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Re: Media Fragments in Opera

From: Silvia Pfeiffer <silviapfeiffer1@gmail.com>
Date: Wed, 20 Oct 2010 22:31:17 +1100
Message-ID: <AANLkTi=o8P7v7s=Aja3428EPGWF7A=p=xc4bNS7gopF2@mail.gmail.com>
To: Philip Jägenstedt <philipj@opera.com>
Cc: public-media-fragment@w3.org
On Wed, Oct 20, 2010 at 8:09 PM, Philip Jägenstedt <philipj@opera.com> wrote:
> On Mon, 18 Oct 2010 12:25:27 +0200, Silvia Pfeiffer
> <silviapfeiffer1@gmail.com> wrote:
>
>> On Mon, Oct 18, 2010 at 7:55 PM, Philip Jägenstedt <philipj@opera.com>
>> wrote:
>>>
>>> * It's not clear to me what to do with the smpte formats. In our
>>> underlying
>>> media framework (GStreamer) time is expressed in nanoseconds, so it
>>> doesn't
>>> actually give any great precision that using 9 decimals. For now, I've
>>> not
>>> added support for the smpte formats at all. Are there any existing
>>> implementations or indications that anyone does want to implement it?
>>
>> It's mostly there because RTP/RTSP uses it, too, IIRC.
>
> Is this reason enough for it to be part of MF? Are there compatibility
> requirements I'm not aware of?
>
>>> * The use case for 'clock' syntax is pretty clear, but AFAIK the time in
>>> UTC
>>> isn't available in Ogg or WebM, so I'm not sure what to do with it.
>>
>> Ogg Skeleton has the possibility to add a UTC marker and all time
>> offsets from there can be added onto the UTC time marker. See
>> http://wiki.xiph.org/Ogg_Skeleton_4 and search for UTC. Not that I've
>> seen it used yet, but flumotion might need it if/when it's going to do
>> timed fragment URIs with UTC time.
>
> OK, thanks! I guess for WebM this won't happen at least until we add
> metadata support.

Yeah, a UTC time stamp is basically just metadata on what the very
first time stamp in the video means.

S.
Received on Wednesday, 20 October 2010 11:32:14 GMT

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