Author Topic: Dvd Playback On Z? (Read 4003 times)

alee16 · « **on:** June 08, 2006, 11:28:37 am »

Is there a way to make mplayer lower the bitrate of a DVD before it plays it? Some sort of preprocessing filter that would "re-encode" the video to a lower bitrate (making it playable on a Z). I know you can lower the framrerate. I have the external DVD burner hooked up, can mount it, and can make mplayer play from it, but I'm having some problems with the audio: Mplayer gives an error "a52: error resampling". Because the audio isn't working, it's hard to tell if the video is playing at full speed or not (it's dropping quite a few frames). The video plays ok with -framedrop option, but I think it could be better if a sort of "on-the-fly" pre-processing filter would work.

I'd be glad to tell anyone how I got my DVD burner working through USB if there is interest.

DaemonsGR · « **Reply #1 on:** June 08, 2006, 12:03:08 pm »

I think that DVD movies have a minimum of 5Mbits/s transfer rate for the video only! So, you expect to downsample and play a DVD via USB on a Z (Low CPU- Low USB speed!) ??
Im not a Z expert but I think you must be joking!

alee16 · « **Reply #2 on:** June 08, 2006, 01:56:54 pm »

I have a 1450kbit/sec video 224kbit/sec audio DVD playing fine on my Z from the USB 1.1 connection. I tried playing a normal (8000kbit/sec video 256kbit/sec audio) dvd over USB 1.1 on my desktop computer, and it worked fine, so the USB 1.1 isn't a problem. It may be impossible because of the Z's processor and/or video card (or lack of one), but I wouldn't mind trying if I knew how to make Mplayer downsample the bitrate of Audio/Video while it is playing a dvd. I was able to change the audio to 1 channel (mono), but the audio still isn't playing correctly, because liba52 is giving an "error in resampling".

Basically what I was wondering was if instead of having to convert dvds before playing them, you could make mplayer "convert" them to the lower quality while it is playing from the external USB DVD drive. It would be pretty cool, but maybe not possible.

JohnX · « **Reply #3 on:** June 08, 2006, 05:48:52 pm »

If you found someone who got mencoder to compile/run on a Z you could use that to re-encode on the fly. Unfortunately this wouldn't accomplish anything useful in this case. What you're suggesting is:
1) Have mencoder decode the video
2) Have mencoder re-encode the video at a lower bitrate
3) Have mplayer play the resulting stream

As you've already seen, having the Z decode DVD video (even without audio) is not quite possible to do in realtime. Also keep in mind that not only does encoding take lots more processing power than decoding, but it's also much more heavy on floating point usage (the Z doesn't have a floating point unit, thus emulates one ...slowly). I was interested in seeing how much CPU time this takes so I tested it on my desktop (Athlon 64 3000+). I used dvd::rip to decode/re-encode a DVD into an xvid/avi (~800kbit/s bitrate on the video). During the opening title it was pulling off a very repectible ~20fps and I was able to let it sit then start up mplayer and watch the early part of the movie pretty much as it was being encoded. Once it got to scenes with more motion, however, dvd::rip bogged down to 14fps (even without me wasting cycles by watching it with mplayer). I imagine that a Core Duo or Athlon 64 X2 (along with a multithreaded video encoding program) should be able to decode/re-encode/watch a DVD in realtime, possibly with a little CPU time to spare, but I'm pretty sure that something like this is pretty much beyond the Z's processing power.

DaemonsGR · « **Reply #4 on:** June 08, 2006, 05:52:16 pm »

This needs "encoding" all the frames on-the-fly! I think that even a amd64 cant do it!

adf · « **Reply #5 on:** June 08, 2006, 05:55:28 pm »

for about $100 you can get a portable dvd player with a bigger screen than a zaurus that is not too much bigger than the portable drive. ...

alee16 · « **Reply #6 on:** June 08, 2006, 06:26:16 pm »

I was confused about the way mplayer worked from reading the man page. I also figured out that my Z couldn't play the 2000kbits/sec mpegs I had recorded, so it looks like if it were to play DVDs, they would have to be below 1500kbits/sec (basically homemade). Does anyone know the max bitrate for the Z playing mp4 files?

Also, on a second note, can the version of mencoder encode from dvds to mpeg4 on the Z (it would definitely take longer). I tried, but I still get the a52: error in resampling message.

