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• av_interleaved_write_frame return 0 but no data written

  11 août 2015, par Jerikc XIONG

  I use the ffmpeg to stream the encoded aac data , i use the

  av_interleaved_write_frame()

  to write frame.

  The return value is 0,and it means success as the description.

  Write a packet to an output media file ensuring correct interleaving.

  The packet must contain one audio or video frame. If the packets are already correctly interleaved, the application should call av_write_frame() instead as it is slightly faster. It is also important to keep in mind that completely non-interleaved input will need huge amounts of memory to interleave with this, so it is preferable to interleave at the demuxer level.

  Parameters

  s media file handle

  pkt The packet containing the data to be written. pkt->buf must be set to a valid AVBufferRef describing the packet data. Libavformat takes ownership of this reference and will unref it when it sees fit. The caller must not access the data through this reference after this function returns. This can be NULL (at any time, not just at the end), to flush the interleaving queues. Packet’s stream_index field must be set to the index of the corresponding stream in s.streams. It is very strongly recommended that timing information (pts, dts duration) is set to correct values.

  Returns

  0 on success, a negative AVERROR on error.

  However, I found no data written.

  What did i miss ? How to solve it ?

• opencv V3 mixing shared and non shared

  31 décembre 2015, par Kellerspeicher

  The current stable (V3.0.0) and unstable (V3.1.0) version of openCV is mixing shared and non shared libraries if compiled on an Ubuntu 14.04.3 LTS.

  Linking CXX shared library ../../lib/libopencv_videoio.so
  
  /usr/bin/ld: /usr/local/lib/libavcodec.a(avpacket.o): relocation R_X86_64_32 against `.rodata.str1.1' can not be used when making a shared object; recompile with -fPIC
  
  /usr/local/lib/libavcodec.a: error adding symbols: Bad value
  
  collect2: error: ld returned 1 exit status
  
  make[2]: *** [lib/libopencv_videoio.so.3.1.0] Error 1
  
  make[1]: *** [modules/videoio/CMakeFiles/opencv_videoio.dir/all] Error 2
  
  make: *** [all] Error 2

  Trying to create libopencv_videoio.so using libavcodec.a seems to be the problem. There is a bug report about that, but it is only giving the advice to check if libavcodec.so is installed (which is) and a workaround to use -DBUILD_SHARED_LIBS=OFF to prevent creation of shared libraries. Does anyone knows the reason for this problem. The openCV people just state the Ubuntu packaged ffmpeg library to be not correct. Any idea ?

  The problem seems to be old. I just found a very similar question not answered but commented with the advice of compiling ffmpeg with ./configure --enable-shared. But there is already a shared library /usr/lib/x86_64-linux-gnu/libavcodec.so which obviously is not found. I am not a cmake expert but couldn’t it be a problem of a miss leaded build process ?

• How to speed up ffmpeg video conversion

  22 avril 2018, par user2993497

  ffmpeg -i video.mp4 -c:v libvpx-vp9 -keyint_min 150 -g 150 -tile-columns 4 -frame-parallel 1  -f webm -dash 1 -an -vf scale=160:190 -b:v 250k -dash 1 video_160x90_250k.webm -an -vf scale=320:180 -b:v 500k -dash 1 video_320x180_500k.webm -an -vf scale=640:360 -b:v 750k -dash 1 video_640x360_750k.webm -an -vf scale=640:360 -b:v 1000k -dash 1 video_640x360_1000k.webm -an -vf scale=1280:720 -b:v 1500k -dash 1 video_1280x720_1500k.webm

  I’m converting a single video into multiple videos at different resolutions. But it’s painfully slow. how can I speed this up ?