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• Can ffmpeg transcode an audio track and add it as a second audio track at the same time, or if not, how to do it as separate commands ?

  31 mai 2020, par wb6vpm

  A bit of history. I am using Plex as my media server, but for reasons unknown, it has issues transcoding the DTS-HD MA 7.1 audio to EAC3 stereo and keeps buffering (the server has plenty of horsepower on all fronts, CPU/RAM/drive space & speed, gigabit networks connections for all devices. The playback device (TCL Roku TV, with a 3rd party soundbar connected via HDMI ARC) doesn't support the built-in 7.1 audio, so I get silence if I play it back directly by putting the file on a USB stick.

  



  Also, I am by no means a ffmpeg guru, I figured out what I do know by Google University and asking questions, so please be kind and forgive me if I ask follow-up questions that may seem n00b-ish, and please provide example commands (preferably in the context of my command below so that I can have a known point of reference to start with).

  



  I have a movie with 4K (HEVC Main 10 HDR) video and DTS-HD MA 7.1 audio that I am looking to leave the video and audio untouched, but to add a 2nd audio track in either EAC3 or if necessary, just AC3 in stereo

  



  So what I am looking for is as follows :

  



  video.mkv

  



  

  • Existing->4k video file (no change)

  


  • Existing->7.1 audio (no change)

  


  • Convert and add->stereo audio as a 2nd audio track to the output.mkv file

  


  



  Below is the command I've historically used with ffmpeg to convert and replace the audio file with the stereo audio, but since I'd prefer to leave the 7.1 audio in place, this doesn't work :
ffmpeg -i "D:\video.mkv" -c:v copy -c:a aac -b:a 128k "D:\output.mkv"

  



  And if this cannot be done as a single command, please also let me know what steps I do need to take to be able to do it.

  



  Thanks in advace,
Mike

  


• Can you stream multiple video clips to youtube or twitch with a separate audio track with a different length than the video clips with FFMPEG ?

  8 juin 2020, par Fight Fire With Fire

  What I'd like to do is stream a set of video clips to youtube or twitch using FFMPEG. Right now i loop thru the videos file names in a list called DIRECTORY. video[0] is the file name and send to stream_url with the audio for the video attached.

  



  What i would love to figure out, is there a way I could mux in a single audio track streaming to youtube/twitch but switch the video clips out live. Here is the code I am working with right now :

  



  
     for video in directory:
            command = [
            "ffmpeg" , "-re" , "-i" , video[0] ,
            "-vcodec" , "libx264", "-pix_fmt", "yuv420p",
            "-preset" , "medium" , "-r" , "30" , "-g" , "48" , "-b:v" , "2500k" ,
            "-acodec" , "libmp3lame" , "-ar" , "44100", "-threads" , "6" ,
            "-q:a" , "3" , "-b:a" , "712000" ,"-bufsize", "512k" , "-f" ,
            "flv" , STREAM_URL,
        ]
             subprocess.run(command)



  


• ffmpeg - Apply padding to input images while combining multiple images and audio track

  12 juin 2020, par Khawar Raza

  I am using below command to create a slideshow using ffmpeg :

  



  ffmpeg -r 1 -i IMG_%04d.jpeg -i audio.mp3 -c:v libx264 -c:a aac -pix_fmt yuv420p -r 24 -y output.mp4 -vf pad=ceil(iw/2)*2:ceil(ih/2)*2


  



  I had to add pad=ceil(iw/2)*2:ceil(ih/2)*2 to make width or height even number because if one of the input image width/height is odd, ffmpeg throws error. Now my problem is ; input images can be of different resolution and aspect ratio. I want to add padding (left/right or top/bottom) to all images to make them of equal size before they are converted into video frames. How can I achieve this in efficient way ?

  



  It would be nice if I can specify output resolution and all images are either scaled down or up keeping their aspect ratio intact according to that resolution.