Test clips

Many users have wondered what kind of test clips are used to test x264 during development. In this post, I will attempt to enlighten readers on my personal suite of test clips and why I chose each one.

My first test clip is a roughly 3600-frame-long segment from Pirates of the Carribean: The Curse of the Black Pearl. I often just use the first 500 or so frames of this. The primary reason this test clip was chosen was to serve as an "ordinary" standard-definition video with a reasonable amount of film grain and the same sort of imperfections that most DVD sources have. The clip can be downloaded here.

My second test clip is a section from Elephant's Dream, the free full-CGI short made in Blender and released by the Orange Open Movie Project studio. This sample is useful for a number of reasons: first, it is available in true lossless 1080p, so I can use a completely flawless source as input to the encoder. Second, of course, it is completely free. Finally, it serves as a good example of a CGI source for which to test x264 on. The full lossless original can be found in PNG sequence format here. If I need an extra HD CGI short, I usually use For the Birds or Lifted.

Next, I usually have an anime/cartoon source of some sort. I sometimes use the Flash version of the Azumanga Daioh OP, but this clip is often less useful than one would think; because its Flash, it is completely lossless. Most real anime/cartoon sources are either DVD or TV broadcast and are therefore far less clean than the above clip. Since x264 has to be able to deal with the flaws in its input, I usually use a fansub copy of the Haruhi ED sequence.

My penultimate test clip is from the VC-1 Blu-ray version of "300." This is a serious torture test for any video encoder; the artificial grain in this source is unbelievable and requires a ridiculously high bitrate to maintain at any resolution. This is also one of the main test clips I used in developing my film grain optimization. While I obviously can't upload the whole video nor even a reasonably sized segment of the source, a relatively high quality sample rip can be found here.

My final test clip is the ultimate torture test: a set of 640x480 videos that need over 4 megabits to avoid noticeable visual artifacts. These are lossless FRAPS captures of Touhou Project games, a series of "danmaku" vertical-scrolling shmups with a difficulty ranging from high to completely ridiculous. With this difficulty comes incredibly complex bullet patterns that make can make many video encoders completely choke; it is nearly impossible to effectively compress the sharp-edged bullets enough to reach the target bitrate without completely decimating the backgrounds. I have used these clips for a comparison between x264 and Elecard and a sample video for H.264-in-browser using Flash. I also have a short lossless clip available for those interested.