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• FFMpeg command to merge 1 video and 2 audio files while also reducing volume of one audio

  26 septembre 2022, par UserM

  I need to construct a FFMpeg using amix or any equivalent command to merge 1 video and 2 audio files while also reducing volume of one background music file (ukulele.mp3).
Refer : https://ffmpeg.org/ffmpeg-filters.html#Examples-11

  


  //cmd works with out volume reduction of background music file
anima_buf = ("C:/ffmpeg/bin/ffmpeg -thread_queue_size 8192 -safe 0 -f concat -i %s -t %s -safe 0 -f concat -i %s -i ./music/ukulele.mp3\
-filter_complex amix=inputs=2:duration=shortest -c:v libx264 -profile:v high -crf 20 -pix_fmt yuv420p -y %s" % ( anima_img_file, anima_len, anima_audio_file, anima_opvideo_file))
os.system(anima_buf)
//successful

//cmd to reduce volume of background music
    anima_buf = ("C:/ffmpeg/bin/ffmpeg -thread_queue_size 8192 -safe 0 -f concat -i %s -t %s -safe 0 -f concat -i %s -i ./music/ukulele.mp3\
    -filter_complex amix=inputs=2:duration=shortest:dropout_transition=0:weights="1 0.25":normalize=0 -c:v libx264 -profile:v high -crf 20 -pix_fmt yuv420p -y %s" % ( anima_img_file, anima_len, anima_audio_file, anima_opvideo_file) )
os.system(anima_buf)
                                                                                   
SyntaxError: invalid syntax mentioned at weights="1 0.25"


  


  FFmpeg version :

  


  ffmpeg version 2022-05-23-git-6076dbcb55-full_build-www.gyan.dev Copyright (c) 2000-2022 the FFmpeg developers
built with gcc 11.3.0 (Rev1, Built by MSYS2 project)
configuration: --enable-gpl --enable-version3 --enable-static --disable-w32threads --disable-autodetect --enable-fontconfig --enable-iconv --enable-gnutls --enable-libxml2 --enable-gmp --enable-bzlib --enable-lzma --enable-libsnappy --enable-zlib --enable-librist --enable-libsrt --enable-libssh --enable-libzmq --enable-avisynth --enable-libbluray --enable-libcaca --enable-sdl2 --enable-libdav1d --enable-libdavs2 --enable-libuavs3d --enable-libzvbi --enable-librav1e --enable-libsvtav1 --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid --enable-libaom --enable-libjxl --enable-libopenjpeg --enable-libvpx --enable-mediafoundation --enable-libass --enable-frei0r --enable-libfreetype --enable-libfribidi --enable-liblensfun --enable-libvidstab --enable-libvmaf --enable-libzimg --enable-amf --enable-cuda-llvm --enable-cuvid --enable-ffnvcodec --enable-nvdec --enable-nvenc --enable-d3d11va --enable-dxva2 --enable-libmfx 
--enable-libshaderc --enable-vulkan --enable-libplacebo --enable-opencl --enable-libcdio --enable-libgme --enable-libmodplug --enable-libopenmpt --enable-libopencore-amrwb --enable-libmp3lame 
--enable-libshine --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libilbc --enable-libgsm --enable-libopencore-amrnb --enable-libopus --enable-libspeex --enable-libvorbis --enable-ladspa --enable-libbs2b --enable-libflite --enable-libmysofa --enable-librubberband --enable-libsoxr --enable-chromaprint
libavutil      57. 25.100 / 57. 25.100
libavcodec     59. 28.100 / 59. 28.100
libavformat    59. 24.100 / 59. 24.100
libavdevice    59.  6.100 / 59.  6.100
libavfilter     8. 38.100 /  8. 38.100
libswscale      6.  6.100 /  6.  6.100
libswresample   4.  6.100 /  4.  6.100
libpostproc    56.  5.100 / 56.  5.100


  


  Can someone guide me, thanks in advance

  


• cv::VideoWriter Class Failing to Write Frames to Video File

  23 septembre 2022, par adav0033

  I am attempting to using the OpenCV VideoWriter class to save a two camera video feed to a single video file. I am using the FFMPEG API to ahcieve the desired outcome and am trying to generate an .mkv file with the Fourcc code FFV1 for lossless frame writing. Currently I am expriencing upon launching of the pipeline the file writer is creating a file in the directory specified and upon completion of the pipeline the writer is transformed into a video file .mkv however no frames are being written to said file.
My constructor :

  


  cv::VideoWriter writer(out_vid_name + ".mkv", cv::VideoWriter::fourcc('F','F','V','1'), cam_fps,frame_double_size, true);


  


  Note that cv::Size(3840,1080) = frame_double_size and cam_fps is a param

  


  My video capture :

  


  cv::VideoCapture cap(out_vid_name + ".mkv", cv::CAP_FFMPEG);


  


  and my writer :

  


  while (controller->running && ros::ok()) //Shutdown race condition exists. One thread will have to be SIGTERM'ed
        {
            std::shared_lock guard(doubleSaveFrame->mtx);
            doubleSaveFrame->cond_var.wait(guard, [&]{ return doubleSaveFrame->cond_bool_save; });
            doubleSaveFrame->cond_bool_save = false;
            std_msgs::String msg;
            msg.data = std::to_string(frame_count);
            frame_count++;
            frame_pub.publish(msg);

            writer.write(doubleSaveFrame->getHost());
            cv::Mat frame = doubleSaveFrame->getHost();
            int rows = frame.rows;
            int cols = frame.cols;
            std::cout << "rows: " << std::to_string(rows) << " cols: "<< std::to_string(cols) << std::endl;
            cv::imwrite("home/Documents/camera/imwritefun"+ std::to_string(frame_count) +".JPG", doubleSaveFrame->getHost());
        }
        writer.release();


  


  Note that this code above produced successfully the camera frames to file when cv::imwrite was executed, however the the writer failed to write to video file. I am very new to OpenCV and the associated methods used here, if anyone has an idea on what is causing the issue that would be extremely helpful as research has not prevailed a solution.

  


• Function calling using class() not working when used to add video files with mkvmerge, FFmpeg

  7 septembre 2022, par jiraiya_sensei

  import subprocess
filename = input('file name: ')
track1 = input('file name: ')
track2 = input('file name: ')
outputfile = input('file name: ')


class trial:

    #constructor of trial class
    def __init__(self):
        self.filename =filename
        self.track1 =track1
        self.track2 =track2
        self.outputfile =outputfile

    def mkvmerge(self):
        self.commandlist = [
            "mkvmerge",
            "-o",
            self.outputfile,
            self.track1,
            self.track2,
            self.filename

            ]
        return

    def runmkvmerge(self):
        self.mkvmerge()
        print(self.commandlist)

object = trial()
object.runmkvmerge()


  


  //I learned about the init and class() so I used that to write this code but although it shows no error the script does not work. I am trying to add audio files to a video file using mkvmerge and the command is very simple but strangely it does not work//