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Engineering an External Recorder
  • Are there any users on here that would be interested in collaborating with engineering an external recorder?

  • 23 Replies sorted by
  • What you mean exactly? :-)

  • To be brief, something open source and modular. I have been less then satisfied with the recorders that are coming out, and the 4k support. I imagine with the support of the bright minds here we could come up with something pretty nice, crowd fund it, and we all get pretty new External recorders for our respective Gh4 and a7s users, and what ever may come in the future.

  • I will spec up some ideas tonight and post them, if anyone wants to add on feel free.

  • Well, it does not sound serious. At least for now.

    All external recorders, except top professional models will go into oblivion in coming years, btw.

  • sounds very interesting! the recording part is still missing in the apertus project too. in contrast to high quality sensors procurement etc., there are good chances to construct very interesting niche products for this tasks by just using very common/cheap parts. interesting alternatives in this field could be very encouraging for creative minds.

    do you know the "inogeni" 4k capturing device? (http://www.dexteralabs.com/inogeni/) it looks like the most affordable 4K capturing solution coming with drivers for windows/mac/linux right now. this could be an interesting starting point for more advanced/open development.

  • Hi there all, @Vitaliy_Kiselev

    What do you mean by : "All external recorders, except top professional models will go into oblivion in coming years, btw." ?

  • @mash, that is a very interesting starting point. I was imagining something about that size. The only problem is that it is limited to an 8 bit signal at 4k... but a good starting point.

  • just did some research and a 10bit upgrade is in the works

  • Well, for sure I would love to have an external recorder that did both H264 and H265 compression, to cut down on file size, but alas I have no engineering skill to offer.

  • What do you mean by : "All external recorders, except top professional models will go into oblivion in coming years, btw." ?

    Due to cards speed rise and LSI improvements cameras could just record in all formats you want by themselves.

    Plus, you can already see cameras with USB 3.0 ports, but developers not using them properly.

  • @vitaliy

    Due to cards speed rise and LSI improvements cameras could just record in all formats you want by themselves.

    i would agree with you, if you would write "...cameras could just record in all formats they [the manufacturers] want". that's an important difference! there are often features to find, that would be simple to implement from a technical point of view, but are deliberately used to discriminate products.

    the stupid 30 min recording limitation of european DSLR cameras is a well known example for this kind of problems. sure, sooner or later someone will find a clever way to bypass this limitation for the GH4 by a simple firmware-hack, but right now (and with any new model again!) external recording looks like the only straight forward solution.

    Plus, you can already see cameras with USB 3.0 ports, but developers not using them properly.

    i agree with you: USB would open fantastic opportunities for cameras. but -- again(!) -- it doesn't look look like a strange coincidence to me, that we didn't discover on our cameras:

    • UVC access
    • access to external SSD mass storage devices in master mode
    • a more reliably network connection than WLAN

    @discomandavis

    yes -- 8bit 4:2:0 4K recording does not sound very exciting for us, watching new product presentations every day, but in fact it's about the limit you can get this days by gluing together some common HDMI RX chip (e.g. ADV7619 or ADV7612) with an USB 3.0 controller. for a little spare time project this looks challenging enough. ;) if you want to succeed, it doesn't make much sense to compete with the strongest forces in bleeding edge industrial development.

    using more advanced recording modes you would also have to look for an external UHD/4K downscale/monitoring solution. the GH4 display isn't available when you enable 10bit output. (see: http://jogara.me/category/4k/)

    look at the apertus web site for similar considerations (e.g. membership in the HDMI consortium; various HDMI troubles of FPGA development boards...). i think, they are very interested in exactly such a recording module, so it's probably the best place to find like-minded people.

  • @mash

    i would agree with you, if you would write "...cameras could just record in all formats they [the manufacturers] want". that's an important difference! there are often features to find, that would be simple to implement from a technical point of view, but are deliberately used to discriminate products.

    Fun thing that you misunderstand their intentions. Technology is not just up to it yet in mainstream. Close, but not yet.

    I can make parallels with Tablet PC discussions (yep, I owned one) and discussion about why greedy corporations won't make them small and thin. Tech was just not up to it yet.

    And Japanese corporations are masters of copy. As soon as you will see any first mainstream (not BM! :-) ) camera recording in ProRes and raw as options - you'll see it in all similar specced competition.

