On Friday 22 January 2010 04:00:53 Andy Walls wrote: > On Fri, 2010-01-22 at 10:42 +0800, Michael Qiu wrote: > > Hi all, > > > > How can I export my MPEG decoder control interface to user space? > > Or in other words, which device file(/dev/xxx) should a proper > > driver for mpeg decoder provide? > > The MPEG decoder on a PVR-350 PCI card provides a /dev/video interface > (normally /dev/video16). > > The interface specification to userspace is the V4L2 API: > > http://www.linuxtv.org/downloads/video4linux/API/V4L2_API/spec-single/v4l2.html Not really. The v4l2 API specifies the MPEG encoder part, but not the decode part. The decoder part is (unfortunately) part of the DVB API. Some ioctls are documented here: http://www.linuxtv.org/downloads/v4l-dvb-apis/ch11s02.html However, that documentation is very out of date and you are better off looking in the include/linux/dvb/video.h header. In particular the new struct video_command and associated ioctls provides you with more control than the older VIDEO_CMD_ ioctls. Note that the V4L2 API will get a new event API soon that should supercede the event implementation in this video.h. The video.h implementation is pretty crappy (most of what is in there is crappy: poorly designed without much thought for extendability). > > And, in linux dvb documents, all the frontend interface looks like > > /dev/dvb/adapter/xxx, it looks just for PCI based tv card. > > If it's not a TV card, but a frontend for a embedded system without > > PCI, which interface should I use? V4L2, but with the ioctls defined in dvb/video.h. See for example the ivtv driver (ivtv-ioctl.c). If the video.h API is not powerful enough, then please discuss that on this list. Frankly, that might give me a good excuse to create a better API that is properly integrated with V4L2. Regards, Hans > The V4L2 specification should be OK for basic functionality. Hans > might be able to talk about more advanced interfaces that are in work > for embedded platforms, if the V4L2 API is not good enough for you as > is. > > Regards, > Andy > > > Best regards > > Michael Qiu > > > -- Hans Verkuil - video4linux developer - sponsored by TANDBERG -- 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
