Re: [media-workshop] [ANNOUNCE] Linux Kernel Media mini-summit on Oct, 16-17 in Düsseldorf, Germany
Guennadi Liakhovetski writes: > I'll likely be able to attend too. ATM I'm working on camera support in > Android. I think Hans discussed related topics at the previous summit in > the US too, which I didn't manage to attend unfortunately. I'll try to > double-check results of those discussions and see which topics I'd be > interested in discussing further. I'll also try to be there for the mini-summit. So, if anybody wants to discuss APIs for DVB-T2/C2, CI, modulators, DVB network streaming or anything else related to DVB drivers ... > On a related note, since I live something like 80km from the venue, I was > thinking about possibly helping to organise a media event in my town - in > Aachen, or in Düsseldorf itself or in neighbouring Cologne (Köln). Let me > know if there's interest. We could use Saturday the 18th of October for > that. I also live just 50km from the venue. Regards, Ralph -- 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
Re: [media-workshop] [ANNOUNCE] Linux Kernel Media mini-summit on Oct, 16-17 in Düsseldorf, Germany
On 08/19/2014 09:00 PM, Laurent Pinchart wrote: > On Tuesday 19 August 2014 18:29:08 Ricardo Ribalda Delgado wrote: >> Hello Laurent >> >>> Could you elaborate a bit on that last point ? What kind of timestamps >>> would you need, and what are the use cases ? >> >> Right now we only have one timestamp field on the buffer structure, it >> might be a good idea to leave space for some more. >> >> My user case is a camera that is recording a conveyor belt at a very >> high frame rate. Instead of tracking the objects on the image with I >> use one or more encoders on the belt. The encoder count is read on >> vsync and kept it on a register(s). When an image is ready, the cpu >> starts the dma and read this "belt timestamps" registers. >> >> It would be nice to have an standard way to expose this alternative >> timestamps or at least find out if I am the only one with this issue >> and/or how you have solve it :) > > I have a similar use cases. UVC transmits a device clock timestamp to the > host, as well as the corresponding USB SOF counter value. This can be used to > translate the device clock timestamp to a host timestamp. The uvcvideo driver > is currently performing that translation in the kernel, but moving it to > userspace would allow more accurate host timestamp computation by using > floating-point math. > > In a similar fashion CSI2 cameras transmit a 16-bit frame number to the > receiver. That number is currently expanded to 32-bits by the driver and > passed to userspace in the v4l2_buffer sequence number. That's fine from a > kernel point of view, but in userspace the sequence number is lost when using > the gstreamer v4l2src element. > > Have you thought about how you would like to implement those advanced > timestamps ? Reusing the v4l2_buffer timecode field might be an option, but > I'm not sure whether it would be the best one. Using a metadata plane also > comes to mind. > Just my two cents: I think the timecode field should be reused for this as a way of storing driver/hardware-specific timestamps. Such timestamps are likely to be different for different hardware since I do not think that hardware timestamps can always be converted reliably to the kernel time. They may just be numbers that software needs to interpret according to what hardware was used. M2M devices already copy the timecode field when copying frames (or at least they should), so changing v4l2_timecode to a union would make sense as that behavior of m2m devices remains preserved for hardware timestamps. Regards, Hans -- 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
Re: [media-workshop] [ANNOUNCE] Linux Kernel Media mini-summit on Oct, 16-17 in Düsseldorf, Germany
On Tuesday 19 August 2014 18:29:08 Ricardo Ribalda Delgado wrote: > Hello Laurent > > > Could you elaborate a bit on that last point ? What kind of timestamps > > would you need, and what are the use cases ? > > Right now we only have one timestamp field on the buffer structure, it > might be a good idea to leave space for some more. > > My user case is a camera that is recording a conveyor belt at a very > high frame rate. Instead of tracking the objects on the image with I > use one or more encoders on the belt. The encoder count is read on > vsync and kept it on a register(s). When an image is ready, the cpu > starts the dma and read this "belt timestamps" registers. > > It would be nice to have an standard way to expose this alternative > timestamps or at least find out if I am the only one with this issue > and/or how you have solve it :) I have a similar use cases. UVC transmits a device clock timestamp to the host, as well as the corresponding USB SOF counter value. This can be used to translate the device clock timestamp to a host timestamp. The uvcvideo driver is currently performing that translation in the kernel, but moving it to userspace would allow more accurate host timestamp computation by using floating-point math. In a similar fashion CSI2 cameras transmit a 16-bit frame number to the receiver. That number is currently expanded to 32-bits by the driver and passed to userspace in the v4l2_buffer sequence number. That's fine from a kernel point of view, but in userspace the sequence number is lost when using the gstreamer v4l2src element. Have you thought about how you would like to implement those advanced timestamps ? Reusing the v4l2_buffer timecode field might be an option, but I'm not sure whether it would be the best one. Using a metadata plane also comes to mind. -- Regards, Laurent Pinchart -- 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
