Why game recordings need encoding before you keep or upload them

Recorders such as Fraps save video with very light compression, because there is no time to compress properly while a game is running. Encoding afterwards with a modern codec cuts the file to a small fraction of its size, and the result plays on computers without Fraps and matches the format YouTube asks for.

How big a raw recording is

Wikipedia's example is two minutes of a 1920×1080 screen recorded by Fraps in 3.95 GiB, about 34 MiB, or roughly 285 megabits, every second. YouTube's recommended bitrate for 1080p at 60 fps is 12 megabits per second. Encoding to that rate makes the file about 24 times smaller.

What encoding changes

• Size: codecs such as H.264 store what changes between frames instead of every frame in full.
• Playback: Beepa's FAQ notes that media players often skip and crackle on raw Fraps files because they can't read the data fast enough, while an encoded copy plays smoothly.
• Compatibility: a Fraps file needs the FPS1 codec, which only Fraps installs. An MP4 with H.264 video and AAC audio is the format YouTube recommends for uploads.

Lossless copies for editing

Each lossy encode loses a little detail, so editing a file that is already compressed and then compressing it again adds up. If you plan to cut and re-edit, convert the recording to a lossless intermediate codec first, such as Lagarith or Ut Video, both made for editing and free under the GPL. Encode to H.264 once, at the end.

Encoder settings

For the settings themselves, see x264 or x265 and what CRF means, or VirtualDub to MP4.