CBR settings for x264 in Hybrid

[Jan Tokki]

Hello,

I need to set the x264 encoder in Hybrid to CBR, since the scenario is 12 files that must play absolutely in synch for an art installation. After reading a bit about the x264 encoder I still have not found an answer that seems clear/certain to me.

Seems like setting 1-pass and the "data rate fluctuation =1" (VBV) was suggested by someone, but I just don't understand why there is not CBR under encoding mode?
What would be the bes way to ensure CBR- encoding?

[poisondeathray]

x264 does not have true CBR encoding. At all. Period.

There is a "semi" CBR encoding when you set the --vbv-bufsize and --vbv-maxrate along with --bitrate to the same value

[jagabo]

And CBR encoding will not improve A/V sync, or multiple file sync.

[krykmoon]

VBR/CBR is about visual quality / speed of the encoding / filesize .. it has nothing to do with the framerate or the flowing of frames .. they all remain in their places/times xD

[Selur]

If you really want to have a cbr which might be needed for some old satelite hardware, then you could use ts/m2ts as container and enable "Config->Containers->Transport Stream settings->TS Bitrate stuffing" this will tell Hybrid to use tsMuxeR and enable it's bitrate stuffing support.
That said: Unless you have highly specialized hardware that would not help sync playback or transfer in any way, but may even hinder it.

-> I would suggest to read up on what VBV is intended to do and configure the VBV according to your needs.

Cu Selur

[Cornucopia]

"12 files playing exactly in sync" sounds interesting, but I expect you are leaving out a whole bunch of the details of the setup, some of which are more likely to be crucial to the success of this project than the assumption about CBR.

Maybe you are confusing this with CFR (Constant Framerate). This WOULD be crucial to proper multi-file, and/or multi-player playback.

Scott

[Jan Tokki]

"12 files playing exactly in sync" sounds interesting, but I expect you are leaving out a whole bunch of the details of the setup, some of which are more likely to be crucial to the success of this project than the assumption about CBR.

Maybe you are confusing this with CFR (Constant Framerate). This WOULD be crucial to proper multi-file, and/or multi-player playback.

Scott

Thanks for this info: this project was originally encoded as 12x mpegs and yes CBR was specified by the media-player manufactorer for synch playing. Now "restoring" this project requires H264 and upscaling, so I assumed the CBR-route was the solution. But CFR was an unknown to me, sounds promising.

I searched all thru Hybrif for this "CFR" setting but the only thing I could find seems to deal with the INPUT for Hybrid itself, not the actual playback of the encoded files.
Or am I misunderstanding what this setting is for?
[Attachment 66181 - Click to enlarge]

[Selur]

The setting you are highlightening tells the decoder to output the constant frame rate that was detected, even if the content is VFR.
If you open a file in Hybrid on the right side in the Video info box the frame rate is indicated by frame rate / frame rate mode.
For example 25/CFR would indicate 25fps constant frame rate, while 25/VFR would indicate 25fps variable frame rate.
Hybrid will not create VFR unless the input is already variable frame rate and no operation that enforces cfr decoding is used.

-> I would suggest to read up on what VBV is intended to do and configure the VBV according to your needs.

Cu Selur

[Cornucopia]

"specified by the media player manufacturer" sounds like there are more details that we don't yet know.


Scott

[Jan Tokki]

Thanks.
Seems like setting the VBV max/min to same value would be the closest to CBR I will get, as was previously suggested.

If I really want to cover my ass, I could simply go the mpeg-2 route, as this was how the original data was encoded in 2006, and the specs from the manufacturer BACK THEN required CBR-mpegs.

Now it looks like their devices are more sophisticated in staying in synch now, and I am probably making a mountain out of a mole-hill.

BrightSign media-players + synch:
https://support.brightsign.biz/hc/en-us/articles/360003401794-Some-video-encoding-advi...video-bitrate-

I appreciate all the input, thanks all around.

The setting you are highlightening tells the decoder to output the constant frame rate that was detected, even if the content is VFR.
If you open a file in Hybrid on the right side in the Video info box the frame rate is indicated by frame rate / frame rate mode.
For example 25/CFR would indicate 25fps constant frame rate, while 25/VFR would indicate 25fps variable frame rate.
Hybrid will not create VFR unless the input is already variable frame rate and no operation that enforces cfr decoding is used.

-> I would suggest to read up on what VBV is intended to do and configure the VBV according to your needs.

Cu Selur

[Jan Tokki]

A brief word of praise for the unbelievable wonderful HYBRID ! After years of struggling with AviSynth syntax, double-checking every comma and dash, it is such a relief to just tick some boxed, check results and refine subseqently.
Thanks much, donating to project today!