Hi Andy, On 10/26/2014 07:28 PM, Andy Walls wrote: > 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 <hverkuil@xxxxxxxxx> 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. I did check various apps (including mythtv) at the time whether they were using vbi nodes for doing vbi parsing, but I missed the sliced vbi handling in the mpegrecorder. This patch was part of the ongoing effort to be more picky about what drivers allow. It makes no sense to setup a vbi format on a video node. There is a reason we have vbi nodes, after all. Thanks for taking the time to track this down! Regards, Hans > > 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 majordomo@xxxxxxxxxxxxxxx >> 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 majordomo@xxxxxxxxxxxxxxx > 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 majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
