BlackMagic Declink Card Installation

Go To:

Choose the Card from Dropdown List – on Top Right

Note: When the DecLink card is changed to another model, the driver remains the same but need to execute the BlackmagicFirmwareUpdater commands (status/update) for the Linux OS to identify it.

$cd Blackmagic_Desktop_Video_Linux_10.9a7/amd64/deb/
$dpkg -i desktopvideo_*.deb
$apt-get install libgl1-mesa-glx
$apt-get -f install 
$BlackmagicFirmwareUpdater status
$BlackmagicFirmwareUpdater update /dev/blackmagic/io0
$BlackmagicFirmwareUpdater update /dev/blackmagic/io4
$init 6
  • Prequisites:
$apt-get install libavformat-dev libswscale-dev libavresample-dev 
$apt-get install pkgconf cmake yasm libtool libx264-dev
  • Install x264:
git clone
# cd x264
# ./configure
# make
# make install
  • x265
# git clone git://
# cd x265/build
# cmake ../source
# make
# make install
  • fdk-aac
# git clone git://
# cd fdk-aac
# autoreconf -if
# ./configure
# make
# make install
  • opus
# git clone git://
# cd opus
# autoreconf -if
# ./configure
# make
# make install
  • libav
# git clone git://
# cd libav
# ./configure --enable-gpl --enable-nonfree --enable-libx264 --enable-libx265 --enable-libfdk-aac
# make -j 8 && make install
Download SDK from

Build & Install BMDCapture

# git clone git://
# cd bmdtools
# make SDK_PATH=<path where you unpacked the decklink sdk>/<Target OS>/include

Note: The SDK currently supports Linux and MacOSX. Thus the <Target OS can be either Linux or Mac.

Install BMDCapture
$cp bmdcapture bmdplay /usr/local/bincd /root/Blackmagic_Desktop_Video_Linux_10.9a7/deb/amd64/
$dpkg -i mediaexpress_3.5.3a1_amd64.deb
$apt-get install libatk1.0-0
$apt-get -f install
$dpkg -i mediaexpress_3.5.3a1_amd64.deb
Sample Command to Initiate streaming via wowza:
bmdcapture -C 0 -m 2 -A 2 -c 2  -V 4  -F nut -f pipe:1  | avconv -loglevel warning -i - -async 1 -vsync passthrough -flags +global_header -c:v libx264 -pix_fmt yuv420p -preset:v superfast -tune zerolatency -threads 0  -b:v 700k -minrate 700k -maxrate 700k -bufsize 700k   -r 30 -c:a aac -ar 48000   -strict experimental  -profile:v baseline -f flv rtmp://


Reference Links (Steps are included here)


Docker Swarm

Create a Manager Node:

$docker-machine create -d amazonec2 --swarm --amazonec2-region ap-southeast-1 --amazonec2-zone a --amazonec2-vpc-id vpc-12112 --amazonec2-ssh-keypath [SSH-PRIV-KEY-FILE] master

Note: Public Key should also be present in the same directory.

Create 2 Slave Nodes:

$docker-machine create -d amazonec2 --swarm --amazonec2-region ap-southeast-1 --amazonec2-zone a --amazonec2-vpc-id vpc-121212 --amazonec2-ssh-keypath [SSH-PRIV-KEY-FILE] slave1
$docker-machine create -d amazonec2 --swarm --amazonec2-region ap-southeast-1 --amazonec2-zone a --amazonec2-vpc-id vpc-121212 --amazonec2-ssh-keypath [SSH-PRIV-KEY-FILE] slave2

To default docker commands to Manager machine:

$docker-machine env master

Login to master and configure it as Manager node:

$docker-machine ssh master


$docker swarm init --advertise-addr [PUBLIC-IP]

To add a worker to this swarm, run the following command:

$docker swarm join \
--token SWMTKN-1-34t11111111111111111021crh0xwoktwxzwb \

To add a manager to this swarm, run ‘docker swarm join-token manager’ and follow the instructions.
Login to Slave and execute the above command to add as a worker.




NOTE: To resolve to the container based on the service name you provide, you have to create separate networking with overlay driver and use that driver for service creation(use –publish option to expose the port outside).

$docker network create --driver overlay my_net
$docker service create --replicas 2 --network my_net -p 80:80 --name web --mount type=bind,src=/etc/hostname,dst=/usr/share/nginx/html/index.html,readonly nginx
  • This will resolve the name “web” to a virtual IP inside the container but it will not be accessible outside the containers.
  • This will load Nginx containers in both master and slave.

