Sunday, November 29, 2009

Apple TV Potpourri

It's been a while since I said much about my (count 'em, two) Apple TV units. About time I rectified that ...

In case you missed it — admittedly, an easy thing to do — Apple's Steve Jobs unveiled the Apple TV in Sept. 2006 as a sort of home theater-connected iPod on steroids. You were expected to connect the petite box, less than eight inches square, to a TV or home theater system. Then iTunes on your computer would sync songs, videos, podcasts, photos, and other digital content to it's hard drive, just as with an iPod or iPhone. You could then play that content through your home entertainment system and/or HDTV.

Apple shipped the first Apple TVs in March 2007 — to deafening silence, aside from the technorati, most of whom held their collective noses. Sales were abysmal. I won't detail all the complaints of that time, but the main issue was that Apple TV didn't do enough, and it did what it did slowly, unreliably, and generally badly.

Over the last 2 1/2 years, Apple has slowly addressed the gripes (most of them). Apple TV is now a pretty good product, and in the fourth quarter of 2008, as the economy was tanking, sales were actually triple those of the fourth quarter of 2007.

The Apple Store's Apple TV page currently shows the product at $229.00 with a 160-GB internal hard drive, the original 40-GB model having been retired. (The fact that the internal drive is so small by today's standards is less of an issue than you might think, because Apple TV easily streams iTunes content that doesn't reside on it.)

In 2007 Mr. Jobs famously (?) spoke of the Apple TV as a "hobby" of the folks at Apple, Inc., not a full-fledged business. The Mac, the iPhone/iPod, the iTunes Store — they're real businesses, Jobs said. Apple TV was something of a household pet in Cupertino. He of course was right about that.

That may change — not real soon, but in the not too distant future. This blogger thinks it will and hopes it does. The key will be that Apple TV is now seen by Apple more as an all-purpose media client, and less as an iPod on steroids.

This paragraph from the Wikipedia article on Apple TV gets at what I mean:

With the "Take Two" software update announced by Steve Jobs at Macworld 2008, Apple TV became capable of acting as a pure stand-alone device, no longer requiring a computer running iTunes on Mac OS X or Windows to stream or sync content to it. Jobs stated, "Apple TV was designed to be an accessory for iTunes and your computer. It was not what people wanted. We learned what people wanted was movies, movies, movies." Users can access the iTunes store directly through Apple TV to purchase movies, music, music videos, and television shows. Customers can also use Apple TV to rent standard or HD-quality movies. Until mid-March 2009, iTunes HD movies could only be purchased from Apple TV.

If your computer goes down, or if iTunes is not running, the only thing you lose is the ability to stream — not sync, but stream — content from it to Apple TV. You can still play your previously synced video, audio, and photo content (as long as it resides on Apple TV's hard drive; if not, Apple TV does want to stream it from iTunes instead). You can still grab content, including HD movies and TV shows, from the iTunes Store directly. You can still play YouTube videos and listen to Internet radio stations (this last being a welcome new feature).

OK, so Apple TV has become a real product, in my eyes at least. Herein, a potpourri of cool stuff about it:

First, there is now a neat iPhone/iPod Touch app called (naturally) Remote (web page here; App Store download link here) that turns your mobile device's touch screen into a way to control an Apple TV. It's free, and it works. It presents the iPhone/iTouch user with an interface very much like the iPod app itself, with the addition of a Control tab that does what Apple TV's Apple Remote does, but more easily and intuitively.

The Control tab in effect turns your touch screen into an Apple TV remote control. You drag your finger along the touch screen, either side-to-side or up and down, to do what the Apple remote (-->) does with its control ring and central Play/Pause/Select button.

The Apple Remote's Menu button, meanwhile, is replaced by a virtual Menu button (<--) in the Remote App — I'll call the app RA for short. The RA > or Exit button brings up various tabs for exiting the Control Tab and accessing "Playlists," an "Artists" list, a "Search" function, and "More": Albums, Audiobooks, Composers, Genres, Movies, Music Videos, Podcasts, Songs, and TV Shows.

In the right-bottom corner is an Options button used to display on your TV Apple TV commands: basically, Start Genius, Add to On-The-Go, Browse Artist, Browse Album, and Cancel.

RA also controls iTunes playback. If (as I do) you have Airport Express units installed on your home network and connected to your home entertainment center(s), RA can tell iTunes to select among those and your computer's own speakers.

