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• Checkinstall equivalent on Red Hat (Santiago)

  29 octobre 2013, par Dalius

  I'm not familiar with Red Hat, never used it before.

  I'm installing ffmpeg from source, following this guide https://trac.ffmpeg.org/wiki/CentosCompilationGuide

  On Debian, after using make to compile ffmpeg, I would use checkinstall to install ffmpeg for all users. How can I do the same on Red Hat ?

• Mp4 files generated from FFMPEG can not be trimmed on quick time player

  29 avril 2021, par Abadi

  I am using FFMPEG to generate mp4 file while recording the screen on a Linux machine.
I am using Spawn with nodeJs :

  


  


  


  const transcodeStreamToOutput = spawn('ffmpeg',[
    '-hide_banner',
    '-loglevel', 'error',
    // disable interaction via stdin
    '-nostdin',
    // screen image size
    '-s', `${BROWSER_SCREEN_WIDTH}x${BROWSER_SCREEN_HEIGHT}`,
    // video frame rate
    '-r', `${VIDEO_FRAMERATE}`,
    // hides the mouse cursor from the resulting video
    '-draw_mouse', '0',
    // grab the x11 display as video input
    '-f', 'x11grab',
        '-i', `${DISPLAY}`,
    // grab pulse as audio input
    '-f', 'pulse',
        '-ac', '2',
        '-i', 'default',
    // codec video with libx264
    '-c:v', 'libx264',
        '-pix_fmt', 'yuv420p',
        '-profile:v', 'main',
        '-preset', 'veryfast',
        '-x264opts', 'nal-hrd=cbr:no-scenecut',
        '-minrate', `${VIDEO_BITRATE}`,
        '-maxrate', `${VIDEO_BITRATE}`,
        '-g', `${VIDEO_GOP}`,
    // apply a fixed delay to the audio stream in order to synchronize it with the video stream
    '-filter_complex', 'adelay=delays=1000|1000',
    // codec audio with aac
    '-c:a', 'aac',
        '-b:a', `${AUDIO_BITRATE}`,
        '-ac', `${AUDIO_CHANNELS}`,
        '-ar', `${AUDIO_SAMPLERATE}`,
    // adjust fragmentation to prevent seeking(resolve issue: muxer does not support non seekable output)
    '-movflags', 'frag_keyframe+empty_moov',
    // set output format to mp4 and output file to stdout
    '-f', 'mp4', '-'
    ]
);

  


  


  



  The file opens normally on Mac using quick time player but my problem is that it is not editable.
The trim option is disabled on QuickTime player.

  


• How to implement audio scrubbing using FFmpeg and PortAudio [on hold]

  19 février 2017, par megoo

  currently am implementing a slider that supports mouse scrubbing, during scrubbing the audio is played.
  I chose FFMpeg to read the audio, so the audio is read and loaded in to buffer in one go already. I use QAudioOutput to play the audio, but have no idea how to implement the scrubbing audio playing. The slider is corresponding to the video frames, so each time user change current frame by scrubbing on the slider, it just plays the single video frame of audio. I try these methods in my mind :

  1. QAudioOutput ::start(Buffer) and then QAudioOutput::seek(startingByteIndexForCurrentScrubbingFrame), than use a timer that stop playing audio in 1/24 second. Each time current frame changed, stop previous play, start current play. The result is bad, low performance, and really unsync to the mouse scrubbing.
  2. Maintain an extra buffer, which only copys 1/24 second of audio data, and play it.Each time current frame changed, stop previous play, start current play. The result is the same.

  I throught the methods below might be wrong ? How can I implement with QAudioOutput for audio scrubbing ?
  Thanks so much.