Category: Uncategorized

I’ve recently created a Power BI Custom Visual for our BOQ report headers, as we have a specific header visual style that we want all reports to have:

Normally when theming a custom visual that you import as a file, you just need to use the guid property of the custom visual (in pbiviz.json) as the key in the theme JSON file. For example, we use BOQGroupHeader in both pbiviz.json and theme.json:

pbiviz.json

{
    "visual": {
        "name": "BOQGroupHeader",
        "displayName": "BOQ Group Header",
        "guid": "BOQGroupHeader",
    }
}

theme.json

{
    "visualStyles": {
        "BOQGroupHeader": {
          "*": {
            "background": [
              {
                "show": false
              }
            ],
            "title": [
              {
                "show": false
              }
            ]
          }
        }
    }
}

However, when users download the custom visual from Power BI Service as a Organisational Visual, the theme file does not work. This is because Microsoft must change the guid property of the visual to ensure it doesn’t collide with file imported visuals vs Organisational Visuals.

If you open up the pbix file, you can find that Microsoft add a suffix of _OrgStore to the Organisational Visual, and this needs to be added to the theme file for the custom visual then to use that theme.

So our new theme.json looks like:

{
    "visualStyles": {
        "BOQGroupHeader_OrgStore": {
          "*": {
            "background": [
              {
                "show": false
              }
            ],
            "title": [
              {
                "show": false
              }
            ]
          }
        }
    }
}

I recently wanted to trim and fade out an MP4 file. I wasn’t inclined at the effort of putting it in a non-linear editor and was looking for a quick way to achieve this.

I found that ffmpeg had the necessary functionality to do this. The command I used in the end was:

ffmpeg -i in.mp4 -ss 00:00:00 -t 00:05:00 -vf "fade=t=out:st=297:d=3" -af "afade=t=out:st=297:d=3" out.mp4

The commands are:

• -i in.mp4 is the input file
• -ss 00:00:00 is where the video should start from (set this to other than zero to trim the start)
• -t 00:05:00 is the duration of the video, trimming any video after that
• -vf "fade=t=out:st=297:d=3" is a video filter which fades out at 297 seconds (4:57) over a 3 second duration
• -af "afade=t=out:st=297:d=3" is the corresponding audio filter which fades out at 297 seconds (4:57) over a 3 second duration
• out.mp4 is the output file

The video and audio filters have several more properties you can play with, such as if you want to fade to white using a log curve for the audio fade.

You can also combine filter commands by separating them with a comma, if you want both a fade in and fade out, for example:

-vf "fade=t=in:st=0:d=3,fade=t=out:st=297:d=3" -af "afade=t=out:st=0:d=3,afade=t=out:st=297:d=3"

One of the problems we often face when diffing Analysis Services Tabular models in a collaborative development environment is that tables, columns, and relationships can often be reordered. This is because Visual Studio caches data to disk, and when the Model.bim is reloaded, the order from disk is used, and any extra items are appended to the end of the item array.

For example, if Alice loads Bob’s changes in Visual Studio, Alice’s cached data is used to determine the order, and then Bob’s changes are appended to the end of the array. So if Alice adds a single column, the diff will appear to contain all of Bob’s changes (reordering) as well as Alice’s changes.

To help with providing more accurate diffs, we can sort the item arrays deterministically (i.e. by name). When used as a git post-commit hook, this will take care of any diffs done in code review.

I created a tiny Node.js script to perform the reordering: Tabular Normalizer.

I recently had to debug an application that uses SecurePay as an online payment system. Rather than using API integration, the application used SecureFrame, where SecurePay provides the payment page (e.g. via an iframe). I couldn’t find an example in the SecureFrame documentation, so here’s a minimal working example:

<!DOCTYPE html>
<html>
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.2/components/core-min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.2/components/sha1-min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.11.2/moment.min.js"></script>
<script>
$(function() {
  var merchantId = "ABC0001";
  var password = "abc123";
  var txnType = "0";
  var primaryRef = "Test Reference";
  var amount = "100";
  var timestamp = moment.utc().format("YYYYMMDDHHMMSS");
  var fingerprint = CryptoJS.enc.Hex.stringify(
    CryptoJS.SHA1([merchantId, password, txnType, primaryRef, amount, timestamp].join("|"))
  );
  $('input[name="merchant_id"]').val(merchantId);
  $('input[name="txn_type"]').val(txnType);
  $('input[name="primary_ref"]').val(primaryRef);
  $('input[name="amount"]').val(amount);
  $('input[name="fp_timestamp"]').val(timestamp);
  $('input[name="fingerprint"]').val(fingerprint);
  $("form").submit();
});
</script>
</head>
<body>
<form action="https://payment.securepay.com.au/test/v2/invoice" method="post">
  <input type="hidden" name="bill_name" value="transact">
  <input type="hidden" name="merchant_id">
  <input type="hidden" name="txn_type">
  <input type="hidden" name="primary_ref">
  <input type="hidden" name="amount">
  <input type="hidden" name="fp_timestamp">
  <input type="hidden" name="fingerprint">
</form>
</body>
</html>

I recently published an article on the MIMOSA website that discusses the virtues of SOAP and REST in the context of the information and interoperability standards that we support.

Read the article

I’ve been looking to get ducted AC installed at my residence and have had a few quotes come in. As the AC units, zoning and controls came with a similar set of features, I investigate the decision from an objective financial standpoint by ranking the offerings by comparing both the capital and operating costs. The rank* is calculated by:

where
capital_cost is the total installation price in dollars
number_of_years is the number of years the AC will be in operation
cost_per_unit_capacity is the electricity price (e.g. cents per kWh)
max_cooling_usage is the number of hours per year the AC will run on max cooling capacity
min_cooling_usage is the number of hours per year the AC will run on min cooling capacity
max_heating_usage is the number of hours per year the AC will run on max heating capacity
min_heating_usage is the number of hours per year the AC will run on min heating capacity
cooling_input_power is the rated input power in kW for cooling
heating_input_power is the rated input power in kW for heating
min_cooling_capacity is the minimum cooling capacity in kW
min_cooling_capacity is the minimum heating capacity in kW
min_eer is the min EER (Energy Efficiency Ratio) out of all the ACs being compared
current_eer is the EER of this particular AC
min_cop is the min COP (Coefficient Of Performance) out of all the ACs being compared
current_cop is the COP of this particular AC

I use the term rank rather than Total Cost of Ownership since I don’t bother discounting future cashflows nor take into account maintenance (since I couldn’t get a hold of spare parts price lists).

Most spec sheets also don’t provide an input power at min capacity, so the calculation tries to make an estimate based on the EER/COP, input power and min capacity. For those that do provide an input power at min capacity, the 2nd and 4th components within the parentheses can be made similar to the 1st and 4th components.

Ironically, I ended up choosing the AC ranked second, because of a qualitative aspect – the brand value that would have a bearing on price and availability of spare parts required outside the warranty period.