iTunes, aspect ratios, and so forth
Yes, a matter of aspect ratio.
YouTube videos can range the spectrum in aspect ratio, so perhaps not the best reference. Within iTunes, there are basically three sizes offered: full screen, and two versions of widescreen.
Full screen is what anybody having used old analog televisions is familiar with. The tube was nearly square, thus as well the picture presented. Television programs of the era were filmed at this aspect ratio, or nearly square, due the medium everyone was watching them on. Theatrical movies on the other hand, have of course more usually been filmed and presented in theaters as something far wider, and seemingly more narrow in height, this being widescreen. However, as standard once and even today, they are more usually cropped when presented on television. Meaning one is seeing only a portion of the original movie, and any given frame, with the editor making the decision what portion will be most relevant and thus seen. This so that viewed will fill the entire screen of that nearly square; otherwise, as one will see at times, the full width movie displayed, in which case as a wide narrow band with necessarily black bars above and below. Full screen programs usually have an aspect ratio of 1.33:1.
While video can theoretically be created at any aspect ratio, by convention it is more often found at a widescreen aspect ratio of either 1.85:1 or 2.35:1. The former is taller, filling more of a screen, customarily with less of a black bar above and below. The latter, or 2.35:1, is the wider and more narrow, or more commonly what one would expect to see in a theater. Bear in mind, also, that the amount of any black bars present will depend not only on the aspect ratio but also on the dimension of the screen viewed on: newer flat panel televisions are wider to begin with, so even widescreen media will display less black bars (perhaps none) than an older near-square television.
For those wanting any given TV program or movie as filmed, a few considerations. Many movies presented on television have been highly edited from the original, not only in aspect ratio so they will fill a screen fully (with no black bars), but also deletion of scenes towards censorship and time constraints (so they can squeeze more commercials in for an allotted time).
But even foregoing that freely provided and buying it is no guarantee. An older television program was likely filmed at 1.33:1, so that is just what it is; even if abbreviated by widescreen standards, there was never anything more provided, so one receives the director's vision (such as it was). But widescreen movies can be more problematic, if not careful.
Many if not most movies begin life as filmed with a widescreen aspect ratio of 2.35:1. Where they go from there can vary. That one movie can be offered for sale in a variety of aspect ratios, possibly 1.33:1 (full screen), or 1.85:1 (widescreen, technically). 1.85:1 is a widescreen aspect ratio, and if a movie or TV program was filmed at that then one is receiving the full original content. But if originally filmed at 2.35:1, then anything other signifies it has been edited, and one is not receiving the full original content; something had to be cut out to change the aspect ratio.
iTunes offers some full screen media. Most of their movies are offered as widescreen only, generally provided in their original aspect ratio. So they might be, depending, delivered at either 1.85:1 or 2.35:1. There is no way of knowing in advance, although as the original one is receiving the full content in either case.
Where this goes off the tracks is when they do NOT. Something no director could like is when someone else in their greater wisdom later tampers with the aspect ratio of that created. iTunes will not inform one in advance, only denoting a movie as "full screen" or "widescreen," but some of that marketed as widescreen is less than. In some rare instances a 1.85:1 version of a movie provided of that originally filmed at 2.35:1. Being of course undesirable (to put it mildly) for those wanting the full original content. One way of checking after the fact, or at least knowing what is up, would be to check sources such as Amazon or imdb.com, either of which will most usually provide the original aspect ratio of the media in question. Although note that Amazon will often market the same move in different aspect ratios, so check a number to determine what it began as. If not definitive, also look closely at the cover art prior to purchase, as this often indicative of what aspect ratio will be delivered.
Mention of another aspect in this might also be in order. Aside from aspect ratio, one can receive less than the original in its resolution or clarity. Commercial digital film cameras are making their advent; but traditionally and even now most movies were filmed on film, which provides a very high quality master. What one ends up with in their hands is almost always something less. Due space limitations, most digital media has been compressed, which necessarily means discarding some of the original data and thus resolution. If interested in about the best there is, then Blu-ray is a good option, being of high quality. The common DVD is something decidedly less, with the picture obviously not as sharp, etc.
In the world of iTunes, one basically has one of two choices in this respect: in choosing either standard definition (SD), or high definition (HD). SD is most akin to a standard DVD in resolution quality. An HD file will be larger due the greater amount of data present, thus also of a higher quality (as obviously seen when viewed). Either is a compression from the original, and compromise.
To further confuse this somewhat, in at least iTunes there are two versions and qualities of HD offered: 720p or 1080p. Both are high definition, either better than SD, but with 1080p the higher quality choice. iTunes once only offered SD content, and first began offering HD content only as 720p. Now, when there is an option, one can choose within the preferences of iTunes which HD version they wish to download when purchasing HD content. Know that 720p HD will play on many older Macs, but 1080p will not flawlessly unless with a newer model (there is simply too much data to process). If in question, check the requirements from Apple; or one may also receive a dialogue box on first opening the media saying it is not compatible.
If increasingly so, not all offerings from iTunes are offered as HD. Newer TV programs seemingly invariably are; and as many older were filmed on film, they can be offered in HD as well. In movies, the newer and more popular are usually now offered in HD. Some older movies are not, even if technically, as filmed on film, they certainly could be. This is more a marketing decision one can thank Apple and the studios for. One may also notice that some popular movies only lately are offered in HD, in the providers surely hoping they will first be purchased in SD—and then in resignation again in HD. As far as that goes, one may already have the experience of having purchased the same movie twice (perhaps from VHS to DVD, etc.), and may be tempted again with the advent of 4k.
Anyway, this a long ways of saying that the black bars visible are fine, and even desirable. If you do not see them, then perhaps wonder what is going on.
