最近几天在试着做基本ffmpeg静态库的开发，只有main中包含了avdevice_register_all 或avfilter_register_all，编译就通不过，undefined refrence ，静态库的链接次序一直搞不定。
后尝试了pkg-config命令，首先配置PKG_CONFIG_PATH环境变量
pkg-config --libs libavdevice
-pthread -L/usr/local/test_ffmpeg/lib -lavdevice -lavfilter -lpostproc -lswresample -lswscale -lavformat -lavcodec -ldl -lasound -lx264 -lfaac -lz -lrt -lavutil -lm
根据这个次序，调整编译shell，则成功编译。
arm-linux-gnueabihf-gcc device.c -o device
-I/usr/local/test_ffmpeg/include -I/usr/local/faac/include -I/usr/local/include
-L/usr/local/test_ffmpeg/lib -L/usr/local/faac/lib -L/usr/local/lib
-lavdevice -lavfilter -lpostproc -lswresample -lswscale -lavformat -lavcodec -lavutil -ldl -lasound -lx264 -lfaac -pthread -lz -lrt -lm
或使用下面的Makefile文件编译（从ffmpeg1.1.16/doc/example中拷贝，已修改并测试通过）
CC = arm-linux-gnueabihf-gcc
# use pkg-config for getting CFLAGS and LDLIBS
FFMPEG_LIBS= libavdevice
libavformat
libavfilter
libavcodec
libswresample
libswscale
libavutil
CFLAGS += -Wall -O2 -g
LDLIBS += -L/usr/local/faac/lib -L/usr/local/lib ##这句为增加的语句
CFLAGS := $(shell pkg-config --cflags $(FFMPEG_LIBS)) $(CFLAGS)
LDLIBS := $(shell pkg-config --libs $(FFMPEG_LIBS)) $(LDLIBS)
EXAMPLES= decoding_encoding
demuxing
filtering_video
filtering_audio
metadata
muxing
resampling_audio
scaling_video
OBJS=$(addsuffix .o,$(EXAMPLES))
# the following examples make explicit use of the math library
decoding_encoding: LDLIBS += -lm
muxing: LDLIBS += -lm
.phony: all clean-test clean
all: $(OBJS) $(EXAMPLES)
clean-test:
$(RM) test*.pgm test.h264 test.mp2 test.sw test.mpg
clean: clean-test
$(RM) $(EXAMPLES) $(OBJS)