The resolution is wrong! I asked for 640x480, and I got 640x360. What's up?
Resolution is complicated. There are several reasons why the output file could be different than the resolution target you asked for.
- You asked for a size that is larger than the input file, and you didn't set the "upscale" option. By default, if you ask for 1280x720, and your input is 640x360, we'll leave the file small. Your playback device can scale the video back up to 1280x720, whether it's Flash, HTML5 video, a mobile device, or a desktop player. This saves bandwidth. If you want us to increase the resolution (and the file size), set the "upscale" option to true.
- Sometimes, we have to make the height and width divisible by 2 or 4. Some codecs or settings don't work well with odd-numbered resolutions, or require resolutions divisible by 4.
- You asked for a target with one aspect ratio, and your input has another aspect ratio. If you don't set the video aspect_mode to "stretch", we'll preserve the aspect ratio by default. Really, you want this -- stretching a video from 640x480 to 640x360 is going to make it look bad. Most players can account for this and pad the area with black bars, just like a letterboxed movie. If you really don't want this, set aspect_mode to "stretch" and we'll distort the movie to fit the target aspect ratio.