Understanding interlaced broadcasting…

Why try to understand, as everything is automated? - out of intellectual curiosity. - to be able to bypass MovieConverter Studio's automations and make even more ;-)

If you followed the previous chapter "Understanding interlaced video…", you realised the differences:

• Between a frame and a field (reminder: 1 frame contains 2 fields).
• Between a progressive source and an interlaced source file (top or bottom)

You also realised that, at the end, your video will be displayed in terms of fields on your TV screen (regardless of whether its content is progressive or interlaced).

And sources broadcasted by television?

While HD television is sometimes broadcast as progressive, ALL other television channels broadcast in interlaced (PAL or NTSC) mode. But while content is not always interlaced, the "wrapper" is always interlaced (it is the normal way of broadcasting).

Streams (Satellite, TV, TV by Internet, etc) that you record (DVD Recorder, EyeTV, VLC, etc) are transmitted "wrapped" in interlaced top or bottom. But their content is not always interlaced…

Their content can be:

Interlaced wrapping + Interlaced content		Interlaced source file

or

Interlaced wrapping + Progressive content		Progressive source file

You will say to me: "OK, yes, and then?"

Then?!? A source file will not be processed in the same way if it's interlaced or progressive.

• If it's interlaced, it will be necessary to keep fields and to handle the 2 "half-images" (red fields and blue fields).
• If it is progressive, we will handle the whole frame (both fields at the same time).

Thus 2 different procedures which are useless depending on the content (and can even cause damage in some cases, like telecine/transcoding or transforming a 4:3 into 16:9).
There's no need to do complex (longer) treatments for a basic (not interlaced) source file!

MovieConverter Studio

By default MovieConverter will automatically recognize interlaced video and its field order (so you will never loose the quality of your source file), but it will never know if its content is really interlaced(only your eyes are able to recognize that). Thus, MovieConverter Studio allows you:

• To check if a source is interlaced by "Checking field order" (the same tool which allows you to check if your interlaced source is top-field-first or bottom-field-first)
• To modify MovieConverter's analysis (and thus the process of encoding) to adapt it to the content of the source file.

If your goal is only to check if a source has interlaced or progressive content, there is a faster and simpler way: your eyes. Open the source file with VLC and see if you have "comb effects". You don't have any? Your source is progressive. Mark it like such in MovieConverter Studio.

The contents of your source wasn't interlaced in spite of its wrapping? Just mark the source as "none/progressive" in the pop-up options's window (you'll save encoding time and -in some cases- a little more quality ;-))