1. RTP Payload Format for DV Video
draft-ietf-avt-dv-video-02.txt
This is about the draft of RTP Payload Format for DV Video

2. updates 01 -> 02 Some minor changes
We had feedback from implementers
Some implementers consider DV audio only format is not necessary
Audio for DV is shuffled
Reshuffling is needed to convert DV audio to common audio formats
Today’s CPU has enough performance for reshuffling
Compatibility with other audio format is much important
We had some minor changes when updating the draft from 01 to 02.
We also received some issues from implementers for this DV video draft.
Some implementers considered DV audio only format is unnecessary.
The Audio in the DV format is shuffled.
But, Today’s CPU has enough performance for reshuffling in realtime,
AND, Compatibility with other audio format is much more important.

3. Issues When sending unbundled DV stream,,,,
Using legacy format (L16, DAT12, L20, L24) is RECOMMENDED
RECOMMENDED -> MUST ????
Do not allow DV DIF block only audio
When sending DV audio only, use legacy audio format
Which do you think is better?
RECOMMENDED
MUST
So, this is the issue for the DV video draft.
In the DV video draft, it says,
When sending unbundled DV stream, it is RECOMMENDED to send unbundled audio
Using legacy format, like, L16, DAT12, L20 and L24.
The issue from some implementers, was, to change RECOMMENDED to a MUST.
When RECOMMENDED is changed to a MUST,
DV DIF block only audio can not be sent.
Which do you think is better?
Recommended or MUST?
We think MUST is too strict.

4. RTP Payload Format for 12 bits, 20bits and 24 bits DV Audio
draft-ietf-avt-dv-audio-01.txt
This is about the RTP Payload Format for 12 bits, 20bits and 24bits DV audio.

5. Changes (added non AIFF-C audio channel convention)
DV audio channel allocation
DAT12 audio mode in DV format has maximum of 8 channels
For example…
Audio with….
Left, Right, Center,
Woofer, Left Surround, Right Surround
AIFF-C can not specify “woofer”
AIFF-C only contains location information
Non AIFF-C audio channel convention was added to this draft.
This was needed because, DAT12 audio mode in DV format has maximum of 8 channels,
AND, for example the audio channel can go like,
Audio with left, right, center, woofer, left surround, and right surround.
And when trying to show the audio channels in a AIFF-C manner,
the allocation of some channels can not be done.
For example, AIFF-C can not specify “woofer”.

6. SDP format for audio channel convention
a=fmtp:<payload type>
channels:<channel convention>
[<symbol1 [/symbol2…]>]
・　channel convention
　 - AIFF-C (default)
　- DV
・　symbols (next page)
This is the SDP format for audio channel convention.
We defined a new fmtp record to resolve the channel allocation issue.
“Channels” field represent the channel convention
The symbols stand for each channel.

7. Symbols used for DV(1) L: Left channel of stereo
R: Right channel of stereo
M: Monoral signal
C: Center channel of 3,4,6 or 8 ch stereo
S: Surround channel of 4 ch stereo
LS, LS1, LS2: Left surround channel
RS, RS1, RS2: Right surround channel
These are the name of the channels.
L is left channel of stereo
R is right channel of stereo
M is monoral
C center
S surround,
LS LS1 LS2 are left surround channel
RS RS1 RS2 are right surround channel

8. Symbols used for DV(2) LC: Left center channel of 8 ch stereo
RC: Right center channel of 8 ch stereo
Q1: LS RS
Q2: LS RS
WO: Woofer channel
Lmix: L C LS
Rmix: R C RS
T: C
These are also channels description for DV audio.

9. SDP example v=0 o=ikob 2890844526 2890842807 IN IP4 126.16.64.4
s=POI (Audio only)
i=A Seminar of how to make Presentation u=
(Katsushi Kobayashi)
c=IN IP /127 t=
m=audio RTP/AVP
a=rtpmap:112 L16/48000/2
a=rtpmap:113 DAT12/32000/4
a=fmtp:113 contents:DV L/R/C/WO
Audio is sent using RTP payload type 112 and 113
Payload type 112 sends L16 audio
Payload type 113 sends DAT12 audio
This is a SDP example.
Audio is sent using RTP payload type 112 and 113.
Payload type 112 sends L16 audio.
Payload type 113 sends DAT12 audio.
DAT12 audio contains 4 channel audio : left, right, center and woofer.
DAT12 audio contains 4 channel audio :
Left, Right, Center, Woofer

10. Use of audio channels attribute
Audio “channels” attributes
AIFF-C (this is default) DV
AIFF-C MUST be use if possible
DV is used when channel allocation is beyond AIFF-C convention
AIFF-C will be used for default for The audio “channels” attribute.
And, when AIFF-C can not show the description for the audio channels, channel description DV is used.
If you have interest, we can show the sample implementation of the DV over RTP.
Please contact us when we are in the terminal room.
Thank you.