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• The challenges in using proprietary standards (linked)

  12 juin 2010, par Basil Gohar — Software, adobe, flash, H.264, licensing, macromedia, mpeg-la, royalty

  Venkatesh Hariharan, author of the Open Source India blog, has made a post that quotes Jonathan Gay, co-creator of the Flash, on the challenges in using proprietary standards. It’s a good read demonstrating the real & practical roadblocks that royalty-based … Read more (...)

• FFMPEG in Android Kotlin - processed video should have specific resolution

  31 mai 2024, par Utsav

  I'm recording video from both the front and back cameras and I get a PIP video and a horizontal stacked video. I need to merge both videos after that. The problem with merging is that it requires both the videos (PIP and stacked) to have the same resolution and aspect ratio. This is not the case. So the FFMPEG command being executed in code to generate both these videos needs to be modified to make the resolution and aspect ratio the same.

  


  //app -> build.gradle
implementation "com.writingminds:FFmpegAndroid:0.3.2"


  


      private fun connectFfmPeg() {
        val overlayX = 10
        val overlayY = 10
        val overlayWidth = 200
        val overlayHeight = 350

        outputFile1 = createVideoPath().absolutePath
        outputFile2 = createVideoPath().absolutePath
        //Command to generate PIP video
        val cmd1 = arrayOf(
            "-y",
            "-i",
            videoPath1,
            "-i",
            videoPath2,
            "-filter_complex",
            "[1:v]scale=$overlayWidth:$overlayHeight [pip]; [0:v][pip] overlay=$overlayX:$overlayY",
            "-preset",
            "ultrafast",
            outputFile1
        )

        //Command to generate horizontal stack video
        val cmd2 = arrayOf(
            "-y",
            "-i",
            videoPath1,
            "-i",
            videoPath2,
            "-filter_complex",
            "hstack",
            "-preset",
            "ultrafast",
            outputFile2
        )

        val ffmpeg = FFmpeg.getInstance(this)
        //Both commands are executed
        //Following execution code is OK
        //Omitted for brevity
    }


  


  Here is mergeVideos() executed lastly.

  


      private fun mergeVideos(ffmpeg: FFmpeg) {
        //Sample command:
        /*
        ffmpeg -y -i output_a.mp4 -i output_b.mp4 \
        -filter_complex "[0:v:0][0:a:0][1:v:0][1:a:0]concat=n=2:v=1:a=1[outv][outa]" \
        -map "[outv]" -map "[outa]" -preset "ultrafast" output.mp4
        */
        finalOutputFile = createVideoPath().absolutePath

        val cmd = arrayOf(
            "-y",
            "-i",
            outputFile1,
            "-i",
            outputFile2,
            "-filter_complex",
            "[0:v:0][0:a:0][1:v:0][1:a:0]concat=n=2:v=1:a=1[outv][outa]",
            "-map", "[outv]",
            "-map", "[outa]",
            "-preset", "ultrafast",
            finalOutputFile
        )
        //Execution code omitted for brevity
}


  


  Error : Upon execution of mergeVideos(), there is no progress or failure method called. The Logcat stays where it is and the app does not crash either.

  


  Possible solution :
Once I got the generated PIP and horizontal stacked videos to my device's local storage, I tried out some FFMPEG commands on the prompt to process them after moving them to my laptop and it works on the command line :

  


  //First two commands can't be executed in Kotlin code
//This is the main problem
ffmpeg -i v1.mp4 -vf "scale=640:640,setdar=1:1" output_a.mp4
ffmpeg -i v2.mp4 -vf "scale=640:640,setdar=1:1" output_b.mp4
ffmpeg -y -i output_a.mp4 -i output_b.mp4 -filter_complex "[0:v:0][0:a:0][1:v:0][1:a:0]concat=n=2:v=1:a=1[outv][outa]" -map "[outv]" -map "[outa]" -preset "ultrafast" output.mp4
//Merge is successful via command prompt


  


  Please suggest a solution

  


• Add a text/caption to the first few seconds of a cut video ?

  6 mai 2022, par JR Jr.

  I want to cut a video and at the same time add a caption during the first few seconds of the video using drawtext. I have tried lots of different google searches but all turned out to be totally unhelpful for this specific purpose (even the answers on the SS pages). Also, I am on Windows, I don't care for other OS's, such as Unix/ubuntu/Mac.

  


  Let's use the below cut syntax as an example. It's cutting and changing the format from mkv to mp4, and I want to add a simple title to be displayed in the first 5 seconds of the video, since this will be done to various files and then they will be concatenated together and it's good to let the viewer know which movie each excerpt belongs to (without doing that manually for each single video, the goal is to add these texts to each of the below commands).

  


  "C:\ffmpeg\bin\ffmpeg.exe" -y -i "D:\S01\SATC - S01E03 - Bay of Married Pigs.mkv" -ss 00:18:05 -to 00:19:15 -codec copy "002-SATC - S01E03 - Bay of Married Pigs-00_18_05-00_19_15.mp4"


  


  Let's say I want to add the title "S01E03 - Bay of Married Pigs" in the center of the screen, in white, with font size 12, displayed between 1 and 5 seconds. How do I do that ?

  


  And more importantly, since these syntaxes tend to make the command line insanely long and it needs to be a one liner, is there a smarter way to feed the settings/configuration of the drawtext clause into the command line, as to not make the code very messy, long and chaotic ?
Besides, do white spaces matter/would misplaced blank spaces make the command line crash ?

  


  Been trying this for hours now, so I really appreciate your help on this.