[Bf-committers] Cineon/DPX speed up

[Sergey Sharybin]

Julien,

When IB_test flag is set, no rect, rect_float buffers shall be allocated
and no pixels reading from file shall happen. If it happens in Cineon/DPX
that'd be bad and code shall be modified to be aware of this flag.

IMB_rect_from_float shall not be called unless it's needed to the format
itself. If codec outputs linear rect_float, it's indeed better to skip byte
buffer generation.

Troy,
No, we could not "unbind" in my understanding of this word. Float buffers
are always scene linear space with premultiplied alpha. Linearization
happens after codec returned float buffer using ocio, for sure. You could
not skip this step.

If the question is more about 'if we could use ocio instead of hardcoded
conversions" -- yes we could. If we shall -- no idea, depends on what's
exactly going on there.

If the question is more about "whether ocio is able to convert files'
curves and primaries to internal blender's" yes it's able. You would only
need to add some more spaces to your config. But that's not something i
would want to happen in trunk -- exposing all the spaces which only one
single person from this mailing list could follow is a crap ;)

Long story short:
- If DPX code is not aware of IB_test flag, that shall be easy to change
- If DPX code itself does not rely on byte buffer, no rect_from_float shall
happen
- If there're some hardcoded curves in the code, we could check on
switching them to generic ocio transform code. But please, do not introduce
new spaces.



On Wed, Mar 13, 2013 at 5:49 AM, Troy Sobotka <troy.sobotka at gmail.com>wrote:

> On Mar 12, 2013 3:27 PM, "Julien Enche" <julien.enche at gmail.com> wrote:
>
> > 1) At the moment, the IB_test flag is not taken in account in the
> > imb_load_dpx_cineon function, so color conversion happens twice. I
> > haven't really find out what should be done and what can be skipped when
> > this flag is set. Can you give me more information on the purpose of
> > this flag so that I could adapt the code to use it efficiently (and
> safely).
>
> Is there any way we can unbind the DPX code in such a way that it uses OCIO
> and merely flags it as log etc? As I understood it, the DPX code makes
> assumptions on the format and decodes accordingly?
>
> I ask because it would permit loading of different styled logs (Josh Pines
> versus Cineon etc.), color primaries, etc.
>
> Curious if it is feasible to hand the log transfer curve conversion and
> color primaries off to OCIO?
>
> With respect,
> TJS
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-- 
With best regards, Sergey Sharybin