Hi,
As a potential adopter, I think being able to have a playlist
passed to the engage player and other encoding services would be really
beneficial. We have the same requirement in our current system and we
use an internal format for that. It seems that SMIL is a good choice. It
would probably be better to have the element id as Tobias suggested, but
I don't know enough... Here are more details on what we need:
Our current system plays the talking head video along synchronized
snapshots of the screen (jpegs). In some of our classrooms, we only
record the talking head video and synchronize the powerpoint, pdf, etc
slides to the video later, before publishing the lecture. Even when we
migrate to Matterhorn, there may be still the need for keeping some of that:
- To support students that don't have enough bandwidth for two streams;
- To be able to ingest and publish old lectures from our current system
without loosing the slides;
- In case the capture agent fails, we still have the camera cards and
the slide material and we would still be able to produce a complete
lecture...
Right now I am thinking of uploading the slide images as
"presentation/segment+preview" attachments and changing the UI to
display them in a bigger size in order to support that. SMIL supports
referencing slides that could be launched by the player at specific
times. Is this something that is being considered too?
Thanks,
Rute
Harvard DCE
On 6/20/2012 6:08 AM, Tobias Wunden wrote:
Hi Rüdiger,
it seems that SMIL may indeed be a good fit for what we are looking for. One
question that came to mind is:
Should we use the mediapackage's track id or even the track's flavor instead of
the filename? We may have different tracks in a mediapackage with the given
name, and it should be considered that it's not only the player that is
evaluating the SMIL instructions but also other services, for example those
that are creating reencoded versions of the video(s) based on the playlist.
Another thought (tying into the same topic) is that there may be institutions
that would like to pull in attachments as well (I remember Len from Harvard
talking about how they would like to pull up images of slides during video
playback that would most probably be attached to the mediapackage as
attachments). This again indicates to me that the mediapackage element id may
be a good thing to use rather than filenames.
I am looking forward to anyone's thoughts on this.
Tobias
On 18.06.2012, at 13:44, Ruediger Rolf <[email protected]> wrote:
Hi list,
as we have encountered on the Harvard Un-Conference there are currently some
groups working on video editing functions. The bandwith of the ideas that came
up during the discussions was from compositions of video segments that are
remixed in the browser, over services that re-encode the video based on the
playlist up to streaming servers that exclude parts of the video without the
player even knowing this.
I feel the strong need that we agree on a common exchange format of the needed
video edit list. From my point of view it would be the best to use an open
standard for this and so SMIL 3.0 Tiny Profile [1] seems to be a good choice.
As an example a "playlist" for a single stream video might look like this:
<?xml version="1.0"?>
<smil xmlns="http://www.w3.org/2001/SMIL20/Language";>
<body>
<seq>
<video src="lecturer.mpg" clipBegin="00:01:44.360"
clipEnd="00:04:06.720"/>
<video src="lecturer.mpg" clipBegin="00:38:54.480"
clipEnd="00:50:08.240"/>
<video src="lecturer.mpg" clipBegin="00:59:56.640"
clipEnd="01:13:51.720"/>
<video src="lecturer.mpg" clipBegin="00:31:28.440"
clipEnd="00:49:30.280"/>
</seq>
</body>
</smil>
If we have a dual stream video it might look like this:
<?xml version="1.0"?>
<smil xmlns="http://www.w3.org/2001/SMIL20/Language";>
<body>
<seq>
<par>
<video src="lecturer.mpg" clipBegin="00:01:44.360"
clipEnd="00:04:06.720"/>
<video src="vga.mpg" clipBegin="00:01:44.360" clipEnd="00:04:06.720"/>
</par>
<par>
<video src="lecturer.mpg" clipBegin="00:38:54.480"
clipEnd="00:50:08.240"/>
<video src="vga.mpg" clipBegin="00:38:54.480" clipEnd="00:50:08.240"/>
</par>
<par>
<video src="lecturer.mpg" clipBegin="00:59:56.640"
clipEnd="01:13:51.720"/>
<video src="vga.mpg" clipBegin="00:59:56.640" clipEnd="01:13:51.720"/>
</par>
<par>
<video src="lecturer.mpg" clipBegin="00:31:28.440"
clipEnd="00:49:30.280"/>
<video src="vga.mpg" clipBegin="00:31:28.440" clipEnd="00:49:30.280"/>
</par>
</seq>
</body>
</smil>
In general it might be useful to create a (REST)-service that delivers the SMIL
file that the current service needs. So in the player we need one of the
distribution copies (streaming or not), while we would need a link to the
source files for a re-emcoding and we might need a link to the file in the
file-system on the streaming server.
Specialized output formats like simple JSON lists that the REST-endpoint
creates might be a valid export format for the player too.
So I'm open for comments on this issue. What do others think about this
proposal? Are there alternative formats to SMIL that are worth considering?
Regards
Rüdiger
[1] http://www.w3.org/TR/smil/smil-tiny-profile.html
--
________________________________________________
Rüdiger Rolf, M.A.
Universität Osnabrück - Zentrum virtUOS
Heger-Tor-Wall 12, 49069 Osnabrück
Telefon: (0541) 969-6511 - Fax: (0541) 969-16511
E-Mail:[email protected]
Internet:www.virtuos.uni-osnabrueck.de
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