[FFmpeg-user] how do I set configuration the H264/MPEG4 in decoding?

[Carl Eugen Hoyos]

SON NAM RYE <nrson <at> win4net.com> writes:

> Whenever I have compiled the ffmpeg, sizes of 
> created files are different.

You mean if you compile the same FFmpeg version twice, 
the resulting binaries have different sizes? That would 
indeed be surprising.

Or do you mean that if you compile different versions 
of FFmpeg, you get different output files? That is 
expected.

> In testing, memory occupancy and cpu performance are 
> different according to those.

For different versions, that is to be expected.

> I just want to decode H264 and MPEG4. How do I set configure?

You can try the following:
./configure --disable-everything --enable-decoder=h264,mpeg4

But I am not sure if I understand your question:
Do you only want to use the library (that is what your 
question implies) or do you want to use the ffmpeg 
executable (but only to decode a limited set of files)?
If that is what you want, note that you also have to 
define the allowed demuxers, and that parsers may also 
be necessary.

Carl Eugen