[Elphel-support] Viewfinder / preview considerations

Tue Nov 9 01:43:29 PST 2010

On Mon, Nov 8, 2010 at 23:54, François Demange
<francois.demange at ubicast.eu> wrote:
> Hi all,
> I confirm we used a 40ms, 25 fps setting w/ JP4.
>
> I am rather new to the elphel and development worlds, and I hope you
>
> Basically, we are trying achieve the highest possible horizontal
> resolution for custom pan and scan within the frame, while keeping a
> decent frame rate.
> Since we're going to run some detection within the frame, the pan and
> scan cannot be done dynamically within the sensor, which would have
> yielded better results...
>
> In any case, i truly believe pushing the sensor's limits that way
> could be of interest to fiction guys looking for a cheap way to make
> special effects, like post production panning, judder correction and
> what not.
>
> On another subject, the dual stream LAN/SATA is an interesting
> feature, if one could dump both, the downsampled stream could be used
> for a quick edit and conform job within an NLE system.
> Such proxying features are done internally by some hard drives such as
> the firestore line from Focus Enhancements, which also enables live
> logging of clips through a web interface over wifi, and that gets
> really handy when on set !
>
> Exactly how much hardware/software hacking would be required for us to
> get the camera to dump to SATA ? Wouldn't that be be more expensive
> than just to buy a new sample ?

http://www3.elphel.com/price_list
10369 	IO board: CF/IDE/SATA, RS232, GPIO, ... 	$500

Replacing the board inside the enclosure is easily possible on your
own if you are careful.

No software hacking is required to do that, its a quite comon standard feature.

Regards Sebastian

>
>
>
> 2010/11/8, Alexandre Poltorak <alexandre at elphel.com>:
>> Hi guys,
>>
>> This is an interesting discussion and it would be nice to CC this kind of
>> stuff to Elphel's ML...  many not cinema related customers may benefit from
>> better JP4 support.
>>
>> First about NFS, camogm support QoS for IDE/SATA/CF over network stream, but
>> of course it is not possible with NFS.
>>
>> Ubicast have a very old dev version of NC353L with 10349 board. It was my
>> dev camera for a while. To replace it by 10369 it also need a new camera
>> case and some hacking to fix everything since it was not the latest 10353
>> release. If we take the last camera case, probably we will also have to
>> change the metal parts of the sensor front-end. 1,8" ZIF HDD scotched to the
>> camera case can do the job for testing with what you already have, but it
>> may require some manual hacking as the 10349 board is not released /
>> supported and so not auto-detected / configured.
>>
>> VLC, GStreamer and MPlayer all support live stream with as small as possible
>> latency. Gstreamer's rtspsrc have latency parameter.
>> gst-launch rtspsrc location=rtsp://192.168.0.9:554 latency=20 ...
>>
>> Flowty: 40ms is 25 FPS ;) and it must be JP4 mode as Sebastian suggested.
>>
>> Best regards,
>> Alexandre
>>
>> On Mon, Nov 8, 2010 at 9:26 PM, Cinema Project | Sebastian Pichelhofer <
>> cinema at elphel.com> wrote:
>>
>>> On Mon, Nov 8, 2010 at 21:15, Florent Thiery <florent.thiery at ubicast.eu>
>>> wrote:
>>> > Hello,
>>> >
>>> >> So far I had no time to test video streaming from the camera though,
>>> >> also since it is based on an ARM CPU I need cross compiled software
>>> >> all the time which for me is a certain barrier.
>>> >
>>> > Well, openembedded/Angström works with the TouchBook out of the box so i
>>> > guess this is possible with reasonably low effort.
>>>
>>> I will give it another try once I got my replacement battery pack :)
>>>
>>> >>
>>> >> In ElphelVision I recently switched from mplayer to VLC because you
>>> >> can get very low latency with VLC (almost realtime) that simply was
>>> >> not possible with mplayer or gstreamer before.
>>> >
>>> > Really ? Did you play with rtspsrc's latency property (e.g. to 30) ? You
>>> can
>>> > get very very low latency on gstreamer, at least from our tests it's
>>> very,
>>> > very fast.
>>>
>>> TBH I can't remember what exactly I did try and what the improvements
>>> or troubles were but I know that I am very happy with VLC now ;)
>>>
>>> Latency depends on datarate but can be as low as 20ms which is already
>>> pretty much the lowest you can go considering monitor refresh rates.
>>>
>>> >
>>> >>
>>> >> Did you make sure that exposure time was short enough to allow 30 fps?
>>> >
>>> > Are you referring to the variable on the Automatic Exposure Daemon max
>>> > exposure (which in JP46 i cannot change) or to the first parameter in
>>> > the
>>> > home control interface (along with RGB etc...) ? We set it to 40, maybe
>>> not
>>> > 33 i'll double check.
>>>
>>> I would just turn off autoexposure and set it manually, unless you
>>> need auto brightness for your application....
>>>
>>>
>>>
>>> >
>>> >>
>>> >> In camvc the correct option is "jp4" (option 5)
>>> >> JP46 (option 3) does not have the performance gain.
>>> >
>>> > Thanks
>>> >>
>>> >> If you have the 10369 board you should have both SATA and USB, USB is
>>> >> 1.1 correct so connecting an USB-HDD is really not an option I am
>>> >> afraid.
>>> >
>>> > I have an ooold 353 donated by Elphel (thanks elphel!) with a serial
>>> > port
>>> > and usb, i guess this is an older board revision...
>>>
>>> I see, well then you are already using all possible options, unless
>>> you want to purchase a newer 10369 replacement board (~500$)
>>>
>>> >>
>>> >> NFS should work fine, though you need to set that up manually over the
>>> >> commandline.
>>> >
>>> > I'm just afraid of the conflict between live stream grabbing and nfs
>>>
>>> well yes bandwidth will definitely become an issue here. so dumping
>>> the stream with the software that displays it (gstreamer, etc.) might
>>> be the better option.
>>>
>>> > writes...
>>> > Cheers
>>> > Florent
>>>
>>
>
> --
> Envoyé avec mon mobile
>