So I’ve been experimenting with video broadcasts since June now, and its been an interesting experience. It seems the “free” services like LiveStream and Justin (can’t speak for the others) are making it harder to get good results.

In June, the demand on the streaming server (an old iMac that I had which was idle) was able to handle things very nicely. As with all software upgrades, they swell up to take all processing power. I started with Wirecast 4.01 which is very easy to setup and get going, and it has worked great. I have 3 video sources that it is handling (2 webcams and 1 screen capture) I was sending audio via the Mac Pro which is running Logic Pro 9 (Agogee Ensemble is the converter) and a MOTU 8Pre to handle the mic inputs. I have 6 mic sources ( 2 mics on vocals, 2 mics on guitars and 2 mics in a Blumlein pair configuration to pickup the room and whirl’s squeeky chair) and one pedal board source. This is all mixed down into 2 stereo channels and sent over to the iMac. This has worked very well.

Wirecast 4.1 came out over the summer, I tried it, but the video results were not good, I was getting quite a lot of frame loss and had to go back to 4.01. This has since been fixed in 4.1.2, so I tried this configuration over the weekend.

The audio now falls out of sync, although when I was testing this. I did not see this problem initially. I understand Wirecast now uses VBR (variable bit rate) which could be the cause of this new issue. So I may have to once again return to 4.01 and wait until a patch comes out for this as well.

In the meantime I have been looking into ways to replace the webcams (I mean they do a decent job for the cost of them I couldn’t ask for better video – they are Logitech C615′s and have a camera mount on the bottom of them (the C910s do not). There are several problems with webcams. First, they have a wide camera angle and it is not possible to change this. Second, on the Mac Logitech got lazy and has never released a driver and supporting software which will allow you to control the camera, so it will blow out the whites in studio lights.

So I have been over to http://www.aja.com picking up two pieces of free software, one is called AJA DataCalc and the other is AJA System Test. The former will tell you who much throughput you need to drive an HD video / audio stream, the later will actually measure the performance of the system, and has options to tell you the disk read/write speed, frame rate your machine will support and the maximum number of video streams your machine can support.

I will need to have 2 HD video sources in order to pull off the next round of “upgrades” to the system, and to do that and record without frames dropping, I have to move up to a RAID in order to get the 55 MB/sec this will require (per video stream). And that is to support recording a 720p @ 30 fps. This is close to the performance of current WD Cavier Black, but there is headroom needed, and if I decide to add more video sources, then I need a design that will support that as well.

More on the RAID design next time…