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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

• MAC's "say" command to MP3 [closed]

  15 juin 2023, par Oussama L.

  I want to read a very long text with the SAY mac's command (say -f file.txt), and to record the output to file.mp3. I thought about using ffmpeg to record all of it, but then i'll need to wait for all the reading process to complete..

  



  I don't really need to listen to it, so if there is a way to directly have an mp3 file just by hitting enter, it would be great..

  



  There is also this project txt2mp3mac but i can't use it in a shell script..

  



  Thanks..

  


• Extracting sound from videos using subprocess and ffmpeg

  19 décembre 2019, par NoLand'sMan

  I am trying to extract a .wav file from a .mp4 file using the following code :

  import subprocess
  
  import ffmpeg
  
  
  
  command = "ffmpeg -i afoomtx.mp4 -ab 160k -ac 2 -ar 44100 -vn audio.wav"
  
  
  
  subprocess.call(command, shell=True)

  The only output I get is 127. What am I doing wrong ?