archos screen Resolution

[wangsiyu]

My 605wifi can only play videos by 720×576 or less ,but I often get some film by800×480 and more,and the machine refuses to play.I think that's not convinient .I hope that Archos can cancel the Restrictions.especially,rmvb is the most important(I'm from China)

[Catsrules]

I have run into that problem as well. it is becasue the archos screen is 800x400 so any thing above that you can't play it.

I think the new Archos 5 and 7 thye have fixed that problem

[wangsiyu]

In fact,it is not linked with screen.To fix the problem,Archos should make a HD plus-in,like that on Archos 5.Because the chip in 605 supports 1280*720.

[cosmicnut]

The problem is the screen itself can't support resoultions that high. It will also take too much CPU power to re-size them for the smaller screen.

[Pete_S]

But the Archos screen is 800x480 (not 400), so it shouldn't have to resize a 800x480 video.

[Catsrules]

Opps sorry about that.

[wangsiyu]

(First,I declare that it's a debate not an argue.)
What do you think of the problem?Is it linked with the screen?No,it isn't.
You can play a full HD video on you PC,although you PC screen resolution isn't as high as 1920×1080.In other word,the video resolution is over that on the screen,but It can be Played.And Archos 5,its screen resolution is also 800×480,it can paly HD videos(with HiDef Plug-in).How do you explain it?
Let me tell you the truth.As long as the CPU supporting HD,your PMP is able to play.But Archos placed a restricting on image size with his software.In fact,this is a software problem,not a hardware problem.As long as Archos issues a HD Plug-in,we can play These videos over 720×576(DVDdefinition).
Maybe you don't think word said by a Chinese is authentic,but I assert my opinion to be ture.

[cosmicnut]

OK, here we go.

PC's are POWERFUL!!!!!!!!!!!!!!!!!!
They usually have video accelerated by expensive video cards as well.

HD has a very high data rate, SD DVD's have a bitrate of 1000kps or 1mpbs. Blueray has 11Mbps!!!!!

What does this mean...

Well the archos has a lot of data to go through. The larger the resolution, the higher the bitrate. If you can push that data straight to the screen, without modifing it, then it will work fine. If you have to resize it, the the processor on the archos will have to transcode each frame (in between frames as well as keyframes). If the bit rate is high, like in a HD movie, this will KILL the processor and result in a very glitchy experience.

How can the Archos 5 do it? Look at the specs, one of the main things they point out is a FASTER PROCESSOR

at the end of the day its really the bitrate thats the problem. They stopped you using files larger than the actual screen resolution on the 605 as they are more likey to have too higher bit rate for the device. You could encode a 1080 HD move at 1000kbps but you would loose so much picture quality it would be rediculous. Then the 605 would have to resize it, further reducing the quality.

There was a rumoured 720 HD plugin for the 605 but it was never relased. Probably because the CPU couldn't handle the resize

[kb]

I doubt that the CPU is used for image scaling. It certainly isn't in the earlier models. I think that images are decoded onto a virtual framebuffer of the same size as the image (that isn't done by the CPU, either, so far as I can tell), and that is pushed to a hardware image scaler. Image scaling of the type that Archos uses -- I think it's just column/line removal -- is not computationally expensive, even if it is done on the CPU.

I suspect that the problem is more likely with the DSP routine they run for video decoding. If I had to bet money, I would bet that Archos have bought DSP code that has a limited image size (perhaps because of memory limitations). It might be the bandwidth that creates the limitation, but it seems to me that a larger image doesn't necessarily equate to a higher bandwidth (although I agree that it often does work out that way).

[wangsiyu]

Dear Cosmicnut,I agree with you on some of you opinion.I think maybe the number you said aren't right.The DVD bitrate is about 8Mbps(I sure)and blueray is maybe 100Mbps(I guess).There're few rmvb videos that have a bitrate over 1.5Mbps (including ones by 960├ù540)and an avi one over 3Mbps.But Archos 605 supports bitrate of 10Mbps!I think for the machine,it's not necessary to support such high bitrate but not to do on resolution.And about another topic of resize,I think it do need more CPU resource to resize the image,but not much.To play a 720├ù576 video,the image must be resized(576>480).Is there any problem?And you could learn a Chinese PMP "V3000HD"(about ´┐Ñ550,8GB).It has a very cheap CPU,but it supports 720p Xvid AVI and does well.Compared with TI's Davince chip(used in Archos Gen 5),that chip is ordinary.I'm sure that Davince can does better!
Dear kb,I don't think DSP code result in this problem.iAudio A3 also surpports 720p and the same CPU in.Why don't I choose A3?Because it doesn't support rmvb but Archos 605 does!In fact,except Archos's products,almost all the PMPs with Davince chip allow us to play 720p!

[kb]

Dear kb,I don't think DSP code result in this problem.iAudio A3 also surpports 720p and the same CPU in.Why don't I choose A3?Because it doesn't support rmvb but Archos 605 does!In fact,except Archos's products,almost all the PMPs with Davince chip allow us to play 720p!

I don't know -- I'm merely speculating wildly. DSP code is pretty specialized -- it's not like coding for an ordinary CPU, and I don't think Archos wrote the video decoder implementation for the x05s (and I presume the later model). In fact, I did at one time know where this code came from, but I have forgotten. My speculation is that, because Archos didn't write this code, they will have difficulties getting it enhanced to support higher resolutions (if that is where the problem is). I don't know where Cowon gets its DSP code from -- perhaps they develop it in house?