Recherche avancée

Sur d’autres sites (8133)

• Correctly stop FFMPeg from contiuous operation

  17 décembre 2020, par Ole Albers

  I want to use FFMPeg / alsa to record audio from a microphone. I use this call :

  


  ffmpeg -f alsa -i default:CARD=U0x46d0x809 out.wav


  


  I call this as an external process from my program. When the user presses a key I want to stop the recording. This is the way it is implemented :

  


  string ffmpegParams=$"-f alsa -i default:{carname} {outputfilename";
Process ffmpeg = new Process();
ffmpeg.StartInfo.FileName   = "ffmpeg";
ffmpeg.StartInfo.Arguments =ffmpegParams;
ffmpeg.Start();
// do stuff until keypressed
ffmpeg.Kill();


  


  Now I wonder if it is a "good" way to simply kill the process to stop FFMpeg. It feels like the outcome could be unpredictable.

  


  Is there a better way or is this just fine ?

  


• Quickly split videos into parts with ffmpeg

  20 avril 2021, par RewossKy

  I'm doing splitting on FFMPEG. I divide 1.5 hour videos into 30 minutes. I have two ways of partitioning, the first is the method of rendering by recodecing on the top, I do not have any problem in this, but the time is quite long despite the GTX 1660s graphics card and the ryzen5 3500x processor.

  


  At the bottom, the time is short, but the first 3-4 seconds of the second part videos are frozen. Sometimes this causes problems like not reading in video editing programs.

  


  With recodec (slow, no problem)
ffmpeg -i 1.mp4 -vcodec libx264 -crf 30 -ss 00:00:00 -t 00:29:30 s1.mp4
ffmpeg -i 1.mp4 -vcodec libx264 -crf 30 -ss 00:29:31 -t 00:29:30 s2.mp4
ffmpeg -i 1.mp4 -vcodec libx264 -crf 30 -ss 00:59:01 -t 00:29:30 s3.mp4
ffmpeg -i 1.mp4 -vcodec libx264 -crf 30 -ss 01:28:30 -t 00:29:30 s4.mp4

  


  Without recodec (fast but have problem sometimes)
ffmpeg -i 1.mp4 -vcodec copy -ss 00:00:00 -t 00:29:30 s1.mp4
ffmpeg -i 1.mp4 -vcodec copy -ss 00:29:31 -t 00:29:30 s2.mp4
ffmpeg -i 1.mp4 -vcodec copy -ss 00:59:01 -t 00:29:30 s3.mp4
ffmpeg -i 1.mp4 -vcodec copy -ss 01:28:30 -t 00:29:30 s4.mp4

  


• Ffmpeg : Improve results with h264_nvenc video codec

  7 avril 2024, par Sulli

  I was very happy to discover ffmpeg is compatible with Cuda as using a GPU speeds up my processing time by 10 at least. But I was very sad to discover codec libx264 can’t be used and h264_nvenc is of much poorer quality (my videos are visibly pixelated, to the point I actually don’t see why ffmpeg was made compatible with Cuda in the first place :) ).

  


  I did not tweak my ffmpeg commands at all when I switched from libx264 to h264_nvenc, but maybe there are some parameters I could add to get a better quality ? Even if it leads to longer processing time, I don’t mind trading a bit of that for a better quality. Or maybe another video codec I wouldn’t know about ?

  


  I usually run my scripts on Google Colab if that matters (tesla T4 graphics card, Driver Version : 535.104.05, CUDA Version : 12.2)