Mittwoch, 31. Juli 2013

HDMI Livestreaming: CPU, Harddive, Thunderbolt ...the search for the bottleneck

After coming yesterday to the conclusion that maybe the CPU in my computer is not fast enough to take in the HDMI signal ( that is merged on the Blackmagick Design with the phono sound input ) via Thunderbolt and therefore causes a challenge during the livestream, I put it up for a test on hardware benchmarking today.

Using Apples Activity Monitor, I wanted to see if my CPU is actually suffering under the data on-slaught it has to deal with while taking in the uncompressed signal and then having to compress it to a streaming format ( in this case "Flash 720p" ) with Telestream Wirecaster.

First i started with BM Media Express, to see how the intake of the signal will work all by itself. While just previewing, the CPU still had around 80% idle space and neither the memory nor the harddrive got any access...except the occasional pages written and read by the operating system. But nothing that broke my computer into sweat. We had the standard preview delay of about 1-2 frames when moving the camera. This seems to result from the general output of the camera. I realized i had the same delay when using my Zacuto EVF, even before the HDMI output was uncompressed clean HDMI. So i guess we just have to live with that delay, which seems to happen on the camera side.

So I moved on to see if the problems get bigger when starting to stream ( means, the signal gets compressed in real time ) and send over the internet to UStream.

This is the CPU usage:
Based on the endresult, which is heavily lagged, I would guess that most gets lost via the internet connection from here ( im located in Kenya now none-the-less ).

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