What do you need to know before buying a portable DVD player? First, you should decide how the device will be used:

• for long trips on your own (by train or by airplane). If so, size, battery life and weight matter the most.
• for long car vacation trips while kids from back seat must be entertained and kept busy. If so, pay attention to: screen size and a wide field of view.

Then you need to know about:

1. screen. This is usually a liquid-crystal display (LCD), but there are essential differences in size and sharpness. In portable DVD players, the largest screen currently available is 10"; the smallest is about 4 inch, which makes a letter-boxed image rather tiny. Screen size influences the price of the device. If more than a person will be watching the display, you should verify the view from more angles. Resolution loss might occur on some LCD screens.
2. power of portables is important because you don't want to be left in the middle of a movie or show. Besides, you probably don't want to carry heavy batteries. What can you expect from batteries? The average life is about two-and-a-half hours, which is enough for an usual movie. There are some batteries giving less than two hours of play, but there are also batteries giving up to five. In case you consider an extra battery, you should endure the extra weight, too. Fortunately, many portable DVD players can be delivered with an AC adapter/recharger, by order.
3. sound. All units are designed with built-in speakers. But the majority of consumers will listen by headphones. So, you should pay attention to the headphone output before buying. If you don't travel alone, look for a unit with two headphone mini jacks.
4. connectivity is to be considered if you aim to use the portable DVD player in your "in home theater". Before buying, you should ask which types of outputs a player can support. Many DVD players release video output through a composite connection. There are few which transmit through S-Video, which is considered higher quality. Besides, all portable DVD players output a digital signal containing either Dolby Digital or DTS multichannel surround sound, which is after that decoded by an A/V receiver or surround-sound processor.

In addition to basic features required from a portable DVD player, there are helpful tips to ensure you make the best choice:

• pay attention to multi language capability, a DVD player's feature which lets you choose dialog or subtitles in different languages for a given movie. Usually, DVDs contain soundtracks in up to 8 different languages.
• look for parental lockout which enables parents to select films by remote control depending on their rating code. According to the movie rating selection, the DVD player will skip certain scenes, playing the version that you choose from those available on the DVD disk. Moreover, by selecting your own identification number, someone else won't be able to change the rating level.
• be aware of signal to noise ratio. Essentially, a S/N ratio basically tells you how clean the video signal is. On a DVD player, this ratio is very good. A S/N ratio of 65 db means that you get 25 or 15 times less noise in the signal than in a VCR or laser disc player.
• verify the regional code, as we have seen before. Choose a DVD player able to play DVDs that have the same region code.