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• Using ffplay as a C++ library ?

  20 janvier 2024, par Victor M

  I want to be able to use the functionality of ffplay as a C++ library, as opposed to a standalone command line tool. Right now in C++, I am able to call ffplay via std::system, but this isn't ideal for performance as is documented extensively here, chief of which is simply that we need to spawn new shell processes in order to execute this.

  


  My application attempts to feed in a bytestream of audio data to a media player. Running a command like cat /tmp/f.mp3 | ffplay -v 0 -nodisp -autoexit - runs smoothly but somewhat slowly/not instantaneously. I would ideally like to be able pass in a bytestream to an ffplay function or via some library that I can link directly to my application. I think ffplay is quite useful here, as it integrates ffmpeg and SDL together.

  


  Is this possible at all ? Or is the only hope to use the command line functionality ?

  


• ffplay - error seeking

  23 février 2018, par francis

  I was trying to get top video and bottom audio waveform. However i couldn’t scrub/seek back and forth with left/right mouse. A normal ffplay command works for seeking.

  I got the error while seeking in my shell running :

  Example1

  ffplay -f lavfi \
  
  "amovie=abc.mp4, asplit [a][out1]; [a]showvolume=f=255:b=2:w=720:h=68 [av]; \
  
  movie=abc.mp4, split [v][out2]; [v]scale=720x360[vs]; [vs][av]vstack=2"

  Example2

  ffplay -f lavfi \
  
  "amovie=abc.mp4, asplit [waves][out1]; [waves]pan=1c|c0=c0,showwaves=s=720x100[av]; \
  
  movie=abc.mp4, split [v][out2]; [v]scale=720x360[vs]; [vs][av]vstack=2"

• errors of 'vaGetDisplay' and `vaGetDisplayDRM' [duplicate]

  29 novembre 2018, par Kindermann

  This question already has an answer here :

  • errors when compiling c code with ffmpeg library
    
    1 answer
    

  After updating my ubuntu OS from 14.04 to 16.04, I installed the ffmpeg library using the following configurations :

  PATH="$HOME/bin:$PATH" PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure \
  
    --prefix="$HOME/ffmpeg_build" \
  
    --pkg-config-flags="--static" \
  
    --extra-cflags="-I$HOME/ffmpeg_build/include" \
  
    --extra-ldflags="-L$HOME/ffmpeg_build/lib" \
  
    --bindir="$HOME/bin" \
  
    --enable-gpl \
  
    --enable-libass \
  
    --enable-libfdk-aac \
  
    --enable-libfreetype \
  
    --enable-libmp3lame \
  
    --enable-libopus \
  
    --enable-libtheora \
  
    --enable-libvorbis \
  
    --enable-libvpx \
  
    --enable-libx264 \
  
    --enable-nonfree
  
  PATH="$HOME/bin:$PATH" make
  
  make install

  It seemed to me the installation process was ok. After that, I tried to compile my own C source code with the following Makefile :

  EDITTED(adding -lva-drm -lva-x11 at line 10)

  FFMPEG_LIBS=    libavdevice                        \
  
                  libavformat                        \
  
                  libavfilter                        \
  
                  libavcodec                         \
  
                  libswresample                      \
  
                  libswscale                         \
  
                  libavutil                          \
  
  
  
  TARGET = video_analysis
  
  LIBS = -lva -lX11 -lvdpau -lm -lva-drm -lva-x11
  
  CC = gcc
  
  CFLAGS += -O2 -g -O0
  
  CFLAGS := $(shell pkg-config --cflags $(FFMPEG_LIBS)) $(CFLAGS)
  
  LDLIBS := $(shell pkg-config --libs $(FFMPEG_LIBS)) $(LDLIBS)
  
  
  
  .PHONY: default all clean
  
  
  
  default: $(TARGET)
  
  all: default
  
  
  
  OBJECTS = $(patsubst %.c, %.o, $(wildcard *.c))
  
  HEADERS = $(wildcard *.h)
  
  
  
  %.o: %.c $(HEADERS)
  
          $(CC) $(CFLAGS) -c $< -o $@
  
  
  
  .PRECIOUS: $(TARGET) $(OBJECTS)
  
  
  
  $(TARGET): $(OBJECTS)
  
      $(CC) $(OBJECTS) $(LDLIBS) $(LIBS) -o $@
  
  
  
  clean:
  
      -rm -f *.o
  
      -rm -f $(TARGET)

  However, my compiler complained the following errors :

  /root/ffmpeg_build/lib/libavutil.a(hwcontext_vaapi.o): In function `vaapi_device_create':
  
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:896: undefined reference to `vaGetDisplay'
  
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:917: undefined reference to `vaGetDisplayDRM'
  
  collect2: error: ld returned 1 exit status
  
  Makefile:30: recipe for target 'video_analysis' failed
  
  make: *** [video_analysis] Error 1

  My question is : in which library do ’vaGetDisplay’ and `vaGetDisplayDRM’ exist ? It’s for sure that libva functions properly. I have no clue how to fix the bugs...Thank you in advance !