CODEWITHSUNDEEP
c++c++11ffmpeglibavcodeclibav
pseudo_teetotaler
pseudo_teetotaler

Reputation: 1575

What is av_opt_set in FFMPEG

I am looking at some code base to encode videos in LibAV. I am unable to understand the purpose of these two lines: 

av_opt_set(context->priv_data, "tune", "zerolatency", 0);
av_opt_set(context->priv_data, "preset", "fast", 0);

Here, context is AVCodecContext.

I am new to this library and would appreciate a descriptive answer.

Upvotes: 1

Views: 4216

Answers (2)

woder
woder

Reputation: 805

supplement for Gyan:

when we use av_opt_set() , here is prototype

av_opt_set (void *obj, const char *name, const char *val, int search_flags)

the first argument is type AvClass defined in: https://www.ffmpeg.org/doxygen/trunk/structAVClass.html

there are two function pointer in this struct: child_next() and child_class_iterate() which can get AvClass object child, so it is clearly that AvClass is formed as tree and has childern, search_flags decides whether to opearate on childern;

Upvotes: 1

Gyan
Gyan

Reputation: 93058

That's a utility function to set the value of defined AVOption members in the struct ref passed in the first arg. The 2nd arg is the member and the 3rd is the value. The 4th arg is a search flag that tells the fn whether to search child structs.

See https://www.ffmpeg.org/doxygen/trunk/group__opt__set__funcs.html

and https://www.ffmpeg.org/doxygen/trunk/group__avoptions.html

Upvotes: 3

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