_games, whereas i am talking Frame_rate#Digital_video_and_television

There is the hardware refresh rate with which Roku outputs to HDTV, likely limited to some of the values here: https://en.wikipedia.org/wiki/Hdtv#Stan ... ield_rates . When talking about playing video, in 3 places wiki docs say that only 23.976 fps or 29.97 fps are supported, which is likely relevant and connected to the hardware refresh rate.

But you asked specifically in relation to roScreen, which uses the graphics plane, not the video plane. The refresh rate of the video is completely independent of that of the roScreen (though it's harder to achieve higher framerates with the roScreen when video is playing, presumably due to the video decoder eating up CPU cycles).

[EnTerr]

"TheEndless" wrote:
But you asked specifically in relation to roScreen, which uses the graphics plane, not the video plane. The refresh rate of the video is completely independent of that of the roScreen (though it's harder to achieve higher framerates with the roScreen when video is playing, presumably due to the video decoder eating up CPU cycles).

They cannot be "completely independent". At the end of the day - no matter the conceptual separation to planes - the video processor has to push a new, fully rasterized frame (say 1280×720p) over HDMI - every X ms, on the clock (somewhere in 17-42ms). And if the output video signal rate is not a multiple (1x, 2x) of the video frame rate, ugly things happen. Rate syncing is a huge PITA; e.g. if you have not encountered the term "telecine" before, look it up to see more that one would ever care to know.

ps. i said "roScreen" specifically to narrow the possibilities. I assume that to display 1080p video, Roku switches HDMI output format from 720p to 1080 - and i am not interested in 1080p since i can't use roScreen with 1080.

[TheEndless]

"EnTerr" wrote:

"TheEndless" wrote:
But you asked specifically in relation to roScreen, which uses the graphics plane, not the video plane. The refresh rate of the video is completely independent of that of the roScreen (though it's harder to achieve higher framerates with the roScreen when video is playing, presumably due to the video decoder eating up CPU cycles).

They cannot be "completely independent". At the end of the day - no matter the conceptual separation to planes - the video processor has to push a new, fully rasterized frame (say 1280×720p) over HDMI - every X ms, on the clock (typically 17-42ms). And if the output video signal rate is not a multiple (1x, 2x) of the video frame rate, ugly things happen. Rate syncing is a huge PITA; e.g. if you have not encountered the term "telecine" before, look it up to see more that one would ever care to know.

The output refresh rate is always 60Hz (in the US), regardless of how long it takes you to draw a single roScreen frame.

"EnTerr" wrote:
ps. i said "roScreen" specifically to narrow the possibilities. I assume that to display 1080p video, Roku switches HDMI output format from 720p to 1080 - and i am not interested in 1080p since i can't use roScreen with 1080.

When the Roku is set to 1080p, it always outputs at 1080p (with the exception of legacy 3.x boxes)... it upscales the graphics plane to 1080p. You can do 1080p video with a 720p roScreen, but you're restricted considerably more on graphics memory, which can cause playback errors if you overrun it.

[EnTerr]

"TheEndless" wrote:
The output refresh rate is always 60Hz (in the US), regardless of how long it takes you to draw a single roScreen frame.

How do you know that? You say it with conviction, is there a spec (radical idea) i can find? My censored Sony TV shows resolution but not Hz.

When the Roku is set to 1080p, it always outputs at 1080p (with the exception of legacy 3.x boxes)... it upscales the graphics plane to 1080p. You can do 1080p video with a 720p roScreen, but you're restricted considerably more on graphics memory, which can cause playback errors if you overrun it.

Ha, this caught me by surprise. Did not expect to be able to mix "different resolutions" beyond roScreen scaling. There is lots of buffers being used, one output frame in 1080 is likely about 8MB; doco mentions level 4 of H264, which i see allows 4 reference frames, so that's 40MB before even considering graphics overlay and video stream buffering. This OpenGL stuff must be very good in frame buffer shaking and stirring - will have to read about that - but that will explain why 27xx models are lagging in your tests while having faster CPU - if there is no OpenGL hardware there, it has to be emulated.

[TheEndless]

"EnTerr" wrote:

"TheEndless" wrote:
The output refresh rate is always 60Hz (in the US), regardless of how long it takes you to draw a single roScreen frame.

How do you know that? You say it with conviction, is there a spec (radical idea) i can find? My censored Sony TV shows resolution but not Hz.

Primarily because the video framerate isn't affected when drawing overlays to the roScreen. If you break into the debugger, for instance, video continues to play, while the last frame of your roScreen is also displayed. But also because the monitor I use for development does display the refresh rate, and it's always 60Hz, with or without video playing, even for the SD resolutions.

I'd have sworn they listed that online in the detailed specs on the comparison chart at one time, but I can't find it now.