So the summary is that if you are looking to watch a HD video then you need to find sources where you can get such HD videos as direct downloads. So you should not confuse between these two types of converter softwares. There are some converter softwares which only convert videos from one format to other. Though there are some converters which do add more pixels to video but output obtained will not be a true HD quality video. It is not possible for a converter software to add more number of pixels in an existing video. So you see that HD video has more number of pixels compared to normal video. Hence a full HD video gives a good viewing experience. More the number of pixels in a video more is the clarity and sharpness of the video.
#Sothink video converter failed to add the following files 480p
On the other hand non HD video like 480p will have 640X480 number of pixels. A full HD video with 1080p resolution of 1920X1080 number of pixels. So a typical video is made up of number of pixels together.
First of all it is necessary to understand what is a "pixel"? Pixel is a single dot or smallest unit of information in an image or video. Let me technically explain this for better understanding. For example with your smartphone you have option to capture video either in HD resolution or other non HD resolutions. HD video will be generated only when video is shot with camera which can capture in HD resolution. Many of the software available over internet claim to do so but it is not true and converted video will not be anything near to the HD quality. Practically speaking it is not possible to convert normal video to HD video by any converter software.