Selecting a web cam for barcode scanning:
- the higher resolution is better. But 1-2 MP is enough for most barcode types
- manual focus capability is preferred (webcam should support this feature). Most modern webcams are coming with auto-focus which could work too but you may have issues when scanning a barcode with a bad light and from the close position: autofocus may move to the scene behind and this may cause blurred barcodes.
The barcode reading confidence does depend on many factors: barcode type, barcode print quality, distance, lighting conditions. And also it depends on the type of barcode you use: QR Code or PDF417 (which provide built-in error correction), Code 39 or Code 128 (which are coming without the error correction)