Hi, The VIDIOC_G_JPEGCOMP / VIDIOC_S_JPEGCOMP v4l2 ioctls seem not to be used by many drivers / applications. They should! In some ms-win traces, there are automatic and dynamic adjustments of the JPEG quality according to... who knows? Also, most webcams do not include the quantization tables in the images. Then, (in gspca), these tables are added by the subdrivers with a quality defined by the testers and according to their taste. As I understand, the JPEGCOMP ioctls permit to set the JPEG quality and to define the content of the JPEG frames. If I implement these controls in gspca: - by default, I could not add the quantization and Huffman tables in the image frames, - the quality could be set dynamically, this value being used to load the quantization tables in the webcam and also to convert the images. The questions are: 1) May the driver refuse to set some values on VIDIOC_S_JPEGCOMP? For example, if it cannot add the Huffman table in the frames. 2) Will the VIDIOC_G_JPEGCOMP ioctl be used by the v4l library (for conversion purpose)? 3) Does anybody know a command line or X application which may get/set these JPEG parameters? Regards. -- Ken ar c'hentañ | ** Breizh ha Linux atav! ** Jef | http://moinejf.free.fr/ -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