JohnX · « **Reply #7 on:** June 09, 2006, 12:48:14 am »

I've heard reasonable bitrates for playing back mpeg4 on the Zaurus to be somewhere around 500kilobit/s. You might want to search the forums for other people's encoder settings. As for the mplayer/mencoder having problems with a52 audio on the Z, I have no idea. Before you take a lot of time trying to get mencoder re-encoding DVDs on the Zaurus, I think I should point out it will take a *long* time to re-encode video that way. I don't really have any way to measure something like that but if I were to guess I would bet that a Zaurus Cxx00 (one of the one's with a microdrive) would take at a bare minimum 24 hours to do the re-encoding but most likely more like 60+.

alee16 · « **Reply #8 on:** June 09, 2006, 09:43:55 am »

The reason I thought my Z could do these things was that just about a year ago, I still had a Pentium II 266 with 256 mb of ram, and I was burning dvds at 8x while I played video, and it worked just fine. Does anyone know some kind of comparison? Does swap in any way make up for only having 64 mb of ram on the Z? How does the 416mhz ARM compare to a Pentium II 266?

adf · « **Reply #9 on:** June 09, 2006, 11:12:04 am »

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The reason I thought my Z could do these things was that just about a year ago, I still had a Pentium II 266 with 256 mb of ram, and I was burning dvds at 8x while I played video, and it worked just fine. Does anyone know some kind of comparison? Does swap in any way make up for only having 64 mb of ram on the Z? How does the 416mhz ARM compare to a Pentium II 266?
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I think the problem is more with the video processing bottleneck than with the processor. But I'm only guessing.

kahm · « **Reply #10 on:** June 11, 2006, 08:45:42 pm »

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The reason I thought my Z could do these things was that just about a year ago, I still had a Pentium II 266 with 256 mb of ram, and I was burning dvds at 8x while I played video, and it worked just fine. Does anyone know some kind of comparison? Does swap in any way make up for only having 64 mb of ram on the Z? How does the 416mhz ARM compare to a Pentium II 266?
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I think the problem is more with the video processing bottleneck than with the processor. But I'm only guessing.
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Swap does not replace ram. Ever. You use swap so the computer doesn't crash or close programs on you, but that's all it's good for. The performance sucks.

I'd guess that floating point operations on the Z take a ~10x speed hit over your PII-266. Integer operations may be close to par, but the supporting subsystems on the PII (Ram, PCI, AGP, Bus speed, etc) would also be much faster.

On the Z, everything comes down to processor speed. Unlike a larger computer, almost all of the chipset functions and controllers are handled by the CPU, or are built into the CPU itself. On a chip like the StrongARM, that means that it's going to be built for battery life instead of speed.

Video playback on the Z seems to be heavily dependant on the CPU. The best video playback comes from a MMMX (Mobile MMX) enabled kernel and software. On my 3100, I can play 640x480 video encoded in Divx at 850 to 1000 kb/s, with stereo sound @ 192kb/s. I've got a lot of videos I can dump straight on the Z and watch acceptably. The same videos play at about 5-9 frames/s on the 860, which doesn't have the mobile MMX.

alee16 · « **Reply #11 on:** June 11, 2006, 09:44:10 pm »

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Video playback on the Z seems to be heavily dependant on the CPU. The best video playback comes from a MMMX (Mobile MMX) enabled kernel and software. On my 3100, I can play 640x480 video encoded in Divx at 850 to 1000 kb/s, with stereo sound @ 192kb/s. I've got a lot of videos I can dump straight on the Z and watch acceptably. The same videos play at about 5-9 frames/s on the 860, which doesn't have the mobile MMX.
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Wow! Thanks for the information. Now I am beginning to understand the differences. But what's Mobile MMX? I assume my C1000 has it because it should be the same as the 3100, do I need to enable it somehow, or is it already enabled?

Da_Blitz · « **Reply #12 on:** June 11, 2006, 10:53:37 pm »

the c1k has it but you need bvdd and a bvdd mplayer.

dvd is mpeg2 which is supposed to be easier on the cpu to decode however i am not sure if that ment at the same bitrate or in general

mith mplayer you dont need to mount the dvd instead do mplayer dvd:// and let mplayer take care of it as it will autmatically set the dvd player to 1x to keep the noise down

as for rencoding, its pointless as encoding is more cpu intensive than decoding (thats why if you encode you get 20fps but decoding on the same machine mention above with --benchmark to get rid of the decoding throttle you will get 60fps or more)

same thing for resampling, what you want instead is to drop frames with the usual options, disable all postprocessing and turn on low quality decoding (not every decoder ie xvid mp3 divx aac offers this)

alee16 · « **Reply #13 on:** June 15, 2006, 11:42:07 pm »

Ok, so will I get better performance with bvdd-iwmmx installed than with just bvdd?
Also, along the same line, will I get better video performance with mplayer-bvdd-iwmmx?

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Author Topic: Dvd Playback On Z? (Read 4003 times)