b-frames causing a strobe-like effect?

[k0r0n4]

I was recently encoding a very simple clip in xvid 1.0.1 because my drive isn't fast enough to play back uncompressed (or even huffyuv) video at my video's resolution and frame rate. However, after I was finished encoding the clip I noticed a strange problem.

I was getting what can best be described as a "strobe-like" effect when playing back the video, causing it to look jerky. At first I thought it was the source footage so I went back and checked it, and it seemed just fine. I reencoded the same clip, but this time turned off b-frames. This time, the clip played back perfectly without any jerkiness.

Now, my question is, is there a way to still use b-frames while NOT getting a jerky clip? And, if so, what should I change in the b-frame encoding settings? My guess would be less consecutive b-frames, but what about the quantizers?

Thanks in advance...
k0r0n4

P.S. - If samples would help, just ask and I will host the 2 different encodes temporarally at my website so you can see the difference.

[Blue_MiSfit]

did you have packed bitstream enabled?

[k0r0n4]

Yes, and Closed GOV :D

[k0r0n4]

I did another check, this time using the XviD VFW codec instead of the DS codec, and it's a little better, but still has a slight strobe effect.

I also tried lowering the consecutive b-frames down to 1, and that seems to have done the trick. However, if you have a better idea on how to prevent the strobing, feel free to post. Thanks again.

[cheerow]

Try playing it without post-processing. Just a thought...

[ChronoCross]

turn off packed bitstream and it'll play perfectly with bframes. Packed bitstream(if memory serves me right) is only needed if you plan on playing it on Hardware mp4 decoders, else on pc's it is always jerky.

[Koepi]

That's quite a misinformation.

Without packed bitstream there is a 1 frame delay at playback time.
With packed bitstream, there is no such delay.

That's why packed bitstream is default.

It doesn't affect anything which could produce jerkyness. This can only happen with i.e. old ffdshow versions. Try to install a newer one - but as you use xvid to decode it, I just think your computer isn't fast enough to properly decode the bitstream (bframe decoding is more cpu and memory bandwidth intensive than i/p-frame only decoding).

If you encode to a smaller resolution, the jerkyness should go away in that case, you could do that for checking if this is your problem.

Regards
Koepi

[ChronoCross]

sorry Koepi. Sometimes my experience with it and the actual information gets in the way. my Computer stats(seen in my sig) usually always have jerkiness when playing things with packed bitstream enabled. latest fddshow or even the latest xvid decoder same problem. Turning it off is a good solution for most people. Once again sorry for the misinformation.

[portrgirl]

I have a bunch of movies that have this weird jerky/strobe-like effect going on. Is there a way for me to fix it or should I just junk them?

[Xperience]

Hi,

I have an Yamada 6600 dvd player and it plays xvid, divx, mpeg files great.
Sadly some xvids and divxs also show a strobe effect on it.

My question is: is there a way to shut that b-frames down with some sort of program in the file ?
Or do i need to re-encode it ?

Xperience

[ChronoCross]

Originally posted by portrgirl
I have a bunch of movies that have this weird jerky/strobe-like effect going on. Is there a way for me to fix it or should I just junk them?

You can try MPEG4Modifier which is in another thread just use the search button. it'll allow you to turn off packed bitstream and if that doesn't correct it there isn't much you can do aside from trying to increase the framerate(this means reencoding) and hope you get lucky. Without the source you can't do much.

@Xperience
Reencoding the file is the only way to get rid of b-frames. sorry.