[x265] [PATCH] CLI: Fix wrong condition for "--strict-cbr" option

[Jean Cruypenynck]

Hello,

Thank you for your answer!
You mention that “the strict-cbr option today works only for CBR encodes that use the --bitrate option”.
However, when I use "--bitrate <somevalue> --strict-cbr”, I get the error "Strict-cbr cannot be applied without specifying target bitrate or vbv bufsize”.

From your comment, I understand that this is not the intended behaviour? Or should “bitrate” and “vbv-bufsize” be specified for “strict-cbr” to work?

Many thanks,
Jean.

Steps to reproduce:

• git clone https://github.com/videolan/x265.git
• build the CLI target for your platform
• ffmpeg -i <input.avi> -f yuv4mpegpipe -pix_fmt yuv420p - | x265 --y4m --bitrate 1000 --strict-cbr -o encoded.265 -


On 1 Feb 2017, 12:16 +0100, Pradeep Ramachandran <pradeep at multicorewareinc.com>, wrote:
> > On Tue, Jan 31, 2017 at 5:10 PM, Jean CRUYPENYNCK <filaton at me.com> wrote:
> > > # HG changeset patch
> > > # User Jean Cruypenynck <filaton at me.com>
> > > # Date 1485860877 -3600
> > > #      Tue Jan 31 12:07:57 2017 +0100
> > > # Node ID 93d09ad23a514172f0d143b0a194c607963db57b
> > > # Parent  fa52b516f5ff122c4486ed840c5bf1de3c06e974
> > > [CLI] Fix wrong condition for "--strict-cbr" option
> > >
> > > Checking for "--strict-cbr" should succeed if either "--bitrate" or "--vbv-bufsize" is specified.
> > >
> > > It means that an error should be thrown if:
> > >     param-rc->bStrictCbr && NOT (param->rc.bitrate > 0 || param->rc.vbvBufferSize > 0)
> > > evaluates to true.
> > >
> > > According to De Morgan's laws, it is equivalent to:
> > >     param-rc->bStrictCbr && (NOT param->rc.bitrate > 0 && NOT param->rc.vbvBufferSize > 0)
> > > which is in turn equivalent to:
> > >     param-rc->bStrictCbr && (param->rc.bitrate <= 0 && param->rc.vbvBufferSize <= 0)
> > >
> > > Currently, one must set both "--bitrate" AND "--vbv-bufsize" to use "--strict-cbr".
> >
> > The strict-cbr option today works only for CBR encodes that use the --bitrate option. If you want to enable CBR via CRF + VBV, this option doesn't work.
> > Maybe the check error message is confusing in its construction and therefore leads to misunderstandings.
> >
> > >
> > > diff -r fa52b516f5ff -r 93d09ad23a51 source/common/param.cpp
> > > --- a/source/common/param.cpp   Mon Jan 30 10:35:00 2017 +0530
> > > +++ b/source/common/param.cpp   Tue Jan 31 12:07:57 2017 +0100
> > > @@ -1269,7 +1269,7 @@
> > >          CHECK(0 > param->noiseReductionInter || param->noiseReductionInter > 2000, "Valid noise reduction range 0 - 2000");
> > >      CHECK(param->rc.rateControlMode == X265_RC_CQP && param->rc.bStatRead,
> > >            "Constant QP is incompatible with 2pass");
> > > -    CHECK(param->rc.bStrictCbr && (param->rc.bitrate <= 0 || param->rc.vbvBufferSize <=0),
> > > +    CHECK(param->rc.bStrictCbr && (param->rc.bitrate <= 0 && param->rc.vbvBufferSize <=0),
> > >            "Strict-cbr cannot be applied without specifying target bitrate or vbv bufsize");
> > >      CHECK(param->analysisMode && (param->analysisMode < X265_ANALYSIS_OFF || param->analysisMode > X265_ANALYSIS_LOAD),
> > >          "Invalid analysis mode. Analysis mode 0: OFF 1: SAVE : 2 LOAD");
> > > _______________________________________________
> > > x265-devel mailing list
> > > x265-devel at videolan.org
> > > https://mailman.videolan.org/listinfo/x265-devel
>
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