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• The most efficient way to generate mp4 video containing looped boomerang-alike video file ?

  29 juillet 2019, par B. Palka

  I’ve developed an Android app that allows user to create boomerang-alike mp4 video. This video consists of 10 still images being played back and forth quite fast. I know that such video (boomerang effect) can be easily looped from single video file while playing it, but I really need to create a mp4 video that would essentially contain already prepared boomerang video. The output video can be downloaded and played by user on any external player (over which obviously I don’t have any control).

  For that purpose currently I create a video from images in a loop. The loop starts from 1st picture and goes to 10th picture with 0.25 sec delay between frames, then goes back from 10th to 1st including delay. And there is 5 of those loops, which essentialy means creating a single video from 5 * 10 * 2 = 100 images. I know it’s kinda ridiculous, so the time that it takes to prepare this video is riduculous as well (around 1:40 min).

  What solution could you recommend assuming that the output video really has to consist of 5 loops back-and-forth ? I’ve thought about creating single loop video (20 pictures) and then create final output video by concatenating it 5 times. But could it be any good ? I’m trying to find an efficient yet understandable for a beginner Android programmer way.

• C# binaryreader and binarywriter any file

  19 janvier 2016, par Jökull Snær Gylfason

  I am trying to create a video using ffmpeg and I have managed it but my purpose is to create a raw video from a byte array that i have created and put it to youtube and be able to get it back raw but now because I could only get raw video through avi the youtube compression algorithm is messing up my data. I am not sure if it is even possible to get through youtube and back without any loss of data but I would like to know if it is and if I can make an mp4 video with no loss of data
  Im using ffmpeg videofilewriter

  writer.Open("test.avi", 320, 240, 25, VideoCodec.Raw, 10);

  And then I am just running it through a few for loops witch creates a bitmap and sets it in the frame

  Bitmap image = new Bitmap(width, height, PixelFormat.Format32bppPArgb);

  maybe I could somehow edit the mp4 file

• Is it possible to "lossless"-ly speed up a video ?

  15 novembre 2020, par Synn Ko

  Might sound like a strange question, but hear me out. I have hours of video I want to cut up and edit together, but a lot of it is just junk I don't need. I don't want to lose any quality, so I use LosslessCut.

  


  The problem for me is that it's... A LOT of footage, and I don't need to see every single second of it. It would be nice if LosslessCut had a button to change the speed of the playback, but it doesn't have that.

  


  So another idea would be to speed up all the videos in advance with ffmpeg, cut them up using LosslessCut, then change the remaining clips back to their original speed using ffmpeg again. Is it possible to speed up a video and change it back to its original speed without losing any quality or changing the video ?