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• Trouble linking ffmpeg example source code

  30 janvier 2012, par Leonard Teo

  I managed to build ffmpeg and libx264 on my Ubuntu 11.10 machine from source.

  I'm trying to work on the example source file decoding_encoding.c. The examples comes with a makefile, so I can just type in "make all" and it magically compiles and links everything. Now, I'm trying to compile and link from the command line but I can't seem to get it to link.

  Here is the makefile :

  # use pkg-config for getting CFLAGS abd LDFLAGS
  
  FFMPEG_LIBS=libavdevice libavformat libavfilter libavcodec libswscale libavutil
  
  CFLAGS+=$(shell pkg-config  --cflags $(FFMPEG_LIBS))
  
  LDFLAGS+=$(shell pkg-config --libs $(FFMPEG_LIBS))
  
  
  
  EXAMPLES=decoding_encoding filtering metadata muxing
  
  
  
  OBJS=$(addsuffix .o,$(EXAMPLES))
  
  
  
  %: %.o
  
          $(CC) $< $(LDFLAGS) -o $@
  
  
  
  %.o: %.c
  
          $(CC) $< $(CFLAGS) -c -o $@
  
  
  
  .phony: all clean
  
  
  
  all: $(OBJS) $(EXAMPLES)
  
  
  
  clean:
  
          rm -rf $(EXAMPLES) $(OBJS)

  I can compile the source using this :

  gcc -Wall -I/usr/local/include -c -o decoding_encoding.o decoding_encoding.c

  When I try to link using this :

  gcc -Wall -L/usr/local/lib -lavdevice -lavformat -lavfilter -lavcodec -lswscale -lavutil -o decoding_encoding decoding_encoding.o

  At this point, I get a huge list of 'undefined reference error'

  decoding_encoding.o: In function `audio_encode_example':
  
  decoding_encoding.c:(.text+0x25): undefined reference to `avcodec_find_encoder'
  
  decoding_encoding.c:(.text+0x6a): undefined reference to `avcodec_alloc_context3'
  
  decoding_encoding.c:(.text+0xad): undefined reference to `avcodec_open'
  
  decoding_encoding.c:(.text+0x1ce): undefined reference to `sin'
  
  decoding_encoding.c:(.text+0x238): undefined reference to `avcodec_encode_audio'
  
  decoding_encoding.c:(.text+0x297): undefined reference to `avcodec_close'
  
  decoding_encoding.c:(.text+0x2a3): undefined reference to `av_free'
  
  decoding_encoding.o: In function `audio_decode_example':
  
  decoding_encoding.c:(.text+0x2f7): undefined reference to `av_init_packet'
  
  decoding_encoding.c:(.text+0x30b): undefined reference to `avcodec_find_decoder'
  
  decoding_encoding.c:(.text+0x359): undefined reference to `avcodec_alloc_context3'
  
  decoding_encoding.c:(.text+0x379): undefined reference to `avcodec_open'
  
  ..... etc.
  
  collect2: ld returned 1 exit status

  Am I doing something wrong with my linker command ? I've examined the makefile and I believe that I'm doing exactly what the makefile is....or am I ?

  Thanks,

  Leo

• ffmpeg : move non monotone prevention code down

  3 mai 2013, par Michael Niedermayer

  ffmpeg : move non monotone prevention code down
  This moves the code to after the bitstream filters
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] ffmpeg.c

• Hello i need a some istructions to use ffmpeg, I would like a code to get media file info

  16 juillet 2014, par user3547175

  I want to start by saying that i don’t know how to use FFMPEG in C#. I have a program that reads the information of a media file, I use this code about resolution, bitrate

  var player = new WindowsMediaPlayer();
  
  var clip = player.newMedia(file.FullName);
  
  lblLenght_.Text = (TimeSpan.FromSeconds(clip.duration)).ToString();       
  
  
  
  
  
  
  
  ShellFile shellFile = ShellFile.FromFilePath(file.FullName);
  
  lblFPS_.Text = (shellFile.Properties.System.Video.FrameRate.Value / 1000).ToString();
  
  
  
  lblHeight_.Text = shellFile.Properties.System.Video.FrameHeight.Value.ToString() + " px";
  
  lblWidth_.Text = shellFile.Properties.System.Video.FrameWidth.Value.ToString() + " px";
  
  lblResolution_.Text = shellFile.Properties.System.Video.FrameWidth.Value.ToString() + "x" + shellFile.Properties.System.Video.FrameHeight.Value.ToString() + " px";
  
  blBitrate_.Text = (shellFile.Properties.System.Video.TotalBitrate.Value / 1000).ToString() + " kb/s";

  but the problem is that ShellFile supports only a few formats, so I found some FFMPEG uses but I don’t know how to work with it. Can someone post the solution or some link to learn how to use it about my problem ?