SheerVideoWhy can I export RGB[A] to Sheer YCbCr[A] in Perfect mode?
If you set the Pixel Format Conversion in the Sheer Settings dialog box to ‘Perfect’, the Sheer encoder will only accept pixel formats which it can nondestructively encode. For unfortunate historical reasons, most QuickTime applications require a video compressor to accept RGB[A] 8bf input, even for compressing pure Y’CbCr material. For example, the preview image in the QuickTime Compression Settings dialog box only accepts RGB 8b input, even for Y’CbCr sources going to Y’CbCr formats. However, it is theoretically impossible, even with SheerVideo’s Synchromy technology, to losslessly convert from RGB[A] 8bf to Y’CbCr[A] 8b or from 4:4:4[:4] to 4:2:2[:4]. The only Sheer Y’CbCr[A] encoder which nondestructively encodes RGB[A] 8bf is Sheer Y’CbCr[A] 10bv 4:4:4[:4]. All other Sheer Y’CbCr[A] encoders refuse to accept RGB[A] 8bf input in Perfect mode, so all QuickTime applications which require the encoder to accept RGB[A] input will fail.
