VBV Maximum Bitrate

[elguaxo]

--vbv-maxrate 25000 is included now in some of the newest 'MeGUI Custom x264/AVC video profiles'.

I tried the DeathTheSheep's Guide and the search here at doom9, but I couldn't find any explanations. What does this option?

Thanks.

[Sharktooth]

it sets the maximum bitrate to 25000. it wont influence quality coz it's a very high cap.
remember to not crosspost please ( http://forum.doom9.org/showthread.php?p=857471#post857471 )

[elguaxo]

it sets the maximum bitrate to 25000. it wont influence quality coz it's a very high cap.
remember to not crosspost please.

Sorry for crossposting! Your first answer at MPEG-4 Encoder GUIs/...video profiles was rather short, but I guess it was ok since the thread is about the profiles and not about x264 itself, so I posted it here.

Thanks!

[DarkZell666]

may I add that this option has been added in order to make files playable in "bandwith limited" environments ? Such as internet streaming, playback in standalone players or on portable devices ...

The goal of the VBV principle is to limit the number of bits used for a certain time frame.

For playback on a computer it needn't be touched :)

[Oline 61]

Such as internet streaming
25 MB/s intarweb?

[DarkZell666]

the value is tweakable right ?

25000 is the default value in MeGUI's profiles because many of them aim for computer playback.

If I wanted to encode for streaming over ADSL I would set it to 512, not 25000 :)

In fact, sorry, after re-reading I noticed that I wasn't clear myself, lol.

The vbv switches are there for what I was talking about, but the 25000 setting comes from MeGUI. My bad :D

[GodofaGap]

Why was 25000 chosen? Why not 15000 or 50000?

[DarkZell666]

Why do you ask why ? :D

25Mbps seems to correspond to the limit of one of the AVC levels ... x264's default is 0 btw (which means no limit I suppose ?)

[Sharktooth]

25000 wont be a limit unless you encode at resolutions much higher than 1920x1080 and will help the playback on some devices/decoders.