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• What is the difference between ffmpeg and opencv when recording screen ? [closed]

  12 août 2022, par Sadık Demir

  I am making a screen recording app with Qt. I tried both libraries. CPU load is less in Opencv. What is the reason of this ? (About 10% difference between).
Opencv Code :

  


     while( 1 )
{
    Mat src = hwnd2mat(hwndDesktop);
    imshow("output", src);

    cvtColor(src,src,COLOR_BGRA2BGR);


    if(src.data)
        writer.write(src);
    int c = waitKey(1);
    if((char)c == 'c')
        break;
}


  


• ffmpeg screen blending mode with transparency

  17 novembre 2013, par gilad s

  I have a sequence of PNG files with transparency and a video- video1.mp4

  1. I'd like to convert the PNG files into a video with an alpha channel- video2.mp4

  2. I'd like to merge video2.mp4 with video1.mp4 while the transparent parts in video2 are

  not seen and the other parts are blended using screen blending mode with video1

  when I do :

  ffmpeg -i "%03d.png" -vf scale=640:480 -vcodec libx264 video2.mp4

  a video is created with a black color where the transperent parts are supposed to be (I'm not sure if it's really transparent - I tryied other encoders - all gave the same result).

  afterwards when I do :

  ffmpeg -i video1.mp4 -i video2.mp4 -filter_complex "blend=all_mode='screen'" output.mp4

  the videos are indeed merged but the video has a pink overlay ?!

• How to prevent ffmpeg lib from printing in a command line when playing audio with a discord bot ?

  26 janvier 2021, par ICookieI

  I have a question about ffmpeg. I wrote a discord bot with discord.py lib, which plays audio when somebody joins a channel. I wanted the program to run on my computer in the background, so no console log will appear. Therefore I start the python script using a .bat and a .vbs file, so the process runs in the background. This works fine so far. The problem is that the ffmpeg lib (I assume it's the ffmpeg lib...) prints out a line ("[mp3 @ 0000020168869040] Estimating duration from bitrate, this may be inaccurate") in the command prompt when it plays audio, so everytime somebody joins a channel a command prompt appear on my desktop for 1 sec only to show this line, afterwards it closes, but it's really annoying that it shows up everytime. I was wondering if there is a way to prevent the ffmpeg lib to print out this line, but i couldnt find out how so far.
Can someone help me with that ?
Thanks Cookie

  


  my Code :

  


  def getAudioSource(source):

    audio_source = discord.FFmpegPCMAudio(executable="E:/PythonPrograms/DiscordBotHallo/Dateien/ffmpeg-win64-v4.2.2.exe", source=source)
    return audio_source


def getRandomGreeting():

    list = os.listdir("E:/PythonPrograms/DiscordBotHallo/Begrüßungen")
    Greeting = list[random.randrange(len(list))]
    Greeting = "Begrüßungen/" + Greeting
    return Greeting


@client.event
async def on_voice_state_update(member, before, after):

    if before.channel == None and member.id != 801800464756768768:
        greetingPath = getRandomGreeting()
        audio_source = getAudioSource(greetingPath)
        vc = await after.channel.connect()
        vc.play(audio_source)
        while vc.is_playing():
            await asyncio.sleep(1)
        vc.stop()
        await vc.disconnect()