Log into one of the containers

$apt-get udpate
$apt-get install dns-utils curl net-tools
$nslookup web

The IPs of nslookup and ifconfig are different, the IP of nslookup is Virtual IP.

This will RR between containers running on the same host only.
Status Check of Service:

$docker service ls
$docker service ps web

To scale up a service:

$docker service scale web=5

To remove the whole setup

$docker service rm web



SWARM has a built-in load balancer, why another load balancer?

SWARM does not have:

  1. SSL Termination
  2. Content Based routing
  3. Access control and authorization
  4. Rewrites and redirects.
  5. More on Nginx – Advance LB Algorithms, Multiprotocol support, Advanced logging, limits, scripting, security.
    (Native mod-security available for Nginx.)

[BLOG Incomplete]

Segmentation Fault


OS extends its physical memory by using virtual memory which is implemented using a technique called paging.
Paging is another form of swapping between HDD and Physical Memory.
If application requests a page in memory and it could find it then a Page Fault occurs.
If the address of the page requested is invalid then Invalid Page Fault occurs which causes the program to abort.

What is segmentation fault?

In operating systems that use virtual memory, every process is given the impression that it is working with large, contiguous sections of memory. In reality, each process’ memory may be dispersed across different areas of physical memory, or may have been paged out to a backup storage (typically the hard disk). When a process requests access to its memory, it is the responsibility of the operating system to map the virtual address provided by the process to the physical address where that memory is stored. The page table is where the operating system stores its mappings of virtual addresses to physical addresses.

The page table lookup may fail for two reasons. The first is if there is no translation available for that address, meaning the memory access to that virtual address is invalid. This will typically occur because of a programming error, and the operating system must take some action to deal with the problem. On modern operating systems, it will send a segmentation fault to the offending program.

The page table lookup may also fail if the page is not resident in physical memory. This will occur if the requested page has been paged out of physical memory to make room for another page. In this case the page is paged to a secondary store located on a medium such as a hard disk drive (this secondary store, or “backing store”, is often called a “swap partition” if it’s a disk partition or a swap file, “swapfile”, or “page file” if it’s a file). When this happens the page needs to be taken from disk and put back into physical memory.

Common causes segmentation fault:

The following are some typical causes of a segmentation fault:

Attempting to execute a program that does not compile correctly. Some compilers will output an executable file despite the presence of compile-time errors.

  •     Dereferencing NULL pointers
  •     Attempting to access memory the program does not have rights to (such as kernel structures in process context)
  •     Attempting to access a nonexistent memory address (outside process’s address space)
  •     Attempting to write read-only memory (such as code segment)
  •     A buffer overflow
  •     Using uninitialized pointers

When a Page Fault occurs, OS does the following:

  •     Determine the location of the data in auxiliary storage.
  •     Obtain an empty page frame in RAM to use as a container for the data.
  •     Load the requested data into the available page frame.
  •     Update the page table to show the new data.
  •     Return control to the program, transparently retrying the instruction that caused the page fault.


source : wikipedia and webopedia

To Understand IF

To Understand IF

AWS Security Token Service API Actions

AssumeRole (temp creds for upto 1hr)

Returns a set of temporary security credentials. You call this API using the credentials of an existing IAM user. This API is useful to grant AWS access to users who do not have an IAM identity (that is, to federated users). It is also useful to allow existing IAM users to access AWS resources that they don’t already have access to, such as resources in another account. For more information, see Creating Temporary Security Credentials for Delegating API Access.


Returns a set of temporary security credentials for federated users who are authenticated using a public identity provider like Login with Amazon, Facebook, or Google. This API is useful for creating mobile applications or client-based web applications that require access to AWS but where users do not have their own AWS or IAM identity. For more information, see Creating a Role to Allow AWS Access for the Mobile App.

GetFederationToken (Temp creds for upto 36hr)

Returns a set of temporary security credentials for federated users. This API differs from AssumeRole in that the default expiration period is substantially longer (up to 36 hours instead of up to 1 hour); this can help reduce the number of calls to AWS because you do not need to get new credentials as often. For more information, see Creating Temporary Security Credentials to Enable Access for Federated Users.


