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• ffmpeg encoding sample wanted ?

  24 juin 2015, par Rella

  I found this tutorial about ffmpeg the thing i do not get is how to encode video.

  can any one, please provide a tutorial.. with explanations for that ? (not that i dont get this official one but i’d love to see more comments)

• How to add subtitles to PowerPoint presentation

  5 septembre 2018, par ppdlx

  Okay, to clear things up I will say that I’m posting here because I found the answer and want to help people in future who come upon the same problem. Since PowerPoint is not the right tool to title an presentation I will tell you my way of doing this. If you can do it in PowerPoint alone, super for you but I could not do it in PowerPoint alone, therefore this way. So what I did is the following, I simply recorded the presentation and made subtitles for it and in the final I hardcoded the subtitles into the video. Here is how I did it.

  How to add subtitles to your PowerPoint presentation

  First, I downloaded the latest SnagIt software from their official website. You can have a free trial there. Click here to download SnagIt. Then using SnagIt I recorded my whole screen and played the presentation. I made a video file of the presentation. Let’s call it presentation.mp4.

  Then I downloaded my subtitle making software, an awesome open source program called Subtitle Edit from it’s official website. It’s really simple to use it and it is awesome and user friendly. It doesn’t take too long to subtitle a three minute presentation. When you are satisfied with the subtitles save them as .srt and call them whatever you like. Now we have a video file and corresponding subtitles for it.

  Now we need to hardcode the subtitles into the video file, in other words to burn the subtitles to the video. I did this using another awesome open source software called ffmpeg. See the website and download it from official ffmpeg website. Extract it somewhere and for convinience put subtitle and video file to it’s bin directory. You can put it elsewhere if you like it that way. The first command I used is to transform .srt to .ass.

  ffmpeg -i subtitles.srt subtitles.ass

  Afterwards it’s easy to make a subtitled video file with the following command :

  ffmpeg -i presentation.mp4 -vf ass=subtitles.ass presentation_subtitled.mp4

  I am not sure for the command and can’t get now to see the correct command but if it fails you can seek help on this page.

  Now that we have our presentation_subtitled.mp4 we can now trim the video to our likings.

  ffmpeg -i presentation_subtitled.mp4 -ss 00:01:00 -to 00:02:00 -c copy presentation_final.mp4

  Of course, edit the -ss and -to option, it’s the start time and the end time of your video.

  That’s it ! Now you have your presentation_final.mp4 video file where you have your presentation with subtitles. Ffmpeg is awesome because you can convert it to any format you like.

  You have some help with hardcoding subtitles on Subtitle Edit web page, but one software gave me a virus, one software didn’t work, and after trial and error this is the way that worked for me and it’s really convinied due to great open source software - Subtitle Edit and ffmpeg.

• FPV-Camera Input in Black and White / losses Color on conversion with FFMPEG [closed]

  22 décembre 2023, par LyffLyff

  so we're working on our end-of-school project and it's an FPV-Drone with an Analogue Camera on it. Plan is to send the video feed to a Raspberry Pi running an RTMP-Server from where a Phone-Application can view the live Video of the camera.

  


  To convert this analogue Data from the camera we use a USB2.0 Grabber (this one).

  


  To create the RTMP Stream from the converted USB-Input we use FFMPEG with the following command :

  


  


  fmpeg -f v4l2 -input_format yuyv422 -i /dev/video0 -c:v libx264 -crf 20 -preset ultrafast -b:v 2000k -fflags nobuffer -rtmp_live live -f flv rtmp ://192.168.8.107:554/live/stream

  


  


  It works fine, but the main problems at the moment are :

  


  

  • the video is in Black and White
B&W Image Stream

  


  • the stream has a delay of 10-20s depending on the network

  


  


  When I'm using the official Software provided by the Reseller I had the same problem, but as soon as it set PAL/BDGHI in the Settings the colour was shown correctly :

  


  Settings and Color Image in official software

  


  the video is in Black and White

  


  Does anyone know what settings there are to correctly decode the feed from the Camera and send the video with the colour over RTMP ? I don't know if this is the right place to ask this question, but I'm running out of ideas and every single decoder I have tried apart from the ones I'm currently using does not work.

  


  Any help is greatly appreciated :)