On Tuesday, March 20, 2012, David Gerard dgerard@gmail.com wrote:
On 20 March 2012 19:06, Ian Baker ian@wikimedia.org wrote:
- WebM (aka VP8) is really not bad, but is technically inferior to h.264
Main and High Profiles[1].
This comparison appears specious in the context of this thread, which is the iPhone - the iPhone (which is the context of this thread) doesn't support Main or High, only Baseline.
How does VP8 compare to H.264 Baseline profile?
(Up to 640x480, 'cos the iPhone doesn't go any higher of course. Is the proposal to limit Wikimedia video to 640x480 as well, for the mobile market?)
The iPhone 4s can play 1080p videos according to specs (scaled down to fit 960x640 of course). Several high-end phones now have 720p screens, and are happy to play matching media. Tablets running related operating systems have screen resolutions running from 1024x600 to 2048x1536. Other phones with smaller screens, or on slow networks, might prefer to consume smaller files.
TimedMediaHandler provides us the ability to generate transcodes at several suitable sizes/bit rates. This is par for the course for video upload sites, and simply brings us into line with standard industry practice. We would already, per plan, be producing both smaller SD and larger HD files.
We can also produce Theora, WebM, *and* h.264 versions, or some subset thereof, though additional formats mean more disk space and more transcode time on upload.
But on a lot of devices, h.264 is the only realistic playback option. Java's not available, JavaScript's not fast enough on little ARM CPUs. A dedicated app might work (using more battery due to limited acceleration) but would require additional installation with no benefit to the end-user, who has already paid the patent license for the h.264 decoder in their device as part of its price.
Our commitment to user freedom means we need to use patent-unencumbered formats so *anyone* can use our stuff, including those on free platforms who may not have a licensed h.264 decoder. The idea isn't actually to *limit* our users to only free platforms. I think we do need to consider reach and user experience here.
-- brion
- d.
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