In fact, RA seems in some sense to be leveraging the ability of Apple TV to turn itself into an AirTunes device, à la an Airport Express. I don't fully understand what's going on ... but never mind. The important thing is that RA controls Apple TV (or iTunes itself) wirelessly, using WiFi. Unlike with the the infrared Apple Remote, you don't have to be in the same room with Apple TV or a computer running iTunes. That's marvelous. I like to start music playing and wander (with my iPhone) into a different room. RA can direct operations truly remotely, even to the extent of letting me turn up or down the volume when need be, from anywhere in your house.

Another cool thing: RA displays, on the iPhone/iTouch's screen, the cover art of the music you're playing on Apple TV! Cover art also appears next to songs, albums, etc., as you flip through them in RA, looking for something to play.

Here is the take Christopher Breen of Macworld had on RA. (I'm not precisely sure what "Oooh" and "Feh" mean in his lexicon, BTW ... )

* * *

The next item in my Apple TV potpourri is about a neat website, Apple TV Junkie. ATVJ covers Apple TV in depth. I especially like its The More You Know page, where you can learn about such things as:

Check it out!

Friday, November 27, 2009

VOD Video Quality Comparison

In earlier Video On Demand posts, I've talked about using the Netflix Watch Instantly capability to stream movies and TV shows to your computer or — via a TiVo, a Sony PlayStation 3, or any other "Netflix-ready" device — directly to your HDTV screen. I've also talked about using the Amazon Video On Demand store to rent or purchase videos and then watch them in your computer browser or download them to a TiVo or other "Amazon-ready" device.

I haven't said much yet about the ability to rent or buy videos at the iTunes Store, via the iTunes application on your Mac or PC, as opposed to your web browser. The iTunes Store offers video content for iPhones and iPods, for the Apple TV, and for play on your desktop in iTunes.

I recently rented the 1958 classic horror flick The Fly at Amazon and iTunes and compared the quality of the video with that at Netflix. All these are standard-def versions.

Here is how a particularly useful frame of the movie looks in the Netflix version:

In the iTunes version:

And in the Amazon version:

To see what the differences are, you'll need to click on each of these images to enlarge them in your browser window. The best way to do that is to open each in a new tab in the same browser window, then click on each tab in turn to note the rather obvious differences.

First, rapidly alternate between the Netflix and Amazon versions. They're similar in frame size, but the Netflix covers just a tad more of the original 2.35:1 CinemaScope film frame — compare especially the amount of the grid of the depicted window screen that you can see at the left edge of the picture.

The Netflix image is also sharper. Look at the Roman numeral date MCMLVIII in both images. It's a little more legible in the Netflix than in the Amazon.

Now switch to the iTunes version. The MCMLVIII is downright blurry. The frame is stretched vertically to yield a subtly incorrect picture geometry. The left edge of the picture reveals less of the depicted screen than the Netflix version does — about as much as the Amazon version does. Also, the iTunes version looks duller and darker; the reddish brown background color isn't as vibrant.

In other words, the iTunes image is geared to the low available resolution and nonstandard aspect ratio of an iPhone/iPod screen. The subtle vertical stretching allows the image to use more of the mobile device's limited screen area than would otherwise be the case, given that (nearly) the entire width of the original (extremely wide) film frame is being shown.

Most users probably prefer the slight geometric distortion to having wider black bars at the top and bottom of the iPhone/iPod screen, so this is a compromise that makes some sense. However, if you are watching on a big computer monitor, the soft, stretched image looks pretty bad when compared, in full-screen mode on the same monitor, with the Netflix version — which, after all, is free to anyone with a Netflix-ready TV setup and a standard Netflix account.

Meanwhile, the Amazon version is just a tick inferior to the Netflix version, and far preferable to the iTunes version on any reasonably large screen. If you lack a Netflix-ready setup but have one that is Amazon-ready, you will lose little in terms of video quality (though you will have to pay for each rental or purchase).

Strictly speaking, this comparison applies only to this one movie; it may be that Amazon is better than Netflix for other titles. However, I think it likely that iTunes will be generally unable to match either Netflix or Amazon in terms of video quality, simply because it targets iPhones/iPods first, and bigger, higher-resolution viewscreens second.

An exception: HD content. You can buy or rent certain titles in HD from an Apple TV, for use on the Apple TV. I'll deal with that in a subsequent post.

