[Elphel-support] General questions about Elphel cameras

[Andrey Filippov]

Hi Aleks,


> As far as I understand is the Imgsrv a program which sends 'snapshots'
> from the current picture, no streaming, right.
>

Yes, you are right. It is "image server", standalone web server that is
designed to send out images from the camera internal circular buffer, it is
not designed for streaming (not counting the multipart JPEG option).  The
goal of this program is to minimize copying and use minimal CPU resources
while sending out images at the highest possible speed.


> Do you know about the russian fast webserver nginx, he have similar
> features as lighty but looks more stable?
>

No, I never used this web server, but I do not see any reasons to abandon
lighttpd - it does its job nicely in the camera, the speed is limited by the
100 mbps network, supports FastCGI and we did not have any stability
problems. So even if the other server is better I think it will not justify
spending our limited resources to get some 3% of performance increase.


>
> http://www3.elphel.com/importwiki?title=Camogm
>
> Is there a possibility to get the streams to the network, maybe I missed
> something on this site?
>

This program goal is to record video to the mass storage device (CF card,
internal 1.8" IDE HDD,  extrenal SATA HDD) connected directly to the camera,
in that case the 353 camera is capable of recording at average data rate of
16MB/sec (limited by the CPU), it is 50+% more than possible over the 100
mbps network.  Camogm can record over the network (i.e. using nfs share) but
in that case the data rate will be obviously lower.  RTSP/RTP streamer in
the camera is a separate program.


> In the current video surveillance market the MPEG4 2 & Mpeg4 10 (H.264)
> format comes more and more common.
>

Yes, we are aware of it. The focus of Elphel cameras is providing highest
image quality with low latency, we do not plan H.264 implementation


> Depend on the vendor the streams are send over UDP RTP/RTSP or HTTP/TCP is
> it possible to get such stream from elphel cameras instead the current
> supported one:
>
ogm - MJPEG video in Xiph Ogg container
> jpeg - series of the individual JPEG files (1 file per frame) mov - MJPEG
> video in Apple QuickTime(R) container
>

Please see above - camera has tcp/udp unicast/multicast streamer, separate
from camogm. But it streams MJPEG (including JP4), not the H.264

I know that the MPEG4 format need to be licensed, maybe there is a 'open
> source' license from the MPEGroup.
>

There are multiple open source MPEG implementations, but that does not let
you to bypass MPEG licensing. That licensing is based on patents, not
copyright.

>
> I have seen the follwing link to get JP4 Stream from elphel
>
> http://wiki.elphel.com/index.php?title=JP4#GStreamer_plugins_for_Elphel_JP4_image_and_video_processing.C2.A0
> please can you help me to get a ogm or mov stream from the camera.
>
> When streaming, the camera provides RTSP/RTP stream, not not mov or ogm
(these files are using when recording, not streaming video). Bare RTP is
insufficient fro streaming MJPEG data  as it does not support more than
2040x2040 pixels - less than the sesnor resolution. RTSP (with live555
library) support larger frames.

Andrey
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