Returns a set of temporary security credentials to an existing IAM user. This API is useful to provide enhanced security, such as to make AWS requests when MFA is enabled for the IAM user. For more information, see Creating Temporary Security Credentials to Enable Access for IAM Users.
Information Available in Requests for Federated Users

Federated users are users who are authenticated using a system other than IAM. For example, a company might have an application for use in-house that makes calls to AWS. It might be impractical to give an IAM identity to every corporate user who uses the application. Instead, the company might use a proxy (middle-tier) application that has a single IAM identity. This proxy application first authenticates individual users using the corporate network; the proxy application then uses its IAM identity to get temporary security credentials for individual users and gives them to the user’s local copy of the corporate application. The user’s local copy of the corporate application can use these temporary credentials to call AWS.

Similarly, you might create an app for a mobile device in which the app needs to access AWS resources. In that case, you might use web identity federation, where the app authenticates the user using a well-known identity provider like Login with Amazon, Facebook, or Google. The app can then use the user’s authentication information from these providers to get temporary security credentials for accessing AWS resources.
Using Your Company’s Own Authentication System to Grant Access to AWS Resources

2.Ways to Get Temporary Security Credentials

3.Permissions in Temporary Security Credentials for Federated Users
Calls to the AssumeRole action are made using the long-term security credentials of an IAM user. The call must specify the ARN of the role to assume. The IAM user whose credentials are used to make the call must as a minimum have sts:AssumeRole permissions, and must be listed as the principal in the role that is being assumed. By default, the role being assumed determines the permissions that are granted to the temporary security credentials. The permissions of the IAM user that’s used to make the AssumeRole API have no effect on the permissions granted to the temporary security credentials that are returned by the API. Optionally, the call can include a policy that further restricts the permissions of the temporary security credentials. The resulting credentials are based on the intersection of the role’s permissions and the passed permissions. (This means that the passed permissions can never escalate the permissions defined in the role.)


How do I choose which API?

When deciding which API to use, you should consider what services are required for your use case and where you want to maintain the policies associated with your federated users.

How do you want to maintain the policies associated with your delegated users?

If you prefer to maintain permissions solely within your organization, GetFederationToken is the better choice. Since the base permissions will be derived from the IAM user making the request and you need to cover your entire delegated user base, this IAM user will require the combination of all permissions of all federated users.

If you prefer to maintain permissions within AWS, choose AssumeRole, since the base permissions for the temporary credentials will be derived from the policy on a role. Like a GetFederationToken request, you can optionally scope down permissions by attaching a policy to the request. Using this method, the IAM user credentials used by your proxy server only requires the ability to call sts:AssumeRole.


Install MySQL plugin for Newrelic in a Minute

To use this plugin, you must have:

  • a Java Runtime Environment (JRE) of 1.6 or higher
  • at least one database to monitor (MySQL 5.0 or higher)
  • a New Relic account

New Relic Platform Installer (NPI) is a simple, lightweight command line tool that helps you easily download, configure and manage New Relic Platform Plugins

Plugin for Generic Linux OS (OS = Opensuse)

LICENSE_KEY=4eeeeeeeeeeeeeeeeeeeeeeee2e bash -c "$(curl -sSL"
npi install com.newrelic.plugins.mysql.instance

Configuration File

#vim ~/newrelic-npi/plugins/com.newrelic.plugins.mysql.instance/newrelic_mysql_plugin-2.0.0/config/plugin.json


"agents": [
"name" : "Host Name on Newrelic UI",
"host" : "localhost/RDS ENpoint",
"metrics" : "status,newrelic",
"user" : "DB_USER_NAME",
"passwd" : "DB_PASSWORD"

Start Plugin:

#cd /root/newrelic-npi/plugins/com.newrelic.plugins.mysql.instance/newrelic_mysql_plugin-2.0.0
#java -Xmx128m -jar plugin.jar



GitHub =
Plugin Home Page =

Run commands in Opsworks Instances using chef recipe

Using Custom Recipes in Opsworks

MY Recipe

Create the follwoing DIR structure:

myCookbookRepo -> myCustomCookbook -> recipe -> myCustomRecipe.rb

The name “recipe” must not be changed, remaining we can give the names we like.

vim myCustomRecipe.rb

execute 'bundle install' do
cwd '/srv/www/testapp/current'

Save it.

ZIP the directory and upload to S3 Bucket.

In Opsworks, Click “Stack” , Click “Stack Settings” , Click “Edit

Paste the AWS S3 URL for and AK , PK as well.

Now Click “Run Command” and Select “Execute Recipes” from the Command drop down list and mention the following in “Recipes to execute” box

cookbook::recipe (eg. myCustomCookbook::myCustomRecipe.rb)

Click “Execute Recipes