[x265] [PATCH 1 of 6] rc: introduce param variables for 2 pass

[Steve Borho]

On Mon, Jun 16, 2014 at 1:17 AM, Aarthi Priya Thirumalai
<aarthi at multicorewareinc.com> wrote:
>
>
>
> On Mon, Jun 16, 2014 at 9:33 AM, Steve Borho <steve at borho.org> wrote:
>>
>> On Sun, Jun 15, 2014 at 1:50 PM,  <aarthi at multicorewareinc.com> wrote:
>> > # HG changeset patch
>> > # User Aarthi Thirumalai<aarthi at multicorewareinc.com>
>> > # Date 1402856954 -19800
>> > #      Sun Jun 15 23:59:14 2014 +0530
>> > # Node ID 438a03ff94830fbc17457b6f324397e643c17cba
>> > # Parent  e69a427e461f8c8944b68323a3d77295b65ec779
>> > rc: introduce param variables for 2 pass
>>
>> Yeah! two-pass patches \o/
>>
>> > diff -r e69a427e461f -r 438a03ff9483 source/x265.h
>> > --- a/source/x265.h     Thu Jun 12 22:53:47 2014 -0500
>> > +++ b/source/x265.h     Sun Jun 15 23:59:14 2014 +0530
>> > @@ -745,8 +745,26 @@
>> >
>> >          /* In CRF mode, minimum CRF as caused by VBV */
>> >          double    rfConstantMin;
>> > +
>> > +        /* 2pass */
>> > +        /* Enable stat writing in psz_stat_out */
>> > +        bool         statWrite;
>>
>> these comments are pasted from x264, with their variable names, which
>> is unhelpful.
>
> sorry, my bad. ll clean up properly.
>>
>>
>> we don't allow bool types in x265.h; all types must be C native types
>>
>> > +
>> > +        /* Read stat from psz_stat_in and use it */
>> > +        int         statRead;
>>
>> parameters with boolean behaviors should start with lower case b.
>>
>> > +        /* output filename of the 2pass stats file */
>> > +        char        *pszStatOut;
>>
>> can statWrite be implied from pszStatOut, and statRead from pszStatIn?
>>
>> should statRead be a bool like statWrite? Can it be implied from
>> pszStatIn? Can we assume the user wants to read a stats file if they
>> supply an input filename (and abort if the file cannot be opened)?
>
> actually, we can do away with both statWrite and statRead bool..if we
> shouldn't use default file names to set up pszStatIn/Out ,
> then the user should necessarily provide a filename for each pass, we can
> set it to either input/output file or both according to the pass sequence
> (--pass)
> and use them to detect the pass type later on.

For CLI users, we can follow x264's somewhat strange semantics of
--pass 1 for first pass (write-only), --pass 2 for last pass
(read-only), and --pass N>2 (read and write) for intermediate passes.

API users can set input or output filenames as they like to achieve
the same semantics.

So we only need two char* in the param struct, and internally can
treat each char* like a bool to determine if stat reading or writing
is happening.

-- 
Steve Borho