Why am I not allowed to send the DRM key to video player?

I don’t know exactly, and I am still thinking.

This is the current DRM flow: I, as the content provider, use a key to encrypt my video, and send to player, e.g. JW Player. I send the key to Third Party DRM Provider, e.g. DRMToday, and DRMToday sends the key to JW Player.

I cannot send my key to JW Player unless I have a contract with DRM OEM, e.g. Google WideVine. Why is a contract required? I think it is related to the fact that DRM is never open source; it’s security-by-obscurity. The contract would say: WideVine provides SDK to DRMToday to obscure the key, and DRMToday promises to keep obscuring process a secret. Otherwise, unauthorized party may get the key in clear text and therefore decrypt the video and defeat the DRM.


AWS fails to Redirect emails, and there is no cure

I asked SES (Amazon Simple Email Service) to Redirect(instead of forward) my emails to Gmail.

It works most of the time, but fails redirecting emails from Framos.com, who makes GeniCam cameras for us.

Here is the error message:”This message was not eligible for redirection because the sender was not authorized according to the published SPF record”

When I googled this message, two items showed up, but both unanswered.

This failure is a result of fighting email spoofing. Here is my explanation, in an intuitive way.

Framos tells the world (by SPF) who is allowed to send email for him.

(decent servers respect his request, such as SES)

Since Framos doesn’t list SES on his list, SES doesn’t send (same as redirect) his email to me.

Redirection failed by design, and nothing can be done to fix this.

I expect when more domains publish SPF, more emails will fail to redirect.

Extra notes:

Redirecting is different from forwarding.

When SES “forward” Framos’s email to me, and I hit Reply button, I am replying to my SES address, instead of Framos.

With “redirect”, I reply to Framos, which is what I wanted.

Sync video from multiple IP cameras

When live streaming the same hockey game with two RTSP H.264 cameras, can the two video streams play in sync?

No wall clock in this setup; both cameras are standalone.

I think Yes, in theory.

We expect the clocks on the two cameras accurate enough. (frequent NTP helps)

The two RTCP servers on the cameras map the RTP time stamps to UTC time.

PTS can be calculated from RTP time stamp.

By RTP and RTCP, we have the PTS in UTC, and therefore, sync the two videos.

Problem: packages from RTCP may not inaccurate/missing in reality.


1: https://stackoverflow.com/questions/2439096/h264-rtp-timestamp

[“Non interleaved”, in which, you must set the RTP timestamp to the PTS + offset]

2: https://groups.google.com/forum/#!msg/discuss-webrtc/npLmOesI8A4/oL2p_HbhAgAJ

[synchronization between two RTP streams using RTCP SR]