W3C

Media Fragments Working Group Teleconference

01 Apr 2009

Agenda

See also: IRC log

Attendees

Present
Erik, Davy, Jack, Raphael, Silvia
Regrets
Michael, Yves, Conrad
Chair
Erik, Raphael
Scribe
Raphael

Contents


 

 

<trackbot> Date: 01 April 2009

<scribe> Scribe: Raphael

<scribe> scribenick: raphael

1. Admin

Propose to accept the minutes of 25/03?

YEs

RESOLUTION: minutes of 25/03 are accepted

Raphael: should we move the telecon hour, to be more convenient for Silvia ?

Jack: I will miss one telecon every two weeks

Raphael: proposal to have the telecon 2 hours later
... to be more convenient for Silvia

<scribe> ACTION: Raphael asks Silvia if she would like to have the telecon 2 hours later [recorded in http://www.w3.org/2009/04/01-mediafrag-minutes.html#action01]

<trackbot> Sorry, couldn't find user - Raphael

trackbot, status

<scribe> ACTION: Raphaël asks Silvia if she would like to have the telecon 2 hours later [recorded in http://www.w3.org/2009/04/01-mediafrag-minutes.html#action02]

<trackbot> Created ACTION-54 - Asks Silvia if she would like to have the telecon 2 hours later [on Raphaël Troncy - due 2009-04-08].

2. F2F meeting

Erik list the participants: Michael, Jack, Erik, Davy, Raphael, Conrad, David, Franck, Guillaume

scribe: + Yves / Silvia on the phone

3. WD Document

Erik: we will re-organize the section 5 significantly

Raphael: my proposal, finish the document by next Wed 8 of April, and vote for publishing the document
... in our next telecon
... make a quick publication request

and hope to have the document published on the 9th

Erik: agree

Jack: Michael took my action, because I was busy ... but perhaps I can take over
... I will send an email to Michael, to ask him if I can take over

Erik: difference between reference and informative sections?

Raphael: informative parts are just for giving hints to the reader, generally dtd or schemas

3.1: Syntax

Problem 1: not use '%' but spell it

<scribe> ACTION: Yves to change the formal grammar to have 'percent' spelled [recorded in http://www.w3.org/2009/04/01-mediafrag-minutes.html#action03]

<trackbot> Created ACTION-55 - Change the formal grammar to have 'percent' spelled [on Yves Lafon - due 2009-04-08].

Problem 2: use of single quote (') and sub-delims in utf8string

<scribe> ACTION: Yves to change the formal grammar to have unreserved characters + %-escaped ones in utf8string and _not_ a set of pchars [recorded in http://www.w3.org/2009/04/01-mediafrag-minutes.html#action04]

<trackbot> Created ACTION-56 - Change the formal grammar to have unreserved characters + %-escaped ones in utf8string and _not_ a set of pchars [on Yves Lafon - due 2009-04-08].

3.2: Technologies Survey

Erik and Davy will work on it on Monday / Tuesday

3.3: HTTP implementation

http://www.w3.org/2008/WebVideo/Fragments/wiki/HTTP_implementation

close ACTION-52

<trackbot> ACTION-52 Replace all examples in the HTTP implementation wiki page with the video Jack took closed

Raphael: how can I have the byte ranges that correspond to my temporal interval?

Jack: now we are entering into a different problem, that is, should we do transcoding or not?
... the bytes range will be different depending on transcoding or not
... I have just sent an email stating we should consider more the user
... see: http://lists.w3.org/Archives/Public/public-media-fragment/2009Apr/0003.html

Raphael: I think we should go for your option 2, and define what is reasonable
... what is the point 4? Is it related to the in-context discussion?

Jack: no, no, no

Point 5: we leave that away, we haven't specified what the spatial cropping will actually do!

Point 3: it seems to be related to the issue: transcoding or not

Davy: if we want to re-syn the audio and video, then we need to transcode

Raphael: what is the worst thing that can happen?

Davy: the audio and video might not be aligned

Jack: the reason while I use a wget example, is that you want to store this piece and re-use it later on

Davy: my proposal was to do no transcoding and have a reasonable out-of-synch
... same than for the I-Frame
... we choose the closest timeframe

Jack: what is reasonable?

Davy: I think there is studies which show what is the largest not-synch temporal interval that users can support
... you and I have different interpretation of what we allow for transcoding
... I prefer Jack's interpretation

Jack: I had interpreted it as "we will not standardise any type of fragmenting that we think cannot be implemented without using transcoding".

Davy: I interpret it as "an implementation is not allowed to do any transcoding".

Davy also now prefers Jack's interpretation

Jack: I think we can standardize a spec that can be implemented without transcoding

Raphael: I'm also now confused, it is different from your previous statement

Jack: if we have no boundary cases for media fragments, it should work

Raphael: should we make the algorithm in the spec, that says, jump to the previous I-Frame, etc.

Jack: no, we should have in the spec, the user expectation

Silvia: we should send larger sequence, in order to not transcode

<davy> +1 to Silvia

+1 to Silvia

Silvia: get wider intervals, on a best-effort basis

4. Implementation

Silvia: talk about the new ogg spec

<davy> I think mp4 is also capable of skipping frames

Silvia: the YouTube player is also working on a best effort, if you click on a time offset, then the player goes to the closest frame he can start to play

Raphael: what is the closest? can it be after?

Silvia: I think it always goes back in time
... I need to check, but this is my experience

close ACTION-53

<trackbot> ACTION-53 Check whether ffmpeg can slide movies easily, need for implementation on client and server side closed

<jackjansen> give me an action

<scribe> ACTION: Jack to enter formally in the tracker the ISSUE he has found, regarding a) transcoding and b) spatial cropping [recorded in http://www.w3.org/2009/04/01-mediafrag-minutes.html#action05]

<trackbot> Created ACTION-57 - Enter formally in the tracker the ISSUE he has found, regarding a) transcoding and b) spatial cropping [on Jack Jansen - due 2009-04-08].

Silvia: I would like to have the telecon 2 hours later
... I think the section use case and requirements is ready

<Gui> I agree

Look at http://www.w3.org/2008/WebVideo/Fragments/wiki/HTTP_implementation

<Gui> Looking

<Gui> I am all sorry for myself, I didn't know I was late till now ! :-( I thought we were back to normal hours.

Davy: I will use our platform to discover the mapping between seconds and bytes for this particular video
... and update the wiki

No, AOB, Meeting adjourned

Summary of Action Items

[NEW] ACTION: Jack to enter formally in the tracker the ISSUE he has found, regarding a) transcoding and b) spatial cropping [recorded in http://www.w3.org/2009/04/01-mediafrag-minutes.html#action05]
[NEW] ACTION: Raphael asks Silvia if she would like to have the telecon 2 hours later [recorded in http://www.w3.org/2009/04/01-mediafrag-minutes.html#action01]
[NEW] ACTION: Raphaël asks Silvia if she would like to have the telecon 2 hours later [recorded in http://www.w3.org/2009/04/01-mediafrag-minutes.html#action02]
[NEW] ACTION: Yves to change the formal grammar to have 'percent' spelled [recorded in http://www.w3.org/2009/04/01-mediafrag-minutes.html#action03]
[NEW] ACTION: Yves to change the formal grammar to have unreserved characters + %-escaped ones in utf8string and _not_ a set of pchars [recorded in http://www.w3.org/2009/04/01-mediafrag-minutes.html#action04]
 
[End of minutes]

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$Date: 2009/04/01 13:30:08 $