difference between Easycap v tv card with video capture.

Sometimes there is a small difference in the real video quality that the hardware does, but most often it is features (like hardware compression), drivers, codecs, and codec settings.

Some more expensive video capture adapters and some TV cards come with a built in CPU that does compression inside the adapter. This is good because the compression quality does not depend on the PC CPU or on PC settings. This is good because the PC CPU can then be used for other things. This is good because it even works on a slow PC CPU. This is bad because the hardware will only do that exact kind of compression and no other.

EasyCap, like most video capture devices, relies on the PC CPU to compress the very large video into something smaller. No current CPU's are fast enough to do the very best compression on live video, that is, frames will be dropped and it will look jerky if you try to compress live video more than your CPU can do. On the other hand, you can capture live video using less compression (a bigger file) and later recompress it (takes several hours per hour of video file) to a smaller file. You can also select different codecs, frame sizes (resolution), bit rates, and quality to get the most out of your system's live capture.

So selecting and configuring a video codec for video capture is a compromise between how fast your CPU is and how large your hard drive is and depends on what the video is about. A constantly changing scene with lots of motion in it is the hardest to compress. I usually use something close to DVD quality MPEG2 and reduce it from there. For my requirements, this is a good compromise between CPU and hard drive space.