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I have few slides sent by my professor. In those slides, each slide is embeded with an audio file. I want to view them as a video file.

In Microsoft Office PowerPoint for Windows, there is an option in export as to convert it to .mp4 format. What it does is make the slide as the image and puts the recorded voice as the audio file. And the output is a .mp4 file.

Is this type of export possible on Ubuntu 20.04 LTS. I have LibreOffice Impress in which under export as options, there is only a.pdf format option.

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  • Save it as PDF. Using ffmpeg, convert each page to an image. Then again using ffmpeg, combine all images to form a video. If you use this often, write a script to do this. Let me know if you need help in doing so. Jun 23, 2020 at 11:48
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    @SeverusTux but what about the voice recordings? Jun 23, 2020 at 12:39
  • Did you find any solutions?
    – Ali Tou
    Jul 5, 2020 at 6:24
  • @AliTou not yet more the people upvote this, more are the chances of getting the answer Jul 5, 2020 at 6:25
  • @AbhayPatil You have another (late) answer. How did you solve?
    – Hastur
    May 13 at 11:47

2 Answers 2

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I use a workaround with the screen recording application - SimpleScreenRecorder

  • start your presentation in the full screen mode
  • start recording
  • stop recording when it's done

It will allow you to record the presentation with animation/video in a mp4-file. But unfortunately I didn't manage to record the sound.

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Late answer, I know. At the moment this possibility seems that has not been directly-implemented.

Openoffice Extensions

You may give it a look to the impress video converter extension.

Command line with ffmpeg

You can export the ppt(x) as pdf, sfw, gif, png, jpg, whatever..., and then convert the result in a video. (You may need imagemagick).

Assuming you have installed on your system the right codecs (libx264 or better, I refer here explicitly to the encoding libraries) and that the images are named picture01.png ...
you can use a command line similar to the following one:

ffmpeg -r 1/10 -i picture-%01d.png -c:v libx264 -r 30 -pix_fmt yuv420p video.mp4
  • -c:v libx264 : Output video codec (i.e h264) but if you have h265 is better.
  • -r 1/10 : Display each image for 10 seconds.
  • -r 30 : framerate of output video.
  • -pix_fmt yuv420p : Output video resolution (not really needed)

There are tons of options. Moreover, with ffmpeg it is also possible to add audio tracks to a video.
For example to add the audio of the file input.mp3 you can use:

ffmpeg -i video.mp4 -i input.mp3 -c copy -map 0:v:0 -map 1:a:0 output.mp4

Again there are tons of options (you can compact in only one command line, stretch the audio ...)

Bonus: the following line will shorten of 20% a video and audio (note atempo=1.25 is 1./0.80 where 0.80 is the compressing ratio for video -- useless complication but it works in this way).

ffmpeg -i output.mp4  -filter_complex "[0:v]setpts=0.8*PTS[v];[0:a]atempo=1.25[a]" -map "[v]" -map "[a]"  output_02.mp4

Video Editing Programs

As you see this is a path that may lead to use video editing programs such as avidemux, kdenlive...

ScreenRecorder

You can use a Screen Recorder (also know as screencast programs) as suggested from the other answer.
Here a Comparison of screencasting software by wikipedia.

Video conferencing software

There is a wide number of Video conferencing software that allows to share your screen, add your audio and record the session. Pick one.
(Among the others: Zoho Meeting, Zoom, FreeConference.com, BigBlueButton, FreeConferenceCall.com, Jitsi, Lifesize, Cisco WebEx, Google Meet, Skype, GoToMeeting, Microsoft Teams, Whereby)

It may be useful the wiki List of video telecommunication services and product brands.
Read the user agreement for any aspect related to confidentiality and privacy.

The World WIDE Web

A good number of sites offer for free and online the possibility to convert a powerpoint to mp4. A simple search on your preferred search engine will show you a bunch of them... and all your intentions of confidentiality and privacy may RIP.

References (Some words more)

  1. How To Create A Video From PDF Files In Linux
  2. Add audio to video using FFmpeg
  3. Copying the audio without re-encoding

Final remark

Note that a pptx file is a zip file. If you rename into zip and you extract with its subfolders, you will be able to find the media included, original audio files too, and to use these to build your video.

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  • well this almost solves my problem. The main issue is that the audio files on each slide are of variable lengths, which your solution doesn't quite solve. It gets very close. It was nice to know the info stated under Final Remark. Really helpful Jun 4 at 20:47
  • That has not (yet) been directly-implemented (IMK). BTW, once you extracted audio and converted into pictures the slides (with the desired video definition), with a Video Editing Program you will have the complete control: you can add the audio tracks one after the other, add the pause you need between, then add the video importing the picture for the needed time... It is an overkill, but it will ensure the best and lossless procedure. The Screen recorder or the Video conferencing software solutions may work too, but you have to be careful to avoid if possible audio re-encoding.
    – Hastur
    Jun 8 at 14:30

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