PVR Basics
From DIY PVR DVR HTPC Wiki
PVR Basics, and what is what. By reboot
Video codecs/formats:
There are basically two types of video (for PC) that are used all the time, and two types that are used somewhat, but are rarely used (if at all) for PVR, and never used for capture.
MPG This is the video standard for writing to disk, in either VCD, SVCD, or DVD format. VCD is mpeg-1, and is outdated and rarely used. Mpeg-2 is dvd spec (at the right aspect ratio). DVD Aspect ratio is normally 720x480/576 (the number before the slash is NTSC, and after it, is PAL), although 352x480/576 (known as Half D1) and 352x240/288 (1/4 D1) are acceptable. Most authoring programs will NOT accept anything but Full D1, so beware.
AVI This is used for 99% of downloads because of it's small size and quality. Could be DivX, XviD, or any number of other compression codec's used. To make a DVD, one must encode this video to mpeg-2, dvd spec (see above).
RM We all know that Real Media is the devil's work, and should be banned. Possibly OK for streaming over internet, nothing else.
QT aka .mov Great quality, lousy support. Nobody serious about DVD or PVR video would consider this.
Audio Because everyone assumes that downloads must be as small as possible, audio formats are also usually compressed (like an avi video). When transcoding this audio to dvd spec, audio can go out of sync. Beware VBR MP3 audio, as the worst type to deal with.
DVD Spec is AC3 audio, although 99% of standalone players will play MP2 (mpeg-1 layer 2), but NOT mp3!
There's simply not enough time, nor space to deal with the unlimited variations in audio formats, and how to keep sync while making a dvd.
Capture cards come in two flavors. Hardware and software controlled. Hardware cards have an onboard hardware encoder (usually mpeg-2) chip, and do not rely on your cpu to do any of the work. Hardware cards are great for lower end systems (less than 2ghz), and although they do cost more, they provide video in DVD spec mpeg-2 format, so no encoding nor audio sync issues usually arise Software cards do not, and rely on your CPU and installed codecs to do all the work. Unless you're familiar with the method and codecs you use to capture, and how to get a successful dvd from these captures, I don't ever recommend a soft card. Digital cards don't actually encode anything, they simply format the video onto your hard drive, because it's already in digital format.
Quality is subjective. I much prefer hardware mpeg-2 cards (Hauppauge PVR series), although great qualtiy can be achieved with soft cards, and the right hardware/software combination to run them. Usually involving a TBC and/or a video stabilizer, as well as the capture card, to get good quality. Price prohibitive imho.
Archiving mpg to avi (compressed) to save space: I use virtualdubmod. It's free. Some PVR software has built in avi archiving ability (gb-pvr does). There are numerous other methods, but they require a steeper learning curve, or don't work as well as advertised.
I hope some of this may clear up some basic confusion beginners have, when the question arises, "What card do I get?" Cheers, Jim