Another exception: standard-def videos from the iTunes Store, when rented directly from an Apple TV (see this Apple Support document). They can have up to 720x480-pixel widescreen resolution, while the same titles rented from a computer or iPhone/iTouch max out at 640x480. (I rented The Fly from my computer.)

This exception applies only to iTunes Store rentals of videos. iStore video purchases are stuck with 640x480 resolution, no matter what device you use to make the purchase. 720x480 supposedly won't play on an iPhone/iTouch, only on an Apple TV. If you bought a video on your Apple TV and later tried to move it to your iPhone, it wouldn't play ... and Apple doesn't want to deal with the customer complaints when that happens.

An aside for techies:

(The main part of the article is done. If you don't want to be bored by a raft of technical detail, you can stop reading now.)

640x480-pixel anamorphic resolution squeezes a 16:9 widescreen picture into a nominally 4:3 video frame that uses "square" pixels: the individual pixels are exactly as wide as they are tall. The decoder expands the frame again into its original 16:9 aspect ratio, a process that is relatively easy when the pixels are square. Of course, after the pixels are "unsqueezed," they're no longer square, but having square pixels prior to the unsqueezing allows the decoding to be done by a processor of quite limited power, such as is found in an iPhone/iTouch.

720x480-pixel anamorphic widescreen, unsqueezed to 16:9, has non-square pixels both for the input to the decoder and for the output, so the strain on processing capacity is much greater — too great for an iPhone/iTouch. But the Apple TV has (somewhat) greater processing capacity, so
720x480-pixel anamorphic widescreen input works with it.

There are
other potential ways in which videos that work on an Apple TV can be incompatible with an iPhone/iTouch. For example, if a video has a bitrate of over 1,500 kbps, iPhone/iTouch won't touch it. iPhone/iTouch can't use videos encoded with bidirectionally predictive frames (B-frames), either. B-frames allow for more compact files and hold down transmitted bitrates. If B-frames were allowed, 1,500 kbps could yield a sharper, more artifact-free image.

But the iPhone/iTouch, because of its tiny, low-resolution screen, can't render any sharper and better images than it does. Plus, higher bitrates require larger memories and faster processors in a decoding device, while B-frames likewise tax the decoding processor and require the frames of displayed video to be held in memory after they have been displayed, "wasting" available memory space. Apple made the compromises that it did in order that the processor speed and memory size of the iPhone/iTouch could be held within reason.

Now, these considerations don't apply at all to Netflix video streaming, for the simple reason that the list of Netflix-ready devices includes no mobile or portable devices.

What about Amazon VOD? Again, Amazon's official list of ways to watch their videos conspicuously fails to mention mobile or portable devices.

In its earlier incarnation as Amazon Unbox, the Amazon VOD service supported Microsoft PlaysForSure portable devices. Those were non-PC devices that were certified by Microsoft to be able to play anything their Windows Media Player app could play on a real computer. PlaysForSure certification was rebranded as "Certified for Windows Vista" in 2007.

Meanwhile, Microsoft had come out with it's own iTouch competitor, the Zune portable media player — and Zune cannot play all
PlaysForSure content!

Remind you of anything? Such as: the iPhone/iPod Touch can't play all the content an Apple TV can play (including HD content).

The message here is that it is as yet extremely difficult — nay, impossible — to stream highest-quality video content that "plays for sure" on all manner of devices that turn out to be price-competitive in a competitive, real-world marketplace.

Thursday, November 26, 2009

Amazon VOD Rentals

In Amazon's Video On Demand I talked about buying videos from Amazon's VOD store. You can also rent many titles. As this is written, there are 17,327 rental titles and 23,459 titles that can be purchased.

Many of the rentals and to-buy titles are the same. For example, Borat, the 2006 Sacha Baron Cohen hit, costs $2.99 to rent, $5.49 to buy:

When you buy a TV show or movie, it goes permanently into your video library at

But when you rent, the title is only temporarily in your library until it is downloaded to a device you own that can play it. After the download, you have 30 days to begin playing it on that device. Once you begin watching it, you have 24 hours to finish. When the 24 hours are up, the downloaded copy goes poof.

You can also play the rental on your computer, right in your web browser. Again, you have 24 hours to finish before it vanishes forever.

