B frames in X264

[funduguy]

Hi experts,
i'm new to the encoding world and i came across the X264 video encoder. i'm trying to encode a video and want to know how can i have constant number of B frames between P frames.

i tried using the --no-b-adapt option but it seems to have no change in the selection of B frames.

Basically, i want to fix the number of B frames between P frames, say 2, how do i do that?

:thanks:

[Dark Shikari]

That's what --no-b-adapt does. Of course, if you're running in twopass mode, it has to be enabled in the first pass too.

[funduguy]

Thanks for the reply,
This is my command line and i thought i'll get 2B frames consistently, but no so, i got 1B frame also at some locations.

x264 --keyint 180 --min-keyint 30 --scenecut 40 --bframes 2 --b-bias 100 --no-b-adapt --no-cabac --ref 2 --direct spatial --qp 30 --ipratio 1.15 --pbratio 1.15 --partitions all --me umh --merange 16 --subme 1 --no-chroma-me --no-fast-pskip --no-ssim --progress --level 1.3 --fps 30 --frames 300 --threads 4

Any pointers as to what could be the reason?

Regards,

[Dark Shikari]

Try it without threads.

Either way, those are some really bizarre settings.

[funduguy]

Thanks for the info.
cool, that works just fine. but why it does not work with more threads?

Regards,

:thanks:

[Ranguvar]

I think you win the freakiest settings award xD

And I don't know why not using threads will make it work... just spamming :p

[audyovydeo]

--bframes 2 --b-bias 100

huh ???

try --bframes 2 --b-bias 2. Threads should not matter imo

cheers
audyovydeo

[nm]

The b-bias range is -90--100 and 100 is a valid setting to enforce more b-frames to be inserted when b-adapt is used. B-bias 2 would be about the same as the default behaviour.

[DarkZell666]

Why keep the --b-bias anyway if you're going to use --no-b-adapt ? Just remove --b-bias and try again, I suspect --b-bias (when manually set) overrides --no-b-adapt instead of the opposite ... (but I've never read the code right ? just my 0.02€ ^^). Those two settings are mutually exclusive and shouldn't even be allowed to be specified together imho :)

Or is it the threaded part that doesn't take any notice of --no-b-adapt ?

[neuron2]

@funduguy

Please don't delete threads after someone else has answered. You can delte your own posts, but it's rude to delete other people's posts. Thank you.

[DarkZell666]

So that's why I couldn't find it anymore ? -_-