ElphelWiki - User contributions [en]

Theora

2007-05-18T13:58:04Z

Eplese: Elaborated on the causes.

The model 333 camera is able to encode and stream video in Ogg Theora in
realtime. In order to encode in Theora the older 6.3.9 firmware must be
loaded onto the camera. Due to space limitations in the FPGA, each firmware
can only support a single encoding algorithm, either MJPEG or Theora. The
6.3.x series supports Theora and the 6.4.x and 6.5.x series support MJPEG.

The 353 camera has a larger FPGA with space for both Theora and MJPEG
compressors. Porting the Theora compressor to the 353 is targeted to begin
around September 2007.

We plan to [[Design_Ideas#FPGA_Theora_Encoder_for_Videoconferencing | resume]] Ogg Theora project on the new 353 hardware - Axis ETRAX FS
is faster so it will better handle streaming (the bottleneck of the Ogg Theora
implementation in Model 333).

Combining MJPEG and Theora in the same FPGA would complicate things - my plan
is to unify the software part and the non-compressor part of the FPGA code that
now are more advanced in MJPEG branch (histograms, gamma correction,
timestamping, support of newer sensors). It will be possible to replace
FPGA code at run-time or use software (lossless) Theora->JPEG conversion with
the faster CPU. I'm also counting on native support of Theora in the browsers
(like in Opera) so we can completely switch to Theora.--[[User:Andrey.filippov|Andrey.filippov]] 11:57, 14 May 2007 (CDT)

== Web Interface ==
Once the 6.3.9 firmware is loaded and an IP address is configured, the web
interface on the camera is used to download short Theora clips for testing
and also to set the video parameters which are also used by the Theora
streamer. There are quite a few settings so it can take some time to adjust
them properly to get a good picture.

Instead of requesting the page through a browser, wget can be used to download
short Theora clips from the camera. When processing web requests the camera
will first capture the entire clip to RAM and then begin to send the clip
over the network. Requesting a Theora clip of only a single frame can be used
to quickly adjust the video parameters from a script without taking much time
to capture any video.

== Theora Streamer ==
The Theora streamer can be acquired from the SourceForge download site
and the file is Theora_str_1.0.tgz. This contains the source and compiled
binaries for the streamer (theora_str) and the receiver (theorartp-client).

For the following examples it's assumed that the streamer has an IP address of
1.2.3.4 and the receiver has an IP address of 1.2.3.5. The examples use
unicast rather than multicast for simplicity.

=== Streamer ===
This method uses HTTP to transfer the executable to the camera so a webserver
of some sort is required. In addition this is temporary and will be
completely lost when the camera is powered off.

<pre>
$ telnet 1.2.3.4
$ cd /tmp
$ wget http://webserver/theora_str
$ chmod +x theora_str
$ ./theora_str -a 1.2.3.5 -p 20000 -k 25
</pre>

This will download and run the streamer on the camera. The -p option is the
IP port and the -k is the number of interframes between intraframes
(keyframes) in the Theora stream.

=== Receiver ===
<pre>
$ theorartp-client -i 1.2.3.5 -p 20000 -f output.ogg
</pre>

=== Framerate Adjustments ===
By default the camera will stream as fast as possible which may not be
desirable. The theora_str program has a -f/--fps option that appears to
allow the framerate to be adjusted but this ends up corrupting the Theora
stream, rendering it unusable.

The maximum framerate is affected by the resolution of the frames, the
exposure time, and the sensor clock. Of these three variables, the sensor
clock is the only option that can be adjusted that won't dramatically affect
the appearance of the frames.

To adjust the sensor clock, add an sclk parameter to the URL with a value
specified in megahertz. The default and maximum sensor clock is 48 MHz.
For example, to cut the framerate approximately in half, add "&sclk=24" to the
URL.

== Outstanding Issues ==
These are issues that exist with the existing Theora streamer version 1.0:
* Frames with encoded sizes larger than around 100KB aren't transmitted. This appears to be caused by an explicit check of the frame size at line 469 of theora_str's main.c.
* An integer overflow exists in theora_str which causes streaming to halt after 45 minutes (at 5 FPS). The delta variable used in the while loop at line 454 of theora_str's main.c becomes negative and causes a very long sleep in the program.
* The -f/--fps option for theora_str doesn't work properly. The framerate must be throttled with the sclk option added to the configuration URL as mentioned above.

