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• Real time compression/encoding using ffmpeg in objective c

  20 février 2014, par halfwaythru

  I have a small application written in Objective-c that looks for the video devices on the machine and allows the user to record video. I need to be able to compress this video stream in real time. I do not want to save the whole video, I want to compress it as much as possible and only write out the compressed version.

  I also don't want to use the AVFoundation's build in compression methods and need to use a third party library like ffmpeg.

  So far, I have been able to record the video and get individual frames using 'AVCaptureVideoDataOutputSampleBufferDelegate' in this method :

  - (void)captureOutput:(AVCaptureOutput *)captureOutput
  
     didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
  
     fromConnection:(AVCaptureConnection *)connection

  So I have a stream of images basically, and I want to throw them into ffmpeg (which is all set up on my machine). Do I need to call a terminal command to do this ? And if I do, how do I use the image stack as my input to the ffmpeg command, instead of the video. Also, how do I combine all the little videos in the end ?

  Any help is appreciated. Thanks !

• Ffmpeg won't copy excerpt of video correctly

  5 mai 2022, par JR Jr.

  I am using a DOS batch to automate and copy excerpts of various high definition videos (mkv's with more than 1GB each).
The script is very convenient and runs fast and fine, but Ffmpeg is not doing its job correctly (it seems Murphy's law is inexorably enthralled into technology, things never come easy, which is why I love and hate it).

  


  Anyway, to cut a long story short, each time the batch job runs, a code like below is executed (pardon me the indiscrete folder name, it's about the 90's TV show, it's not porn !).

  


  call "C:\ffmpeg\bin\ffmpeg.exe" -y -i "D:\100\Sexo\S01\SATC - S01E03 - Bay of Married Pigs.mkv" -ss 00:18:05 -to 00:19:15 -codec copy "002-SATC - S01E03 - Bay of Married Pigs-00_18_05-00_19_15.mp4"


  


  The problem is that the first 6 seconds or so of the resulting video has no video, only audio with a frozen image that only starts to move after about 6 seconds, which is a huge defect, not to mention very annoying (a big let down, after all my meticulous scripting work :(). And this happens for most of the files, except a few ones.

  


  Even though this is copying and changing the format from mkv to mp4, per another thread on this site (https://askubuntu.com/questions/396883/how-to-simply-convert-video-files-i-e-mkv-to-mp4), this is not re-encoding, so this is not the issue. Actually, the same problem occurs even if I don't change the format from mkv to mp4.

  


  Even though I foresee a "there's no way to fix this", let me ask : is there a way to fix this ? Hopefully there is a way.

  


• How to save video recording(webcam) and screen recording to directly Mp4 in windows ?

  10 juillet 2019, par SaddamBinSyed

  I have an applicaiton which running as a windows service which is responsible for Recording the video/audio and screen capture as well.

  now I am using DirectX lib and Aforge dll to save recorded file to AVI format which is not supported by HTML 5 so I am then converting the same to mp4 using NVideoConverter dll.

  now I am facing high CPU utilization (30% -recording service) FFmpeg (30% conversion task).

  So I wanting a solution/method to directly record as an MP4 format to get rid of conversion part as well as CPU utilization.

  I couldn’t use FFmpeg directly to the record since when user logoff/signout the current recording will get corrupted.

  So How can I record as an Mp4 in windows 7 and 10 ?

  also, I came across that win10 default camera application is saving the recording directly as Mp4 file which is playing well in both IE and chrome.

  so it means there is a way in windows 10.

  If anyone implemented/knows about the same please advise me.

  help highly appreciated.

  thanks.