Re: [media-workshop] [ANNOUNCE] Linux Kernel Media mini-summit on Oct, 16-17 in Düsseldorf, Germany
Hello Laurent > Could you elaborate a bit on that last point ? What kind of timestamps would > you need, and what are the use cases ? Right now we only have one timestamp field on the buffer structure, it might be a good idea to leave space for some more. My user case is a camera that is recording a conveyor belt at a very high frame rate. Instead of tracking the objects on the image with I use one or more encoders on the belt. The encoder count is read on vsync and kept it on a register(s). When an image is ready, the cpu starts the dma and read this "belt timestamps" registers. It would be nice to have an standard way to expose this alternative timestamps or at least find out if I am the only one with this issue and/or how you have solve it :) Best regards! -- Ricardo Ribalda -- 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
Re: [media-workshop] [ANNOUNCE] Linux Kernel Media mini-summit on Oct, 16-17 in Düsseldorf, Germany
Hi Ricardo, On Tuesday 19 August 2014 16:48:19 Ricardo Ribalda Delgado wrote: > Hello > > I will also be in Düsseldorf the whole week for ELCE and LPC. I would > love to attend the media mini-summit. > > I am interested in multiselection, deadpixels API and multiple > timestamps per buffer. Could you elaborate a bit on that last point ? What kind of timestamps would you need, and what are the use cases ? -- Regards, Laurent Pinchart -- 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
Re: [media-workshop] [ANNOUNCE] Linux Kernel Media mini-summit on Oct, 16-17 in Düsseldorf, Germany
Hello I will also be in Düsseldorf the whole week for ELCE and LPC. I would love to attend the media mini-summit. I am interested in multiselection, deadpixels API and multiple timestamps per buffer. Thank you very much! On Thu, Aug 14, 2014 at 1:43 PM, Laurent Pinchart wrote: > Hi Mauro, > > On Wednesday 13 August 2014 10:14:11 Mauro Carvalho Chehab wrote: >> Hi, >> >> As there are still too things to be discussed in order to improve media >> stuff, and most of the developers nowadays are located in Europe and >> usually go to ELCE, we're scheduling a two day mini-summit in Düsseldorf, >> Germany, on Thrusday/Friday. >> >> There is a perfect opportunity to discuss the media Kernel-Userspace >> API improvements that are required for newer devices to work. >> So, we hope to have there the major Kernel contributors to the media >> subsystem, and some people working on userspace, in order to be sure that >> we'll match the needs required on userspace. >> >> In order to properly organize the event, I need the name of the >> developers interested on joining us, plus the themes proposed for >> discussions. >> >> As usual, we'll be using the media-works...@linuxtv.org ML for specific >> discussions about that, so the ones interested on participate are >> requested to subscribe it. > > Thank you for organizing this. I'll be in Düsseldorf the whole week for ELCE > and LPC, and I will need to attend the IOMMU microconference at LPC on Friday > the 17th in the afternoon. Apart from that I'm interested and happy to > participate in the media mini-summit. > > Regarding topics, I'm thinking about runtime reconfiguration of pipelines, but > it's a bit early to tell. I have customer demand for that, but no exact > schedule yet, so it might be too early. > > -- > Regards, > > Laurent Pinchart > > > ___ > media-workshop mailing list > media-works...@linuxtv.org > http://www.linuxtv.org/cgi-bin/mailman/listinfo/media-workshop -- Ricardo Ribalda -- 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
Re: [media-workshop] [ANNOUNCE] Linux Kernel Media mini-summit on Oct, 16-17 in Düsseldorf, Germany
Hi Mauro, On Wednesday 13 August 2014 10:14:11 Mauro Carvalho Chehab wrote: > Hi, > > As there are still too things to be discussed in order to improve media > stuff, and most of the developers nowadays are located in Europe and > usually go to ELCE, we're scheduling a two day mini-summit in Düsseldorf, > Germany, on Thrusday/Friday. > > There is a perfect opportunity to discuss the media Kernel-Userspace > API improvements that are required for newer devices to work. > So, we hope to have there the major Kernel contributors to the media > subsystem, and some people working on userspace, in order to be sure that > we'll match the needs required on userspace. > > In order to properly organize the event, I need the name of the > developers interested on joining us, plus the themes proposed for > discussions. > > As usual, we'll be using the media-works...@linuxtv.org ML for specific > discussions about that, so the ones interested on participate are > requested to subscribe it. Thank you for organizing this. I'll be in Düsseldorf the whole week for ELCE and LPC, and I will need to attend the IOMMU microconference at LPC on Friday the 17th in the afternoon. Apart from that I'm interested and happy to participate in the media mini-summit. Regarding topics, I'm thinking about runtime reconfiguration of pipelines, but it's a bit early to tell. I have customer demand for that, but no exact schedule yet, so it might be too early. -- Regards, Laurent Pinchart -- 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