Theora

2007-05-18T00:44:06Z

Eplese:

The model 333 camera is able to encode and stream video in Ogg Theora in
realtime. In order to encode in Theora the older 6.3.9 firmware must be
loaded onto the camera. Due to space limitations in the FPGA, each firmware
can only support a single encoding algorithm, either MJPEG or Theora. The
6.3.x series supports Theora and the 6.4.x and 6.5.x series support MJPEG.

The 353 camera has a larger FPGA with space for both Theora and MJPEG
compressors. Porting the Theora compressor to the 353 is targeted to begin
around September 2007.

We plan to [[Design_Ideas#FPGA_Theora_Encoder_for_Videoconferencing | resume]] Ogg Theora project on the new 353 hardware - Axis ETRAX FS
is faster so it will better handle streaming (the bottleneck of the Ogg Theora
implementation in Model 333).

Combining MJPEG and Theora in the same FPGA would complicate things - my plan
is to unify the software part and the non-compressor part of the FPGA code that
now are more advanced in MJPEG branch (histograms, gamma correction,
timestamping, support of newer sensors). It will be possible to replace
FPGA code at run-time or use software (lossless) Theora->JPEG conversion with
the faster CPU. I'm also counting on native support of Theora in the browsers
(like in Opera) so we can completely switch to Theora.--[[User:Andrey.filippov|Andrey.filippov]] 11:57, 14 May 2007 (CDT)

== Web Interface ==
Once the 6.3.9 firmware is loaded and an IP address is configured, the web
interface on the camera is used to download short Theora clips for testing
and also to set the video parameters which are also used by the Theora
streamer. There are quite a few settings so it can take some time to adjust
them properly to get a good picture.

Instead of requesting the page through a browser, wget can be used to download
short Theora clips from the camera. When processing web requests the camera
will first capture the entire clip to RAM and then begin to send the clip
over the network. Requesting a Theora clip of only a single frame can be used
to quickly adjust the video parameters from a script without taking much time
to capture any video.

== Theora Streamer ==
The Theora streamer can be acquired from the SourceForge download site
and the file is Theora_str_1.0.tgz. This contains the source and compiled
binaries for the streamer (theora_str) and the receiver (theorartp-client).

For the following examples it's assumed that the streamer has an IP address of
1.2.3.4 and the receiver has an IP address of 1.2.3.5. The examples use
unicast rather than multicast for simplicity.

=== Streamer ===
This method uses HTTP to transfer the executable to the camera so a webserver
of some sort is required. In addition this is temporary and will be
completely lost when the camera is powered off.

<pre>
$ telnet 1.2.3.4
$ cd /tmp
$ wget http://webserver/theora_str
$ chmod +x theora_str
$ ./theora_str -a 1.2.3.5 -p 20000 -k 25
</pre>

This will download and run the streamer on the camera. The -p option is the
IP port and the -k is the number of interframes between intraframes
(keyframes) in the Theora stream.

=== Receiver ===
<pre>
$ theorartp-client -i 1.2.3.5 -p 20000 -f output.ogg
</pre>

=== Framerate Adjustments ===
By default the camera will stream as fast as possible which may not be
desirable. The theora_str program has a -f/--fps option that appears to
allow the framerate to be adjusted but this ends up corrupting the Theora
stream, rendering it unusable.

The maximum framerate is affected by the resolution of the frames, the
exposure time, and the sensor clock. Of these three variables, the sensor
clock is the only option that can be adjusted that won't dramatically affect
the appearance of the frames.

To adjust the sensor clock, add an sclk parameter to the URL with a value
specified in megahertz. The default and maximum sensor clock is 48 MHz.
For example, to cut the framerate approximately in half, add "&sclk=24" to the
URL.

== Outstanding Issues ==
These are issues that exist with the existing Theora streamer version 1.0:
* Frames with encoded sizes larger than around 100KB aren't transmitted (or received) properly.
* An integer overflow exists in theora_str which causes issues streaming to be interrupted after 45 minutes (at 5 FPS).
* The -f/--fps option for theora_str doesn't work properly. The framerate must be throttled with the sclk option added to the configuration URL as mentioned above.

Theora

2007-05-15T00:00:29Z

Eplese: Framerate adjustments.

Theora

2007-05-14T22:29:00Z

Eplese: Mention wget.

Theora

2007-05-14T16:09:05Z

Eplese:

Theora

2007-05-14T15:53:41Z

Eplese: