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• Ffmpeg seeking to successive key frame

  10 janvier 2017, par user1447257

  I can cut a video using ffmpeg, which will result in a video that starts at the key frame before the time stamp ss :

  ffmpeg -ss 10 input.mp4 -t 2 output.mp4

  This video cutting is used in a pipeline, that removes dirty parts in an image processing pipeline. Hence, the above command also adds some dirty parts in the first chunk to the output.

  How can I tell ffmpeg to start the video on the successive key frame after ss ? Bonus question : How can I tell ffmpeg to end the video on the key frame before my dirty parts in the input start again ?

  Thanks in advance !

• ffmpeg incorrect border width of ass subtitles

  7 avril 2021, par Tac

  This is what i met when burning the subtitle to the video.

  



  Here is the ass code, I have to use 640x360 in resolution :

  



  [Script Info]
; Script generated by Aegisub 3.2.2
; http://www.aegisub.org/
Title: Default Aegisub file
ScriptType: v4.00+
WrapStyle: 0
YCbCr Matrix: None
PlayResX: 640
PlayResY: 360

[Aegisub Project Garbage]
Last Style Storage: Default
Scroll Position: 154
Active Line: 172
Video Position: 10429

[V4+ Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, OutlineColour, BackColour, Bold, Italic, Underline, StrikeOut, ScaleX, ScaleY, Spacing, Angle, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, Encoding
Style: Default,Arial,45,&H00FFFFFF,&H000000FF,&H00FF0000,&H00000000,0,0,0,0,100,100,0,0,1,5.125,3.125,2,28,28,16,1

[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.94,0:05:12.11,*Default,NTP,0,0,0,,the quick brown dog jumps over the lazy fox.


  



  I usually use MeGUI on Windows (with avs script) to burn. Here is the avs code :

  



  DirectShowSource("C:\Users\xxx\Downloads\test.mp4", fps=25.000, audio=false, convertfps=true).AssumeFPS(25,1)
#deinterlace
#crop
#resize
#denoise

LoadPlugin("C:\Users\xxx\Desktop\megui\tools\avisynth_plugin\VSFilter.dll")
TextSub("C:\Users\xxx\Desktop\ass.ass", 1)

ConvertToYV12()


  



  The subtitle after burning looks like this :

  



  On Windows

  



  

  



  However, it is unable to use MeGui on Linux. Thus I used ffmpeg. The command I used is like this :

  



  ffmpeg -i test.mp4 -vf ass=ass.ass -crf 25 -an -f mp4 done.mp4
ffmpeg -i test.mp4 -vf ass=ass.ass:original_size=640x360 -crf 25 -an -f mp4 done.mp4
ffmpeg -i test.mp4 -vf ass=ass.ass:original_size=1920x1080 -crf 25 -an -f mp4 done.mp4
ffmpeg -i test.mp4 -vf subtitles=ass.ass -crf 25 -an -f mp4 done.mp4
ffmpeg -i test.mp4 -vf subtitles=ass.ass:original_size=640x360 -crf 25 -an -f mp4 done.mp4
ffmpeg -i test.mp4 -vf subtitles=ass.ass:original_size=1920x1080 -crf 25 -an -f mp4 done.mp4


  



  However, they all looks like this

  



  Subtitle on Linux

  



  

  



  The effect on windows is what I want. How can i get the effect like that on Linux ? Thanks !

  


• Using Qt Media Player on Raspberry Pi 1

  18 mai 2015, par Mauker

  I have a project built using Qt5 which has to play a video. Just like in the videowidget sample code.

  I’ve followed these instructions to build qt5 on my Pi. And it went just fine. But when I try to run any qt program that uses QMediaPlayer, I get the error message :

  defaultServiceProvider::requestService(): no service found for - "org.qt-project.qt.mediaplayer"

  Which means I don’t have a backend to play the video, right ? Is there any one that I can use which will with Qt, like ffmpeg ? And how can I get it to work ? Specially for h264 videos.

  I’ve tried to install gstreamer as is told on this link, but it’s not working. Will I have to rebuild the entire qt5 again ?

  P.S. : I have the raspberry pi 1 model B with raspbian installed.

  Edit : As mentioned by Greenflow, I checked the ./configure log and saw that the GStreamer was compiled in, but the video apps are still not working...

  The message on the log was like this :

  GStreamer .............. yes (0.10)

  And the message on Greenflow’s log was like this :

  GStreamer .............. yes (1.0)

  Clearly it’s another version of GStreamer, but is it the problem ?

  I’ve also found this post which says QtMultimedia on the Pi is rather useless, but the post is from 2013, so I’m not sure if it’s really relevant. I’d like to have this app playing hardware accelerated videos on my Raspberry Pi, but I’m almost dropping the idea.

  Anyways, thanks Greenflow for the head start.

  Edit 2 : Found this thread on the Qtcentre. Damn, this thing is not going to be easy to solve, I guess...