Here's me renting The Phantom of the Opera (2004). First, I search for "phantom of the opera" at the Amazon VOD store and get:

I click on "The Phantom of the Opera (Rental — 2009)" and see:

(I still have the option to buy the video, as you can see.) At this point I need to already have an account with a credit card or other default payment method on file, and 1-Click ordering enabled. After I click on "24 hour rental with 1-Click $2.99," after a few seconds during which Amazon is processing my order, I see:

I opt to click on the "Your Video Library" link at this point, to see:

Notice that this entry is truly a phantom. Come Dec. 26 at 4:01 PM, if I haven't watched it, it will vanish!

Going back to the "Thank you for your purchase" panel: it gives the options to "Watch Now," "Watch Later," or "Download." You should choose one of these very, very carefully, bearing in mind that "Once you download or start to watch this rental you can't change your viewing choice." That means your choice of a device such as a TiVo to download the rental to is irrevocable. You can't change your mind later and move it to a different device, or decide to play the rental instead in your browser window.

Likewise, if you start playing the rental in your browser, you can't change your mind and download it to your TiVo.

"Watch Now" is what you click to play the rental right in your browser window. "Watch Later" does nothing except leave the rental sitting in Your Video Library, awaiting further disposition. "Download" is the way to initiate a download to your TiVo or other device compatible with Amazon VOD. For purposes of this example, I'll click "Download."

Before I click it, I need to make sure the download is going to go to the right device, so I need to make a selection from the download device drop-down menu:

In this menu I see my two TiVo units, "Living Room TiVo" and "Bedroom," and one Windows computer, "Clone of winxp," running Amazon's Unbox viewer in Windows. (The Unbox software won't run on a Mac.) I want to send my download to my "Living Room TiVo," so I select that, click "Download," and see:

At this point the download has begun. My TiVo box shows a blue LED on its front panel, and if I look in its Now Playing list, I see "The Phantom of the Opera" with a simulated blue LED next to it. The same item appears (redundantly) in the folder representing my "Amazon Video On Demand" group.

I can begin playing the video almost immediately, thanks to the fact that this is a "progressive" download that does not require me to twiddle my thumbs until the whole video has been downloaded.

(If at this juncture I look, in my computer browser, again at my Amazon "Your Video Library," I note that "The Phantom of the Opera" has disappeared from it. Once the rental has begun downloading, that's it: it's no longer in the library.)

Getting back to my Living Room TiVo: whenever I begin playing the rental, before it actually starts I have to wade through a warning to the effect that I'll have just 24 hours to finish watching. When I confirm that starting the 24-hour clock ticking is what I truly intend to do, the video starts playing, just like any other video I have on the TiVo.

If I like, I can temporarily stop playing it — planning to come back to it later — whereupon it acquires a flashing red flag next to its entry in the Now Playing list. This is a warning that at a time 24 hours from when I began watching the rental, it will cease to exist — even if I haven't finished watching it! And sure enough, exactly 24 hours after I first hit Play, the downloaded file disappears from the TiVo.

Amazon's Video On Demand

So far in my Netflix Streaming series, I've talked about the ability to stream Netflix video to your home computers-slash-HDTV screens. Now I'd like to branch out and discuss Amazon Video On Demand.

At's main page you can set the Search drop-down menu to Video On Demand, leave the search box empty, and click Go. If you do, you'll see this. As this post is being written on Nov. 26, 2009, there are 40,691 results, each a movie or TV show that you can rent or buy.

Many titles can be rented or bought — for example, Borat, the 2006 Sacha Baron Cohen hit:

This post covers buying. I'll talk about renting in a subsequent post.

Amazon VOD used to be called Amazon Unbox (Get it? It's a video you can buy, like a DVD or a Blu-ray. But it's not a DVD, so you can't hold it in your hand, it doesn't come in a box, there's no shrink wrap, etc.). Amazon Unbox has been around since Fall 2006; since Fall '08 it's been rebranded Amazon Video on Demand. Where Unbox required you to use a software player that worked only on Windows PCs, Amazon VOD works on PCs and Macs. You don't even need a special player now; a web browser is all you need. (Plus, there is still an Amazon Unbox player that you can use in Windows. Download it here.)

Say you'd like to watch every show in the entire first season of The West Wing. At Amazon's VOD shop, you type "West Wing" into the search box and see various seasons of the late, great NBC political drama at the top of the results:

If you click on Season 1, you'll see (click the image to enlarge):

Here's a close-up of the "Order Now" panel:

Assuming you already have an Amazon account with a credit card and 1-Click buying enabled, purchasing just the first episode for $1.99 is pretty straightforward — it's the default purchase, shown as "Now Playing" in the "Preview" column in the episode list. Scroll down in the list, and you can select other first-season episodes, either singly or as a group, by putting check marks by those you want. Each episode, purchased singly, is $1.99.

