Forwarded for Bill Hayes. As an aside, note that iptv has a
meaning other than video over IP.
-----Original Message-----
From: Bill Hayes
[mailto:Hayes at iptv.org]
Sent: Thu 3/2/2006 2:26 PM
To:
Miller, William C
Cc:
Subject: RE: (s22-list) FW: [AVT]
Carrying SMPTE TimeCode in RTP
In life there are few certainties. Death, taxes and SMPTE
timecode. If the proposed modification fixes the first two than I am in
favor of it. But if I still have to pay taxes and die...than I'd like to
see all of the SMPTE timecode carried.
Bill
William T. Hayes
Director of Engineering and
Technology
Iowa Public Television
P.O. Box 6450
Johnston, IA 50131-6450
515-242-3116 (v)
515-242-3109 (f)
Anyone want to comment?
Bill
-----Original Message-----
From:
avt-bounces at ietf.org on behalf of Colin Perkins
Sent:
Thu 3/2/2006 12:23 PM
To: Dave Singer
Cc: avt at ietf.org
Subject: Re: [AVT] Carrying SMPTE TimeCode in
RTP
On 2 Mar 2006, at 00:42, Dave Singer wrote:
>
Answering my own email here, I'm assuming that the answer is yes
to
> the 2nd question.
>
> The extra bits in an
8-byte SMPTE time-code can be used to
> a) maintain the polarity of
the code (numbers of 1s and 0s)
> b) indicate the relationship of the
codes to color fields
> c) indicate whether it's drop-frame
coding
> d) and then do one of
> i) carry 4
characters more
> ii) carry a date and time-zone
indication (SMPTE 309M)
> iii) carry some general
SMPTE 262M data (control codes, text,
> production info
etc.)
>
> I don't believe we need color and polarity handling in
RTP.
> We have drop-frame in the signalling.
>
> If we
want to carry something as slowly-changing as a date or as
>
unchanging as a time-zone, I on't believe that embedding it here
is
> right. Certainly thought should be applied before
blindly applying
> it. If a date is needed, it's not
needed inline; at most it would
> be in RTCP, and then I
would argue for a new RTCP packet type to
> carry
it.
>
> The other two possibilities are 'general meta-data' and
should not
> be sub-embedded in a time-code, in RTP, but
elevated and properly
> labelled at the stream
level.
>
> So, my answer is no, we do not need the full 8-byte
SMPTE time-code.
Seems
reasonable.
Colin
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