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• How to setup live video stream from webcam to the server, and then beyond ? [closed]

  15 mai 2020, par Parth Sarthi

  I have an application, that is written in Node and Nuxt, to host online exams. My clients are now demanding youtube like livestream for their students. I can't use WebRTC because there will be thousands of students watching the live video, so I don't think teacher's bandwidth will be able to deliver that.

  



  Now I want to know what other options do I have ? How do I send video stream from teacher's laptop to the server in real time ? I am assuming getUserMedia ? Then how do I convert the live stream incoming from the teacher into something like HLS ? I am assuming ffmpeg ? but what commands will do that actually ? cause i can't seem to find any which will take in Media Stream and convert it into HLS. And lastly how do I server it back to the students.

  



  I have already setup the live chat for every classroom with socket.io so I am stuck here.

  


• How to convert mo4 to mp3 in android java ?

  3 août 2023, par Akshit

  I have the mp4 link of a video but don't have a link for the mp3 version of that mp4 video. So is there any way that I can convert that mp4 video to mp3 in Android ? I saw some resources but nothing works for me. I have two ways in which I believe this can be achieved

  


  

  1. Convert the mp4 link to mp3 directly. ( Not Sure if this is achievable )

  


  2. Download the mp4 on the device with the help of a link and then use some code to convert that mp4 to mp3.

  


  


  I also tried some solutions which are available online

  


  https://github.com/tanersener/mobile-ffmpeg

  


  I tried the above library to achieve the final goal. But got Async command execution failed with returnCode=1. This error in the code I am using is

  


      private class Mp4ToMp3ConverterTask extends AsyncTask {

    @Override
    protected String doInBackground(String... params) {
        String mp4FilePath = params[0];
        String mp3OutputPath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/output.mp3";

        String[] ffmpegCommand = {"-i", mp4FilePath, "-vn", "-ar", "44100", "-ac", "2", "-b:a", "192k", mp3OutputPath};


        Config.enableStatisticsCallback(new StatisticsCallback() {
            public void apply(Statistics newStatistics) {
                Log.d("Dekh", String.format("frame: %d, time: %d", newStatistics.getVideoFrameNumber(), newStatistics.getTime()));
            }
        });

        long executionIdd = FFmpeg.executeAsync(ffmpegCommand, new ExecuteCallback() {

            @Override
            public void apply(final long executionId, final int returnCode) {
                if (returnCode == RETURN_CODE_SUCCESS) {
                    Log.i("Dekh", "Async command execution completed successfully.");
                } else if (returnCode == RETURN_CODE_CANCEL) {
                    Log.i("Dekh", "Async command execution cancelled by user.");
                } else {
                    Log.i("Dekh", String.format("Async command execution failed with returnCode=%d.", returnCode));
                }
            }
        });

        FFmpeg.cancel(executionIdd);

        return mp3OutputPath;
    }
}


  


  Solution number 2 which I used is

  


  https://androidprogrammatically425516919.wordpress.com/2020/04/21/how-to-convert-video-to-audio-in-android-programmatically/

  


  But I got an error here also Failed to instantiate extractor. and another error is java.io.FileNotFoundException : open failed : EISDIR (Is a directory)
I tried the online available solution to solve these errors but nothing worked. Such as granting write permission. Providing a valid location to save the output.

  


  But nothing work so far. Please help me on this. Thank you

  


• Vertically stack two images, draw a box on the bottom image then write multiline text in that box

  31 août 2020, par Sarmad S.

  I am trying to make a video from two images, where the two images should be vertically stacked. This is easy and can be done with the vstack command. I also managed to write text on the bottom image with the drawtext command. However I want to draw a blue box that covers half of the bottom image (the bottom part of the image) and write the text in that blue box.

  


  How do I go about doing so ?

  


  My code so far :

  


  ffmpeg -loop 1 -i image1 -i image2 -c:v libx264 -t 3 -pix_fmt yuv420p -filter_complex "[1]drawtext=my-font.otf: text='some multiline text': fontcolor=white: fontsize=50: x=(w-text_w)/2: y=(h-text_h)/2[v1], drawbox; [0][v1]vstack" -s 1080:1920 output.mp4"


  


  I also want to zoom slowly in the images (not the box or the text). Anyone can help me connect things ?

  


  I am able to zoom, drawbox, write text etc, but not able to combine them together.