N810 as a PMP - Page 2 - maemo.org

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	Karel Jansens	2008-01-16 , 23:18
	Posts: 3,220 \| Thanked: 326 times \| Joined on Oct 2005 @ "Almost there!" (Monte Christo, Count of)	#11

Originally Posted by dubiousmike

To clarify, I was speaking more in terms of pushing the bitrate he mentioned through a portable device.

I don't know, so I'll ask, does the Pepper Pad play an xvid file at 1128 kbps and at the resolution he mentioned without chugging? If so, I'm happy to say I am wrong. But I suspected that his bitrate was too high for most devices that will play xvid files. Thus the need for transcoding.

I have to admit that I'm really confused about the whole kbps thing. Different sources give me different numbers for -- seemingly -- identical files.

So here's the info Windows gave me on a movie:
Evil Dead 3 - Army of Darkness (what can I say, I love pulp)
624x368, audio: MP3, 160kbps, video: DivX, 23fps, data 127kbps, 24 bits (I have no idea what those last two numbers mean, but VirtualDub tells me the "data rate" of the file is 882kbps with 0.52% overhead, and those numbers appear to have absolutely nothing to do with the Windows numbers).

This movie plays flawlessly on my Pad3, no hicking, no jumping no desynching, just Bruce Campbell doing his stuff. May I add that the Pad3 has mplayer as its video player and runs an AMD Geode 800 MHz processor with 256 MB RAM, but it appears Hanbit went through the trouble of actually activating the graphics possibilities of their chip.

About all the bits thing: All my movies are encoded to a size of around 700 MB; this just felt like the best compromise between quality and storage space (meaning that my gellifying eyes can't see much difference between those DivX and Xvid files and the real DVD), so maybe I'm just lucky in that they play on the Pad. In any case, I no longer try to play these un-transcoded files on my Itablet, because it doesn't work. I might as well take a series of stills of the movie and run a slideshow (in fact, that might give even slightly bètter fps results).

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Kong	2008-01-17 , 13:37
Posts: 5 \| Thanked: 0 times \| Joined on Jan 2008	#12

30% hitches.... that doesn't sound very encouraging!

Generally I use VirtualDub in 2-pass mode with XviD. You can use the bitrate calculator in XviD to get whatever file size you want.

More than likely, if you want to pay less that a grand for a device, you may have to re encode. Why you say you "certainly" wouldn't do so doesn't make a lot of sense to me.

I believe the Axim was cheaper than the N810 and it has no problems with these files!

Having to re-encode means having an entire new set of video files just for a device that can't cope. I'm looking to upgrade, not downgrade!

I will encode a short video (say 2 minutes) recorded from TV. Is there somewhere to upload it in this forum?

I don't know, so I'll ask, does the Pepper Pad play an xvid file at 1128 kbps and at the resolution he mentioned without chugging?

It should. The Raon Vega which has the same LX800 CPU and cS5536 companion chip can decode up to 2 Mbps DivX and XviD files according to the UMPCPortal review.

624x368, audio: MP3, 160kbps, video: DivX, 23fps, data 127kbps, 24 bits (I have no idea what those last two numbers mean, but VirtualDub tells me the "data rate" of the file is 882kbps with 0.52% overhead, and those numbers appear to have absolutely nothing to do with the Windows numbers).

I think Windows gives the data rate for the entire file in kilobytes/sec.

VirtualDub breaks it down to video bitrate (in kilobits/sec) and audio bitrate (also in kilobits/sec).

Also is mplayer optimised to run on the OMAP2420? Does it make full use of the hardware video decoding features?

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	GeneralAntilles	2008-01-17 , 13:41
	Posts: 5,478 \| Thanked: 5,222 times \| Joined on Jan 2006 @ St. Petersburg, FL	#13

The issue is not the CPU decoding, it's the low bandwidth to the LCD controller.

Because of this, neither the N810 nor the N800 make really good media players (though I use my N800 as a media player and absolutely love it). Wait for the next generation maemo tablet within the next 6-10 months (probably the N900), as it will most likely be using the new TI OMAP3 CPUs and will be able to decode 720p with ease.

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Tuxedosteve	2008-01-17 , 14:28
Posts: 220 \| Thanked: 11 times \| Joined on Nov 2005	#14

Originally Posted by Karel Jansens

That's -- wrong (I wanted to write another word there, but decided to try politeness for a change). My Pepper Pad3 plays just about any Divx/Xvid video file without transcoding and it certainly doesn't cost a grand in whatever money you've got.

