[FFmpeg-user] Weird issue when to link libraries of ffmpeg.

[stanley zhang]

I just tried and it worked through adjusting the order of the libraries.

Thanks  a lot, Pavel.

Stanley



On Sat, May 25, 2013 at 7:39 PM, Pavel Koshevoy <pkoshevoy at gmail.com> wrote:

> On 5/24/13 6:30 PM, stanley zhang wrote:
>
>> Hi, All,
>>
>> I want to  build myself application based on ffmpeg libraries. What I did
>> are very simple:
>> (1) Configure, build and install latest ffmpeg;
>> (2) Copy ffplay.c (changed to play.c), cmdutils.c, config.h,
>> cmdutils_common_opts.h,  and cmdutils.h from the parent directory of
>> ffmpeg
>> to my self directory.
>> (3) Create a simple Makefile as the followings:
>> all: play
>> play:play.c cmdutils.c
>>      gcc -o play play.c cmdutils.c -lSDL -lavcodec -lavformat -lavutil
>> -lswscale -lavfilter -lpostproc -lswresample
>>
>> (4) Build it. The errors can be met as the followings:
>>     ~/fftest/play$ make
>> gcc -o play play.c cmdutils.c -lSDL -lavcodec -lavformat -lavutil
>> -lswscale
>> -lavfilter -lpostproc -lswresample
>> /usr/local/lib/libavfilter.a(**buffersink.o): In function
>> `read_from_fifo':
>> /home/stanley/ffmpeg/**libavfilter/buffersink.c:166: undefined reference
>> to
>> `av_audio_fifo_read'
>> ...(Some other logs are omitted)
>>
>> But I am sure the right libraries are linked and the function
>> "read_from_fifo" are defined in the library libavutil.a:
>> stanley at stanley-P31-ES3G:~/**fftest/play$ objdump
>> /usr/local/lib/libavutil.a
>> -t |grep av_audio_fifo_size
>> 00000480 g     F .text    00000008 av_audio_fifo_size
>> stanley at stanley-P31-ES3G:~/**fftest/play$ objdump
>> /usr/local/lib/libavfilter.a -t|grep av_buffersink_get_samples
>> 00000790 g     F .text    000001d3 av_buffersink_get_samples
>>
>> It seems not to be version issue.
>>
>>
>>
> You are linking to static libraries, therefore the order in which you link
> to each library matters.  avfilter probably depends on avutil, so try
> putting -lavutil after -lavfilter
>
> Pavel.
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