[whatwg] Limiting the amount of downloaded but not watched video

[Silvia Pfeiffer]

On Tue, Jan 18, 2011 at 1:30 AM, Boris Zbarsky <bzbarsky at mit.edu> wrote:
> On 1/17/11 6:04 PM, Boris Zbarsky wrote:
>>
>>  From a user's perspective (which is what I'm speaking as here), it
>> doesn't matter what the technology is. The point is that there is
>> prevalent UI out there right now where pausing a moving will keep
>> buffering it up and then you can watch it later. This is just as true
>> for 2-hour movies as it is for 2-minute ones, last I checked.
>>
>> So one question is whether this is a UI that we want to support, given
>> existing user familiarity with it. If so, there are separate questions
>> about how to support it, of course.
>
> I checked with some other users who aren't me, as a sanity check, and while
> all of them expected pausing a movie to buffer far enough to be able to play
> through when unpaused, none of them really expected the whole movie to
> buffer.  So it might in fact make the most sense to stick to buffering when
> paused until we're in the playthrough state and then stop, and have some
> other UI for making the moving available offline.

I think that's indeed one obvious improvement, i.e. when going to
pause stat, stop buffering when readyState=HAVE_ENOUGH_DATA (i.e. we
have reached canplaythrough state).

However, again, I don't think that's sufficient. Because we will also
buffer during playback and it is possible that we buffer fast enough
to have buffered e.g. the whole of a 10min video by the time we hit
pause after 1 min and stop watching. That's far beyond canplaythrough
and that's 9min worth of video download wasted bandwidth. This is
where the suggested downloadBufferTarget would make sense. It would
basically specify how much more to download beyond HAVE_ENOUGH_DATA
before pausing the download.

Cheers,
Silvia.