Yeah. I've got a Cowon A2 PMP. It cost me less than £300 and it plays almost any xvid/divx I throw at it (Flac too which is nice). The A3 supports even more formats.

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	Karel Jansens	2008-01-17 , 16:09
	Posts: 3,220 \| Thanked: 326 times \| Joined on Oct 2005 @ "Almost there!" (Monte Christo, Count of)	#15

Originally Posted by Tuxedosteve

Yeah. I've got a Cowon A2 PMP. It cost me less than £300 and it plays almost any xvid/divx I throw at it (Flac too which is nice). The A3 supports even more formats.

But the A2 has "only" a 480x272 screen, while the Pad 3 has the same resolution as the N800 (800x480). Wouldn't that make a difference?

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	dubiousmike	2008-01-17 , 17:28
	Posts: 120 \| Thanked: 16 times \| Joined on Nov 2007 @ NYC	#16

Low res is what killed the ipod touch for me. That and no bluetooth.

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nosam	2008-01-17 , 18:42
Posts: 133 \| Thanked: 8 times \| Joined on Aug 2007 @ SF, CA	#17

I have a 770 (which had decent video abilities) and a Cowon A2. I wanted to use the Nokia 770 to watch videos but the Cowon was so much better. I am not complaining - love my 770, but just want to note that the NITs can't compare to a dedicated PMP such as Archos or Cowon A2. Why? because the image is better (screen just looks better), and for me the ability to zoom in on the fly means I can watch videos larger when some cropping doesn't matter (like in dialog scenes). I was thinking if the OP will mostly be watching videos, he should get a PMP because the experience is much better. (I am not a N810 user, but I believe video on N810 is not that much better that a 770).

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Kong	2008-01-17 , 22:10
Posts: 5 \| Thanked: 0 times \| Joined on Jan 2008	#18

Originally Posted by GeneralAntilles

The issue is not the CPU decoding, it's the low bandwidth to the LCD controller.

Because of this, neither the N810 nor the N800 make really good media players (though I use my N800 as a media player and absolutely love it). Wait for the next generation maemo tablet within the next 6-10 months (probably the N900), as it will most likely be using the new TI OMAP3 CPUs and will be able to decode 720p with ease.

Hmmm.. if it's the low bandwidth to the LCD controller, wouldn't it be dropping frames 100% of the time? Dropping frames in high-motion scenes suggests to me that the CPU or DSP doesn't have the horsepower to decode the MPEG4 video.

Low res is what killed the ipod touch for me. That and no bluetooth.

If the iPod Touch had bluetooth (with DUN), I would buy one in an instant! I'd even overlook its pathetic video support.

Last edited by Kong; 2008-01-18 at 02:25.

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	GeneralAntilles	2008-01-18 , 01:06
	Posts: 5,478 \| Thanked: 5,222 times \| Joined on Jan 2006 @ St. Petersburg, FL	#19

Originally Posted by Kong

Hmmm.. if it's the low bandwidth to the LCD controller, wouldn't it be dropping frames 100% of the time? Dropping frames in high-motion scenes suggests to me that the CPU or DSP doesn't have the horsepower to decode the MPEG4 video.

It's a combination of both, mostly the LCD controller is to blame. The CPU is sometimes the culprit for larger stuff (it plays MPEG4 stuff at 400x240 with a bitrate of about 800-1200Kbps and MP3 audio 100% everytime, so it certainly has the horsepower to decode MPEG4), but the LCD controller is the true bottleneck (as we'd have hardware video decoding from the OMAP2420 if we could use the built-in decoder).

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Kong	2008-01-18 , 02:52
Posts: 5 \| Thanked: 0 times \| Joined on Jan 2008	#20

it plays MPEG4 stuff at 400x240 with a bitrate of about 800-1200Kbps and MP3 audio 100% everytime, so it certainly has the horsepower to decode MPEG4

Actually this strengthens my views that it is the CPU/DSP to blame. MPEG4-ASP is more CPU intensive to decode when you increase the resolution. Higher bitrates will also increase the CPU processing required but not to the same extent.

When the device plays 400x240 MPEG4 files, wouldn't the CPU/DSP have scaled the video to the LCD's native resolution (800x480) before it gets to the LCD controller? This would mean that the LCD controller wouldn't know the difference between the 400x240 and 800x480 files.

Also I've just tested my Axim X30H and it was able to play a 624x352 file at approximately 126% normal speed using TCPMP. Since the Axim is in theory much faster (although its hard to compare with a different ARM architecture, DSP, OS and player), it seems likely that the N8x0's OMAP2420 is right on the border of being able to play back this file without a hitch.