Sony's new A7s (12mp FF) why do you need a separate "recorder"to record HD and 4K video?

On 27/05/2014 11:38 a.m., RichA wrote:
I don't get it, how can the camera not record the images it is taking??

http://web.forret.com/tools/video_fp...gb444&depth=12

On 2014.05.26, 20:13 , Me wrote:
On 27/05/2014 11:38 a.m., RichA wrote:
I don't get it, how can the camera not record the images it is taking??

http://web.forret.com/tools/video_fp...gb444&depth=12

Bring it down a notch to 4:2:2 (per the dpreview article).

"The camera can read out its entire sensor fast enough to output 8-bit
4:2:2 4K video over HDMI at up to 30p, without the need for line
skipping or pixel binning."

Still - a lot of bandwidth - about 800 MB/s.

--
I was born a 1%er - I'm just more equal than the rest.

In article , Alan Browne
says...
Bring it down a notch to 4:2:2 (per the dpreview article).

"The camera can read out its entire sensor fast enough to output 8-bit
4:2:2 4K video over HDMI at up to 30p, without the need for line
skipping or pixel binning."

Still - a lot of bandwidth - about 800 MB/s.

Doesn't the camera use at least a bit of compression to bring down the
data volume?
--
Alfred Molon

Olympus E-series DSLRs and micro 4/3 forum at
http://tech.groups.yahoo.com/group/MyOlympus/
http://myolympus.org/ photo sharing site

On 2014.05.28, 18:26 , Alfred Molon wrote:
In article , Alan Browne
says...
Bring it down a notch to 4:2:2 (per the dpreview article).

"The camera can read out its entire sensor fast enough to output 8-bit
4:2:2 4K video over HDMI at up to 30p, without the need for line
skipping or pixel binning."

Still - a lot of bandwidth - about 800 MB/s.

Doesn't the camera use at least a bit of compression to bring down the
data volume?

I don't know. The above is a rough (from the linked calculator) about
how much information is produced. Compression could probably cut that
by about 20%, perhaps more.

Another issue is how fast a disk drive can take a sustained write. RAID
arrays are used to split the bandwidth (striping). Compression would
help reduce that load as well.

Redundancy would drive the disk number up (double or triple). RAID
striping increases complexity (and processing at the storage end too, I
guess).


--
I was born a 1%er - I'm just more equal than the rest.

On Wed, 28 May 2014 21:55:01 -0400, Alan Browne
wrote:
: On 2014.05.28, 18:26 , Alfred Molon wrote:
: In article , Alan Browne
: says...
: Bring it down a notch to 4:2:2 (per the dpreview article).
:
: "The camera can read out its entire sensor fast enough to output 8-bit
: 4:2:2 4K video over HDMI at up to 30p, without the need for line
: skipping or pixel binning."
:
: Still - a lot of bandwidth - about 800 MB/s.
:
: Doesn't the camera use at least a bit of compression to bring down the
: data volume?
:
: I don't know. The above is a rough (from the linked calculator) about
: how much information is produced. Compression could probably cut that
: by about 20%, perhaps more.
:
: Another issue is how fast a disk drive can take a sustained write. RAID
: arrays are used to split the bandwidth (striping). Compression would
: help reduce that load as well.
:
: Redundancy would drive the disk number up (double or triple). RAID
: striping increases complexity (and processing at the storage end too, I
: guess).

It's difficult to generalize, because there are so many accepted RAID formats.
But the most efficient layout provides single-error-correcting redundancy with
a space penalty of about 16%. The penalty in processing speed is harder to
calculate, but there will surely be one.

Bob