determining maximum playable fps

[aurgathor]

I have 2 portable devices that are capable of video playback (TomTom GO730 GPS -- 400 MHz ARM, 480x272 display, and Velocity Cruz T301 tablet -- 533 MHz MIPS with a 800x600 display) but have some issues with video, possibly due to a system that wasn't designed for video playback in case of the GPS, and due to the somewhat (?!) underpowered CPU in the T301 tablet.

I converted some DVDs to formats playable on the aforementioned devices while keeping the original frame rate (23.976 fps) and especially in the case of the TomTom, the playback appears to be poor on scenes with lots of quick movements.

I can think of 2 things:
a) frames are being dropped
b) the LCD has a poor response time
How can I determine what is the cause of the poor playback?
Is there an objective way to determine the highest fps a given device can support without dropping frames en masse?

The player for the GPS (Tomplayer) is open source, so *in theory* I could build and instrument my own copy, but I prefer to do something simpler. In case of the T301 which runs Android 2.2, the various video players just provide a shell or wrapper to something called "internal media server" (which seem to be very-very crash prone ) and I don't know if the source for that is available or not, but even if it does, I'd prefer not to go that deep.

TIA

[jagabo]

Unfortunately, the max frame rate will depend on many things including the display size, the video frame size, the codec used, and the settings used in those codecs.

To verify if the LCD response time is a problem you can just encode a small (frame size) video with a lot of motion and simple codec settings that the devices can handle. Create videos at different frame rates and see how they look. But slow LCD response time generally just gives blurry looking video when there's motion.

The refresh rate of the display is a practical limit to the frame rate you want to use. If you watch a 120 Hz video (assuming the player can actually handle 120 Hz video) on a 60 Hz display you'll only see half the frames.

[jman98]

The player for the GPS (Tomplayer) is open source, so *in theory* I could build and instrument my own copy, but I prefer to do something simpler.

Hmm... It would seem to me that if you REALLY had the know how to do that then you would be able to answer your own question. Hint - the source code may tell what's the max it supports. But it seems to me that this is simply a case of you having unrealistic playback expectations + idiot manufacturer knowing that providing a half-assed "feature" like video playback will be a selling point even if it doesn't work very well.

Seriously, if I was buying a GPS about the last thing I would expect out of it is that it would be some kind of excellent portable media player. What video format are you converting to? This seems to be an older single core CPU as far as I can tell so anything above MPEG-2 is likely to be problematic for it. I would expect MPEG-1 to give good results if the device supports it (a quick search was inconclusive on what it supports).

[aurgathor]

Hmm... It would seem to me that if you REALLY had the know how to do that then you would be able to answer your own question. Hint - the source code may tell what's the max it supports.

With one of my previous job title being an 'embedded systems programmer' I think I do have a know-how, but said video player is from a 3rd party not affiliated with TomTom, and based on the developer's response to video encoding questions, most likely he doesn't know the answer, partly because the player supports many TomTom GPS's with slightly different hardware.

But it seems to me that this is simply a case of you having unrealistic playback expectations + idiot manufacturer knowing that providing a half-assed "feature" like video playback will be a selling point even if it doesn't work very well.

I bought said GPS mostly for some of the other features and because it was selling dirt cheap in some places.
And as I already mentioned, the video player is not provided by the manufacturer, and I simply want to know what's the best it can do.

What video format are you converting to? This seems to be an older single core CPU as far as I can tell so anything above MPEG-2 is likely to be problematic for it.

So far I've tried x264 and mpeg4 in avi -- x264 playback is seriously buggy to a point of being unusable, mpeg4 more or less OK, aside from high motion scenes.

[aurgathor]

Unfortunately, the max frame rate will depend on many things including the display size, the video frame size, the codec used, and the settings used in those codecs.

Which codec is likely to require the least amount of CPU for playback?

To verify if the LCD response time is a problem you can just encode a small (frame size) video with a lot of motion and simple codec settings that the devices can handle. Create videos at different frame rates and see how they look. But slow LCD response time generally just gives blurry looking video when there's motion.

Good idea, I'll look into that. That should work on the GPS, but the tablet does auto resize on videos that are smaller than the display.

The refresh rate of the display is a practical limit to the frame rate you want to use. If you watch a 120 Hz video (assuming the player can actually handle 120 Hz video) on a 60 Hz display you'll only see half the frames.

I was hoping that there may be some test videos out there for this.

[jagabo]

Unfortunately, the max frame rate will depend on many things including the display size, the video frame size, the codec used, and the settings used in those codecs.

Which codec is likely to require the least amount of CPU for playback?

MPEG 1 < MPEG 2 < MPEG 4 part 2 (divx/xvid) < MPEG 4 part 10 (h.264)