--strict-cbr usage

[picturebuffer]

I wanted to test that (experimental) swtich but can`t get it to work with current build,

with parameters set to:
--bitrate 1650 --strict-cbr
or
--bitrate 1650 --vbv-maxrate 5000 --vbv-bufsize 5000 --strict-cbr

I get:

x265 [error]: Strict-cbr cannot be applied without specifying target bitrate or vbv bufsize

CLI usage wrong or not working as of now?

[MeteorRain]

./x265 -o t.hevc test.y4m --bitrate 5000 --vbv-maxrate 5000 --vbv-bufsize 5000 --strict-cbr
And no problem.

You need to set bitrate == maxrate to switch to CBR mode. Then specify bufsize should allow you to use strict-cbr.

Also please check your version number. Some legacy version could come with problems that might have been fixed.

[picturebuffer]

That solves it. Totally fine with current build also. Thanks!

[benwaggoner]

I'm not really sure what the scenario for --strict-cbr is.

Can you share what you're planning to use it for, and how you'll be able to tell if it works?

[kolak]

It's what name suggests

Enables stricter conditions to control bitrate deviance from the target bitrate in ABR mode. Bit rate adherence is prioritised over quality. Rate tolerance is reduced to 50%. Default disabled.

This option is for use-cases which require the final average bitrate to be within very strict limits of the target; preventing overshoots, while keeping the bit rate within 5% of the target setting, especially in short segment encodes. Typically, the encoder stays conservative, waiting until there is enough feedback in terms of encoded frames to control QP. strict-cbr allows the encoder to be more aggressive in hitting the target bitrate even for short segment videos.

It does work. Just encode something with and without it and look in bitrate viewer.

[FranceBB]

Originally Posted by kolak

It does work. Just encode something with and without it and look in bitrate viewer.

Since you mentioned Bitrate Viewer I think it only supports up to H.264, but no H.265. Is there an updated version for H.265? 'cause I would like that as it's been my de facto choice for looking at bitrates for years.

Originally Posted by excellentswordfight

I have used it quite a bit. For broadcast scenarios with a set bandwith, without it i got warnings as i got bitrate spikes that surpased the mpeg-ts muxrate even though i had some overhead.

True. I've been using it too to make it as "constant" as possible for quite some time now. It works fine, just like it does for x264.

[MGarret]

Originally Posted by FranceBB

Since you mentioned Bitrate Viewer I think it only supports up to H.264, but no H.265. Is there an updated version for H.265? 'cause I would like that as it's been my de facto choice for looking at bitrates for years.

If you have a Mac, there is updated version of BitrateViewer by the same author which supports H.265.

On Windows I sometimes use CheckBitrate by Rigaya (author of NVencC app) to generate .csv which I then import into Google Sheets to create charts. It's not as convenient as a standalone program but it is what it is.

There's also PlotBitrate and PlotBitrateFaster python scripts that can do the job but I prefer CheckBitrate.

[FranceBB]

Originally Posted by MGarret

If you have a Mac, there is updated version of BitrateViewer by the same author which supports H.265.

It's probably the first time that I see something free more updated on OSX than it is on Windows.

Originally Posted by MGarret

On Windows I sometimes use CheckBitrate by Rigaya (author of NVencC app) to generate .csv which I then import into Google Sheets to create charts. It's not as convenient as a standalone program but it is what it is.

There's also PlotBitrate and PlotBitrateFaster python scripts that can do the job but I prefer CheckBitrate.

I'll try CheckBitrate then as I'm on Windows, thanks for the suggestion.
Too bad the author of Bitrate Viewer didn't update the program for Windows...

[kolak]

Originally Posted by FranceBB

Since you mentioned Bitrate Viewer I think it only supports up to H.264, but no H.265. Is there an updated version for H.265? 'cause I would like that as it's been my de facto choice for looking at bitrates for years.



True. I've been using it too to make it as "constant" as possible for quite some time now. It works fine, just like it does for x264.

Bitrate viewer not BitrateViewer meaning any one
It can be easily checked with eg. DVBInspector (assuming ts file).

[excellentswordfight]

Originally Posted by benwaggoner

I'm not really sure what the scenario for --strict-cbr is.

Can you share what you're planning to use it for, and how you'll be able to tell if it works?

I have used it quite a bit. For broadcast scenarios with a set bandwith, without it i got warnings as i got bitrate spikes that surpased the mpeg-ts muxrate even though i had some overhead.

[kolak]

Yep, same here.