On Sun, 2014-10-26 at 13:41 -0400, Andy Walls wrote: > Hi Chris, > > On Sun, 2014-10-26 at 08:10 -0400, Christopher Neufeld wrote: > > Hello Hans, > > > > On Sun, 26 Oct 2014 06:50:36 +0100, Hans Verkuil <hverk...@xs4all.nl> said: > > > > >> The script that I use to set up captions invokes this command: > > >> v4l2-ctl -d <DEV> --set-fmt-sliced-vbi=cc --set-ctrl=stream_vbi_format=1 > > >> > > >> This now errors out. Part of that is a parsing bug in v4l2-ctl, it wants > > >> to see more text after the 'cc'. I can change it to > > >> v4l2-ctl -d <DEV> --set-fmt-sliced-vbi=cc=1 > > >> --set-ctrl=stream_vbi_format=1 > > > > > This is a v4l2-ctl bug. I'll fix that asap. But using cc=1 is a valid > > > workaround. > > > > >> > > >> with this change, it no longer complains about the command line, but it > > >> errors out in the ioctls. This behaviour is seen with three versions of > > >> v4l2-ctl: the old one packaged with the old kernel, the new one packaged > > >> with the newer kernel, and the git-head, compiled against the headers of > > >> the new kernel. > > Can you verify that > > v4l2-ctl -d <DEV> --get-fmt-sliced-vbi --get-ctrl=stream_vbi_format > > also fails, and that > > v4l2-ctl --list-devices > v4l2-ctl -d /dev/vbi<N> --set-fmt-sliced-vbi=cc=1 > --set-ctrl=stream_vbi_format=1 > v4l2-ctl -d /dev/vbi<N> --get-fmt-sliced-vbi > --get-ctrl=stream_vbi_format > > both succeed on the corresponding vbi node? > > Looking at the v3.16 kernel code that I'm compiling right now, it looks > like extra checks put in the v4l2-core don't allow setting sliced VBI > formats using video device nodes: > > http://git.linuxtv.org/cgit.cgi/v4l-utils.git/tree/utils/v4l2-ctl/v4l2-ctl-vbi.cpp#n209 > http://git.linuxtv.org/cgit.cgi/media_tree.git/tree/drivers/media/v4l2-core/v4l2-ioctl.c#n959 > http://git.linuxtv.org/cgit.cgi/media_tree.git/tree/drivers/media/v4l2-core/v4l2-ioctl.c#n1192 > http://git.linuxtv.org/cgit.cgi/media_tree.git/tree/drivers/media/v4l2-core/v4l2-ioctl.c#n1265 > > I have to actually install and test, but this is my current guess.
FWIW, those checks were introduced in this commit: http://git.linuxtv.org/cgit.cgi/media_tree.git/commit/?id=4b20259fa642d6f7a2dabef0b3adc14ca9dadbde Hans, I'm inclined to say these checks are good things, but they did break existing behavior for user scripts and apps at about kernel v3.7 AFAICT. FYI, MythTV has already worked around it: https://code.mythtv.org/trac/ticket/11723 https://github.com/MythTV/mythtv/commit/25310069a1154213cbc94c903c8b0ace30893ec4 But I don't know about any other apps. Regards, Andy > If you can use the /dev/vbiN node as a work-around, please do. > > Regards, > Andy > > > > Are you calling this when MythTV is already running? If nobody else is > > > using > > > the PVR-500, does it work? > > > > When my script is running, MythTV is not using that unit of the PVR-500. I > > use the "recording groups" feature to ensure that that unit is made > > unavailable for recordings whenever high-definition recordings are being > > made. The details of what I'm doing can be found here: > > https://www.mythtv.org/wiki/Captions_With_HD_PVR > > > > I would not expect this command to succeed if the unit were in use, in fact > > the script detects that as an error case and loops until the device is > > free. The v4l2-ctl command that I use has historically returned an error > > if somebody had the unit's video device open for reading. Now, though, it > > errors even when the unit is unused. > > > > For my script, it is necessary that the MythTV backend be running, the > > script is invoked by the backend, but when it is invoked, nobody is using > > that unit of the PVR-500 (and, in practice, the other unit is almost never > > used, as it's quite rare that I make standard-definition recordings). > > > > My script is not used when MythTV directly makes a standard-definition > > recording from the PVR-500. In that case, the program presumably issues > > its own ioctl equivalents of the v4l2-ctl command, and those are not > > working, because the recordings produced do not have VBI data, while those > > recorded before the kernel upgrade do. > > > > > I won't be able to test this myself until next weekend at the earliest. > > > > Captions are mostly for my wife's benefit, and I checked, most of her > > upcoming shows are being recorded from OTA broadcasts, which provide ATSC > > captions independently of the PVR-500, so I can wait for a week or two. > > > > > > Thank you for looking into this. > > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-media" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
