The HD Showdown: Codec Vendors Battle It Out for Supreme Quality

I’ve been spending a lot of time comparing codecs lately, and I always feel a little uncomfortable when I encode the test files since I assume that the actual codec vendors know how to wring the last bit of quality out of their respective codecs better than I do. So for this particular review, I asked the codec vendors themselves to encode the files.

具体地说, I sent a test file to Microsoft (for VC-1) and On2 (for VP6), and each company preprocessed and encoded the clip to a standard set of parameters using their own tools and compression settings. Unfortunately, the company that had agreed to produce the H.264文件备份. I was unable to find a replacement, so I encoded the files myself.

在过去, for these types of competitions, I sent the participants a prescaled, prefiltered test file so I could isolate codec performance from the qualitative aspects of scaling, 反交错, and noise-reduction filtering. 对于这个测试, 然而, I felt that insight into the types of preprocessing performed by these companies to produce their "trophy footage" would provide some interesting perspective into the art of real-world preprocessing and encoding.

So I produced the test file from seven different HDV-source scenes, edited together in Premiere Pro and exported in HDV parameters (1440x1080i) using the Lagarith YUV 12 lossless codec, which was as close as I could come to the original HDV format without imposing another layer of MPEG-2 compression by rendering back to HDV after editing.

规则很简单. The contestants could use any preprocessing and/or encoding tool available, 不计成本, as long as they disclosed the process to me so I could share it with you. Of course, I was free to do the same when I produced the H.264年文件.

The streaming files had to be delivered at an average data rate of 800Kbps video/128Kbps audio, which is insanely aggressive, but I felt that it was necessary to distinguish the quality of the three codecs. The companies could use the highest quality settings available (such as VP6E rather than VP6S, or the High Profile rather than Baseline for H.264) and either VBR or CBR, as long as the average data rate came in at about 928Kbps.

Once I had all the files in hand, I compared the quality of each. I am reporting the results herein. Note that you can view the files and all preprocessing and encoding preset files at www.doceo.com/HDcomps.html.

预处理
I’ve long believed that preprocessing is the key to high-quality streaming video, and that’s certainly the case with this test file, which is composed of footage shot over the last 12 months or so. Most of the sequences are on-location shoots or stage performances, and lighting is seldom optimal, which often results in noisy footage.

除了, we were working with interlaced source footage delivered in progressive streaming frames and 1440x1080 resolution video delivered at 1280x720, meaning that all contestants would need to scale and deinterlace their videos.

不足为奇的是, all three contenders applied scaling, 反交错, and noise-reduction filters to the source video. What was surprising was that all three contestants used different tools to preprocess their file and that no contender used the tools integrated into their encoding program. But let’s jump in, starting with Microsoft.