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• FFMPEG : undefined reference to `avcodec_register_all' does not link

  30 juin 2014, par Belov

  So I have a very sample code for trying to decode a FFMPEG video stream.
  My problem is avcodec does not want to link, to do so I made a clean installation of Ubuntu 13.04. I have build ffmpeg from source following the guide here : https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu

  I just want to compile my file. Note that my ubuntu does not have any implementations or header files for avcodec. The command line I use is :

  gcc -I/home/USER/ffmpeg_build/include -L/home/USER/ffmpeg_build/lib -lavcodec -o test.exe Downloads/auv/src/dronerosvideo/src/ar2.cpp

  /tmp/ccKTprFq.o : In function `fetch_and_decode(int, int, bool)’ :

  ar2.cpp :(.text+0x36e) :
  undefined reference to `avcodec_register_all’

  ar2.cpp :(.text+0x378) :
  undefined reference to `av_log_set_level’

  ar2.cpp :(.text+0x382) :
  undefined reference to `avcodec_find_decoder’

  ar2.cpp :(.text+0x3b1) :
  undefined reference to `avcodec_alloc_context3’

  ar2.cpp :(.text+0x3d6) :
  undefined reference to `avcodec_open2’

  ar2.cpp :(.text+0x46d) :
  undefined reference to `av_init_packet’

  ar2.cpp :(.text+0x50a) :
  undefined reference to `avcodec_decode_video2’

  ar2.cpp :(.text+0x534) :
  undefined reference to `av_free_packet’

  /tmp/ccKTprFq.o :(.eh_frame+0x13) : undefined reference to
  `__gxx_personality_v0’

  collect2 : error : ld returned 1 exit status

  Just for a sane test if I remove the -L argument compiler says :

  /usr/bin/ld: cannot find -lavcodec

  Which means that the linker finds the library in /home/USER/ffmpeg_build/lib. Also if we check the library for implementation it exists :

  nm ffmpeg_build/lib/libavcodec.a | grep "register_all"
  
  0000000000000000 T avcodec_register_all

  Also as advised since it is C++ I have exten "C" around the include of the library.

  At this point I’m falling out of any ideas at all, why exactly compilation fails ?

• FFmpeg Loop Streaming

  21 septembre 2022, par Dan

  I'm trying to run a stream on YouTube with a video that loops 24/7, using FFmpeg 4.4 from a server with Ubuntu 22, it works but I'm loosing the "Live" red light on YouTube, and here is the message from the "Stream health" tab :

  


  "YouTube is not currently receiving data for this stream. If you believe this is incorrect, ensure you’re sending a stream and that it is configured with the correct stream key."

  


  Here's the script I made :

  


  
VBR="1500k" 
FPS="24" 
QUAL="superfast" 

YOUTUBE_URL="rtmp://a.rtmp.youtube.com/live2" 
SOURCE="/home/ubuntu/Video.mp4" 
KEY="mykey" 
ffmpeg \
-stream_loop -1 -i "$SOURCE" -deinterlace \
-vcodec libx264 -pix_fmt yuv420p -preset $QUAL -r $FPS -g $(($FPS * 2)) -b:v $VBR \
-acodec libmp3lame -ar 44100 -threads 6 -qscale 3 -b:a 712000 -bufsize 512k \
-f flv "$YOUTUBE_URL/$KEY"


  


  Any help would be appreciated.
Thanks.

  


• Delay/Lag in OpenCV VideoCapture

  18 mars 2021, par user244791

  I'm trying to read an rtsp stream from an ip camera using opencv's VideoCapture Class on Ubuntu 20.04 with opencv 4.5. There is a lag in the video on ubuntu but none when I run the same code on a windows 10 machine.

  


  cap.set(cv2.CAP_PROP_BUFFERSIZE, size) returns false and the cameras default buffer size does not change.

  


  cap = cv2.VideoCapture("rtsp://admin:@dmin123@192.168.1.64")
while (cap.isOpened()):
    ret, frame = cap.read()
    cv2.imshow("Live", frame)
    if cv2.waitKey(1) & 0xFF == ord('q'): #press q to quit
        break
cap.release()


  


  The stream works well when I play it using ffplay with the following parameters :

  


  '''ffplay -fflags nobuffer -flags low_delay -tune zerolatency -framedrop -rtsp_transport tcp "rtsp ://192.168.1.64"'''

  


  Need help on how to reduce/handle the lag in my code.