基于ffmpeg静态库的应用开发

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)