[foms] WebM Manifest

[Steve Lhomme]

On Thu, Mar 17, 2011 at 10:53 PM, Timothy B. Terriberry
<tterribe at xiph.org> wrote:
>> life of the encoder (and likely the rate control process) easier. And
>> on the playback side there's hardly any drawback. But that means
>> players have to handle the case they want to switch but the next
>> keyframe is not available in the variant it wants to switch to.
>
> This also assumes this is even expressible in the manifest. I don't know
> DASH well enough yet to say if it is. And it leaves you with the
> possibility of switching to a rate and not being able to switch out of
> it for a long time. Imagine a relatively still scene with only forced
> keyframes at periodic intervals: if these are misaligned at the start,
> it could be many tens of seconds before there is another opportunity to
> switch. This sort of thing is not as uncommon as you think.

It would not be expressed in the manifest (just no forced duration
set). I agree it may not happen all the time, but the possibility
should not be ruled out because it cannot be used 100% of the time.

In the case you describe the only drawback is that playback is not as
perfect as it can theoretically be. But that's expected when using
adaptive streaming anyway.

-- 
Steve Lhomme
Matroska association Chairman