Sometimes I feel like a complete failure. Although I have been fortunate enough to win a lot of awards and have met a lot of fantastic people with whom I think I’ve done some good work, there is still an evil that lurks amongst us:
This evil is being forgotten and often lurks silently and invisibly in our media causing no problems at all UNTIL IT’S TOO LATE. To a young person starting out in our industry this evil is hard to understand and the obvious solution is “JUST GET RID OF IT”.
INTERLACE is EVIL
“Hello young person”, I say.
“Hello old man.” They reply. I look upset. I don’t feel old, but I remember black and white TV broadcasts. In their eyes, I am a fossil.
“I see you’re shooting a documentary”
“Yes, we like the Film Look™”, they reply. “It gives our content a new and modern look. Not like that old fashioned HD stuff from 2008”.
“Progressive!”, I say.
“Yes very” they reply.
Rolling my eyes skywards, I know this conversation is going to get difficult. “No, not progressive style, but progressive scanning”, I start. I am met with the blank stare of two teenagers looking at a kitten that has just started to speak Japanese. They have no idea what the word progressive means when followed by the word “scanning”.
I take a deep breath. “When your electronic camera shoots in Film Look™ in Europe, it is actually taking a series of pictures that have 1920 pixels and 1080 lines and it is doing it 25 times every second. Every pixel in the picture was shot at about the same time and they are transmitted line by line starting at the top left corner and continuing to the bottom right corner. That’s called progressive scanning.”
“You can edit progressively, but when you come to broadcast the picture, you actually have to do it in a mode called interlace where you pretend that all the even lines were shot 1/25 of a second before all of the odd lines in any given frame. That’s called interlaced scanning. Then in the TV set, you have to figure out if the original content was actually shot in Film Look™ or whether it was shot with an ordinary interlaced camera so that the picture isn’t shredded by the cheap deinterlacer in the screen. After all, flat screens are progressive and not interlaced.”
“Woah, old guy”, the spotty teen says. “You’re telling me that even though I’ve shot this movie in super Film-Look™ there is a chance that it will be destroyed in the transmission process? THAT’S NUTS!”
“Well, yes”, I reply. “It is nuts, but that’s how television works. Even more scary is that your great documentary work might be edited for conformance, censorship and duration by some stranger who had their copy of Final Cut Pro set to interlaced mode and it might add a whole bunch of interlaced artefacts throughout the entire production.”
“By that stage”, I continue, “you have no control over your content. The only thing that can save your content in broadcast, on cable and on the web is a great deinterlacer like those from AmberFin. Without that kind of technology, your masterpiece is consigned to look jerky and crinkly and you won’t know why!”
“But, but… “, the young person stammers, “Interlace must be evil. Who invented it and why can’t we get rid of it?”
And so I come to the point of this post. I have tried over the years to help rid the world of interlace. It made a lot of sense back in 1940s when it allowed us to fool the eye into seeing more lines in a picture despite the limited bandwidth available in the valves and electronic components of the day. Today, when all capture devices are progressive, all display devices are progressive and the black-art of good interlace handling is being lost from the collective minds of the industry, interlace makes no sense.
HEVC – High Efficiency Video Coding will, I hope, be one of the last nails in the coffin of interlace. It has been published without interlace modes. This is a GOOD THING and encourages everyone to start using more and more progressive techniques in their distributions. We are, however still generating more 1080i material every year than progressive material. While this continues to be the case, good quality deinterlacing in the value chain will be vital for the success of HEVC in professional deployments.