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• Moviepy write_videofile changes number of video and audio frames even after using 'rawvideo' as the codec parameter

  14 mars 2019, par Jaideep Sagar

  I am using moviepy (Python) to read video and audio frames of a video and after making some changes I am writing them back to a videofile, say new.avi, to preserve the changes, or to avoid compression, I am using codec= ’rawvideo’ in write_videofile function. But when I read the video and audio frames back, the number of video and audio frames are different than when they were when written, they are usually increased.
  Can anybody tell me the reason, ? is it because of the ffmpeg used or some other reason ? Does it happen always or there is some problem in my machine ? Thank you :-)

• Use Static Library Build Shared Library Undefined Reference

  26 mai 2020, par Leo

  I want to use AndroidStudio ndk-build to build Shared Library on Window with ffmpeg lib but i got Undefined Reference Error,Please tell me what I do wrong

  



  ndkVersion = 21.0.6113669
compileSdkVersion 29

  



  I also try to build By GCC , the same error happen
I also try to build By CMake with ffmpeg SourceCode , the same error happen

  



  I try to build .a file with some simple C Code on gcc and use another C Code to use it,it work,but not with ffmpeg .a file i dont know why

  



  this is my Android.mk

  



  `LOCAL_PATH := $(call my-dir)
 include $(CLEAR_VARS)
 LOCAL_MODULE := avcodec
 LOCAL_SRC_FILES := lib/libavcodec.dll.a
 include $(PREBUILT_STATIC_LIBRARY)

 include $(CLEAR_VARS)
 LOCAL_MODULE := avformat
 LOCAL_SRC_FILES := lib/libavformat.dll.a
 include $(PREBUILT_STATIC_LIBRARY)

 ...

 include $(CLEAR_VARS)
 LOCAL_MODULE := avutil
 LOCAL_SRC_FILES := lib/libavutil.dll.a
 include $(PREBUILT_STATIC_LIBRARY)

 include $(CLEAR_VARS)
 LOCAL_MODULE := libTestDll
 LOCAL_SRC_FILES := TestDll.cpp
 LOCAL_C_MODULE := avcodec avformat swscale avutil avfilter avdevice

 include $(BUILD_SHARED_LIBRARY)`


  



  this is my main cpp

  



  #include &#xA;#include &#xA;&#xA;#define __STDC_CONSTANT_MACROS&#xA;&#xA;#include <string>&#xA;&#xA;extern"C"&#xA;{&#xA;#include "libavformat/avformat.h"&#xA;#include "libavutil/mathematics.h"&#xA;#include "libavutil/time.h"&#xA;#include "libavutil/pixfmt.h"&#xA;#include "libavcodec/avcodec.h"&#xA;#include "libavformat/avformat.h"&#xA;#include "libswscale/swscale.h"&#xA;#include "libavutil/imgutils.h"&#xA;}&#xA;&#xA;using namespace std;&#xA;&#xA;char output[99999];&#xA;int frameCount = 0;&#xA;uint8_t* buf;&#xA;int bufLength;&#xA;uint8_t* p_global_bgr_buffer;&#xA;int num_bytes;&#xA;int wrap;&#xA;bool EndReceFrame = false;&#xA;SwsContext* swsContext;&#xA;AVFrame* pFrame = av_frame_alloc();&#xA;AVCodecContext* pCodecContext;&#xA;AVPixelFormat dstFmt = AV_PIX_FMT_RGB24;&#xA;&#xA;static void BGRpgm_save(AVFrame* frame)&#xA;{&#xA;    int linesize[8] = { frame->linesize[0] * 3 };&#xA;&#xA;    uint8_t* bgr_buffer[8] = { p_global_bgr_buffer };&#xA;&#xA;    sws_scale(swsContext, frame->data, frame->linesize, 0, frame->height, bgr_buffer, linesize);&#xA;&#xA;    memcpy(buf, bgr_buffer[0], linesize[0] * frame->height);&#xA;&#xA;    bufLength = linesize[0] * frame->height;&#xA;&#xA;    frameCount&#x2B;&#x2B;;&#xA;&#xA;}&#xA;...&#xA;&#xA;</string>

  



  Error Message

  



  [x86] SharedLibrary  : libTestDll.so
jni/TestDll.cpp:123: error: undefined reference to 'avformat_open_input'
jni/TestDll.cpp:127: error: undefined reference to 'avformat_find_stream_info'
jni/TestDll.cpp:138: error: undefined reference to 'av_dump_format'
jni/TestDll.cpp:144: error: undefined reference to 'avcodec_find_decoder'
jni/TestDll.cpp:146: error: undefined reference to 'avcodec_alloc_context3'


  


• FFMPEG Combining images to video and streaming in one command line

  12 juillet 2017, par Brindha Kanniah

  Currently, using ffmpeg, I am using two commands on my Terminal to :

  1) create a video from a bunch of images :

  ffmpeg -r 60 -f image2 -s 1920x1080 -i rotated-pano_frame%05d_color_corrected_gradblend.jpg -vcodec libx264 -crf 25 -pix_fmt yuv420p test.mp4

  2) stream the video to a udp address :

  ffmpeg -re -i test.mp4 -c copy -f flv udp://127.0.0.1:48550

  How can I combine these two commands, into one single ffmpeg command ?

  A concern I have is that it takes a couple of minutes to generate the video from the images. Therefore, these commands have to happen serially, whereby the second command waits a few minutes for the first command to be completed, before it ensues.