[html5] Autoplay and preload insufficient for proper video playback.

Rik Sagar org.whatwg at sagar.org
Thu Aug 26 13:40:54 PDT 2010

What is the prescribed behavior with "autoplay"?  When should the UA start
 - "canplay"
 - "canplaythrough"


Rik Sagar, San Jose, CA 95124
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On Thu, Aug 26, 2010 at 5:05 AM, Herman Hassel <herman at agrabush.com> wrote:

>  On 26.08.2010 06:58, Eric Carlson wrote:
>>   A static attribute that specifies a minimum buffer size or duration will
>> only help users with exactly the bandwidth the for the attribute value -
>> anyone with less bandwidth will still run out of data, and anyone with more
>> bandwidth will have to wait longer than necessary.
> Yes, but this also depends on how a developer would use the buffer
> attribute, for our use we wouldn't set it too high. (3-5 seconds or so is
> what we would favor at this time). A low bandwidth user would run out of
> data, but he would get at least 5 seconds of video before this would happen.
> From my experience with how users interact with video an end user will
> notice the loaded bar not moving as fast as the scrubber, but at least we've
> given him a teaser of the full content before he needs to wait. For a user
> with exact or higher bandwidth, the 3-5 second buffer loads fast enough to
> not break the experience. :)
>    If you want to prevent users from starting playback too early, use a
>> custom controller and wait for the 'canplaythrough' event. It is fired when
>> the UA estimates that the amount of time it takes to play the movie is less
>> than the time it will take to download the rest of the movie. How can a
>> static attribute be more accurate than this?
> That would be more accurate if our goal is for the end users to start the
> video when they can view the whole video at once, but this would also mean a
> much longer wait for any video at all for the low bandwidth users. We want
> to show video as fast as possible to our users, but we wish to stop the
> initial stutter that occurs if we start playing a video at the same time as
> it starts loading. Giving a low bandwidth user a few seconds of video should
> suffice in most cases, and it would then be up to the low bandwidth end user
> if he wanted to pause and wait for more video or move on. We'd get too many
> users just moving on without any video if we were to impose the full video
> on them before allowing playback. My proposal is to make the buffer
> attribute optional, not a requirement, and it would not break listening to
> the 'canplaythrough' event for those cases where you don't want to present a
> video until the user can watch the whole thing. :)
> --
> Herman Hassel
> Agrabush Design
> mail:    herman at agrabush.com
> twitter: http://twitter.com/agrabush
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