merge multiple audio buffer sources

Question about html5 webaudio: is it possible to merge multiple songs together? I have different tracks that are all played at the same time using webaudio but I need to process the audio so I need all the audio inside one buffer in stead of each of the tracks having it's own buffer. i've tried merging them by adding their channel data but I always get "Uncaught RangeError: Index is out of range. " ``` function mergeBuffers(recBuffers, recLength){ var result = new Float32Array(recLength*2); var offset = 0; for (var i = 0; i < recBuffers.length; i++){ result.set(recBuffers[0], offset); offset += recBuffers[0].length; } return result; } var recBuffersL = []; for (var i=0;i<audioTracks.length; i++) { recBuffersL[i] = audioTracks[i].currentBuffer.getChannelData(0); } var recBuffersR = []; for (var i=0;i<audioTracks.length; i++) { recBuffersR[i] = audioTracks[i].currentBuffer.getChannelData(1); } var buffers = []; buffers.push( mergeBuffers(recBuffersL, recBuffersL.length) ); buffers.push( mergeBuffers(recBuffersR, recBuffersR.length) ); ```