Jökull
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Re: Camera Interface Specs

Mon Dec 09, 2013 10:12 am

Reading these recent posts, I have the impression that one does not just need to connect the wires from an HDMI cable to the CSI port, but that you have use a chip in between (is that the TC358743, reffered to earlier in this thread? http://www.toshiba.com/taec/Catalog/Fam ... id=1779480).

I understand Eben wants you to work on many other things, but perhaps this one can be mostly "handed over" to the community if it does not require too much GPU firmware coding?

Do your current prototype require coding on the Toshiba chip? Coding in the GPU firmware?

My project would be about adding realtime augmented reality insets, like telemetry info, to a video stream coming from a quadcopter's embarked camera. A future version of the quadcopter may embark a Pi and a PiCam, but my current quadcopter has its own camera that streams over a 5.8GHz TX-radios as a component PAL/NTSC signal, that I receive at the groud station and convert to HDMI with a simple CVBS-2-HDMI cheap converter. Would I feed that HDMI stream via your convertor into the Pi's CSI, would I have access to an API that allows the realtime insertion of text and vector graphics over that stream and have it realtime streamed out to the Pi's HDMI output?

Thanks for running that interest poll, and apologize if I am raisong yet more questions rather than answering yours.

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Re: Camera Interface Specs

Mon Dec 09, 2013 5:24 pm

jamesh wrote:Recording output of video cameras.
If it was just a HDMI recorder, or video overlay generator, or network video streamer, that's useful. But since the R-Pi can also do motion detection and take actions in reponse, in combination with the other capabilities, that's another application space.

tonybarry
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Re: Camera Interface Specs

Thu Jan 02, 2014 5:14 am

Hi All,

I am very interested in this discussion.

I am part of a community which uses analog (CVBS) cameras for astronomy occultation work
http://www.asteroidoccultation.com/asteroid_help.htm
and the cameras are very low-light sensitive (quantum efficiencies around 60-70%).

Up till now, the Canon MV30 camcorder has been the staple means of recording (to miniDV tape) but the supply is pretty near dried up. Personal digital video recorders with hard drives are difficult to source, costly, and their compression methods can often be really **not** what is desired. Also prices for such recorders are high, and they frequently go out-of-production, and then it is anyone's guess as to whether the next box will do the job.

A RPi module to take CVBS or any video -in (a video-to-HDMI adapter could be used) and allow write to storage would be of great use.

The occultation community is not large (maybe 3000 people worldwide) but the need for a reliable low cost recorder is really looming in people's minds.

Please add my vote for a video-in to the RPi, for occultation recording use.

Regards,
Tony Barry

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Re: Camera Interface Specs

Thu Jan 02, 2014 9:21 am

tonybarry wrote:Hi All,

I am very interested in this discussion.

I am part of a community which uses analog (CVBS) cameras for astronomy occultation work
http://www.asteroidoccultation.com/asteroid_help.htm
and the cameras are very low-light sensitive (quantum efficiencies around 60-70%).

Up till now, the Canon MV30 camcorder has been the staple means of recording (to miniDV tape) but the supply is pretty near dried up. Personal digital video recorders with hard drives are difficult to source, costly, and their compression methods can often be really **not** what is desired. Also prices for such recorders are high, and they frequently go out-of-production, and then it is anyone's guess as to whether the next box will do the job.

A RPi module to take CVBS or any video -in (a video-to-HDMI adapter could be used) and allow write to storage would be of great use.

The occultation community is not large (maybe 3000 people worldwide) but the need for a reliable low cost recorder is really looming in people's minds.

Please add my vote for a video-in to the RPi, for occultation recording use.

Regards,
Tony Barry
Thanks - its an interesting use case!

A related question for my own interest, what level of quality do you need for the recording? Is H264 a bit too lossy? Or good enough?
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Re: Camera Interface Specs

Thu Jan 02, 2014 10:16 am

Hi James,

H.264 would probably do.

