Dear Mr. Johannson, Mr. Even Roni, Mr. Randell Jesup and other experts of MMUSIC/AVT:
From: Kyunghun Jung [mailto:kyunghun.jung at samsung.com]
Sent: den 31 juli 2008 06:38
To: Ingemar Johansson S
Cc: Even, Roni; Randell Jesup; mmusic at ietf.org; avt at ietf.org
Subject: imageattr and codec parameter sets (with embedded image size info)
The draft of imageattr currently does not introduce the codec parameter set issues, which also have image size information.
For example, sprop-parameter-sets contains pic_width_in_mbs_minus1 and pic_height_in_map_units_minus_1.
Let me summarize.
- profile and level specify the maximum image size
- imageattr specify the image sizes available from sender
- config/sprop-parameters-sets specify the image size to be encoded (but not considered in session setup)
Therefore I asked your opinions on the forming of SDP offer and suggested three (crudely drafted) examples of
imageattr coupled with config/sprop-parameter-sets. In fact, one form showed a possibility that covers multiple levels.
If imageattr is limited to a level, then the following form might be necessary to match the sizes in imageattr with three
sets of config with different image size. My question was whether this form could be acceptable?
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
Or do we need to send config after the image size is decided? This will increase the session setup delay.
We are fine with either one imageattr for one profile/level or one imageattr for multiple profile/levels.
But each possibility of handling parameter sets will influence the format of imageattr. Therefore we asked
experts in IETF to clarify this issue.
Let me answer a question from Mr. Randell Jesup.
Um, a significant problem here. There seems to be a requirement that the negotiation is one-directional. In this case, the offerer provides NO indication about what he prefers to receive, just what he *can* send. When the answerer responds "picking" a resolution, what does the answerer send? The implication is that it's the same as what they picked to receive, which may be seriously sub-optimal.
-> q value, as in Example 3 of the draft, will offer the priority among offered sizes.
Sincerely yours,
Kyunghun Jung
------- Original Message -------
Sender : Ingemar Johansson S<ingemar.s.johansson at ericsson.com>
Date : 2008-07-30 18:23 (GMT+09:00)
Title : RE: RE: [MMUSIC] [AVT] spatial-resolution parameter for RFC 3984bisHi
If I understand your email correctly we will, with the constructed SDP's below, have the potential issue that imageattr may offer combinations (x and y resoluions) that are not allowed for a given profile level ID. The solution I see is that the profile levels provides with an upper (maybe also a lower?) limit.
For instance if we have some (really wierd) imageattr like
a=imageattr:97 [x=[128:16:1920], y=[96:16:1280],par=[1.1 1.3]]
and the profile levels only supports a resolution up to 352x288 , the latter limitation will apply which means that the imageattr should infact be interpreted as
a=imageattr:97 [x=[128:16:352], y=[96:16:288],par=[1.1 1.3]]This is not written anywhere in the draft and I don't right now know if this will hold in the general case, please comment.
/Ingemar
From: Kyunghun Jung [mailto:kyunghun.jung at samsung.com]
Sent: den 30 juli 2008 00:54
To: Even, Roni
Cc: Randell Jesup; Ingemar Johansson S; mmusic at ietf.org; Ye-Kui.Wang at nokia.com; avt at ietf.org
Subject: Re: RE: [MMUSIC] [AVT] spatial-resolution parameter for RFC 3984bisThank you Mr. Even Roni for the information.
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
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