Quicktime File Format (2012-08-14).pdf

Media Data Atom TypesVideo MediaTable 4-5Index0123–678–65535Table of transfer function index and valuesVideo StandardsReservedRecommendation ITU-R BT.709-2, SMPTE 274M-1995, 296M-1997, 293M-1996, 170M-1994See below for transfer function equations.Coefficient values are unknownReservedRecommendation SMPTE 240M-1995 and 274M-1995 See below for transfer functionequations.ReservedThe MPEG-2 sequence display extension transfer_sics defines a code 6 whose transfer function is identicalto that in code 1. QuickTime writers should map 6 to 1 when converting from transfer_characteristicsto transferFunction.Recommendation ITU-R BT.470-4 specified an "assumed gamma value of the receiver for which the primarysignals are pre-corrected" as 2.2 for NTSC and 2.8 for PAL systems. This information is both incomplete andobsolete. Modern 525- and 625-line digital and NTSC/PAL systems use the transfer function with code 1.Figure 4-6 Equations for index code 1Figure 4-7 Equations for index code 7The matrix values are shown in Table 4-6 (page 167) and in Figure 4-8 (page 167), Figure 4-9 (page 167), andFigure 4-10 (page 167). These figures show a formula for obtaining the normalized value of Y´ in the range [0,1].You can derive the formula for normalized values of Cb and Cr as follows:If the equation for normalized Y´ has the form:Then the formulas for normalized Cb and Cr are:2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.166