Recently, doing the same project that I previously blogged about I was also asked to grab a movie off of YouTube (one banned in Cuba and only available through that medium). The quality of YouTube videos obviously is largely based on the slightly archaic codecs used by the YouTube interface to encode videos uploaded to their site. However, there are numerous "cookbook" type recommendations from many different sites for getting the best quality video to appear on YouTube. However, the creators of this particular video seem not to have read those, as the video was full of codec artifacts, dropped audio, and both of these together sometimes made for a difficult viewing experience, especially if there happened to be a lot of movement on-screen. So I searched far and wide for some possible fixes and filters to make this video just a bit higher quality.
I found that this wish of mine is largely impossible. To try and upconvert poor video to higher quality video is near impossible - otherwise filmmakers might be shooting on cell-phone cameras and saving themselves a lot of money. So here are a couple of very minimal filters (all are in FCP) one can try applying to a poor quality YouTube, or any other poor quality video to try and end up with a better result.
1. Blur Filter: This filter can obviously be taken too far, resulting in even poorer video quality. What I did find though, was that the filter cut down the pixelated look of codec artifacts when there was a lot of movement. The best way to use this filter to find a frame with particularly bad artifacts, add the filter, and play with the slider to get some of the sharp, square edges of the artifacts to go away. Move to a frame with less movement to be sure you are not blurring the general picture too much.
2. Desaturate Filter: When you first apply this filter, it will completely desaturate your image, i.e. make it B & W. Do not fear - you can change this. But first, a bit of explanation. Often the codec artifacts that appear will be more pronounced when there are highly saturated colors in the scene, i.e. bright reds, yellows, greens, or blues. So, you can cut down the choppiness of the look in these scenes by desaturating them a bit. When using this filter, choose a frame where there is a highly saturated color (if you have none, this filer probably wont be of much help) and add the effect. There is a slider on the effect that will allow you to change the saturation from black and white (none) to highly saturated colors which will probably bleed on your TV. Choose a happy medium - you do not want to desaturate too much, or else the movie will look drab and even depressing (if this is what you are going for, desaturate away!). Just pull back some of the bright colors if you have them, and you will find that some of the artifacts are a bit less imposing.
3. Deinterlace Filter: This filter depends on where you are showing the movie. If you are looking to show it on a TV (definitely not my recommendation if you capture YouTube videos, unless you are showing on a Apple TV), you cannot use this filter, as it will make the image go fun-house mirror on you. Also, if the image was not originally taken from a TV source, this filter probably will not help. So, all of this being said - this file I was working with was taken from a TV, and not deinterlaced, resulting in lines that appear and make the image look jagged when movement occurred. So, deinterlacing can help too.
All in all, the best solution to all of this if really to see if you can find the source video. Email the person who posted it on YouTube and ask if they can send you even a highly compressed version through email. A well compressed video, even highly so will be better than YouTube codec screen captures.