Forum > Sony Ericsson / Sony > General > SE K850i 30fps - Inquiry

On 2008-01-13 12:43:58, mib1800 wrote:
K850 video record is not true QVGA 30fps. 30fps is only achieved if the scene is relatively static with little movement. Once there are lots of movement, the framerate drops to 15fps. Kind of cheating when SE labels K850 can do 30fps.

On 2007-10-31 17:44:55, chombos1 wrote:
i know that!!

30fps video is not only determined by the frame count of the video.(for example you can make a 30fps video just by 10 to 20 frames per second but the output is choppy an not smooth moving.)

and the reason the video being at 30fps with 384Kbps is for mpeg4 coding process that is based on the frames pixel changes. when you have 15 frames in a second then it has no differences for the mpeg4 codec wether you video is 30fps or 60fps. both will have the same file size.

and the reason that i asked someone to VISUALLY confirm that is because that 30fps video is quite distinguishable by eye comparing to the choppy 15fps.

record some seconds of video of a moving object like your hand with your K850 and then view on the phone itself.

now is that 30fps or not? (i mean it's smoothness is like the picture you see on the tv screen or not?)?? very simple .... no need to view on a computer.!

thanks

On 2006-10-22 05:53:36, mysh wrote:
hi prom1

if you want to get technical....

24 fps is the standard for film, as it is the lowest you can provide perceptibly -perfect- fluid motion. Film costs money, so they picked the lowest framerate they could get away with, to use less frames, less film.

As you say, TVs are interlaced. In canada i expect it's the same as the US, and you use the NTSC picture format, which is a 60Hz interlaced picture - 30 fps. So far as i'm aware, this isn't for visual reasons, but because north american AC power is provided at 60Hz. In fact due to the higher refresh rate of the picture, the image quality is lower. NTSC has a lower pixel resolution and narrower colour definition...

... Compared to PAL, the UK/European TV picture format, which is 50Hz interlaced, 25 fps (50Hz AC power supply here). It has slightly higher resolution, and better colour reproduction.

Technically speaking, about movies on TVs, movies are bested viewed at 25fps on a PAL TV screen, because they can simply be speeded up by 1 fps and then pitch-shift the soundtrack. When a movie is shown on NTSC TV it has to be telecined quite complexly, using a 3:2 (more recently 2:3) pulldown. This introduces annoying visual problems with some camera motion (bump/skips).

Using 24 fps on the phones is a bit hit-and-miss, it's fine if your source is a 23.976 movie DVD, but for most other content it doesn't match up. So 25fps seemed the better choice. It matches PAL DVD content and an awful lot of decent quality video content on the internet. For video such as NTSC DVDs and a small amount of 30fps internet content, 25fps combined with some frame blending maintains smooth motion on that content too.

I won't go into telecine / inverse-telecine pulldown methods, these are just phones!

I'm not sure what you mean about the size making a difference... even 20fps versus 25fps on the little phone screen can be distinguised quite easily.

M3 specifically, will encode source video of 25 fps or higher at a 25fps framerate, using frame blending on > 25fps (eg. 29.97 fps) material to preserve fluid motion. On video below 25 fps and above 23 fps, it will keep the native framerate - ie. your 23.976 fps feature film will remain at 23.976 fps on your phone.

(note this doesn't apply to old generation phones such as the W810/K750 that are limited in terms of bitrate / framerate, getting 24 or 25 fps out of them takes incredibly low bitrates, so m3 will use 20fps on those phones as a framerate / visual quality compromise).

I didn't include 30fps as an option initially because those extra 5 frames per second, that aren't needed in nearly all cases, cost a lot on the phone. If you kept the ~350kbps video bitrate used at 25fps when encoding at 30fps, you still have 20% more frames to spread that bitrate over - less bits per frame - lower video quality. Add to that, that at 30fps you must also lower bitrate to prevent stutters, down to about 275kbps at least, you're looking at at least 33% less bits per frame. It's not like there's enough bitrate at 25fps, so at 30fps visual quality will suffer greatly.

I'm assuming the n73 has better bitrate / framerate support than the K800 etc, much like the symbian-based P990 has. So i mentioned i'd up the limit to 30fps for the n73 for jj03.

About the video recording resolution. I did own a W900i till it suffered an impact, and i think it's above-average video recording (QVGA @ 30fps) was possible due to the nvidia go-force 4800 chip inside it. I believe it provided hardware-accelerated mpeg-4/h.263 encoding as well as decoding. Whatever video acceleration is provided in the current phones, it appears to be much more for decode than encode. So although the camera sensor can provide the images at a good rate, the phone can't compress them fast enough. You can't leave them uncompressed, because there isn't enough storage space. I don't think the ARM cpu in the phones can software-compress QVGA @ 30fps either, it's only 200MHz.

The best hope for improved video recording on SE phones in the future is that SE once again includes a powerful multimedia chip inside the phone for video duties.

Excuse the long post, i couldn't sleep tonight.

On 2007-05-14 01:04, Xajel wrote:
About the VGA@30fps thing

if Sofia was only QVGA@30fps then Sofia's GPU is able to handle VGA@30fps, but SE just set it QVGA@30 for 2 reasons ( maybe one )
- stability issues when setting it VGA@30fps.
- leaving VGA@30fps for speciallized Video Mobile phone, I feel I'm going to this reason rather than the first

in any case, I think modders will be able to make profiles to enable VGA@30fps for Sofia, just like the improvment they did with K750/W800 camera software, but they didn't improve the video that much as K750/W800 hardware are limited, but Sofia's GPU is much powerfull.

I just hope Sofia DOES have that GoForce 5500 chip under it's hood...

On 2007-11-14 15:02:47, chombos1 wrote:
although the K850 is stated to record at 30fps... some of them on the market will drop the frame rate to 15 after some seconds of recording.

don't know if this is fixed on the new release.

and K850 video quality is better than W900 (i know that the resolusion is the same) because of the MP4 encoding....and higher bitrate

EDIT:
@rifqi aziz

as i said the K850 is good in the first 10-15 secs then it drops to 15fps.
saw this bug in most of the K850 recordings i seen.

(some of them was virtually 30fps meaning that each two frames was the same..... so what you get? a choppy 15fps!!! but the player still says that it is 30fps)

[ This Message was edited by: chombos1 on 2007-11-14 14:42 ]

On 2007-11-14 15:02:26, Rifqi_Aziz wrote:
Can someone compare these and decide which is better?

K850 Video Recorded:
http://d.turboupload.com/d/2146809/K850_Video_Recorded.zip.html

W900 Video Recorded:
http://d.turboupload.com/d/2146813/W900_Video_Recorded.3gp.html

Thanks.

On 01-30-2008 wrote:
Video recorder
Video size (resolution): QVGA 320x240 pixels
Frame rate: 30fps (frames per second)