[Ffmpeg-devel] ffmpeg & postprocess_internal.h (colorspace issue)
Michael Niedermayer
michaelni
Sun Jul 24 18:27:57 CEST 2005
Hi
On Sunday 24 July 2005 17:33, Kris A. Wotipka wrote:
> Apologies and thanks for the input. By the time I learn enough C to
> understand the code, the problem will no longer be an issue since we
> will probably be into some direct to brain transfer system with our
> entertainment. It truly is a shame that wonderful programs such as
> these will forever be locked into the hands of those who can program but
> not write documentation.
>
> I as an engineer understand the issues of composite routing, syncing,
> latency, etc of the traditional studio system. Whenever someone who
> wants to learn asks, I always try to explain it in real world terms and
> then hand them one of Grass Valleys wonderful manuals.
and what do you do if someone picks a completely unrelated and unused part and
ask you to explain it? will you tell him its not going to help him with his
problem even if he understands that part? or what else?
lets see the lines you quoted:
/// select between full y range (255-0) or standart one (234-16)
#define FULL_Y_RANGE 0x8000 // 32768
the first line is a comment as it starts with //
the second is a preprocessor directive which has the effect that all
occurances of FULL_Y_RANGE later in the program will be replaced by 0x8000
now what is that FULL_Y_RANGE thing? its a flag and 0x8000 is the bit for that
flag, change 0x8000 to another unused bit and recompile everything and
nothing will change, change it to a bit which is used for something else and
things will break thats it
now what does the flag/bit thing actually switch between? it switches between
the output range of the brightness/contrast correcture filter
what does that filter do? it guesses the maximum and minimum brightness and
adjusts brightness&contrast so the guessed values are changed to the wanted
output ones
how to use the filter in ffmpeg, sorry its not supported currently you would
need to add support for that first
did any of that help you?
[...]
--
Michael
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