[FFmpeg-user] how to specify search folder for external lib while compiling?

[Zhanwu Xiong]

Hi all,

I tried to compile and build ffmpeg in my home folder since I don't have
sudo privilege, and I have the following questions:

First, I don't know how to specify search directories for external libraries
while running *configure*? I try to enable libx264, which is installed in my
home folder instead of '/usr/local/', but

*./configure --enable-libx264*

returns me that libx264 can not be found.

I proceeded without libx264, because I noticed that h264 decoder is enabled
anyway. Does it mean that ffmpeg have a native h264 decoder?

After installation, I tried to extract frames from a h264 encoded video and
save it to png files:

*ffmpeg -i VIRAT_S_000201_03_000640_000672.mp4 -r 30 -f image2 frame%04d.png
*


I got the frames, however there are two message that I couldn't understand


   1. *Seems stream 0 codec frame rate differs from container frame rate:
   30000.00 (30000/1) -> 30.00 (30/1)*
   2. *Incompatible pixel format 'yuv420p' for codec 'png', auto-selecting
   format 'rgb24'*

My guess for the second message is that the original pixel format yuv420p
couldn't be used for the output 'png' file, so it is automatically converted
into 'rgb24' format, and this is done by calling *swscale*, right?

For the first one, the only thing I know is that the frame rate of the input
video is 30 frames/sec, which is obtained by viewing the property of it in
nautilus, but what is the container frame rate?

best regards
/zhanwu