Audio Convolution output is longer than input, how can i get around this when feeding data back to a stream of fixed length?

SDL Development
1

After taking audio data from a stream of length x, the data is then convolved with an impulse response of length 256. This gives the output vector a length of (x + 256 - 1). When the data is then fed back into a stream of length x there are 255 samples of overshoot that then causes popping and clicking.

Is there a work around for this? Im not 100% on how to merge the larger than original buffer into the output again without losing random samples or causing this issue.

I left out the larger irrelevent parts of the code, it all works its just this issue i need fixed. Its just here to give an insight into the problem.

Code:

void ConvolveEffect(int chan, void* stream, int len, void* udata)
{
////...A bunch of settings etc

//Pointer to stream
short* p = (short*)stream;                       //Using short to rep 16 bit ints as the stream is in 16bits.
int length = len / sizeof(short);

//Processing buffer (float)
float* audioData[2];
audioData[0] = new float[length / 2];
audioData[1] = new float[length / 2];

//Demux to L and R
for (int i = 0; i < length; i++)
{           
    bool even = i % 2 == 0 ? true : false;
    audioData[!even][((i - !even) / 2)] = map(p[i], -32767, 32767, -1.0, 1.0);
}

////....Convolution occurs outputting OUT
    std::vector<fftconvolver::Sample> outL = Convolve(audioData[0], IRL, length / 2, 256, 128, 256, 256);


std::vector<fftconvolver::Sample> outR = Convolve(audioData[1], IRR, length / 2, 256, 128, 256, 256);


//Remux
for (int i = 0; i < length; i++)
{
    bool even = i % 2 == 0 ? true : false;
    p[i] = map(Out[!even][(i - !even) / 2], -1.0, 1.0, -32768, 32767);
}