HD video podcasts come to iTunes--and Apple TV

One of our biggest complaints with the Apple TV was the dearth of HD video content. The product is capable of streaming 720p high-definition video, but to date, all of the movies and TV shows at Apple's iTunes Store are encoded at a "near DVD" resolution of 480p. But HD content has finally arrived on iTunes--and it's free. The Washington Post announced today that its online HD video podcast--which is shot in 720p high-definition--will now be available through iTunes.

We downloaded the two most recent episodes of the podcast--Edwards Family Values as well as Contamination and a Crusade--to evaluate the video quality. Overall, it was a big step up from previous iTunes fare, but critical viewers will find it falls short of HD broadcasts and even most DVDs. When viewed on a 42-inch Panasonic plasma TV, the improved resolution was evident on the images of John Edwards speaking to an auditorium full of students, but false contouring and solarization artifacts were easy to pick out in the background (white walls were a prime culprit). Close-ups of Edwards' face also exhibited some swimming pixels. Likewise, the depth of field offered was good, but not comparable to what you'd find on an HD broadcast (let alone a Blu-ray or HD DVD movie).

The problem here isn't resolution but bitrate--4,061Kbps with a mono soundtrack. That's a big improvement over the 1,516Kbps encoding found on a purchased episode of The Office, but merely 40 percent of the 10Mb capacity found on a standard-definition DVD. (Apple TV maxes out at 5Mbps, or about 5,000Kbps.) Of course, the better video quality comes at the expense of file size: the Edwards video was a mere 8.5 minutes long, but the file was a rather meaty 250MB--the same size as the aforementioned 21-minute episode of The Office. In addition to the increased download time, the large file size and bitrate affects streaming performance as well. Live streaming from an 802.11g laptop to the Apple TV (via an 802.11n Belkin N1 router) did produce the occasional buffering hiccup--the source PC would need to be wired or upgraded to 11n wireless to guarantee smooth streaming--but once we synced to the Apple TV's hard drive, play was perfect.

Of course, iTunes and the Apple TV were always capable of HD streaming, but the big news here is that the HD content is available through the iTunes Store. (Previously, you needed to download the HD file--say, a high-definition trailer at Apple's Quicktime site--and then manually import it into iTunes.) Video podcasts are a nice first step, and the fact that they're free is always welcome. But we're hopeful this is a trial balloon that will signal the availability of high-definition movies and TV shows from the iTunes Store in the not too distant future.

Note: Since originally published, this blog post has been updated with hands-on analysis of the HD video performance on Apple TV.

[drhamad]

Bitrate comparisons to DVD are irrelevant... maybe

I've never quite figured out how iTMS manages to have such large files for such low quality... and even here, with 3rd party encoded content, the same thing happens. Why on earth would the bitrates need to be so high? When I encode video in h.264, I use between a 1,300 and 1,500 kbps video bitrate and 320kbps AAC audio. This results, when using h.264 and NOT MPEG-4, in full movies at between 1 and 1.5 GB, and the quality is superb (based on a DVD). So what is iTunes (especially, since it theoretically uses 480p) and the Washington Post (less so) doing wrong? What the heck are they using?

[Daniel L Smith]

Bit rate doesn't measure absolute quality

"The problem here isn't resolution but bitrate--4,061 kbps with a mono
soundtrack. That's a big improvement over the 1,516 kbps encoding found
on a purchased episode of The Office, but merely 40 percent of the 10
megabit capacity found on a standard-definition DVD."

Serious problems with this statement:

- Resolution directly affects bit rate. The difference between 480p and 720p
is 1.5^2 = 2.25, meaning an HD video with the *same* quality would be 2.25
times larger (3,411). So the "big improvement" is only 4061/3411 = 19%.

- You can't infer quality by comparing bit rates of different codecs (MPEG-2
on DVDs vs. H.264 on iTunes) any more than you can compare bit rates of
audio files (mp3 vs. aac) or clock speeds of processors (Intel vs. PowerPC). H.
264 is supposed to use far superior compression, when compared with its
predecessors. It had better *not* require nearly the bit rate of a DVD to
produce good-quality results, or something is seriously wrong.

[juzzle]

Washington Post HD? - cropped windows

Perhaps I skipped over the coverage of this article, however, whilst the supposed HD content by The Washington Post was better that TV Shows from iTunes, it was cropped to about 75% of the screen area. I am not talking about 4:3 bars, I am talking about the 16:9 reduced to take up less pixels. I suspect what they've produced is about 580px high, and not the full 720p. A bit of a stretch (shrink?) if you ask me :-/