Newest 'ffmpeg' Questions - Stack Overflow

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• ffmpeg gives output file with 0 size

  10 octobre 2012, par Sudha

  I'm using ffmpeg for audio conversion. I tried to convert recorded audio into mp3 format. I got the file but with 0 size. Can anyone help me to solve this?

  Here is my code:

          Process ffmpegProcess;
          string strInputFile;
          string strOutputFile;
          strInputFile = Page.MapPath("audio.wav"); 
          strOutputFile = Page.MapPath("audio.mp3"); 
          ffmpegProcess = new Process();
  
          string fileargs = " -i ";
          fileargs += "\"" + strInputFile + "\"";
          fileargs += " \"" + strOutputFile + "\"";
          ffmpegProcess.StartInfo.Arguments = fileargs;
          ffmpegProcess.StartInfo.FileName = Page.MapPath("ffmpeg.exe");
          ffmpegProcess.Start(); 
  

• Android video color adjustments

  9 octobre 2012, par Christian

  I'm working on an Android app that among other things will allow the users to make short videos, apply funny effects to them and share them with one another. To begin with, i'm looking for simple color-effects like grayscale, brightness, contrast, sepiatoning, and such.

  All this would be very simple by using the camera-class which can apply the color effects at recording-time - at least most phone's cameras can - i've tested some using Camera.getParameters().getSupportedColorEffects();. But the thing is: i need to do it after the recording has been done: the user would open a video, and choose among a set of effects to apply; then upload that changed video to a shared server.

  I can't for the love of * find a good way to do this.

  Android doesn't seem to include any videoutilities in the sdk. The android.media.effect package can do some effects, but only backdropper for videos, the rest are for images. Extracting bitmaps from the surfaceview of a videoview during playback doesn't work, it just returns an all-black bitmap. It seems like there's no way to intercept the datastream between the storage and the screen. and apply the effects there. I've started to look into using the FFmpeg library to decode a video file so i can get access to the data, but that requires quite a bit of native coding, and also requires separate compiles for various CPU architectures, so it's very messy. I thought that as the camera can apply these effects (on a Sony LT26i: none, mono, negative, solarize, sepia, posterize), perhaps one could feed the recorder with a videostream not from the camera, but from the memory, and by that way use a stored video file?

  Do anyone know if there is a good way to apply effects to a video - after it has been recorded?

• Paste one video to another on top layer

  9 octobre 2012, par LLAlive

  I have over 100+ videos and i need to paste one 5 sec avi video on top layer of every video (something like watermark or animated logo). It can be performed with Adobe Premiere, but its too long and stupid. Where i can find good framework to work with video to perform this (any language)? Or any other method to do it? Maybe 'ffmpeg' can help? Any help, links, documentations would be great.

• Convert FLV video with alpha channel to PNGs with transparency

  8 octobre 2012, par AZAR

  I have some FLV videos with alpha channels, and I want to convert each of them to PNG images using ffmpeg but keep the transparency.

  So far, I've tried this:

  ffmpeg -i input.flv -an -y %d.png
  

  But this outputs the PNG files with black background.

  Is there any way to do this?

  Alternate acceptable solution: If I can output the images and give the alpha channel a certain color of my choice. I can then remove it later via imagemagick and convert that color to transparency.

• After ffmpeg conversion to mp3, winamp shows half frequency

  8 octobre 2012, par user404781

  I'm converting movie in flv to mp3 format (just to extract soundtrack) with this options:

  ffmpeg -i movie.flv -acodec libmp3lame -ac 2 -ab 128000 -ar 22050 -vn soundtrack.mp3

  When I check with some free tool I get 44100kHz, but winamp shows half of that - 22050kHz. Which one should I trust? Maybe ffmpeg options are wrong?