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  • how to set ffmpeg bitrate, frame per second when scalling from low to high resolution/ high to low

    21 janvier 2015, par user2303069

    I’m developing a video sharing app for mobile device users. I noticed if I convert video with ffmpeg from a low(ex 240x320) to a higher resolution(ex 480x-1) the video looses quality and also there is no sound at the end. My question to you is how should I filter(how many fps,bitrate ect) the converted file ? In terms of parameters, how should I convert to make sure the video comes out in good quality at it’s destination(the user who will play it on their mobile device[Android/BlackBerry]).

    Here is my current code(java) :

    /************************  CONVERTING    TIME   *************************
    
                       method to convert video-clip
    
*/
    
if(sn.toString().trim().startsWith("<>")){
    
    String info=sn.toString().trim().substring(2);
    
    String scale=info.substring(0, info.indexOf("."));
    
    String width=scale.substring(0, scale.indexOf("x"));
    
    String name=info.substring(info.indexOf(".")+1, info.length());
    
    String to = null;
    
    String from;
    

    
    try{
    
        //calculate to and from
    
        to=name.substring(0, name.indexOf("$"));
    
        from=name.substring(name.indexOf("$")+1, name.lastIndexOf("$"));
    
        gui.textArea1.append("\nStart converting...: to="+to+" from="+from+" fileName="+name);
    
    }catch(NullPointerException npe){
    
        gui.textArea1.append("\nNullpointer in calculate name in converting: "+npe.getMessage());
    
    }
    

    
    final Path videoIn = Paths.get("c:\\wamp\\www\\iclips\\videoMessages\\"+name);
    
    final Path encodingFile = Paths.get("c:\\wamp\\www\\iclips\\videoMessages\\scaled-"+name);
    
    final Path errorFile = Paths.get("c:\\ffmpeg\\bin\\error.txt");
    
    String pro;
    
    int w=Integer.parseInt(width);
    

    
    if(w<=240){
    
        pro="baseline";
    
    }else if(w>240&&w<=480){
    
        pro="main";
    
    }else if(w>480){
    
        pro="high";
    
    }else{
    
        pro="baseline";
    
    }
    
    //int retCode;
    

    
    try {
    
        Files.deleteIfExists(encodingFile);
    
        Files.deleteIfExists(errorFile);
    

    
        final ProcessBuilder pb 
    
            = new ProcessBuilder("c:\\ffmpeg\\bin\\ffmpeg.exe",
    
                "-i", videoIn.toString(),
    
                "-y", 
    
                "-vf", "scale="+width+":-1", 
    
                // "-pix_fmt","yuv420p",   
    
                "-vcodec", "libx264",
    
                "-vprofile", pro,    
    
                "c:\\wamp\\www\\iclips\\videoMessages\\scaled-"+name
    
        ); //or other command....                    
    

    
        pb.redirectError(errorFile.toFile());
    
        pb.redirectOutput(encodingFile.toFile());
    

    
        final Process p = pb.start();
    
        try {
    
            p.waitFor();
    
            if(p.exitValue()==0){
    
                gui.textArea1.append("\n+++++++++++++Vic-^clip converted successfully:"
    
                        + " ExitValue=["+String.valueOf(p.exitValue())+"] ++++++++++++++");
    
                if(Files.deleteIfExists(videoIn)){
    
                    gui.textArea1.append("\n"+videoIn.toString()+" deleted!");
    
                }
    
                sendMsg("Scalling successfull:-)   Video-clip name=scaled-"+name+"_", "\nSent scaled successfull "+username);
    
                NotifyClientOfScaledVideoMessage(to,"^scaled-"+name+"_");
    
            }else{
    
                gui.textArea1.append("\nSomething went wrong with process-convert: ExitValue="+String.valueOf(p.exitValue()));
    
                sendMsg("Unable to scale video, try again._", "\nSent scaled failed to "+username);
    
            }
    
        } catch (InterruptedException e) {
    
            gui.textArea1.append("\nInterrupted process convert: "+e.getMessage());
    
        }
    
    } catch (IOException e) {
    
        // deal with e here
    
        gui.textArea1.append("\nIOException in Convert Video: "+e.getMessage());
    
    }
    
}

    Thank you very much.

  • FFMPEG - Overlaying video with transparency, alpha has strange threshold

    6 mars 2019, par tanker_

    I’m attempting to overlay an Apple ProRes 4444 video with a alpha/transparency onto a normal video. However, upon inspecting the final output from FFMPEG, compared to the same files overlaid on top of one another and rendered in Final Cut Pro, there is a discrepancy in how they render the edges around the object.

    Screenshot comparison :

    Screenshot comparison

    Additional closeup :

    Additional closeup

    Here is my input :

    ffmpeg \
    
    -i background.MOV -x264opts colormatrix=bt709 \
    
    -i alpha_object.MOV -x264opts colormatrix=bt709 \
    
    -filter_complex " \
    
        [0:v]setpts=PTS-STARTPTS, scale=1920x1080[top]; \
    
        [1:v]setpts=PTS-STARTPTS, scale=1920x1080, \
    
             colorchannelmixer=aa=1.0[bottom]; \
    
        [top][bottom]overlay=shortest=1" \
    
    -vcodec libx264 -qp 15 -an -shortest output.MOV

    Any idea what could be wrong ? Is there a option within FFMPEG’s available filters that I’m missing ?

    All files are ingested and rendered in 1920x1080.

  • FFMPEG - Overlaying video with transparency, alpha has strange threshold

    3 novembre 2016, par tanker_

    I’m attempting to overlay an Apple ProRes 4444 video with a alpha/transparency onto a normal video. However, upon inspecting the final output from FFMPEG, compared to the same files overlaid on top of one another and rendered in Final Cut Pro, there is a discrepancy in how they render the edges around the object.

    Screenshot comparison.

    Additional closeup.

    Here is my input :

    ffmpeg \
    
    -i background.MOV -x264opts colormatrix=bt709 \
    
    -i alpha_object.MOV -x264opts colormatrix=bt709 \
    
    -filter_complex " \
    
        [0:v]setpts=PTS-STARTPTS, scale=1920x1080[top]; \
    
        [1:v]setpts=PTS-STARTPTS, scale=1920x1080, \
    
             colorchannelmixer=aa=1.0[bottom]; \
    
        [top][bottom]overlay=shortest=1" \
    
    -vcodec libx264 -qp 15 -an -shortest output.MOV

    Any idea what could be wrong ? Is there a option within FFMPEG’s available filters that I’m missing ?

    All files are ingested and rendered in 1920x1080.

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