Hello, I sent a topic to mjpeg-developer@xxxxxxxxxxxxxxxxxxxxx concerning the MJPEG kernel extensions to the V4L API, Andrew Stevens suggested to forwardit to Alan Cos who suggested to forward it to you, so maybe you guys know more about it? :-). If I'm on the wrong mailinglist (again), please tell me. (btw, "gst" is gstreamer in this message) [..start of forwarded message..] Second, I noticed that the gst-guys had already given a mjpeg format entry in their generic v4l plugin. I didn't use this since it would limit myself (no subframe capture) or I would have to extend the plugin with more options that nobody else uses (like subframe, decimation, etc) because they're not supported in the generic BTTV driver. So for now, I use a new plugin. However, this made me think: why is there actually a whole set of MJPEG extensions.... Would it have been possible to embed these MJPEG extension kernel calls in the V4L-generic interface? So then, I would simply capture with format=VIDEO_PALETTE_MJPG and use the VIDIOC* kernel calls instead of MJPIOC_* kernel calls. Does anybody have a clue why this hasn't been done like this? In my opinion, the current solution works wonderful but it could be seen as kind of "attacking the simplicity of V4L" in the way that you don't conform to the V4L-standard (assuming that would have been possible).... On the other hand, the mjpeg/zoran chips do course have features which might not be supported in video4linux itself (I do know, however, that there is a kernel call in video4linux for subframe/decimated capture - it's just not used in BTTV, but that would have been possible!)...... So, does anybody have a clue regaring the reasons for these kernel extensions instead of using basic V4L-functions? [..end of forwarded message..] I'm really not suggesting to rewrite the zoran drivers to conform to the generic video4linux API, if it would be possible at all - we just got into the kernel and we don't need API changes then. However, it might be interesting to see whether you can - in theory - do all the MJPEG/zoran capture work using generic video4linux calls, since some of the MJPEG calls (MJPIOC_SYNC, MJPIOC_QBUFS, ...) also exist in generic video4linux. It would also prevent a lot of extra extensions to video4linux2 (because we would then, for video4linux2, just use the generic calls instead of recreate our extensions) which, as a consequence, would make it possible for simple video4linux applications to record from MJPEG devices as well with only little extra work.... Thanks for any comments, Ronald -- - .-. - /V\ | Ronald Bultje <rbultje@xxxxxxxxxxxxxxxxxxx> - // \\ | Running: Linux 2.4.4 and OpenBSD 2.8 - /( )\ | http://ronald.bitfreak.net/ - ^^-^^
