We would like to ask experts in MMUSIC and AVT to pay a special interest to the relationship
between imageattr and config/sprop-parameter-set. How to stack the set of information in the SDP offer
will influence the session setup.
For example, suppose imageattr specifies image sizes over multiple levels. The following form might be necessary.
m=video 49154 RTP/AVPF 99
b=AS:48
b=RS:0
b=RR:2500
a=rtpmap:99 MP4V-ES/90000
a=imageattr:99 [x=x1,y=y1] [x=x2,y=y2] [x=x3,y=y3]
a=fmtp:99 profile-level-id=a; \
config=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx_1a=fmtp:99 profile-level-id=b; \
config=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx_2
a=fmtp:99 profile-level-id=c; \
config=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx_3
In case imageattr specifies image sizes within a single level.
a=imageattr:99 [x=x1,y=y1] [x=x2,y=y2] [x=x3,y=y3]
a=fmtp:99 profile-level-id=8
a=fmtp:99 config=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx_1
a=fmtp:99 config=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx_2
a=fmtp:99 config=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx_3
The above forms are only basic possibilities and more systematic design and suggestion are
requested from MMUSIC and AVT experts.
Have a nice meeting at Dublin!
Kyunghun Jung
------- Original Message -------
Sender : Even, Roni<roni.even at polycom.co.il>
Date : 2008-07-30 00:13 (GMT+09:00)
Title : RE: [MMUSIC] [AVT] spatial-resolution parameter for RFC 3984bis
Hi,
First of all, ITU-T documents in pdf format are free at
http://www.itu.int/rec/T-REC/e
As for custom format inH.263. RFC 4629 section 8.1.1 had the custom
resolution, no relation to specific level.
CUSTOM: Specifies the MPI (Minimum Picture Interval) for a
custom-defined resolution. The custom parameter receives three
comma-separated values, Xmax, Ymax, and MPI. The Xmax and Ymax
parameters describe the number of pixels in the X and Y axis and
must be evenly divisible by 4. The permissible values for MPI are
integer values from 1 to 32, which correspond to a maximum frame
rate of 30/(1.001 *the specified value).
Also note the next sentence
A system that declares support of a specific MPI for one of the
resolutions SHALL also implicitly support a lower resolution with
the same MPI.
Roni Even
> -----Original Message-----
> From: Randell Jesup [mailto:rjesup at wgate.com]
> Sent: Tuesday, July 29, 2008 5:08 PM
> To: kyunghun.jung at samsung.com
> Cc: Ingemar Johansson S; mmusic at ietf.org; Even, Roni; Ye-
> Kui.Wang at nokia.com; avt at ietf.org
> Subject: Re: [MMUSIC] [AVT] spatial-resolution parameter for RFC
> 3984bis
>
> Kyunghun Jung <kyunghun.jung at samsung.com> writes:
> >Some clarifications are as follows.
> >
> >
> >
> >>So far as I know (and I didn't recheck), H.263 only allows for
> resolutions
> >>specified in the fmtp (though QCIF and CIF are I think required).
If
> you
> >>want 344x288, you need to add a CUSTOM resolution to the fmtp line.
> And
> >>the mpi must be an integer in the fmtp. Now, if both sides use
this,
> then
> >>those restrictions could be relaxed.
> >
> >In H.263, Custom Picture Format (CPFMT) is supported at level 50 or
> >higher.
> >
> >3GPP requires only level 45 of H.263 for its mobile video telephony
> and
> >whether its level is increased further is doubtful. In other words,
> MPEG-4
> >and H.264 are expected to utilize imageattr a lot.
>
> I think you misunderstand my comment. I was referring the the SDP
fmtp
> line for H.263, where custom resolutions (other then CIF, etc) can be
> specified.
>
> Since the ITU specs are a pain to come by (I think I have an old H.263
> and
> Annexes stashed somewhere, but it isn't handy at the moment, from
> home), I
> can't easily look up the Annex X profile/level stuff; I just know how
> the
> SDP works from the IETF spec. (I tried to look it up online - Ugh,
> requires TIES account. The ITU appears to not want anyone except
large
> companies to implement their specs.) :-(
>
> It sounds like "CUSTOM" isn't of any use for many scenarios.
>
> In any case, I was responding to Ingemar's example that used custom
> resolutions in H.263.
>
> >Sincerely yours,
> >
> >Kyunghun Jung
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