Here's what we've learned after doing software encoding with
Quicktime Broadcaster over the last 4-5 years with MPEG-4 and now H.
264 on our DATN project <http://datn.wisc.edu/about/>.
We've had various problems with the way Apple's MPEG-4 and H.264
software codecs interact with QuickTime Broadcaster on Intel-based
Macs. We could do two 640x480 30fps 1.3Mbps MPEG-4 or H.264
broadcasts (or a combination) on a single dual-2GHz Xserve G5, and we
can barely do one at the same quality on modern Intel hardware. This
isn't because there is anything wrong with the Intel systems; it
seemed to be an issue with how QuickTime Broadcaster interacted with
the components for live encoding on only Intel systems.
We have done extensive testing with Wirecast and QuickTime
Broadcaster in various configurations. When a high-end GPU is
present, Wirecast does an excellent job of encoding video. When a
lower end video card (or no video card with special test versions of
Wirecast) is present, Wirecast suffers from the same effective
limitations. For a while this was because the MPEG-4 Part 2 software
codec was not optimized for Intel. In more recent versions of
QuickTime, the software codecs, particularly the H.264 one, improved
to the point where we could get what we considered a reasonable
stream out of an Intel Mac mini...but it was never quite the quality
we were hoping to get. On the other hand, we were able to do very
nice streams for under $1000/stream, whereas commercial/industrial
hardware encoders cost $5000-$30000 each. So I think we have
definitely gotten our money's worth with this system..
But we've always been trying to take it to the next level. For a time
we looked to Stealth. Unfortunately, Stealth Imaging ran into a
number of manufacturing and software issues, and has yet to ship any
of its hardware encoder products.
Recently, we received the good news we had been hoping for. We have
been testing this solution for a few weeks, and I think it's time to
mention it here. Not too long ago, Elgato released its Turbo.264 USB
2.0 H.264 hardware encoder. It's a little USB 2.0 dongle, which
exposes itself to QuickTime via a QuickTime component. However, it
was targeted at doing compression of exports from preexisting files,
not live compression. But the hardware itself can do H.264 encoding
in realtime at 640x480 30fps at 2Mbps (or more; SD quality).
Elgato has been working on a live compressor component for a future
version of the Turbo.264 software. We have been testing this now on
Xserves and Mac minis, and, while the current codec is technically
alpha quality and does have some problems, it works wonderfully. Or,
let's just say, much better than any software or QuickTime encoding
we have ever done on any platform before. So well that we could
deliver a football game (lots of transitions and motion) on the Big
Ten Network (which we just recently picked up) to our campus over the
network via QuickTime, and people could actually watch it and believe
it was normal standard definition TV.
Instead of selecting "H.264" in QuickTime Broadcaster, "H.264
(Turbo)" is selected. This routes the encoding off through the USB
2.0 dongle and its Mobilygen H.264 hardware encoder, and QuickTime/
QuickTime Broadcaster doesn't know the difference. Mac minis that
used to be struggling at 90% CPU to barely get a marginal H.264
stream out are now doing a very nice 640x480 30fps H.264 stream at
about 15-20% CPU.
The cost for the Turbo.264 product?
$99.
Imagine being able to do H.264 encoding regardless of the relative
power of the the machine itself, at arbitrary resolutions,
framerates, and bitrates, live, in realtime, by simply plugging in a
little USB dongle and adding one QuickTime component to the system.
Bottom line: this is the solution a lot of us has been waiting for.
I can't give any specifics on when this software update will ship,
but the hardware itself is already available and shipping, so it's
not vapor: <http://www.elgato.com/index.php?
file=products_eyetvturbo>. I think that many folks will find this a
great option as it is released and evolves. I'll keep everyone in the
loop as we continue our testing.
Regards,
Dave Schroeder | University of Wisconsin - Madison
Email: email@hidden | Division of Information Technology
Web: das.doit.wisc.edu | B263 Computer Science and Statistics
Mobile: +1 608 444-5672 | 1210 West Dayton Street
Office: +1 608 265-4737 | Madison, Wisconsin 53706-1685
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