Dropped frames are more troublesome than compression for occultations. This is because occs are basically a timed event, with the star either being there or being invisible when the asteroid passes in front of it. The interesting thing is the time of disappearance and reappearance. This is the principal scientific value. A dropped frame represents a lost datum, and that is not desirable, whereas a pixel artefact gets kind of blended (averaged out) by the aperture used to measure the star's brightness and the background brightness.

Some folks also try to measure actual light output (photometry), with a view to obtaining Fresnel diffraction curves around the disappearance and reappearance times, but such efforts require Big Scopes and frankly that's not intended to be done with this gear.

Regards,
Tony Barry

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Re: Camera Interface Specs

Thu Jan 02, 2014 12:01 pm

What sort of frame rates are required?

The protoboard is good for 1080p30 H264.

What's you definition of a big scope?
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Re: Camera Interface Specs

Thu Jan 02, 2014 12:13 pm

I found their page on timing:

http://www.asteroidoccultation.com/timing.htm

Most of the material on there is about using a manual stopwatch, so any ordinary video frame rates should easily be adequate for general timings.

(Of course there might be somebody needing higher speeds for shape determination, or the mentioned diffration effects, for example.)

EDIT: also found suggested equipment
http://www.asteroidoccultation.com/SBP_OccEquip.htm
it suggests a time signal video overlaid on to the camera output, which answers the question I was going to ask about synchronising multiple observations.)

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Re: Camera Interface Specs

Thu Jan 02, 2014 12:32 pm

Hi James and Ravenous,

Frame rates are currently 720i60 (i.e field) or 720p30 (i.e.frame) of NTSC or the equivalent PAL.

Most occultations (i.e. more than 70%) are done on dim stars (magnitude > 10) which require accumulation (i.e. stacked, slower frame rates).

My definition of a big scope is anything over 10 inches diameter (250mm). Over that size and it's really getting too heavy to pick up easily, and too costly to easily afford.

Ravenous, yes the timing requirements are quite significant, and I do not know yet whether the Pi can do adequate timing as well as recording.

As a bynote, I was the designer of the IOTA-VTI video time inserter which is mentioned on the IOTA page. Royalties on the sales go to IOTA to help defray costs associated with running the association. The VTI times vSync pulses to 10^-4 second, and that kind of accuracy is considered required for the high-frame-rate recordings.

Regards,
Tony Barry

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Re: Camera Interface Specs

Thu Jan 02, 2014 12:42 pm

I'm pretty sure I could superimpose time stamps of that accuracy on the incoming video. Would require some custom SW on the GPU, but I've done similar stuff to that in the past.

What sort of price point would need to be hit for a HDMI input device (no composite) that could record up to 1080p30, and superimpose a timestamp, outputting H264 (or perhaps MP4 or MJPEG) to make this a worthwhile project?
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Re: Camera Interface Specs

Thu Jan 02, 2014 12:52 pm

jamesh wrote:What sort of frame rates are required?

The protoboard is good for 1080p30 H264.

What's you definition of a big scope?
Actually no its only good for 720P30 (two lanes only)

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Re: Camera Interface Specs

Thu Jan 02, 2014 12:53 pm

Hi James,

The standard in the occultation community is to use GPS based 1PPS signals for absolute time fidelity (referenced to UT). Other references such as NTP might be viewed as not reliable in the peculiar conditions occultation recordings frequently have to operate under (i.e. remote locations, no good network access, away from Stratum 1 NTP timeservers).

As to the price point - I shall get back to you on that one. My suspicion is that $150 would be an upper limit. But I shall advise you better when I have talked with more knowledgeable people than myself.

Regards,
Tony Barry

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Re: Camera Interface Specs

Thu Jan 02, 2014 12:59 pm

Hi Gordon,

Thank you for the post. I would be pleased to see more of your HDMI in board :-)

The low-light cameras currently in use offer field (720i60) and frame (720p30) output (i.e. standard interlaced CVBS).

