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• ffmpeg video recording hangs in Emacs

  3 mars, par Nutritioustim

  A. Using ffmpeg, both of these audio and video captures work correctly in a shell.

  


  # Audio
ffmpeg -y -f avfoundation -t 5 -i :0 -c:a aac audio-recording.m4a

# Video
# i. video only
# ii. audio & video
ffmpeg -y -f avfoundation -framerate 30 -i 0 -t 10 -c:v libx264 -preset fast -pix_fmt yuv420p video-recording.mp4
ffmpeg -y -f avfoundation -framerate 30 -pixel_format "uyvy422" -i 0:0 -t 10 -c:v libx264 -preset fast -pix_fmt yuv420p audio-video-recording.mp4


  


  B. In Emacs (29.4, "Emacs For Mac OS X"), this audio code block completes, and prints the successful callback message ffmpeg-audio , finished.

  


  # Audio, completes successfully
(setq ffmpeg-record--process
      (apply 'start-process "ffmpeg-audio" "*ffmpeg-recording*"
             (list "ffmpeg" "-y" "-f" "avfoundation" "-i" ":0" "-t" "10" "-c:a" "aac" "audio-recording.m4a")))

(set-process-sentinel
 ffmpeg-record--process
 (lambda (process event)
   (message "%s , %s" process event)))


  


  But the video code block hangs, and does not complete with any output message.

  


  # Video, hangs after an initial message
(setq ffmpeg-record--process
      (apply 'start-process "ffmpeg-video" "*ffmpeg-recording*"
             (list "ffmpeg" "-y" "-f" "avfoundation" "-framerate" "30" "-pixel_format" "uyvy422" "-i" "0:none" "-t" "10" "-c:v"
                   "libx264" "-preset" "fast" "-pix_fmt" "yuv420p" "video-recording.mp4")))
(set-process-sentinel
 ffmpeg-record--process
 (lambda (process event)
   (message "%s , %s" process event)))


  


  C. Running diagnostics on the ffmpeg-record--process variable shows the process is still running even after the 10 second duration (-t 10) is long over.

  


  (message "Process: %s, PID: %s, Status: %s"
         (process-name ffmpeg-record--process)
         (process-id ffmpeg-record--process)
         (process-status ffmpeg-record--process))


  


  D. Presumably, it is start-process that is not properly handling the invocation.

  


  But why then is the ffmpeg video invocation hanging, only in Emacs (not in the shell)... when the (Emacs) audio invocation completes fine ?

  


• errors of 'vaGetDisplay' and `vaGetDisplayDRM'

  30 août 2016, par Kindermann

  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 !

• Why does ffmpeg return "No such file or directory"

  4 juillet 2020, par JackNewman

  I'm trying to split a video file into 2 second increments and then merge the video back together.

  


  source_vid_path = r"C:\SplitAndMergeVids\Before\before.mp4"
ffcat_path = r'C:\SplitAndMergeVids\Chunk\video.ffcat'
chunks_path = r'C:\SplitAndMergeVids\Chunk\chunk-%03d.mp4'
segments_time = '2'
cmd_input = rf'ffmpeg -fflags +genpts -i {source_vid_path} -map 0 -c copy -f segment -segment_format mp4 -segment_time {segments_time} -segment_list {ffcat_path} -reset_timestamps 1 -v error {chunks_path}'
output = str(subprocess.run(cmd_input, shell=True, capture_output=True))
print(output)

output_path = r'C:\SplitAndMergeVids\Output\output.mp4'
second_input = rf'ffmpeg -y -v error -i {ffcat_path} -map 0 -c copy {output_path}'
output = str(subprocess.run(second_input, shell=True, capture_output=True))
print(output)


  


  First subprocess runs perfectly although the second outputs returns

  


  "Impossible to open 'chunk-000.mp4'\r\nC:\\SplitAndMergeVids\\Chunk\\video.ffcat: No such file or directory".


  


  Full output looks like

  


  CompletedProcess(args='ffmpeg -fflags +genpts -i C:\\SplitAndMergeVids\\Before\\before.mp4 -map 0 -c copy -f segment -segment_format mp4 -segment_time 2 -segment_list C:\\SplitAndMergeVids\\Chunk\\video.ffcat -reset_timestamps 1 -v error C:\\SplitAndMergeVids\\Chunk\\chunk-%03d.mp4', returncode=0, stdout=b'', stderr=b'')
CompletedProcess(args='ffmpeg -y -v error -i C:\\SplitAndMergeVids\\Chunk\\video.ffcat -map 0 -c copy C:\\SplitAndMergeVids\\Output\\output.mp4', returncode=1, stdout=b'', stderr=b"[concat @ 0000028691a6c6c0] Impossible to open 'chunk-000.mp4'\r\nC:\\SplitAndMergeVids\\Chunk\\video.ffcat: No such file or directory\r\n")


  


  When I run cmd_input and second_input manually in cmd, everything functions perfectly. I don't understand how in the first command I am making a file at "ffcat_path", then in the second command I'm using the same "ffcat_path" and it returns "No such file or directory" when it certainly does exist.