Category Archives: Farsight

GstFilters library released!

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After the various blog posts about it, and the talk I gave at the GStreamer Conference, there was a lot of interest in the GstFilters library that I’ve been working on. The original plan was for it to get merged into gst-plugins-base, however, it seems like that’s not going to happen. The GStreamer developers would prefer seeing some of its features integrated into the core, but they don’t want the library itself. So I have finally decided to release it as a standalone package so everyone interested can already start using it.

As features from GstFilters will slowly get merged into the core of GStreamer, I will adapt the library to make use of these new features, reducing its internal code. However I believe it is still very useful to have Gstfilters as it’s a very simple library for those who are not familiar with GStreamer. Also the concept of the ‘filters’ is very different from the GstElements because an element can only be added once in a pipeline but filters can be added any number of times in a pipeline (a GstFilter doesn’t represent an actual element, it’s more like a helper function for “create and link these elements for me”). Also the points I’ve made about the steep learning curve and the robustness checks will still be valid even after the Gst core makes dynamic pipeline modifications easier.

GstFilters are now released and will be hosted on freedesktop.org under Farstream’s project. While Farstream users will be the most interested in this library and it is very useful for VoIP/Farstream users, it can also be used for non VoIP applications.

On a similar note, the Farsight-Utils library and API that I presented at the GStreamer Conference has been modified to make it even simpler. The library has been renamed into Farstream-IO since it basically takes care of all the Input/Output to the Farstream conference. The new API is based on a single object now, a FsIoPipeline that you create (which is a subclass of GstPipeline) and to which you register the FsConference/FsSession/FsStream. All the methods from the previous Farsight-Utils classes (FsuConference, FsuSession and FsuStream) will stay the same but will be merged into this single FsIoPipeline class, making everything easier and you’d only need to keep track of a single object.

The FsIo API will be merged into Farstream and released for the next version.

Here is the link to the new GstFilters page : http://www.freedesktop.org/wiki/Software/GstFilters 

And you can get the release tarball from here : http://freedesktop.org/software/farstream/releases/gstfilters/

And browse its documentation here : http://www.freedesktop.org/software/farstream/apidoc/gstfilters/ 

 

GStreamer Conference 2011 videos

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The videos of the presentations given at the GStreamer Conference from last month in Prague are finally available online! So if you missed the conference, you can still catch all the interesting talks on video. Thanks to the great work of Ubicast who used a GStreamer-based system for capturing the videos and slides, and it looks awesome!

I gave a presentation in which I introduced two libraries : GstFilters and FsUtils.

Both libraries are  convenience libraries that sit on top of Gstreamer and Farstream respectively, and they should make your lives much easier. I discussed them a bit before in a blog post, but now you can see the full talk with all the details and explanation.

Here’s a link to the conference talks : http://gstconf.ubicast.tv/channels/#conferences2011 

And a link to my presentation about GstFilters and FsUtils : http://gstconf.ubicast.tv/videos/gstreamer-and-farsight/ 

 

Network emulator tool for Linux

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I have finally decided to blog about my netem tool that I wrote a couple of months ago.
First, the introductions, netem is a kernel component for controlling QoS, rate control and various network properties that allows you to emulate a network by modifying the kernel’s IP stack’s queue disciplines. You can read more about it here : http://www.linuxfoundation.org/collaborate/workgroups/networking/netem

The issue I had with the netem queue was that it was hard/complicated to use and required a fair bit of reading and understanding of how the Linux IP stack worked in order to even use it properly. I needed an easy to use tool in order to test multiple network properties quickly. I looked around for a tool that would help me with that and only found phpnetemgui which is a very old piece of code, not even compatible with the latest php versions and which requires you to run a server on localhost and give sudo access to the web server… I didn’t like that, so I wrote my own tool for easy netem configuration (thanks to the phpnetemgui code, it was helpful in providing some of the commands).

You can find my netem tool here : http://cgit.collabora.com/git/user/kakaroto/netem.git/

The README has all the information you need in order to use it, so make sure you read it, but let me summarize a bit how it works.
Netem uses a CSV file in which you can set multiple rules, each with its own set of properties (10% packet loss, 5% duplicated packets, 100ms delay with 25ms of jitter, limit bandwidth to 256Kbps, etc..). Each rule has a name and you can have multiple rules with the same name (limit bandwidth to 256Kbps for IP 1.2.3.4, and 512Kbps to IP 1.2.3.5). All these sub-rules with the same name will be considered as being a single rule. You can run netem on an interface, giving it the CSV filename and the name of the rule that you want to activate and it will output all the commands you need to execute in order to emulate the network as specified in the rules from the CSV file.

To actually run the network emulation, just pipe the output to ‘sh’, for example : ./netem eth0 my_rules.csv 256kbps | sudo sh

The reason I did this was to help my colleague Olivier Crete who was working on TFRC (Tcp-Friendly Rate Control) for RTP in Farsight. He needed to be able to emulate various network configurations, change the bandwidth limitations, introduce packet drop, etc.. and see how TFRC would react to make sure that the video/audio stream’s quality stays acceptable and the bitrate calculation adapts correctly to changing network conditions. I’ve also been recently working on HLS (HTTP Live Streaming) support in GStreamer and I’ve used the tool to make sure that the HLS stream correctly adapts to the network bandwidth and switches the bitrate/resolution correctly. This tool has been a great help in doing all these tests, so it’s time now to share it with whoever it might interest.

