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• How do I make this render callback only provide a specific channel ?

  4 décembre 2013, par awfulcode

  I'm using the wonderful kxmovie as the base for an app I'm writing. Instead of only using the remote I/O, I added a mixer to this. The idea is to have each audio channel from a video file be connected to its own bus on the mixer.

  I have two questions for you.

  1. Is there a way of calling the render callback only once and yet feed each bus only one channel ?

  2. If I need to call separate callbacks for different busses, how can I change the original code so it only renders a specific channel ? Maybe pass the inOutputBusNumber value to the render callback ?

  Here's the code for the original render callback.

  As always, thank you so much.

  P.S. : Does anyone have any idea why it's using _outdata+iChannel in the FFT operation ?

  - (BOOL) renderFrames: (UInt32) numFrames
  
                 ioData: (AudioBufferList *) ioData
  
  {
  
      for (int iBuffer=0; iBuffer < ioData->mNumberBuffers; ++iBuffer) {
  
          memset(ioData->mBuffers[iBuffer].mData, 0, ioData->mBuffers[iBuffer].mDataByteSize);
  
      }
  
  
  
      if (_playing && _outputBlock ) {
  
  
  
          // Collect data to render from the callbacks
  
          _outputBlock(_outData, numFrames, _numOutputChannels);
  
  
  
          // Put the rendered data into the output buffer
  
          if (_numBytesPerSample == 4) // then we've already got floats
  
          {
  
              float zero = 0.0;
  
  
  
              for (int iBuffer=0; iBuffer < ioData->mNumberBuffers; ++iBuffer) {
  
  
  
                  int thisNumChannels = ioData->mBuffers[iBuffer].mNumberChannels;
  
  
  
                  for (int iChannel = 0; iChannel < thisNumChannels; ++iChannel) {
  
                      vDSP_vsadd(_outData+iChannel, _numOutputChannels, &zero, (float *)ioData->mBuffers[iBuffer].mData, thisNumChannels, numFrames);
  
                  }
  
              }
  
          }
  
          else if (_numBytesPerSample == 2) // then we need to convert SInt16 -> Float (and also scale)
  
          {
  
              float scale = (float)INT16_MAX;
  
              vDSP_vsmul(_outData, 1, &scale, _outData, 1, numFrames*_numOutputChannels);
  
  
  
              for (int iBuffer=0; iBuffer < ioData->mNumberBuffers; ++iBuffer) {
  
  
  
                  int thisNumChannels = ioData->mBuffers[iBuffer].mNumberChannels;
  
  
  
                  for (int iChannel = 0; iChannel < thisNumChannels; ++iChannel) {
  
                      vDSP_vfix16(_outData+iChannel, _numOutputChannels, (SInt16 *)ioData->mBuffers[iBuffer].mData+iChannel, thisNumChannels, numFrames);
  
                  }
  
              }
  
  
  
          }        
  
      }
  
  
  
      return noErr;
  
  }

• Horizontally show two videos side by side and export to one video

  15 juin 2015, par Michael Liberman

  What I am trying to achieve :
  Programmatically (using some kind of script) combine two different videos to one video where the videos are shown side by side and sound from both videos is played simultaneously.

  I found at least two ways I could display two videos side by side but in each one I have a different problem that makes it difficult to complete the process :

  1. Avisyth and Avs2Avi :
     Avisyth really makes the process easy. With a simple Avisyth script like this you should be able to play two videos side by side :

     video1=AVISource("d:\file1.avi")<br />
video2=AVISource("d:\file2.avi")<br />
StackHorizontal(video1,video2)

     The creation of a new output file can be done with avs2avi.
     The problem here is that i am not able to play even one avi file with avisyth because I get "AviSource couldn’t locate a decompressor for fourcc xvid" message. I googled for the solutions to that problem but nothing helped. GSpot says that i have all the codecs needed and it seems I can not do anything. Because I can not get to running real videos, I dont know if the final video plays sounds from both videos. Avisyth installed correctly and I am able to run the following script StackHorizontal(version ,version).

  2. ffmpeg
     Works like a charm with two videos and the final file BUT i do not get the sounds from both videos but only the first one. I found out that the solution to add sound from the second video will be by using the libfaac in the command line, like that :
     

     ffmpeg.exe -i video1.mp4 -vf "[in] scale=iw/2:ih/2, pad=2*iw:ih [left]; movie=video2.mp4, scale=iw/3:ih/3 [right]; [left][right] overlay=main_w/2:0 [out]" -c:a libfaac -b:v 768k Output.mp4

  but i always get an error that the encoder libfaac can not be found. I downloaded the libfaac.dll but still no result.

  Is there a solution to any of these problems ? Is there another way to programmatically make one video from two videos that are played side by side ? Thanks in advance.

• Anomalie #2618 : le bouton "ajouter un document" est mensonger

  28 mars 2012, par cedric -

  Discussion du 27/03/2011 sur spip-trad intitulée "télécharger vs. upload / download"