Jump to content
Sign in to follow this  
Doofer

Divx - worse than it looks

Recommended Posts

Hi there all.

We know that FPV video recording is relatively bandwidth-demanding, as it's not a small figure a swimsuit dancing around on a relatively stationary background, but the whole world rotating around our spiraling, out-of-control skyship.

I've been using a 'portable media centre' (Rollei 2020g) that reported, on testing indoors, that it was recording 640x480 at 25fps, bit rate 3MBps (no menu items to adjust any of this). Anyway, not so bad, not as smooth as MiniDV but considerably longer record time and about the size of a cigarette packet, so it fits in my FPV groundstation bag nicely (20x20x6cm - includes Oracle Diversity/2xRx/2x8dB patches/battery/Goggles... so I'm happy!).

However, I only recently noticed that footage recorded in the air is reported as 640x480 -AT-20fps... I thought it was looking a little jerky (even for non-interlaced)...

Is this a DivX thing i.e. "dynamic optimisation" = "if I can't record it at the quality I want I'll reduce the frame rate"?

(I guess that trying to record full-frame movement at these reduced bit rates something's gotta give - frame rate or pixellation - but it surprised me to see frame rate reducing without being asked...)

Share this post


Link to post
Share on other sites

It wouldn't be a DivX thing, but specific to that particular recorder maybe not being able to handle that much processing.

I've seen some that would also report different bitrates each time I would record, with too much variation to possibly be VBR... these things are often weird and we can't really know what goes on behind...

Share this post


Link to post
Share on other sites

I don't think we'll ever have HD, but I was wondering How the 640X480 disregarding the 20 fps looks displayed on your screen. Some of the cameras I've been looking at have 350 or so up to 520 lines/resolution but looking at the videos & links posted on the forum, some of the videos leave a lot to be desired as far as the resolution is concerned. I was just wondering wether this was a result of the constraints of youtube and other video players or wether it was inherent in the systems we use for taking the videos. I wouldn't think the bandwidth is a problem unless one was on dialup.

Hope you can shed a little light on this for me.

Ron

Edited by W3FJW-Ron

Share this post


Link to post
Share on other sites
I was just wondering wether this was a result of the constraints of youtube

Youtube heavily compresses the videos and basically renders them a mess. There are a few links on this site to recent non-YouTube hosted videos that are very decent quality. BTW, sometimes using old technology is not a bad thing. If you want to see what a tape based digital camcorder can do, then just look at Yb2normals old videos. For example, even with wmv compression, this one looks better than some DVRs and just about anything that would be found on Youtube: http://www.yb2normal.com/homercam2.zip.

Share this post


Link to post
Share on other sites

Thank you. That did look quite good in win media player. Gonna have to play around with this equipment a bit myself. Thanks again.

Ron

Share this post


Link to post
Share on other sites

Yes, it's more the compression used by the recorder that matters, rather than the resolution.

Share this post


Link to post
Share on other sites
Yes, it's more the compression used by the recorder that matters, rather than the resolution.

I use the Archos AV500 (as recommended on these forums a while back) to record my stuff and I've been very happy with the results. It records straight into DIVx and I've found it to be 100% reliable.

I'd certainly recommend this versus the cheap Chinese alternatives which are a bit more hit and miss and I'm happier with the Archos over using a laptop because its much more portable and its just "plug and play", I don't have to try and get all of the settings right each time!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×