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Comment by madars | Hacker News Reader

From Wikipedia:

    On 20 January 2009 Adobe announced it will publish the RTMP specification.
    On 21 May 2009 Adobe filed a DMCA removal request on a Sourceforge-hosted
    implementation of the protocol.

And now we are about to believe that:

    The Flash file format (SWF) specifications are open and unrestricted, so any
    company - even Apple - can build their own Flash Player if they want. Also
    freely available are related specifications for the Flash ecosystem: RTMP
    FLV/F4V, AMF, and MCD.

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While it's true that since then Adobe published the RTMP specification, but they left out the description of the handshake procedure, without it cannot be called full and open.

What's more they are constantly changing the handshake procedure in every point release. I wouldn't call that open either.

Is there a good link on more information about this?

Here is a thread from the Red5 mailinglist: http://osflash.org/pipermail/red5_osflash.org/2009-August/03...

The main issue is that the spec says (5.4, page 10) that in C2 and S2 messages you send random bytes. If you do that only VP6 streaming will work but H.264 won't. You have to do a HMAC like digest on the "random bytes" and send it back so that H.264 works.

Of course all of this was reverse-engineered before the spec was released, but later with the release of Player version 10.0.32.18 it stopped working. So it had to be reverse-engineered again.

About that time I stopped working on a Flash Media Server (fortunately), so I just heard from my ex-colleagues that Adobe changed the handshake again with a new Player version.

EDIT: changed the link to a better one.

Most people that are using RTMP are using it to serve static files that they want to make harder to copy than downloading an FLV file.

As I recall, the problem with rtmpdump wasn't that it implemented RTMP, but that it included ways to bypass the "security measures" that are built-in to RTMP. It was able to spoof all of the parameters that FMS uses to determine whether or not it should serve a stream, and would save a copy of the video to disk instead of just displaying it to the user.

sounds perfectly fine to do if the spec is actually open.

Post this info in a reply on that blog entry plz.

Or maybe you did, but their "Open at Adobe" moderator didn't approve it.:)

I've just submitted this comment (we'll see if it gets posted):

Hello Mr. McAllister,

I'm glad to hear that Adobe has opened as much as they have. That's the right direction; I'm glad you're doing it.

I'm a little concerned about your claim that anyone can implement SWF, RTMP, and so forth. Didn't Adobe issue a DMCA takedown when someone implemented RTMP?

Here's a copy of what appears to be the takedown notice: http://www.chillingeffects.org/anticircumvention/notice.cgi?...

I recognize that that the takedown notice says it was issued because the implementation "can be used to download copyrighted works," not because it's an implementation of RTMP. That's a silly argument-- every web browser that uses a Flash player downloads content before it plays it. How could one implement RTMP, the "Real-Time Messaging Protocol" without sending any messages?

I'm willing to believe that there might be some misunderstanding here-- maybe there are two parts to the RTMP spec, and only one is open, or something like that. But at the outset, I can't reconcile what you've written with the rest of the evidence that I see.

Perhaps you could explain what I'm missing?

Utterly uber-lame that no comments get posted on an article about how Adobe is being open.

Open my arse.

Well, it is Sunday morning. I'm not checking for comments on my work blog either.

I now agree. Judging by his Twitter account, Dave McAllister has been awake for at least 3 hours this fine Monday morning. My comment does not appear on his blog yet.

I just tweeted at him. Maybe it's caught in a spam trap or something.

Highly doubtful if Adobe will ever come out with a clear answer, meanwhile - wanted to point you to this comment exchange on another Adobe blog:

http://blogs.adobe.com/jnack/2010/01/sympathy_for_the_devil....

Quote:

  Your comment is extremely interesting because it 
  seems to be the first time Adobe has publicly acknowledged
  that the real reason for that DMCA takedown was the
  encryption scheme NOT *potential* copyright infringement.
  Meaning that Adobe deliberately mis-used the DMCA and mis-led
  the entire community about the real reasons for the takedown
  right?

Thanks for that. It seems like Adobe could actually refute the accusation pretty well if they wanted to. My impression from the exchange you link to is that Mr. Nack (the Adobe guy) has a point, but I can't say that I understand it, since he's only written a couple of sentences.

It looks to me like some of the folks at Adobe are genuinely trying to be open, but others aren't, so it looks like the genuine folks are lying, since you can't tell who's really doing what. It's weird, because I don't see how Flash could possibly win in the long term without becoming completely open. (I do think a non-open option can win, but it doesn't look like it will be Flash.)

They really are beginning to sound like a whining child trying desperately to get it's own way now, and all because Apple doesn't want anything interfering with their app store cash cow.

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