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There has been endless debate on the relative merits of the quality of PAL images versus the quality of NTSC images. In this article, I want to present you with the arguments for and against both PAL and NTSC on DVD so that you can make an informed decision when purchasing your DVDs in regards to the best version to buy. As you will see in this article, it is not necessarily the case that PAL is always better or that NTSC is always better. However, I aim to point out the reasons why you should prefer one format over the other, and in which circumstances you should prefer one format over the other.
read my article on this topic, as your understanding of the remainder of this article will be significantly enhanced if you understand 16x9 enhancement. They're Not Really PAL or NTSC The first thing I need to clarify about DVD is that PAL and NTSC are words and formats that are applied to DVD for convenience, and because of historical convention. There is nothing fundamental about a DVD which makes it either PAL or NTSC, but for simplicity and brevity, I will continue to use these terms throughout this article. At their heart, DVDs are merely carriers of data files with compressed audio-visual information contained therein. This information can be placed on DVD in one of two resolutions; The DVD player itself takes this data file and formats it appropriately for display in either PAL or NTSC. The Issue Of Resolution In principle, PAL DVDs have a compelling advantage over NTSC DVDs. PAL DVDs have 576 pixels of vertical resolution versus 480 pixels of vertical resolution. That's a 20% increase in resolution for a PAL DVD as compared to an NTSC DVD. Increased resolution translates into a better looking image. However, this is an overly simplistic way of looking at the whole PAL vs NTSC issue as there are other factors that need to be taken into account. Active Pixels & 16x9 Enhancement Because programming can be presented on DVD in various aspect ratios, it is useful to consider the active pixels in a given image when considering the overall resolution of a DVD. For a widescreen image, not all of the pixels available on a DVD are actually used for the image. Some of them make up the black bars above and below the image. The format that provides the most overall active pixels for a given aspect ratio will in theory be the best possible format. Complicating the issue is the difference in active pixels when a DVD is 16x9 enhanced. The following table illustrates the common aspect ratios presented on DVD along with the total active pixels presented in each possible DVD format. Aspect Ratio 4x3 PAL 16x9 enhanced PAL 4x3 NTSC 16x9 enhanced NTSC 133:1 720 x 576 = 414,720 538 x 576 = 309,888 720 x 480 = 345,600 538 x 480 = 258,240 166:1 720 x 461 = 331,920 671 x 576 = 386,496 720 x 384 = 276,480 671 x 480 = 322,080 178:1 720 x 430 = 309,600 720 x 576 = 414,720 720 x 358 = 257,760 720 x 480 = 345,600 185:1 720 x 414 = 298,080 720 x 554 = 398,880 720 x 345 = 248,400 720 x 461 = 331,920 235:1 720 x 326 = 234,720 720 x 436 = 313,920 720 x 271 = 195,120 720 x 363 = 261,360 Key Best Second Best Third Best Worst Widescreen Movies For widescreen movies, 16x9 enhanced PAL DVDs provide the highest resolution image, and are theoretically the version of choice. If the PAL version of a widescreen movie is not 16x9 enhanced, then the version of choice is a 16x9 enhanced NTSC DVD. Frame and Field Rates The consideration of which version is best is complicated by the issue of source material. In the case of movies, the choice is simple - pick the disc which has the highest possible image resolution, all else being equal. In the case of video-sourced material, the choice is less simple. Movies Movies the world over are shown at a frame rate of 24 frames per second. That is, 24 images are projected onto the cinema screen every second. Movie film is a very high resolution format, far higher in resolution than the DVD format. Accordingly, the movie itself is not the limiting factor in deciding between PAL and NTSC format DVDs, as the same source material is usually used to create both the PAL and the NTSC versions of a particular DVD. Therefore, the limiting factor in resolution is the DVD itself, with PAL inherently higher in resolution than NTSC. Video With video-based source material, there are two predominant worldwide formats; PAL and NTSC, which differ in both resolution and in frame rate. PAL is higher in resolution (576 horizontal lines) than NTSC (480 horizontal lines), but NTSC updates the on-screen image more frequently than PAL (30 times per second versus 25 times per second). NTSC video is lower in resolution than PAL video, but because the screen updates more frequently, motion is rendered better in NTSC video than it is in PAL video. When video source material is transferred to DVD, it is usually transferred in the format it was created in - PAL or NTSC, and the subsequent image has either higher temporal resolution (more frames per second - NTSC) or higher spatial resolution (more lines per image - PAL). Conversions between the two video formats are possible, and are indeed frequently carried out, as it seems to be far more acceptable to sell PAL transfers in PAL countries and NTSC transfers in NTSC countries, even if the source material did not originate in the respective format. Conversions between these formats is problematic, however, as compromises need to be made in order to accommodate the source material, and visible artefacts can be introduced by the conversion process. Converting NTSC to PAL When converting from NTSC to PAL, two things need to be accomplished. The resolution upconversion does not actually add any real picture information to the image, as you cannot create real picture information where none existed before. It does, however, make the picture viewable on a PAL display, and often results in a superficially better-looking image. The frame rate conversion actually results in a loss of temporal resolution, as PAL has a lower frame rate than NTSC. Converting PAL to NTSC The converse situation applies to PAL to NTSC conversions. Once again, the resultant image is of less actual resolution than the original image, as information is discarded spatially and made up temporally. Implications for Video Programming On DVD The best format to record and play back video programming on DVD in is the format in which the programming was originally created. If it was videotaped in the NTSC format, then the NTSC DVD will be the version of choice. If it was videotaped in the PAL format, then the PAL DVD will be the version of choice. Higher Definition Source Material Complicating this issue is the fact that more and more programming is being created in higher definition video formats these days, and these high definition formats can usually be converted down to PAL or NTSC equally well, with both formats having their respective disadvantages. As a general rule, video programming sourced from PAL-based countries is likely to look better in PAL, and video programming sourced from NTSC-based countries is likely to look better in NTSC, since these are the likely native formats that they have been created in. Other Factors To Consider If all of the above issues aren't enough to consider when deciding whether to purchase a PAL or an NTSC version of a particular title, there are several other factors which are also worth taking into consideration. Compression Ratio Previously, it has been established that a PAL DVD has 20% more resolution than an NTSC DVD. This does not necessarily translate into a superior image. The DVD format relies on a lossy video compression format (MPEG-2) to allow a reasonable length of programming to fit onto a single DVD. The longer the programming, the higher the compression ratio needs to be, and the more likely it is that visible compression artefacts will be present. If an additional 20% of resolution needs to be compressed, then this can potentially result in a lesser quality image if the programming is overcompressed. Fortunately, many PAL DVDs are being produced as dual layer discs, whereas their NTSC counterparts are being ...
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