YouTube has support for many different video formats, so which to use depends mostly on your own personal preference. You should, in most cases, aim not change the aspect ratio of your video, and also not lower the quality below the original source material.
Keep in mind, a high bitrate does not necessarily equal higher quality. It is sometimes possible to get good video quality with bitrates as low as 1-2k, but it depends on your codec and source material.
A very popular video container is .mp4 used with the h.264 or h.265 video codecs. Not every video editor will be able to render video to those formats. But, if you can not choose mp4 when rendering your video, you can just convert the video using either Handbrake or ffmpeg, after rendering it from your editor.
Filesize = bitrate * runtime
Formats supported by YouTube
As of January 2018, YouTube had the following formats listed:
- HEVC (h265)
If the format of your video is not listed, then you likely need to convert your video before uploading. In some cases, this may also speed up the uploading process. Short videos that are only a few minutes in length, should generally not be larger than a 10-100 megabytes, but it will depend on the source material and the target video quality.
Choosing the right format and codecs
For video intended to be uploaded on the Internet, we often want to optimize the filesize, to speed up the uploading of our videos. So, try using either the MP4 or avi container formats with the h.264 or h.265 video codecs. Depending on your requirements in regards to quality, you can generally get away with a fairly low bitrate with those formats. DIVx and xVID are also good options.
Some video editors may have a template specifically created for "Internet", but if your aim is a low file size, then you likely want to use a custom setting. Some codecs, such as h.264, good old DIVx and xVID, can preserve quality at relatively low bitrates.
For videos that will be uploaded, you often want to save your bandwidth and upload time, so using a different codec than those that came with your video editor can sometimes be nessecery.
For xVID, and source video at around DVD quality (480p), a bitrate between 1k and 3k (in kbps) should suffice, and you should not notice much of a drop in quality, if done right.
It depends on the source however. For HD video, you still want to experiment as of what is acceptable to you. You can try around 7000kbps, and then move your way up if needed – this also depends on codec used. For higher quality HD, try aiming at 10-20k.
Remember that Filesize = bitrate * runtime
Video editor and codec support
If your editor does not allow you to choose a codec yourself, you can convert your video after rendering it. Ideally, you should try to render directly to the format you want from the start, but when this is not possible, you can instead convert the video. A good video editor will allow you to select the rendering file format and codec, so if yours does not provide a good selection, be sure to check out other editors to the one you are currently using.
Choosing a video editor can be difficult, because there are so many, and most of them are very expensive. Most will have heard about Adobe Premiere and Final Cut, and those are good editors. But, they are very expensive to hobby-use. Instead, you can try Kdenlive, which is a free alternative. Remember to save your Kdenlive projects often, because it tends to crash a lot.
Converting a video should have very little influence on the quality. Sometimes, you may be able to change only the container format. Doing this avoids re-encoding the video, and therefor it should not change the quality..
To convert your video, you can use free tools such as Handbrake or ffmpeg, which are better than many of the commercial converters on the market.