media-workshop October 2012

media-workshop@linuxtv.org

10 participants
5 discussions

Tentative Agenda for the November workshop
by Hans Verkuil 11 Dec '12

11 Dec '12

Hi all, This is the tentative agenda for the media workshop on November 8, 2012. If you have additional things that you want to discuss, or something is wrong or incomplete in this list, please let me know so I can update the list. - Explain current merging process (Mauro) - Open floor for discussions on how to improve it (Mauro) - Write down minimum requirements for new V4L2 (and DVB?) drivers, both for staging and mainline acceptance: which frameworks to use, v4l2-compliance, etc. (Hans Verkuil) - V4L2 ambiguities (Hans Verkuil) - TSMux device (a mux rather than a demux): Alain Volmat - dmabuf status, esp. with regards to being able to test (Mauro/Samsung) - Device tree support (Guennadi, not known yet whether this topic is needed) - Creating/selecting contexts for hardware that supports this (Samsung, only if time is available) For those whose name is behind a topic: please prepare something before the meeting. We have currently 17 or 18 attendees of a maximum of 25, so there is room for a few more people. Regards, Hans

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Attendee list for the work
by Silvano VIGNA 01 Nov '12

01 Nov '12

Hi Mauro, Sorry for this delay, I confirm that I'll attend to workshop (if still places of course) Thanks, regards Silvano

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Attendee list for the workshop
by Hans Verkuil 22 Oct '12

22 Oct '12

Hi all, This is the list of attendees. Please let me know if information is missing or is wrong. Note that I am missing three email addresses. Attendees: Detlev Casanova <detlev.casanova(a)gmail.com> Mauro Carvalho Chehab <mchehab(a)redhat.com> (Red Hat) Kamil Debski <k.debski(a)samsung.com> (Samsung) Fábio Estevam <festevam(a)gmail.com> (Freescale) Christian Gmeiner <christian.gmeiner(a)gmail.com> Hans de Goede <hdegoede(a)redhat.com> (Red Hat) Erik Johnsen <oskar1969(a)hotmail.com> (tvdaemon) Michael Krufky <mkrufky(a)kernellabs.com> (Hauppauge Computer Works) Guennadi Liakhovetski <g.liakhovetski(a)gmx.de> (Freelance) Brad Love (Hauppauge Computer Works) Sylwester Nawrocki <s.nawrocki(a)samsung.com> (Samsung) Laurent Pinchart <laurent.pinchart(a)ideasonboard.com> (Ideas on Board) André Roth <neolynx(a)gmail.com> (tvdaemon) Jean-Paul Saman <jpsaman(a)videolan.org> Friedrich Schwittay (PCTV Systems) Hans Verkuil <hverkuil(a)xs4all.nl> (Cisco Systems Norway) Silvano Vigna (ST, not yet confirmed) Alain VOLMAT <alain.volmat(a)st.com> (ST)

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RFC: V4L2 API ambiguities
by Hans Verkuil 17 Oct '12

17 Oct '12

During the Plumbers Conference a few weeks ago we had a session to resolve V4L2 ambiguities. It was very successful, but we didn't manage to tackle two of the harder topics, and a third one (timestamps) cause a lot of discussion on the mailinglist after the conference. So here is the list I have today. Any other ambiguities or new features that should be added to the list? Regards, Hans 1) Make a decision how to tell userspace that the monotonic timestamp is used. Several proposals were made, but no decision was taken AFAIK. Can someone (Sakari?) make a summary/current status of this? 2) Pixel Aspect Ratio Pixel aspect: currently this is only available through VIDIOC_CROPCAP. It never really belonged to VIDIOC_CROPCAP IMHO. It's just not a property of cropping or composing. It really belongs to the input/output timings (STD or DV_TIMINGS). That's where the pixel aspect ratio is determined. While it is possible to add it to the dv_timings struct, I see no way of cleanly adding it to struct v4l2_standard (mostly because VIDIOC_ENUMSTD is now handled inside the V4L2 core and doesn't call the drivers anymore). An alternative is to add it to struct v4l2_input/output, but I don't know if it is possible to define a pixelaspect for inputs that are not the current input. What I am thinking of is just to add a new ioctl for this: VIDIOC_G_PIXELASPECT. 3) Tuner Ownership How to handle tuner ownership if both a video and radio node share the same tuner? Obvious rules: - Calling S_FREQ, S_TUNER, S_MODULATOR or S_HW_FREQ_SEEK will make the filehandle the owner if possible. EBUSY is returned if someone else owns the tuner and you would need to switch the tuner mode. - Ditto for ioctls that expect a valid tuner configuration like QUERYSTD. This is likely to be driver dependent, though. - Just opening a device node should not switch ownership. But it is not clear what to do when any of these ioctls are called: - G_FREQUENCY: could just return the last set frequency for radio or TV: requires that that is remembered when switching ownership. This is what happens today, so G_FREQUENCY does not have to switch ownership. - G_TUNER: the rxsubchans, signal and afc fields all require ownership of the tuner. So in principle you would want to switch ownership when G_TUNER is called. On the other hand, that would mean that calling v4l2-ctl --all -d /dev/radio0 would change tuner ownership to radio for /dev/video0. That's rather unexpected. It is possible to just set rxsubchans, signal and afc to 0 if the device node doesn't own the tuner. I'm inclined to do that. - Should closing a device node switch ownership? E.g. if nobody has a radio device open, should the tuner switch back to TV mode automatically? I don't think it should. - How about hybrid tuners?

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[ANNOUNCE] media workshop in November
by Mauro Carvalho Chehab 15 Oct '12

15 Oct '12

Dear developers, We're feeling the need for one more media workshop this year. As there will be already several developers going to LinuxCon Europe and Embedded Linux Conference Europe, we'll be co-locating the workshop together with those two events. As there will be several developers speaking about the media subsystem at both LinuxCon and ELCE, we decided to take just one day (September, 8th) for the media workshop (while we expect that we'll likely have some other discussions during the week). In order to finish the arrangements, I need to know who will be attending, and also we need to receive the theme proposals. Please estimate how long do you think that it would be needed for the proposed theme presentation and discussions. I have a theme proposal already: How to improve the patch submission workflow for media patches - 2 hours. So, please confirm your intention to be there and propose the themes of your interests to media-workshop(a)linuxtv.org mailing list. Thanks! Mauro

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media-workshop October 2012