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

Glenn Maynard glenn at zewt.org
Tue Jan 18 13:37:00 PST 2011

On Tue, Jan 18, 2011 at 8:40 AM, Boris Zbarsky <bzbarsky at mit.edu> wrote:

> On 1/18/11 6:09 AM, Glenn Maynard wrote:
>> I'm confused--how is the required buffer size a function of the length of
>> the video?  Once the buffer is large enough to smooth out network
>> fluctuations, either you have the bandwidth to stream the video or you
>> don't; the length of the video doesn't enter into it.
> The point is that many users _don't_ have enough bandwidth to stream the
> video.  At that point, the size of the buffer that puts you in
> HAVE_ENOUGH_DATA depends on the length of the video.

If you don't have enough bandwidth, then the necessary buffer size is
effectively the entire video[1].  Mikko seems to suggest that it's the
entire video times some multiplier, where that multiplier can be discovered
by binary searching.  This doesn't make sense to me:

> static time period in seconds. This is required because a 5 second
> buffer could be enough for a 20 second clip but a 2 minute buffer could
> be required for one hour video. In both cases, the actual available

[1] (Of course, it's more precisely the size of the video minus a function
of the video size, bitrate and user bandwidth--the amount of data you can
leave unbuffered at the end and have it finish while you're watching.  I
point this out because someone else will if I don't, but I don't think it's
relevant to any buffer size algorithm: it's hard to determine, and if you
get it wrong for a long video you have a very annoyed user with his movie
interrupted two hours in.)

Glenn Maynard

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