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• FFmpeg crop portrait video 1:1 from the top based on dynamic value

  8 avril 2022, par hugger

  I am replacing my video editing component with FFmpeg. So far it has been smooth until getting to this point where I need to crop my vertical (portrait) video to 1080x1080 with a dynamic value.

  


  Essentially, I built a custom component to do the cropping, where I can pan a square box over the video. the Y value for the pan is where I wish to cut the top part of the video.

  


  Here is the code I have tried, which works but is not cropping to my desired specs note : offsetDiff is the space I wish to remove from the top (pan px value) :

  


    cropSelected() {
    const diff =
      this.props.videoHeight / (this.state.aspectRatio * deviceWidth);
    const offsetDiff = this.state.offsetTopTranslate * diff;

    var path =
      this.props.type === 'photo'
        ? RNFS.DocumentDirectoryPath + '/after.png'
        : RNFS.DocumentDirectoryPath + '/after.mp4';

    var filterPath =
      this.props.type === 'photo'
        ? RNFS.DocumentDirectoryPath + '/afterFilter.png'
        : RNFS.DocumentDirectoryPath + '/afterFilter.mp4';

    FFmpegKit.execute(
      `-y -i ${path} -vf "crop=iw:1080:0:${offsetDiff}, scale=1080:1080" -qscale 0 ${filterPath}`,
    ).then(async session => {
      const returnCode = await session.getReturnCode();
      if (ReturnCode.isSuccess(returnCode)) {
        // SUCCESS
        this.setState({
          mediaSource:
            this.props.type === 'video'
              ? `file://${filterPath}?${new Date().getTime()}`
              : filterPath,
          isOpen: !this.state.isOpen,
          ffMPEGinProgress: null,
          aspectRatio: 1080 / 1080,
        });
      } else if (ReturnCode.isCancel(returnCode)) {
        // CANCEL
      } else {
        // ERROR
        alert('error');
      }
    });
  }


  


  Basically here I am trying to tell FFmpeg to keep the width (1080), make the height 1080, ignore X value, crop dynamic amount from the top.

  


  Here is what my cropper component looks like to get an idea.

  


  

  


  I appreciate any help I can get here folks, cheers !

  


• Adding FFmpeg library as dependency in Visual studio project to get rid of LNK2019 error

  13 mars 2019, par MSD Paul

  While compiling a project on Microsoft visual studio (to generate dll), I am getting the following linking errors (LNK2019)

  Severity Code Description Project File Line Suppression State
  Error LNK2019 unresolved external symbol av_strerror referenced in function "private : void __cdecl DecoderFFmpeg::printErrorMsg(int)" (?printErrorMsg@DecoderFFmpeg@@AEAAXH@Z)
  Severity Code Description Project File Line Suppression State
  Error LNK2019 unresolved external symbol av_get_channel_layout_nb_channels referenced in function "private : int __cdecl DecoderFFmpeg::initSwrContext(void)"

  several other functions like av_dict_set, av_dict_free, avcodec_decode2 which is related to the ffmpeg libraries. Can anyone please tell me how to properly add "ffmpeg" as dependenciesto this project and link it properly ?

• avutil/eval : Use even better PRNG

  2 janvier 2024, par Michael Niedermayer

  avutil/eval : Use even better PRNG
  This is the 64bit version of Chris Doty-Humphreys SFC64
  Compared to the LCGs these produce much better quality numbers.
  
  Compared to LFGs this needs less state. (our LFG has 224 byte
  
  state for its 32bit version) this has 32byte state
  
  Also the initialization for our LFG is slower.
  
  This is also much faster than KISS or PCG.
  This commit replaces the broken LCG used before.
  
  (broken as it had only a period 200M due to being put in a double)
  This changes the output from random() which is why libswresample.mak
  
  is updated, update was done using the command in libswresample.mak
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavutil/eval.c
  • [DH] libavutil/sfc64.h
  • [DH] tests/fate/libswresample.mak
  • [DH] tests/ref/fate/eval