I’ll conclude with these example outputs for three different rules (taken from the provided test.csv in git) :

  • Limit inbound and outbound bandwidth to 1024Kbps (2 sub-rules)

kakaroto@kakaroto:~/coding/netem$ ./netem wlan0 test.csv 1024kbps
modprobe ifb
ip link set dev ifb0 up
tc qdisc del dev wlan0 ingress
tc qdisc add dev wlan0 ingress
tc filter add dev wlan0 parent ffff: protocol ip u32 match u32 0 0 flowid 1:1 action mirred egress redirect dev ifb0
tc qdisc del dev ifb0 root
tc qdisc add dev ifb0 root handle 1: prio bands 10
tc qdisc del dev wlan0 root
tc qdisc add dev wlan0 root handle 1: prio bands 10
tc qdisc add dev ifb0 parent 1:1 handle 10: htb default 1
tc class add dev ifb0 parent 10: classid 0:1 htb rate 1024kbit ceil 1024kbit burst 0 cburst 0
tc qdisc add dev wlan0 parent 1:1 handle 10: htb default 1
tc class add dev wlan0 parent 10: classid 0:1 htb rate 1024kbit ceil 1024kbit burst 0 cburst 0
tc filter add dev wlan0 protocol ip parent 1:0 prio 1 u32 match ip src 0.0.0.0/0 match ip dst 0.0.0.0/0 flowid 10:1
tc filter add dev ifb0 protocol ip parent 1:0 prio 1 u32 match ip src 0.0.0.0/0 match ip dst 0.0.0.0/0 flowid 10:1

  • A rule to add 100ms of delay with 25ms of jitter using a normal distribution with 25% of correlation

kakaroto@kakaroto:~/coding/netem$ ./netem wlan0 test.csv delay
tc qdisc del dev wlan0 root
tc qdisc add dev wlan0 root handle 1: prio bands 10
tc qdisc add dev wlan0 parent 1:1 handle 10: netem delay 100ms 25ms 25% distribution normal
tc filter add dev wlan0 protocol ip parent 1:0 prio 1 u32 match ip src 0.0.0.0/0 match ip dst 0.0.0.0/0 flowid 10:1

  • A rule that emulates various packet loss, delay, duplication, packet reordering, rate control, for both inbound and outbound connection with IP and port matching (3 sub-rules)

kakaroto@kakaroto:~/coding/netem$ ./netem wlan0 test.csv test1
modprobe ifb
ip link set dev ifb0 up
tc qdisc del dev wlan0 ingress
tc qdisc add dev wlan0 ingress
tc filter add dev wlan0 parent ffff: protocol ip u32 match u32 0 0 flowid 1:1 action mirred egress redirect dev ifb0
tc qdisc del dev ifb0 root
tc qdisc add dev ifb0 root handle 1: prio bands 10
tc qdisc del dev wlan0 root
tc qdisc add dev wlan0 root handle 1: prio bands 10
tc qdisc add dev wlan0 parent 1:1 handle 10: htb default 1
tc class add dev wlan0 parent 10: classid 0:1 htb rate 256kbit ceil 256kbit burst 0 cburst 0
tc qdisc add dev wlan0 parent 10:1 handle 11: netem loss 0.5% 25% duplicate 5% delay 100ms 50ms 25% distribution pareto reorder 1% limit 1000
tc qdisc add dev wlan0 parent 1:2 handle 20: netem loss 0.5% 50% limit 1000
tc qdisc add dev ifb0 parent 1:1 handle 10: netem loss 5% reorder 5% limit 1000
tc filter add dev wlan0 protocol ip parent 1:0 prio 1 u32 match ip dst 1.2.3.4/32 match ip dport 1234 0xffff flowid 10:1
tc filter add dev wlan0 protocol ip parent 1:0 prio 2 u32 match ip sport 4321 0xffff flowid 10:1
tc qdisc add dev wlan0 parent 1:3 handle 30: pfifo
tc filter add dev wlan0 protocol ip parent 1:0 prio 3 u32 match ip src 0.0.0.0/0 match ip dst 0.0.0.0/0 flowid 30:3
tc filter add dev ifb0 protocol ip parent 1:0 prio 1 u32 match ip src 1.2.3.4/32 match ip sport 1234 0xffff flowid 10:1
tc qdisc add dev ifb0 parent 1:2 handle 20: pfifo
tc filter add dev ifb0 protocol ip parent 1:0 prio 2 u32 match ip src 0.0.0.0/0 match ip dst 0.0.0.0/0 flowid 20:2

GStreamer: GstFilters to be (hopefully) merged into gst-plugins-base

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Today is the day of the Gstreamer Conference 2010 in Cambridge. Unfortunately, I couldn’t attend, but I thought I’d share a little something about the things I’ve done on GStreamer, as part of my work for Collabora.

If you remember my last post about Fsu, I talked about how you could use the FsuFilterManager and FsuFilter  classes to create some really cool GStreamer applications that can modify the pipeline dynamically, using a minimum amount of code and a very easy to use API. There was a lot of interest to this during last GUADEC and I decided to move the code from Farsight into Gstreamer itself. The FsuFilter* objects are independent of Farsight, and can be useful to a lot of people, so there was no reason to keep them there.

I have ported the code from Farsight into gst-plugins-base and renamed the FsuFilter* classes into GstFilter* and made it into a libgstfilters library. I opened a bug report on Gnome’s bugzilla asking for my branch to be merged into gst-plugins-base. I would appreciate it if everyone interested in this could have a look, review the code if possible, mainly review the API and try to use it. I’d like to make sure that the API is stable, feature complete and easy to use for everyone, so if you have any complaints about it, feel free to comment on the bugzilla so I can fix it and hopefully get cleaner/better code merged upstream soon!

You can find the built gtk-doc of the GstFilters library here.

Update: To clear any possible misunderstandings, the GstFilters library hasn’t been accepted yet into gst-plugins-base. So far, I’ve only opened a bug report and hopefully, after it gets reviewed, it might get accepted into -base (or not). I’d just like to get people to comment on the API and help me improve it.

Thanks.