Putting The Fun Back Into QC

OK, let's face it, no one enjoys doing QC. You spent all this time making a great looking and sounding program and now you've got to make sure it meets the various delivery requirements, writes Tom Dove, Vidcheck.

You've done all the checks on the content itself ensuring that it is good for pre-9pm transmission, fuzzed out the faces that should be obscured etc. and rendered out your video. The next step: QC.

QC can be broadly divided into several areas. Firstly there are UK transmission requirements such as ensuring PSE and loudness compliance. Secondly typical UK broadcaster specifications including correct video levels and a DPP delivery certificate. Finally there is usually a long list of delivery requirements specific to the company receiving the content. These could be file formats, video and audio codecs, video resolution, frame rates, bit rates, aspect ratio, time codes, file duration, video levels, sample rate, bit rate and so on ad nauseam.

So many specifications, so little time and so little money
These delivery requirements are perhaps the most difficult to deal with as they are often in long documents. The "iTunes Video and Audio Asset Guide 5.0" is 37 pages long; the NetFlix equivalent is 31 pages long with numerous options. Many others are as large and complex.

Much content is still delivered on tape and in other file formats however the situation has been greatly alleviated in the UK by the advent of the DPP specification. Of course everyone wants their content to be available on as many platforms as possible and this requires looking at many different specifications. Ensuring content is packaged correctly for use on iPhone, Android, VOD, terrestrial transmission etc. requires looking at many different specifications. And for most people, this is where the fun really goes out of QC.

Plus there is typically not a lot more money available for dealing with all these different formats: and it is simply too expensive to manually look at all the resulting output formats yet the end consumer will expect the content to play correctly.

Let the computer be your geek
Computers are good at technical things like counting and measuring, precisely and repeatedly.

Editors may have looked at a timeline in an NLE where the current time indicator is on 00:30:00 and asked themselves, "does this mean that the media length is exactly 30 seconds or is it 30 seconds + 1 frame?" or looked at the RGB parade display to work out if the levels can be tweaked up a bit without going over-range. Checking these and the dozens of other technical parameters manually, for example using MediaInfo to peek inside the file, is enough to give most people brain ache particularly as it may have to be done on multiple files.

Using an expensive edit bay and personnel for something which a computer can do for you typically faster, better, more accurately and reliably is not a good use of your facilities and people. It does not take a huge number of hours saved in the edit bay to pay for auto QC software. In our experience with our auto QC software the ROI is normally three months or less even if you have a relatively low volume of media.

So let the computer do all these checks: it is the right tool for the task.

Specific test templates for the different requirements
The easiest way to deal with these different requirements is to have test templates which match and check the parameters as needed. Our own products Vidchecker and Vidfixer come with a number of standard test templates to cover DPP requirements, Netflix, iTunes which can be edited for specific deliveries.

There are many more different delivery requirements than you can shake a stick at, so how would you deal with something where there is not already a standard template provided? You can copy and modify an existing test template. Or if there is no reasonable starting point, use the "auto template" feature in Vidchecker and Vidfixer, which automatically generates a test template from known good media and takes less than 1 minute to do so.

We can't speak for other QC vendors, but if it is a delivery specification for a large content distributor then we would work with you to create a test template using the content distributor's specification, or help you with the test template as part of the support we provide.

Taking it further - avoid going loopy
Excellent – you have taken the big step of using auto QC software for doing all the technical checks on your media saving you time and cost.

However if you are using a great tool to do the checking you may have a problem when the software actually finds something wrong with your beautiful content! After you have finished gnashing your teeth and questioning the competence of the engineers who wrote the QC software, and accepted that there really is something that needs to be corrected then you have to decide what to do about it.

Certainly, doing the QC checking automatically saves a lot of time and effort. But with auto QC software that only does checking you have to put the media back in the edit bay for edit and re-render, or perhaps through the transcoder again.

If the media goes back into the edit bay e.g. because there is a single black frame where the edit point of 2 clips on the timeline don't quite meet, then as well as fixing this issue it is often tempting to do a few 'tweaks' at the same time, such as "let's make the graphics a little bit punchier here".

Now you re-render the file and as it is a new file you have to repeat the auto QC.

Disaster! That "little bit punchier" now means you have illegal video levels.

You trudge back to the edit bay again, muttering about the joys of HDCam SR tape, put the graphics levels back to where they were before and re–render the file yet again.

Finally, third time through the auto QC, and your media passes.

All joking aside, this is not an uncommon situation and one that we have seen many times over the past 12 years that Vidcheck personnel have been supplying auto QC software.

Just **** fix it!
Computers are good at technical things, so why not let the computer do the technical fixes as well as doing the checking?

We would argue that that is the optimal solution as it gives the fastest, most repeatable and lowest cost workflow, as illustrated on the right. Our Vidchecker product will not only check the many parameters that you may need to check, but will also auto correct the 2 most common areas of errors: video levels, including black level, chroma levels and RGB gamut; and audio loudness and levels, including the various EBU I-, S- and M- modes. And, vitally, Vidchecker will make you a complete new file in the correct format, the same as you input to the QC process.

If you have media with other issues, e.g. where you commonly have PSE flashing failures, or have media which requires a particular layout of colour bars then black then program then our Vidfixer product does these corrections and many more, as well as everything that Vidchecker does.

Fun once more
So if you take the approach of letting the computer do everything it can for you then QC can be a relatively painless process – perhaps not quite fun, but not so bad either.

www.vidcheck.com