Field analysis of occultations is a thorny subject, with some folks saying it is tolerable, and others saying that it can't be relied upon (as the target has to span at least two lines in each field of the image for it to be a reasonable sample of the star).

Frame analysis is much preferred by everyone.

720p30 would be very nice.

Regards,
Tony Barry

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Re: Camera Interface Specs

Thu Jan 02, 2014 1:04 pm

gsh wrote:
jamesh wrote:What sort of frame rates are required?

The protoboard is good for 1080p30 H264.

What's you definition of a big scope?
Actually no its only good for 720P30 (two lanes only)

Gordon
Ah, soz, didn't know that. Although I thought two lanes was enough for 1080p30 (it is for the camera)? Is that a limitation of the capture device?
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Re: Camera Interface Specs

Thu Jan 02, 2014 1:15 pm

Difference is camera is bayer 10 bit per pixel whereas the capture outputs 24bit RGB

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Re: Camera Interface Specs

Thu Jan 02, 2014 1:25 pm

HI folks,

If it's any help, almost all occultation cameras output monochrome. Luminance only.

Regards,
Tony Barry

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Re: Camera Interface Specs

Thu Jan 02, 2014 3:00 pm

gsh wrote:Difference is camera is bayer 10 bit per pixel whereas the capture outputs 24bit RGB

Gordon
Ahhhhhhhhh. Ta.
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Re: Camera Interface Specs

Sun Jan 05, 2014 2:31 pm

Just out of curiosity has the Pi Camera circuit diagram been made public like the Pi board itself??

Also what are power requirements for the board?? I'm assuming it uses both 3.3v and 5v given the fact that banding is a common issue for shoddy PSUs and communication with the SoC would be at 3.3v TTL

Edit: I just checked the Pi circuit diagram the S5 connection has no 5v supply rail so all power is drained from the 3.3v supply rail.

Richard S.
Last edited by redhawk on Sun Jan 05, 2014 9:38 pm, edited 3 times in total.

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Re: Camera Interface Specs

Sun Jan 05, 2014 3:58 pm

Are you talking about the camera board or the prototype HDMI capture board?

Camera board schematics I am not sure about. Certainly the HDMI in board is not public. The camera board takes about 200mA ish.
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Re: Camera Interface Specs

Sun Jan 05, 2014 5:46 pm

Actually I was talking about the Pi Camera although it’s loosely related to another post.
Someone knocked off their C1 capacitor but as far as I’m aware there’s no wiring diagram so no way of knowing the part value.
Since the Pi board already has the wiring diagram available for public consumption it would be nice to include the camera board too for referencing.

As for the HDMI capture board this sounds interesting, does this mean I could theoretically hook up a CVBS / S-Video to HDMI converter box and then capture the HDMI output at 576i 25fps or 576p 50fps??

Richard S.

dessat
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Re: Camera Interface Specs

Tue Jan 28, 2014 8:28 pm

Gordon,

Could you share info on board manufacturer? I'm really interested in this for project I'm working on.

>Yes I've got an HDMI input board a couple of them actually, unfortunately I'm not sure they're particularly useful to the general users

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Re: Camera Interface Specs

Tue Jan 28, 2014 9:58 pm

The Foundation made a few prototypes and got them working. Not sure what the plan is for sale though.

I've got one, it works well. Just appears as a camera to the system.
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dessat
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Re: Camera Interface Specs

Tue Jan 28, 2014 10:18 pm

Very cool! Could you share any specs and details?

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Re: Camera Interface Specs

Tue Jan 28, 2014 10:56 pm

dessat wrote:Very cool! Could you share any specs and details?
Afraid not, as I don't know them, except I know it worked with the output of a PC. It certainly doesn't do HDCP.
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Re: Camera Interface Specs

Tue Jan 28, 2014 11:00 pm

If the board supports HDMI to CSI does that mean HDMI audio can pass-through as well??

Richard S.

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Re: Camera Interface Specs

Wed Jan 29, 2014 6:26 am

Yes,

The drivers allow HDMI audio to make it into ALSA in the end

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