But you are interested in the entire season, so you would just click "Buy Season 1 with 1-Click $17.99."

Once you enter your Amazon password and confirm your purchase, all the videos become a permanent part of your online video library at Amazon. To see them listed there, click on "Your Video Library" in the Video On Demand menu bar in your browser window. You'll see a graphic labeled "The West Wing Season 1." Here is mine for Season 2 (I don't own Season 1):

(You can click on the screen image above to enlarge it. The "Your Video Library" tab at upper right is what you clicked on to arrive at this screen in the first place.)

Clicked on, the thumbnail graphic will expand to show all the individual episodes of The West Wing for that particular season:

Clicking on one of the episodes brings up:

You can elect to download the selected episode, or you can watch it right away.

Choosing the download option gives you:

In this case, my download destination is a TiVo video recorder in my "Bedroom." (I'd already downloaded it to my "Living Room TiVo," as the "Locations" entry indicates.)

You can download the videos you buy to various compatible computers and devices in your household, but you have to initiate the download from a computer browser. You can't manipulate your Amazon Video Library from a device such as a TiVo itself.

"Bedroom" is an available download destination for me, since I have already registered that TiVo with Amazon. To do that in my computer browser I went here, then clicked on Refresh list of registered TiVo DVRs. (Go here to confirm what TiVos you have already registered with Amazon, if any.) You can also register the TiVo from the TiVo box itself by selecting "Video on Demand" from the main TiVo menu, selecting "Amazon Video On Demand" from the next menu, and then following the on-screen registration instructions.

Once you have initiated an Amazon VOD download, within a minute or so the destination device will actually begin receiving the video. If the device is a TiVo, a blue LED lights up on its front to indicate that a download is in progress. You can go into its Now Playing list and see the video already listed there. While it is downloading, it will display an imitation of the blue front-panel LED next to its name.

If you want, you can start watching the video even while the download proceeds. This capability of watching an in-progress download is called "progressive download."

If you have a slow Internet connection, it is possible that the progressive download will not keep up with the playback — in which case you will be returned to the TiVo menu screen for the video. You can resume playback of the video at will, but you may have to wait a bit for enough of the video to be transferred to avoid further interruption.

If you prefer, you can bypass downloading the video to a TiVo or other compatible device and just watch it instantly on your computer, in your web browser:

(Click on the image above to see it full size. The grain in the image is a byproduct of my screen capture software and does not appear in the actual video.)

The Adobe Flash Player plugin must be installed in your browser for this to work.

Once the purchased video is in your Amazon VOD library online, you can play it in your browser any time you want, as often as you want.

Remember, watching an Amazon VOD video in your browser starts instantly, since the whole file is not actually downloaded. This is different from a progressive download, for which you may have to wait five minutes or so before beginning to watch the video. That's why if you elect to use the Amazon Unbox player on a Windows PC, you have to wait for enough of the video to be downloaded, before starting to watch.

You don't have to pay extra for each use of the video, whether in a browser window, in the Unbox player, or on a device like a TiVo. You can also re-download it at any time for free; if you delete it from Unbox or your TiVo you can get it back at will. This is the advantage of buying rather than renting.

However, if you will only be watching a video once or twice, and if Amazon offers it for rental rather than purchase, renting can save you money. Renting will be the topic of my next post ...

Sunday, November 22, 2009

Of NeRDs and Silverlight

My last post, Instant Netflix on PS3 and TiVo, was about how you can stream movies and TV shows directly from Netflix, via the Internet, to a home TV or computer screen. You don't even need to wait for a DVD in the mail.

Here I'd like to begin going into more depth about how Netflix accomplishes this magic. I'll discuss various topics, plus I'll give links to where you can find out more. Fair warning: I don't guarantee that all of my information is perfectly accurate or complete. I'll try to do the best I can.

You can stream Netflix content onto your computer via a Web browser, or you can stream it to a TV screen through any of several home entertainment devices: certain recent-model TVs that allow Internet access; certain set-top boxes such as TiVo DVRs; certain Blu-ray players that can get online using BD-Live connectivity; and certain game consoles like the Microsoft Xbox 360 and Sony PlayStation 3. These non-computer devices that can stream Netflix are what Netflix calls Netflix-Ready Devices; I call them "NeRDs."

