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• ‘undefined reference to xxxxx’ , 'check the directory for the files' it does not work

  26 décembre 2011, par sirupa

  Merry Christmas, everybody,

  I’m coding ffmpeg with gcc.

  But, on the build process, I met the errors of ‘undefined reference to xxxxx’ for all functions that I coded in my program, and I recognized that it was due to the libxxx.a file.

  And the every adviser on internet suggested that check the directory for the files.

  So, I searched the files in which include the function names in my computer, and I found the .a files are correctly set in the directory which I coded.

  And there are the other files which are named ‘libxxx.dll.a’, so I tried to build with the files ‘libxxx.dll.a’, but I got the same result.

  On this point, I have got some questions.

  1) If the gcc could not find the libxxx.a files, it would say that ‘cannot find the –lxxx’. But it just said ‘undefined reference to xxxx’. It means that those libxxx.a files are in the correct directories.

  2) And if the files do not define the functions, it is strange. Because those files include the function names and are the same files/directories I had searched in my computer, and I think it should have the definitions of the functions. But I am not sure that the files define the functions or not, because I cannot read the file myself.

  If I am wrong, what was my mistake?

  3) Can libxxxlib.a files be replaced with the libxxx.a? And if it can, what is the difference between libxxxlib.a and libxxx.a? And the same for the libz and libzlib?a

  Here is my line commend, the directory which include the libxxx.a files.

  g++ -o C:\ffmpeg\ffmpegTest C:\ffmpeg\ffmpegTest.cc -IC:\ffmpeg -LC:\ffmpeg\3rdparty\lib -lavutil -lavformat -lavcodec -lz -lavutil -lm -D__STDC_CONSTANT_MACROS

  C:\ffmpeg\3rdparty\lib

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0xec>: undefined reference to 'av_register_all()'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x11c>: undefined reference to 'av_open_input_file(AVFormatContext*, char const, AVInputFormat*, int, AVFormatParameters*)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x13b>: undefined reference to 'av_find_stream_info(AVFormatContext*)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x174>: undefined reference to 'dump_format(AVFormatContext, int, char const*, int)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x224>: undefined reference to 'avcodec_find_decoder(CodecID)'

  and all the errors are

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x281>: undefined reference to 'avcodec_open(AVCodecContext*, AVCodec)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x297>: undefined reference to 'avcodec_alloc_frame()'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x2a3>: undefined reference to 'avcodec_alloc_frame()'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x2e6>: undefined reference to 'avpicture_get_size(PixelFormat,int,int)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x2fc>: undefined reference to 'av_malloc(unsigned int)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x341>: undefined reference to 'avpicture_fill(AVPicture*, unsigned char*, PixelFormat, int, int)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x38c>: undefined reference to 'avcodec_decode_video2(AVCodecContext, AVFrame*, int, AVPacket*)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x409>: undefined reference to 'sws_getContext(int, int, PixelFormat, int, int, PixelFormat, int, SwsFilter*, swsFilter*, double const*)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x463>: undefined reference to 'sws_scale(SwsContext*, unsigned char const* const*, int const*, int, int, unsigned char* const*, int const*)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x4bb>: undefined reference to 'av_free_packet(AVPacket*)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x4cf>: undefined reference to 'av_read_frame(AVFormatContext, AVPacket*)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x36c>: undefined reference to 'av_free(void*)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x36c>: undefined reference to ' avcodec_close(AVCodecContext*)'

  C:\Users\AppData\Local\Temp\ccVHLzjK.o:ffmpegTest.cc:<.text+0x36c>: undefined reference to 'av_close_input_file(AVFormatContext)'

• Should I buy ffmpeg ? [closed]

  25 décembre 2011, par Matt

  I work for a online-video company, and looking for some tools to convert wmv/mkv/avi and so on to mp4. I know ffmpeg can do this. Should I buy it in thes condition?

  thanks.

• command for ffmpeg encode h264 baseline profile level 1

  25 décembre 2011, par Morteza M.

  Can anyone suggest a command to encode video to h264 baseline profile ( level 1)?

  Here is a link for reference: http://blog.mediacoderhq.com/h264-profiles-and-levels/

  I used this command but ffmpeg says it is Main profile not baseline.

  ffmpeg -i  -vcodec libx264 -coder 0 -flags +loop+mv4 \
  -partitions +parti4x4+parti8x8+parti4x4+partp8x8+partb8x8 -me_method hex -subq 7 \
  -trellis 1 -refs 5 -bf 0 -flags2 +mixed_refs -coder 0 -me_range 16 -threads 2 \
  -s 240x160 -b:v 64k -g 250 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 \
  -qmin 10 -qmax 51 -qdiff 4 -strict experimental -acodec aac -ac 1 -ab 48000 \
  -f mpegts udp://127.0.0.1:10006?pkt_size=1316
  

• Downloading and Uploading FFmpeg [closed]

  24 décembre 2011, par user705339

  I have a Windows OS for development, and a Linux server. I downloaded ffmpeg on my Windows, configured everything, and uploaded the application. The video conversion didn't work. After extensive hours figuring out the culprit, I realized that I downloaded the ffmpeg for Windows, and need to download the Linux version. That seemed harder than downloading the Windows version. I have scoured the net, and have come up with squat

  So, my 2 questions are:

  1. Is there an easy way to download/install the linux version of ffmpeg? OR
  2. Is there an easier way to install it straight on the server?

  If it matters, I also have a Linux OS development, but found it hard to install ffmpeg on it anyway.

  Update: After trying apt-get install ffmpeg on my Ubuntu Linux OS, it says it has already been installed. How do I locate what folder it's located?

• mpeg decoding using ffmpeg [closed]

  23 décembre 2011, par shree

  I am working on decoding mpeg video into frames say I,P,B frames. Can anyone suggest me how to do it.

  I am currently using ffmpeg lib to decode. Is it possible to get the frames using ffmpeg. Please suggest me how to do it using c++