I'm about to do a live stream a little later today and thought I would look up the specs again at the source. Things have changed again (not sure when) since my original post (http://www.dvinfo.net/forum/streaming-view/531971-facebooks-live-streaming-go.html), with the maximum data rate now at 4000Kbps.

From their tech details page (https://www.facebook.com/facebookmedia/get-started/live):

We accept video in maximum 720p (1280 x 720) resolution, at 30 frames per second. (or 1 key frame every 2 seconds).
You must send an I-frame (keyframe) at least once every two seconds throughout the stream..
Recommended max bit rate is 4000 Kbps.
Titles must be less than 255 characters otherwise the stream will fail.
The Live API accepts H264 encoded video and AAC encoded audio only.

Worth knowing as the previously listed specs in the forum here was from when video encode rate was at a maximum of only 2500Kbps.

Max video length is now 240 mins, up from 90 mins.

Not sure if it was previously possible, but you can now "schedule Live" a Facebook Live video event. Detailed info is here (https://fbookmedia.files.wordpress.com/2016/10/161027-scheduled-live-e28093-guide.pdf).

Andrew

Added notes:

The default trigger for the start of a scheduled video streaming event is that the scheduled start time arrives. Once you are close to it, a countdown timer comes in to play.

Pre-testing revealed that there was about 10 seconds delay between my encoder and the arrival in the preview window. FB also documents that the countdown timer will finish at different times on different devices (such as mobile phones vs computers). To accommodate this (and not have anyone miss out on our glorious intro, I constructed a 15 second countdown sequence and started it at 10 seconds prior to the countdown timer finishing.

I should have had 5 seconds of countdown before the program start. Instead, the start happened about another 10 seconds later.

These stats are rather unscientific as they are only from one sample, but if you have an important start to a live event then I thoroughly recommend test runs to establish the most reliable length of run up to the main content when streaming through FB.

Andrew

The increase to 4000kbps happened some months ago I think. The odd thing is they had increased the frame size to 1080p but it seems that all references are back at 720p now.

I'm tempted to send out a 1080p encode stream and see what happens. There's go to be people who do that without even thinking.

Andrew