PC users often need to convert video from one format to another. Reasons may be different: to watch video on a TV or gadget, embed into a blog, play in a specific software, or just store it on a PC in a most common video format. Anyway, each time when you convert a video with a video converter, you might not notice that the software does most of the dirty work for you. Most free video conversion tools available today offer a wide range of ready profiles for various devices and video formats, so that you don’t have to learn the insights of video conversion, dig into settings, or decide which video codec is better. Still if you want to know a little more about video conversion than an average novice user, read 10 top Q&A on this topic.
1. What happens to video when it’s being converted?
A digital video consists of a series of still images or frames, from 24 to 72 per second. If all images were displayed “as-is”, one-minute video would weigh several gigabytes, so the frames are usually compressed. When video is being converted, The process of video conversion falls into two stages – decoding (decompression of an original file) and encoding (a new compression).
2. How to choose a video resolution?
Video resolution, or frame size, is width and height of a digital video calculated in pixels (e.g. 320×240, 640×480, 1280×720, etc.). Each device has its own video resolution requirements which often coincide with the screen resolution with some rare exceptions. Therefore, the best resolution for your gadget is the same as its screen resolution. Many gadgets are capable of playing HD and FullHD video, though there is no point converting video to this frame size if the screen resolution is smaller.
3. Is video codec really important?
Yes, it sets the method for encoding and decoding of video data and thus influences the resulted video quality, file size, and even the fact whether this video will be played on a certain device or not. One and the same file extension can have hundreds of codecs within, e.g. for AVI video there may be used H.264, DivX, Xvid, MPEG4. You should choose one that will be surely supported by your device. The most common video codecs are H.264, MPEG4, DivX, VC-1, Theora, Xvid, MPEG2. etc.
4. What is bit rate?
Bit rate is the amount of information (in bits) conveyed or processed per unit of time. A higher bit rate allows better output quality, still the more the bit rate is, the larger output file size will be. The average bit rate varies between 0 and 5000 Kbits/s; the default values are 800 Kbits/s for low quality, 1000 Kbit/s for medium quality and 1200 Kbits/s for high quality.
5. What is the difference between CBR and VBR encoding?
Constant bit rate (CBR) encoding keeps the bit rate the same over the whole video clip. Variable bit rate (VBR) encoding adjusts the bit rate down and to the upper limit you set. VBR takes longer to encode but produces the most favorable results. Still CBR is recognized on all gadgets and media players, so most video conversion tools offer just CBR encoding.
6. Is it possible to turn lower resolution video to HD?
Technically yes, if you stretch or upscale the input video. Still the video quality will be much worse, since HD video requires a higher bit rate.
7. What’s the difference between single-pass and multi-pass encoding?
The pass here stands for a pass through the input data. Single-pass encoding analyzes and encodes the data “on the fly”, when the encoding speed is most important. Multi-pass encoding takes much longer than single-pass encoding but the output video quality is much better. Multi-pass encoding cannot be used in real-time encoding, live broadcast or live streaming.
8. Is it true that a good video converter cost money?
No, today there are numerous good apps which can compete with paid video conversion tools and even do the job better. Most of them are based on ffmpeg libraries which provide quality decoding and encoding facilities. Have a look at such tools as Freemake Video Converter (Windows) or Handbrake (Mac).
9. Why did the output video quality get worse after conversion?
The main reason is the output video parameters differ a lot from the original ones: you might have chosen too small resolution, low bit rate or frame rate. If you don’t need specific video settings, you’d better use “Auto” or “Same as source” preset.
10. Which format does suit better for PC backup?
Whether we rip DVDs or convert your camcorder footage, our main aim is to get a video of good quality and small file size. Plus, this video should be compatible with most video players. The following output options will let do this: AVI (H.264/MPEG4 video codec), MP4 (H.264/MPEG4 video codec), MKV (H.264 codec).
Elena Vakhromova is an IT enthusiast and social media marketer. She blogs on behalf of Freemake, developer of YouTube Video Converter and other audio/video conversion freeware.