Pulling Back the Curtain on MPEG-4
For that kind of money, we expected the system to practically set itself up or, failing that, to be no more difficult to install than a VCR. The reality? It took a little time to introduce the WebCine Server to our Windows network. Like many corporate networks, our network had been configured to block everything except HTTP Web traffic, so we had to change the settings on our firewall and network hub to let RTSP traffic through. We also ran the WebCine Server’s custom configuration script to reassign the server’s IP address for our network.
The server runs Mandrake Linux, and we quickly discovered that only those with a working knowledge of Linux can truly appreciate this server’s simplicity. It offers logins, throughput and all the stats you’d expect of a server, but setting streaming parameters may require more Linux understanding than most people possess, as it requires some script editing to change the buffer and so forth. Administrative tools at the application layer, even a simple playlist program, were noticeably absent as well. Still, this server does serve. We didn’t have the streaming capacity to load test its specified 1,000 users simultaneously, but we served up a few 1.5Mbps files and the resulting throughput convinced us this server can probably do the job advertised.
Most of our testing centered on the WebCine Encoder; which runs on the Windows NT/2000 platform. We did not compliance/conformance test Philips' the Simple profile and partial Core profile claims, though in future MPEG-4 reviews we may execute more exacting compliance testing. This box’s design is well conceived, with a variety of settings and options and a sleek interface. Philips planned for every source; from SDI (digital) input for broadcast quality feeds streaming at a high rate to S-video, component video, and .avi files. The unit came with four XLR audio inputs and four AES/EBU digital inputs. Unfortunately, changing input sources proved to be a pain because of the inability to connect S-video and component video simultaneously. A Matrox breakout panel with switching is available through Philips as an add-on, however.The settings in the encoder screen were reset, not saved, between successive encodes of a single video, causing us to re-enter all the parameters to change even a single setting. This was inconvenient, but not a big deal. There wasn’t much in the way of statistics to look at while encoding, or after encoding. The really important information was presented succinctly, and was adequate. Plus, in order to see video playing on the input screen we had to actually start encoding, which makes it a little awkward to view cuts beforehand. The good news is that the upcoming WebCine Encoder 1.1 will have previewing capabilities, making this a non-issue.
We ran a live S-video feed from our camcorder and a movie off of DVD through the encoder. We were able to create both a local version of MPEG-4 files for previewing on our PC and hinted MP4 files that are packetized for streaming over any IP network. By creating MP4 "redirector" files for hyperlinking, we were able automatically to redirect users to the RTSP URL from a Web page (HTTP).
The bundled Linux Samba application made it possible to view the server’s media content as though it were served on a Windows NT/2000 server, so we were able to use Windows Explorer to drag and drop our MP4 files from the encoder to the server. In all our tests, we ran MP4 files through the WebCine Player. The player offers the option for displaying PAL or NTSC, and is fairly simple to use.
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