private string getErrorMessage(int errorCode) { const ulong buffer_size = 256; byte[] buffer = new byte[buffer_size]; int strErrorCode; fixed(byte *bufPtr = buffer) { strErrorCode = ffmpeg.av_strerror(errorCode, bufPtr, buffer_size); } if (strErrorCode < 0) { return($"{errorCode} (av_strerror failed with code {strErrorCode})"); } var messageLength = Math.Max(0, Array.IndexOf(buffer, (byte)0)); return(Encoding.ASCII.GetString(buffer[..messageLength]));