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Re: Multi-bitrate Quicktime SMIL files

for

From: Andrew Kirkpatrick
Date: Jun 25, 2007 9:40PM


Better still is to use Flash for the video. We support DXFP caption
data, and you can use SMIL for bandwidth negotiation in the Flash
content, AND you can make the user interface to the video controls
accessible.

AWK

> -----Original Message-----
> From: <EMAIL REMOVED>
> [mailto: <EMAIL REMOVED> ] On Behalf Of Jared Smith
> Sent: Monday, June 25, 2007 11:21 PM
> To: <EMAIL REMOVED> ; WebAIM Discussion List
> Subject: Re: [WebAIM] Multi-bitrate Quicktime SMIL files
>
> On 6/25/07, Terry Thompson wrote:
>
> > Does anyone have a sample SMIL file that serves captioned videos to
> > users at different bitrates?
>
> http://webaim.org/techniques/captions/quicktime/smil.php#creating
>
> > It's as if the <root_layout>
> > element doesn't respond to being included within <switch>.
>
> Switch is only allowed within body. Because the region
> dimensions are defined a level above the switch elements, I
> don't think you can change the video and captions dimensions
> using switch.
>
> Maybe try setting root-layout dimensions in pixels, then set
> the width and height of each region to 100%. This *should*
> allow the areas to scale to the appropriate video and caption
> size for each system-bitrate identified in your switch. In
> this case, the video player size (root-layout) will be fixed,
> but the video and caption areas themselves (regions) should
> size appropriately, as Andrew described. Be sure to identify
> width and height in each Quicktime Text file.
>
> Things might be made a bit easier if you embed the captions
> within the .mov files themselves
> (http://webaim.org/techniques/captions/quicktime/add_captions.php)
> rather than using textstream in your SMIL. This way you don't
> have to worry about the size of the caption areas at all -
> they'll be defined in the mail .mov file. There might be an
> easier way, but I'm not one of the three people on the planet
> that are familiar with SMIL. ;-)
>
> Also of note, the system-bitrate isn't determined by the
> user's bandwidth, but by the settings in the user's
> preferences. I've found these to be inaccurate in most cases.
>
> If you use true Quicktime streaming using Quicktime Streaming
> Server or Darwin server, then it will account for
> fluctuations in bandwidth, though not to extreme levels, but
> perhaps enough that you could provide a high and low
> bandwidth option. If you're not doing true streaming, then
> Windows Media Player allows multi-bitrate video that does all
> of this natively. Or you could do some very basic bandwidth
> detection in Flash and then show the video in a quality that
> is appropriate.
>
> If you find a solution, be sure to post it back here so we all know.
>
> Jared Smith
> WebAIM
>