If you're using a computer, the magic formula enlists either Firefox or Safari, web browsers compatible with Silverlight, a plugin from Microsoft that plays video content from Netflix right in a browser window. Let's say you want to watch WALL-E, the 2008 Disney-Pixar hit. You encounter a WALL-E thumbnail at that has a white-on-blue "Play" button below it, or you pull up the dedicated page for the film and see a similar "Play on Computer" button. You click once and watch as a video player appears in your browser window.

But instead of seeing the movie, you get a warning that you need to download and install the software called Silverlight. Your browser offers to do the download, after which you use standard procedures to install it as a browser plugin. It all happens quickly and painlessly. Then you restart your browser and try WALL-E again, and after a few seconds of preliminaries — "Connecting to the Netflix movie server" / "Downloading movie information" / "Determining your video quality" / "Buffering" / "Acquiring content license" — the movie begins, all thanks to Silverlight!

What about those non-computer NeRDs? Home entertainment devices that can stream Netflix content don't use web browsers. They incorporate firmware (aka "system software") that, in turn, incorporates the same functionality as Silverlight. (For all I know, it is Silverlight in a different form ... but it isn't in the form of a browser plugin.)

An exception is the Sony PlayStation game console-cum-Blu-ray player, which won't get firmware that incorporates Silverlight functionality until late 2010. For now, that functionality comes on a Blu-ray disc that you slide into the PS3 each time you want to stream Netflix.

Silverlight (or its NeRD clones) enables Netflix's movie servers to select a bitrate that your network connection to the Netflix server can handle. Each movie is encoded several times, at various bitrates. The higher the bitrate, the better the picture and sound. But if the Internet connection can't keep up with the bitrate that is originally selected, the server won't get "return receipts" (technical term: acknowledgments) back from Silverlight in time. The server can then switch seamlessly to a lower bitrate, and Silverlight is capable of hiding what is going on from the user's eyes and ears.

So, during the "Determining your video quality" preliminary stage, the server cooperates with Silverlight to measure your network speed. Then it selects a bitrate that fits that speed.

Even so, sometimes acknowledgments begin arriving back late, or not at all ... in which case the server assumes some of the information it sends out in the form of message packets is getting lost. It arranges with Silverlight to start using smaller packets. The smaller the packet, the less the information that has to be retransmitted when a packet is lost. Cutting down the packet size saves retransmission overhead and allows the server to avoid dropping down to a lower bitrate. Ideally, playback quality remains the same.

If necessary, though, the server can go so far as to lower the bitrate. If the video is standard definition, 1,500 kbps (the highest SD bitrate that Netflix uses) can drop to 1,000 kbps, 500 kbps, or even as low as 375 kbps. (I'm getting this, by the way, from an article in The Netflix Blog called "Encoding for Streaming.")

When I watch an SD movie using my PlayStation 3, the PS3 lets me display the instantaneous bitrate on the TV screen. I find that the instantaneous bitrate varies widely. Frequently it goes well above 2,000 kbps. When there is little motion in the scene though, the bitrate drops well below 1,000 kbps. In other words, the instantaneous bitrate is variable. This is called "variable bitrate encoding," or VBR. The average bitrate, I assume, is the advertised 1,500 kbps.

Sometimes the speed of the network connection drops enough to cause problems if the original average bitrate isn't likewise dropped down to a lower bitrate.

In the VC-1 Advanced Profile (VC1AP) encoding that Netflix uses, according to the blog post, "each GOP [group-of-pictures; a "picture" is an individual "video frame"] header includes frame size and resolution, which allows [Netflix servers] to assemble a stream on the fly from different bitrate encodes as your broadband bandwidth fluctuates."

This happens without the user being aware of it, because Silverlight recognizes on-the-fly changes in bitrate by inspecting the parameters in the GOP headers, and it accommodates those changes automatically.

The result can, however, be a drop in perceived video quality. Lower average bitrates can mean more digital compression artifacts, hence messier-looking images. Or there can be fewer video frames per second in the lower-bitrate encode, so motion gets choppy.

However, the swings in instantaneous bitrate due to VBR encoding are a different story. They happen in response to the changing complexity of the moving image, just as they do on a DVD. In order for the viewer to perceive unchanging video quality, more bits are needed to encode highly complex images having a lot of fast motion, while fewer bits are needed for simple, static images.