  • yes -- i entirely agree!

    but i think, CHDK and Magic Lantern changed a lot for many users in this respect. so it's really sad to see, that we hold much more promising cameras in our hands, but couldn't establish equivalent powerful extensions and development tools.

  • CHDK and Magic Lantern changed a lot for many users in this respect.

    They changed zero, as any other similar thing. I like that idea to get all the potential, but this idea is very old, and never worked for consumer product in the long term.

  • well -- it will not change they way big companies will play their dirty game, but it change a lot to those people using all this little hacks and workarounds. but you are right, we should not overestimate the practical outcome of all this efforts. nevertheless i would really feel happy, if only a little bit of all those creative power and ambition of previous years would be more tangible in this forum again.

  • I reckon collaborating with the apertus project would be the best way to go about this.

    Personally for me to get one, it would either have to be dirt cheap or have a monitor too with a similar level of functionality that an Atomos Shogun would give me.

  • Mitch Gross (Director of Communications Convergent-Design) yesterday posted some very interesting statements about the actual technical limits of 4K hdmi recording:

    HDMI 1.4 only supports 8 bit at these resolutions, it's HDMI 2.0 that supports 10 and 12 bit. IMHO 1.4 seems an industry stop gap, i can't see it lasting for any real professional use (even on the AV side). So i'd be a bit concerned that the O7Q+ might also be a bit of a stopgap until 2.0 is around. Of course no cameras are outputting 2.0 AFAIK and the O7Q+ is more than just an HDMI recorder.

    and later:

    I have not had a look inside, but I'm pretty sure that the Atomos Shogun is using the same HDMI receiver chip that we are using in the Odyssey7Q+. Because it is the only game in town. So our capabilities here should match. Now if it is true that Panasonic is able to get a true 10-bit signal across this in an output then if there is any way we can extract 10-bit we will make it happen. We have no reason to hold back and certainly the rest of our processing architecture can handle it -- we are 4K 10-bit over SDI right now. This is a question we are looking into and we will determine what is possible and act to get the most out of the machine. If we can't do it, it is because it cannot be done with currently available hardware.

    given this technical constraints it could be indeed easier for the GH4 to realize a standard conform 10bit recording for 4K resolution internaly on sd card than over external hdmi output.

    we'll see :)

  • I think Mitch needs to go back to school ;)

    HDMI 1.4b, Bandwidth 10.2 Gbps (gigabits per second), or 1.275 Gigabytes per second.

    Now lets do the math for say, a DCI 4k, 10 bit, 4:4:4 image.

    30(10 bits to each channel RGB) x 4096(width) x 2160(height) x 24(fps)= 6,370,099,200 (6.37 Gbps, or .79625 GBps).

    Wait a second, you mean I can get 10 bit, 4:4:4, 4k DCI out of the the GH4 HDMI? Theoretically you could get 16 bit color, 4:4:4, 4k DCI out of that HDMI.

    "Wait my GH4 can do all this, what the heck?"

    That is not what I am saying, I am saying that the bottle neck is not HDMI 1.4b.

  • @discomandavis

    Contrary to you Mitch actually make things and knows chips actual abilities. So, calm down and try to listen to ones who know stuff.

  • @Vitaliy_Kiselev, Sorry if you thought I was being hostile. But if Mitch is using a 1.4b compliant chip, then like I said, HDMI is not the issue.

    Edit: That said, I would love for someone to explain why I am wrong? If what I am saying is wrong, and 10bit isn't possible through HDMI 1.4b, then why does Atomos claim they can do it?

  • @discomandavis your calculation does not respect all the protocol overheap -- e.g. 25% for 8B10B encoding (data rate != signal rate) -- and bounding issues.

    i'm not familiar with the hdmi standardization in detail, but it's easy to get common chips/implementations for higher bit depth in 2K resolution, but not for 4k. i don't know, if it's feasible for hdmi1.4 in a non proprietary standard compliant way at all.

  • has anybody done/seen practical 10bit 4K GH4 recodings via HDMI using the BMD Ultrastudio 4K?

    this device should be able to capture at this resolution over an HDMI 1.4b port given its technical specification.

  • So the idea is make something affordable? The problem I see is that external recorders demand something better than hdmi which is not meant for cameras and is unreliable in professional shooting environments imo. SDI is the preferred interface. But if you can afford an SDI camera, you're probably not going to worry about an extra few hundred dollars for an off brand recorder. If the motives are not affordability then disregard my comment. The only recorder I've used is Oddysey and that thing is very fu#king nice.