MPEG-2 Encoders, Part 1
Aug 3, 2010 12:00 PM, By Jan Ozer
The last time I remember writing about MPEG-2 encoders was back in 1996, the year the Olympics was held in Atlanta (and what a time that was). But just last week, I got a random call about MPEG-2 encoding for DVD from Emmy Award-winning producer Connie Simmons. By way of background, Simmons produced a PBS Series entitled Landscapes through Time with David Dunlop, which began airing nationally in June 2008. The series was shot using two Sony CineAlta HDW-F900s and edited using the Apple ProRes HQ codec. When she originally produced DVDs of the series, her ProRes HQ HD Quicktime movies were downconverted to SD and compressed for MPEG-2 using Sonic Scenarist by a the postproduction house Pillar to Post. Now she was reproducing the DVDs, and wondered if the hardware downconvert and encoding process delivered the best encodes for the next DVDs. Her question was simple: What's the best tool for encoding HD footage to MPEG-2 for DVD distribution?
Though DVD sales are dropping, they still totaled $8.8 billion in the U.S. for the first half of 2010, and almost all event shooters like myself still deliver on DVD, making Simmons' question very relevant for many Apple Final Cut Pro producers. Connie donated some test footage, and this month's Final Cut Pro Insider will try to identify the highest-quality Mac-based software encoder for converting HD footage to DVD-compatible MPEG-2.
Tested encoders will include Apple Compressor, Cinema Craft Encoder MP, Innobits BitVice, Sorenson Media Squeeze, and Telestream Episode Encoder. In this issue, I'll discuss features, usability, and performance. In two weeks, I'll discuss comparative quality and what happened when I tried to import the files into DVD Studio Pro.
By way of background, during the encoding speed trials, I encoded standalone files with all programs to the highest possible encoding parameters, which in all cases involved at least two-pass variable-bit-rate (VBR) encoding. My target data rate was 4Mbps total, with a minimum of 2Mbps and maximum of 7Mbps. For consistency, I encoded with a GOP size of 15, with a closed GOP and two B frames (when this option was configurable). When search or other quality-related options were presented, I always chose those that produced the highest possible quality. I produced the files on a dual processor, 2.93GHz quad-core Mac Pro running OS X 10.6.4 with 20GB of RAM.
Apple Compressor is easy to use, works fast, and is free with Final Cut Studio. If the quality compares well, it might be the only MPEG-2 encoder you'll ever need.
Let's face it: Few of us know MPEG-2 encoding parameters well enough to tinker without potentially causing more harm than good, so an MPEG-2 encoding tool with just a few, easily understandable encoding options is better than one with multiple options that would take many hours of testing and reading to fully understand. Compressor's MPEG-2 encoding configuration options are very consistent with this philosophy.
The easiest way to encode to MPEG-2 is to apply and configure a preset, of which Compressor has two classes: highest quality and fastest encode. The differences between the two are both in the Quality tab, the second tab from the left in Figure 1. Specifically, the higher-quality option uses two-pass VBR Best, while the faster option uses one-pass VBR. In addition, the higher-quality option uses Best for Motion Estimation, while the faster preset uses Good. I used the configuration options shown in the figure.
Working through the other tabs, if you leave the automatic buttons enabled, Compressor will analyze the source video footage and choose the proper options, which you can see in the Video Format tab. That is, the video that Simmons supplied was NTSC, with a frame rate of 29.97, 16:9 aspect ratio and shot in interlaced mode. Compressor properly determined all that, so this tab needed no changes. In the Quality tab, I set my average and maximum bit-rate targets, and left the Mode and Motion Estimation fields as set by the preset. I touched nothing in the GOP or extras tabs.
Compressor produced our single 2:52 test file in a snappy 3:35 (min:sec), while encoding our five 1-minute test files in parallel in 1:37.
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