When Netflix uses a 1,500-kbps encode, it is implicit that the instantaneous bitrate will sometimes be much higher than 1,500 kbps — and so the network connection has to be able to deliver more kilobits per second than the average bitrate implies. In other words, the speed of the connection must be fast enough to allow for the occasionally high overhead of VBR encoding.

What about high-definition encodes? At the time the Netflix blog article was written (Nov. 6, 2008) there were some 400 HD streams available. The article says HD is encoded in VC1AP at 3,800 kbps and again at 2,600 kbps. The video resolution in both cases is 720p, which means each video frame, with its 16:9 widescreen aspect ratio, is made up of 720 rows of 1,280 pixels per row.

This is not "Full HD" 1080p encoding, such as is found on Blu-ray, or even 1080i, each of which would require each frame to contain 1,080 rows x 1,920 pixels.

There are 24 frames of 720p video per second for material transferred from film, mimicking the frame rate of film itself. Shot-to-video HD material is at 30 frames per second (25 fps for video material shot in the British PAL standard). Again, this is not as good as Blu-ray, which uses 60 fps for HD video material shot in the U.S. This type of encoding is referred to as 1080p60. Netflix uses 720p30 (or 720p24 for film-based material).

Netflix says it believes "using 1080p60 would require a bitrate out of reach for most domestic broadband today. We believe Moore's law will drive home broadband higher and higher enabling full 1080p60 encodes in a few years."

Another article from the Netflix blog, "Netflix Trying for Consistent Excellence on Streaming," gives more information about what goes on behind the scenes. Netflix streams use servers scattered around the country to avoid congested Internet "backbone" lines. The servers are organized into "content delivery networks" (CDNs). The CDN approach groups servers in regions that serve nearby users. The nodes of the CDNs cooperate with each other to satisfy requests for content by nearby users.

If several users are watching, say, WALL-E at 1,500 kbps, one particular server of one particular CDN is active for all of them. If that server encounters major congestion between itself and any particular user, that one user may develop problems with playback, or lowered video quality. Other WALL-E watchers may see no problems whatever.

In fact, Netflix says, the combination of server and network path may vary depending on what type of device the user is using. "Accordingly," the article says, "[individual] customers may see better performance on [an] Xbox than [on] their PC, or vice-versa."

Netflix's strategy is to keep as many users satisfied as possible, as much of the time as possible, while giving them the best possible video and audio quality. In addition, Netflix wants playback to begin as quickly as possible after the user has initiated it.

This sounds good ... but some users have complained that they typically have slow network connections and never get top-quality results. These users have asked to be able to pre-buffer content using the best-quality encode at the highest available bitrate. They say they don't mind if the start of playback is delayed until a hefty portion of the content — or all of it — has already been buffered.

So far, though, Netflix has not built such a pre-buffering option into Silverlight.

Thursday, November 19, 2009

Instant Netflix on PS3 and TiVo

Got Netflix? You and 11.1 million others in the U.S., as of 9/30/09; Netflix is huge. Unless yours is a so-called "limited" account, you have an Instant Queue (IQ) you can load up with movies that you can then watch instantly to your heart's content. You can do that on a computer. You can also do it on your TV screen, via a TiVo or other set-top-box, a game console such as a Sony PlayStation 3 or a Microsoft Xbox 360, certain models of Blu-ray player (typically, recent ones with BD-Live capability), or even certain TVs that have Internet connections. All these so-called Netflix-ready devices (NeRDs?) connect to the Internet via WiFi, or via an Ethernet cable if you use one.

It's taken me a while to catch on to Netflix streaming. I ignored it when, some time ago, my TiVo #1 began carrying Netflix (see this press release). Then, the other day, I was fiddling with my Sony PlayStation 3, which sits in my living room below my TiVo #2 unit and, just like that TiVo, feeds signals into my favorite flat panel TV. After a firmware upgrade, the PS3 alerted me that I could now use it to stream Netflix (see this press release). Seemingly, all I had to do was use the PS3's built-in browser and visit to begin streaming movies from my Netflix IQ. So I did.

Actually, the browser just let me link to Netflix to ask for an Instant Streaming Blu-ray Disc for the PS3. The disc had to be mailed to me. (I couldn't believe the software can't be downloaded!) Also, you'll need to be sure you've upgraded your PS3's firmware to version 3.01 or later, to allow the Netflix software to work.

