Formats can become a complicated issue in film production. Even when presented with opportunities to simplify and standardise formats (such as with the invention of DVDs and then HD) instead further complications were introduced. There are some good reasons for this -mostly due to regional differences in power supply and to prevent piracy and control pricing (i.e. DVD region codes).
PAL(25p) vs NTSC (30p)
PAL (Phase Alternating Line) is primarily a European/Australasian television format, or used where electricity supply is 50Hz. It now essentially refers to a frame rate of 25 or 50 frames per second . NTSC (National Television System Committee) on the other hand is primarily an American television format, or where electricity is 60Hz and refers to a frame rate of 29.97 or 60 frames per second. In the days before HD, PAL and NTSC also involved differences in vertical and horizontal resolution (PAL: 720x576, NTSC: 720x480), but thankfully that has been standardised, with HD resolution coming in at either 720p (1280x720) or 1080p (1920x1080). But the key difference in frame rates still remain, and the resolution difference does apply for DVDs. (Note: for reasons of simplicity this blog is referring to hard copy media such as discs, and not broadcast formats.)
So if you are purchasing or using equipment in a European country then you are most likely going to be shooting at 25p or 50p. In the US that will likely be either 29.97/30p or 60p. Even if you are filming at 24p (filmic) you will also eventually have to think about having it converted to either the European or US format. Generally speaking, most PAL DVD players in Europe will play a NTSC DVD. However it seems that very few NTSC DVD players can play a PAL disc. So you will eventually have to think of converting.
And this is where it can get really tricky for filmmakers, especially when thinking of submitting films for international festivals. There are two options you have for PAL-NTSC or NTSC-PAL conversion:
1.Conversion with a fixed running length
This method keeps the total length the same, but in order to do so, it has to interpolate (i.e. estimate frames that are between 2 original frames) or blur frames together via "frame blending" or "frame skipping". This maintains the same audio, but can be a slow process and more importantly, result in low quality output and unnatural motion.
2. Conversion with a fixed number of frames
This is what is referred to as ‘conforming'. You keep the same number of frames -they are just played at a slower/faster speed. However, this much better quality conversion also involves changing the speed of the audio. For example film conversion from 24p to PAL involves a 4% increase in speed, which raises the pitch by 0.7 of a semitone, something which is not normally noticeable and can also be 'pitch shifted' (restoring the original pitch).
There are both expensive and cheap (and nasty) options to achieve either of the above -at the top end you have the Snell & Wilcox Alchemist standards converter used by professional companies. At the other end of the scale you can try exporting it directly from your NLE in the desired frame rate -although this will likely be using the fixed running length conversion mentioned above in no.1, which is a low quality method.
Here are some other possible options:
- Use Adobe After Effects. Check this article on how to do it
- Try freeware/shareware programs such as TMPGEnc (http://www.tmpgenc.net) or VirtualDub (www.virtualdub.org)
- Pay for basic software such as DVFilm Atlantis ($45.00, http://dvfilm.com/atlantis/)
- Progressive/interlaced (if interlaced the field order can change i.e. "Upper Field First" or "Lower Field First").
- Changing the frame rate can cause the audio to become unsynchronised.
Please note: If you spot any errors or would like to add some extra advice for filmmakers, please feel free to comment below.