<trackbot> Date: 17 January 2013

thanks glenn

Chair

Sean Hayes

<scribe> scribenick: mmartin3

IETF Registration

Issue-175?

<trackbot> ISSUE-175 -- media type and file extension not registered -- open

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/issues/175

mike: Issue-179 encoding is separate from registration.
...http: //lists.w3.org/Archives/Public/public-tt/2013Jan/0011.html

Issue-179?

<trackbot> ISSUE-179 -- Interpreting the pixel measure -- open

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/issues/179

scribe: RFC 3023 in TTML 1.0
... provided redlines to glenn
... Encoding requirements Section 4.3.3 XML 1.0 - gives rules and provides an Annex that describes an algorithm.
... Issues with transferring the charset for encoding.
... Suggest we constrain to UTF-8 and -16, and that would be supported by an XML processor.

glenn: What about US ASCII.

mike: Wouldn't matter. Use UTF-8.

glenn: Constraint on all interchange of documents?

mike: All identified as ttml/xml.

glenn: Constrain to XML and the use of the MIME type charset.
... Write registration to constrain to UTF-8 and -16.

mike: Don't specify what happens if optional charset is not present.

sean: Doesn't constrain use of other encodings.

glenn: Charset parameter is ignored and what is specified in the document is used.

sean: Japanese may have questions if their encodings are not considered. Don't know if an issue for charset.

mike: Only the encoding is used not the charset.

sean: Japanese may still have questions.

mike: Think this is orthogonal.

glenn: Specify encoding only without a character set.
... Suggest charset be ignored.

sean: Contradicts XML specification.
... Just don't use.

mike: RFC 3023 has "if present xxxxx" language. Better not to override.

glenn: HTML5 changes that.

mike: Could specify should not use, but if you do xxxx.

<glenn> should not use charset param, but if used, must be identical to encoding parameter in document instance

Issue-175?

<trackbot> ISSUE-175 -- media type and file extension not registered -- open

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/issues/175

Issue-179?

<trackbot> ISSUE-179 -- Interpreting the pixel measure -- open

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/issues/179

<glenn> RESOLVED: accept the above language re: charset/encoding

RESOLVED On text re: encoding.

Issue-175?

<trackbot> ISSUE-175 -- media type and file extension not registered -- open

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/issues/175

mike: Provided text.
... No comments from Philippe.
... Appendix C.
... Close Issue-175 and adopt the redlines proposed by Mike.
... Action to Glenn.

RESOLVED to use edits from Mike on Issue-175 and action to Glenn to process. Leave both open.

<glenn> ACTION-136?

<trackbot> ACTION-136 -- Glenn Adams to integrate changes from Action-133 into the TTML 1.0 Second Edition -- due 2013-01-14 -- OPEN

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/actions/136

<glenn> ISSUE-199?

<trackbot> ISSUE-199 -- timeExpression to video frame calculation is unclear in some cases -- raised

<trackbot> http://www.w3.org/AudioVideo/TT/tracker/issues/199

mike: Differences of view between Glenn and I.
... timeExpression
... Conversion to frames of video
... Time values have different frame representation. If 2 are different they resolve to the same frame in the video.
... Do math.
... Non-integer frame rates only.
... One algorithm is to take the seconds and use real frame rate to get frame number. Add frame field to that with final frame number. Sometimes that two different ones resolve to the same frame. TTML is silent on the math.

glenn: Agree current specification is silent on this topic.
... Question is what algorithm do we use?
... Intent of timeExpression was that it was different that implementers have interpreted.
....hh: mm:ss didn't represent media type but frame type.
...hh: mm:ss converted to seconds value.
... Seconds multiplied frame rate to get frame count.
... Fraction could be added to frame count. Could be non-integer.
... Convert to real media type - divide by actual frame rate (frame rate x frame rate multiplier).
... Explains mechanics.
... Alleviates issue.
... Easier to understand in implement in my view.
... Haven't accounted for drop frame rate.
... Need to account for any algorithm.

mike: Time values diverge from media time.

sean: My previous work was similar to Glenn's. That number should uniquely identify what is in the media and it is of concern if they diverge.
... No position at this point.

mike: Significant divergence in a feature film.

glenn: Frames are well understood. How do systems handle non-integer values?

mike: SMPTE repeating combinations are prohibited.
... Solved by not allowing.

glenn: What is the SMPTE interpretation of seconds and frames?
... Discuss illegal combos.

sean: Explains scenario with timeExpression and use of duration.

mike: We have 2 different views of what timeExpression means.

glenn: There may be another option.
... Constrain the use of frames and sub-frames to apply in the SMPTE not the media mode.

sean: Allow frame rate to be present but not apply in a specific case.

mike: Forbid frame expression for media time.
... Your option may also be fatal.

Discuss scenario for breaking up frames with a specific rate.

glenn: Can't convert to an integer value if you don't have an integer frame rate.

mike: Still have the issue that if you have a non-integer rate that isn't the real media time.

sean: Effectively use frameRateMultiplier to get to real time.

glenn: Restrict frameRateMultiplier to 1 over 1.

mike: Can't do that.
... Need to signal conversions when you have a non-integer frame rate.

sean: Table the discussion and bring back next week.

glenn: Try to get more information how this is done in the marketplace.

mijordan: HBO using SMPTE.

mike: May be able to determine what algorithm was used. Need audio and video.
... DECE implemented as frames.

sean: Discuss next week.

trackbot, end meeting

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Found Date: 17 Jan 2013
Guessing minutes URL: http://www.w3.org/2013/01/17-tt-minutes.html
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