Once you get the disc — which you keep and never mail back — you insert it in your PS3 and see an activation code come up on your TV screen. You have to run to your computer to enter that five-character code into this web page, because with the disc in the PS3, the PS3 can't use its own browser, or any of its normal functions(!). With the disc inserted, the PS3 becomes a dedicated Netflix streamer, until you eject the disc or use the Back button on the PS3's remote to idle the disc.

The dedication of the PS3 to Netflix streaming while the disc is active, by the way, is why you need to keep reinserting the disc each time you want to watch Netflix on the PS3. Netflix claims it used an external disc as the quickest and cheapest way to get streaming capability to the PS3, but rumors abound that the real reason was that the company's exclusivity arrangement with Microsoft (whose Xbox 360 already streamed Netflix) had to be worked around — technically — by keeping the Netflix interface off the PS3's Cross Media Bar (XMB). The XMB is the fancy menu system the PS3 uses to allow the user to navigate among the game console's various functions. The Xbox 360's equivalent is the Dashboard. Netflix seems to have felt constrained to keep its streaming function off the PS3's version of the Dashboard.

This is apparently a temporary situation. By late 2010, Netflix expects its software to be embedded in a new release of the PS3 firmware.

After you activate your shiny new disc on your PS3, you'll immediately see your IQ on the TV screen and can navigate to and begin watching any item in the queue. Play begins pretty quickly. It's not at all choppy or pixellated. The video and audio are, I find, basically of DVD quality. Netflix says here that it "automatically chooses the video quality to give you the best image possible based on the speed of your Internet connection. The faster your Internet connection, the higher the quality that we can deliver to you."

Did I mention that watching movies from your IQ is free? It's included with the cost of a regular (i.e., non-"limited") Netflix account! With Netflix, you don't have to pay extra for video-on-demand. Take that, cable companies!

Also, the PS3 Netflix application's attractive and easy-to-use interface lets you locate and add stuff to your Instant Queue, using just your PS3 remote. The IQ updates right away, so you can begin watching new items immediately.

But what you can't do is type in, say, "Kubrick," to see all the available films of Stanley Kubrick. You'll need to use your computer for that sort of thing. Or try the Instantwatcher iPhone app, which lets you manage your Instant Queue from an iPhone or iPod Touch:

There is also an Instantwatcher web site, which you may want to check out.

It gets better. My two TiVo units (as I'd been so blind to) also stream Netflix.

The user interface is different: it's TiVo-like, which has its good points and bad. A good point is that you can opt to have the Netflix IQ show up as a folder (appropriately, red) in your Now Playing list. The folder's individual titles can be sorted alphabetically. If you add (say) the entire first season of The Office to your IQ, it shows up as a subfolder within that folder.

A bad point is that there seems to be no way to add items to the IQ from the TiVo, as is easy to do from the PS3. (But once you add an item via the PS3, you can watch it right away on the TiVo, if you prefer. Or you can just watch it right on the PS3.)

It gets better still. Some of the content that you can stream from Netflix is in HD!

HD streaming works seemingly identically on my two TiVo units and on my PS3. On all of them, I seem to be finding that the resolution is always 720p, never 1080i/p, even on TV shows like The Office that are broadcast in 1080i. I guess the 720p limitation is a compromise to allow Internet streaming of HD content at all. Or it may be that if I had a really extremely fast Internet connection, I'd see 1080i — who knows? 720p looks great, anyway, so I'm not complaining.

You can get another blogger's take on HD content streaming from Netflix to the PS3 here.

Speaking of content, there are today some 17,000 titles at Netflix that can be streamed instantly. That may seem like a lot, until you stop to consider that Netflix has over 100,000 DVD titles (not to mention Blu-rays). It looks as if few if any of the very latest movie releases make it to Netflix streaming until they're past their period of hottest popularity.

That makes sense. Netflix streaming is essentially a free feature — for those who already pay for an account. Why should Netflix give away its most sought after titles? Plus, the movie studios probably wouldn't care much for it. In fact, I'd bet money that it won't be long until Netflix starts charging to stream stuff, either some or all of it.

Netflix says more on-demand titles arrive "every day," and I suppose one reason why it takes a while for new releases to appear may be that they have to be specially rendered into the necessary video format or formats. For example, if The Office is in 1080p on Blu-ray, it has to be converted to 720p for Netflix. If, as I suspect, there are different formats for different connection speeds, that only compounds the problem.

See other posts in my Netflix Streaming series for more ...