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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

  


• What are the size/second convertion rate that I can expect on compressed video

  30 juillet 2013, par Jonathan Thurft

  I am developing an app and I am quite hesitant on allowing my users to share videos.

  Mainly due the space that videos can take up in the server which adds a huge maintainance cost.

  I have been reading around and I can see that there are lots of different libraries that allow me to compress video on iOS to make it easy to share.

  After much researching I couldn't find any estimate on file size / second after compressed.)

  I was wondering if anyone could share their experience with what file size / second I could expect with your preferred library in a video quality setting that is reasonable for mobile (I guess medium).

• RTSP streaming to html5 video

  19 février 2017, par Gautier Drusch

  On a project, we have a camera with a RTSP stream (video & audio, encoded in H264). We need to make the stream available on all browsers (desktop & mobile).

  I’ve seen some solutions :

  • Convert the stream on HLS (iOS) and MPEG DASH (other browsers) with FFMPEG on a server
  • Video only with jsmpeg

  The problem is since we need a really live streaming (e.g. the user can record some pictures/video on live), a low the latency solution is a specification of the project.

  Any ideas ?