Pocket internal recording vs. recording HDMI output

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Steve Holmlund

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Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 4:09 am

Sorry, I searched as best I could to see if this was already addressed. I understand from an earlier thread that Raw is not the same as uncompressed video (i.e. via HDMI).

But I am wondering: Is there any difference between recording ProRes HQ internally on a BMPCC and taking the HDMI output from the BMPCC and recording ProRes HQ on a Hyperdeck Shuttle 2?

Just trying to understand the technology, specifically what happens between the sensor and HDMI output. I saw this topic referred to on another forum but the members here appear to have more in-depth technical knowledge and also appear to suffer fools with greater patience.

Thanks.
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Kingsley Paul

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Re: Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 4:31 am

The HDMI output on BMPCC is a 10 bit 4:2:2 SDI signal which is different from the 12 bit RAW recorded directly to the SD card.
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John Brawley

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Re: Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 4:33 am

Steve Holmlund wrote:Sorry, I searched as best I could to see if this was already addressed. I understand from an earlier thread that Raw is not the same as uncompressed video (i.e. via HDMI).

But I am wondering: Is there any difference between recording ProRes HQ internally on a BMPCC and taking the HDMI output from the BMPCC and recording ProRes HQ on a Hyperdeck Shuttle 2?

Just trying to understand the technology, specifically what happens between the sensor and HDMI output. I saw this topic referred to on another forum but the members here appear to have more in-depth technical knowledge and also appear to suffer fools with greater patience.

Thanks.



The really quick and short answer is there shouldn't be any difference between the internal ProRes and the recorded via HDMI ProRes recorded by a shuttle. It's the same stream.

jb
John Brawley
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Howard L Hughes

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Re: Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 6:46 am

Do you think they will make an external recorder that can record the RAW to a SSD or even this new SSHD Drives.
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John Brawley

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Re: Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 7:42 am

Howard Hughes wrote:Do you think they will make an external recorder that can record the RAW to a SSD or even this new SSHD Drives.


There isn't anyway to get RAW out of the camera so I would think not.

jb
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Mac Jaeger

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Re: Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 8:12 am

Howard Hughes wrote:Do you think they will make an external recorder that can record the RAW to a SSD or even this new SSHD Drives.

I think "they" won't make anything new, but wait for sdxc-uhs1-cards to get larger, faster & cheaper. Right now 64 gb is the largest card to record raw to; technically sdxc-uhs1 ends at 2TB.
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Kingsley Paul

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Re: Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 8:21 am

Mac Jaeger wrote:
Howard Hughes wrote:Do you think they will make an external recorder that can record the RAW to a SSD or even this new SSHD Drives.

I think "they" won't make anything new, but wait for sdxc-uhs1-cards to get larger, faster & cheaper. Right now 64 gb is the largest card to record raw to; technically sdxc-uhs1 ends at 2TB.


Are you sure that BMPCC will support UHS-1 as it is a relatively new specification?? Even BMD has failed to clarify on this issue. At a time when we are witnessing the evolution of UHS-II, Its high time BMD sets the record straight on this.
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Ryan Jones

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Re: Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 11:50 am

satyablack wrote:Are you sure that BMPCC will support UHS-1 as it is a relatively new specification?? Even BMD has failed to clarify on this issue. At a time when we are witnessing the evolution of UHS-II, Its high time BMD sets the record straight on this.

All the approved cards are UHS-I. We're still waiting on confirmation if UHS-II will be supported.
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Mac Jaeger

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Re: Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 12:35 pm

satyablack wrote:Are you sure that BMPCC will support UHS-1 as it is a relatively new specification?

I am sure, as otherwise the camera would not be able to record compressed raw in the future. But no, i have no official quote to support my statement.
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Steve Holmlund

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Re: Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 3:04 pm

Thanks for the quick responses. I thought on another thread someone was looking for DNxHD out of the Pocket and it appears you get this via HDMI with the HyperDeck Shuttle 2 (HDS2). Not an ideal solution obviously and perhaps there would be compromises compared to an internal recording? And I wonder how recording uncompressed out of the Pocket to an HDS2 will compare to ProRes HQ. It seems like uncompressed is "halfway" between RAW and ProRes HQ? I guess at the very least it lets you benchmark how good ProRes HQ is.

EOSHD had a nice article on the BMCC vs. HDMI out of a Nikon 5200. I think the camera folks don't give a lot of info on what comes out of the HDMI port. Supposedly the Nikon 5200 is "Clean HDMI" but is it 1080i, for example?

I looked at the SDI and HDMI specs but I'm not an engineer and can't tell if RAW output is theoretically possible over these interfaces.
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Mac Jaeger

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Re: Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 4:54 pm

As i understand, the data is processed in three stages:

1. analog signal gets converted into 12 bit digital raw data in the sensor
2. 12 bit raw data is debayered and transformed into 10 bit uncompressed true color data
3. 10 bit true color data is compressed to ProResHQ

In Camera you can either record the data after stage 1 (=> raw recording) or stage 3 (=> ProRes recording). At the HDMI port you can grab the data after stage 2; if you use an external ProResHQ recorder you should then get almost the same resultes as after stage 3; if you use an external DNxHD recorder you should get the same quality, but maybe a little different kind of compression aliasing; if you use an external "raw" recorder you _don't_ get the same kind of data as after stage 1 !
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Steve Holmlund

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Re: Pocket internal recording vs. recording HDMI output

PostSat Aug 10, 2013 6:26 pm

Mac, thanks for the very clear response.
Steve
Steve Holmlund
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BMPCC, vintage Rokkor lenses, Olympus 12-40, Panasonic 100-300 II
i7 8700k / GTX 1080

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