[SPAM] Re: MSN Protocol documentation
kakaroto at kakaroto.homelinux.net
Mon Feb 18 14:17:05 EST 2008
Billiob from the aMSN team just found this document :
M$ finally released the file format specs for the ISF (hand written messages)!!! Although we already reversed it, we now have an official specs!
I added the link to the wiki.
Just letting you know...
On Mon, Feb 11, 2008 at 11:58:56PM -0500, Youness Alaoui wrote:
> There is actually an open source codec for both the ML20 video codec (libmimic thanks to Ole Andre) and for the Siren audio codec (libsiren
> thanks to myself :p) The audio can work without problems using the siren codec, and the webcam feature (unidirectional) works just fine with
> the ML20 codec.. the problem is with the bidirectional audio+video which uses WMV3.. libavcodec has an open source implementation of the WMV3
> codec, but it only has the decoder, not the encoder.
> Note that MSN has a lot of different v/v protocols..
> 1 - The 'old style' video call which uses a very old protocol and is still there only for interoperability with windows messenger (not WLM).
> That protocol is compatible with gnomemeeting.
> 2 - The 'Video Call' feature which is bidirectional audio and video and uses the new MSNP2P protocol for the signaling, WMV3 video codec and
> Siren audio codec
> 3 - The 'Computer Call' feature which is bidirectional audio and uses SIP/RTP and supports multiple different possible codecs (which are
> x-msrta, Siren, G722.1 (clock rate of 16000), x-msrta, AAL2-G726-32, G723, PCMA and PCMU (clock rate of 8000)).
> 4 - The 'Webcam' feature which is unidirectional video only, using MSNP2P for signaling and the ML20 codec
> 5 - the 'Voice clips' feature which is unidirectional audio, in form of 'clips' of a maximum of 15 seconds in length, uses MSNP2P and the
> Siren codec.
> (This should probably go into the wiki :p)
> So from all of these implementation, None of them worked for a long time, apart from the 'old style video call' which aMSN implemented
> using a modified version of linphone in the early 2001. Then we dropped it because it became impossible to maintain. Then Ole Andre reverse
> engineered the ML20 codec and made an open source library for it, then the webcam feature was added in some clients (like aMSN), then I
> reverse engineered the Siren codec and made an open source library for it, then voice clips were added into aMSN, and now. I was also able to
> get the 'Computer call' feature to work using SIP and PCMA as codec, but I never incorporated that into aMSN (because it depends on many libs
> and MSNP13). And now finally, I'm working on the 'Video Call' feature.
> In short, yes, there is already a solution for MSN video using aMSN and it works great on Mac, and it's been there for almost 3 years now.
> The Audio/Video codecs are open source, so you won't need mplayer or 'stolen' dlls...
> But you can't get a real-time audio conversation. For Audio, you can still use the 'voice clips', but that's annoying.. but hopefully, soon
> we'll be able to ship a working audio AND video implementation.
> Hope that helps!
> On Mon, Feb 11, 2008 at 08:14:32PM -0700, Alan Humpherys wrote:
> > Great job on the WMV3 decoding! The lack of an open source codec for the
> > MSN voice/video protocol has been a serious impediment to getting MSN v/v
> > working on the Mac. (My understanding was that Linux previously only
> > worked because mplayer used the windows media player DLL in compatibility
> > mode.)
> > Alan
> > On Feb 9, 2008, at 9:35 PM, Youness Alaoui wrote:
> >> arghh.. not intentional.. I just hit 'r' and didn't notice it sent it in
> >> private.. forwarding to the ML now, so guys, read the previous 2 mails
> >> before continuing...
> >> ok, I see about vv==av :p yes, a dedicated section is definitely
> >> necessary, considering the amount of data we'll have to put in there..
> >> On a side note, I've just (5 minutes ago) been able to decode a WMV3
> >> stream received from WLM in the audio/video conference thingy :D
> >> The audio is the problem now because of the stupid snack extension for tcl
> >> opening/closing the audio device on every chunk of sound (every
> >> 50ms).. and now, I have to write a Tcl extension for libavcodec... apart
> >> from that, the only remaining challenge is encoding WMV3 (no encoder
> >> exists in open source), but I'll try to send ML20 frames and see if WLM
> >> uses the FCC in the header to decode, or if it uses the WMV3
> >> decoder hardcoded and skips the FCC field... if it works, then aMSN might
> >> be the first open source solution with interop audio/video
> >> conversations :D
> >> KaKaRoTo
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