Command Center

Monday, August 26, 2013

Name	Size	Aspect
Wide 16:9	480x270	16:9
Old TV 4:3	427x320	4:3
Wide 16:9 /16	480x272	16:9
Old TV 4:3 /16	432x320	4:3

Name	Size	Aspect
Wide 16:9	960x540	16:9
Old TV 4:3	853x640	4:3
Wide 16:9 /16	960x544	16:9
Old TV 4:3 /16	848x640	4:3

Name	Size	Aspect
Wide 16:9	1136x639	16:9
Old TV 4:3	856x640	4:3
Wide 16:9 /16	1136x640	16:9
Old TV 4:3 /16	864x640	4:3

Name	Size	Aspect
Wide 16:9	720x480	16:9
Old TV 4:3	720x480	4:3

Name	Size	Aspect
SD 4:3	640:480	4:3
HD 16:9	1280x720	16:9
Full HD	1920x1080 (1920x1072 base 16)	16:9

Name	Size	Aspect
720p	1280x720	16:9
1080p/i Anamorphic	1440x1080	16:9
1080p/i	1920x1080	16:9

Name	Standard	Fps	FFmpeg
Movies	NTSC	23.976	24000/1001
TV Video	NTSC	29.97	30000/1001
Movies	PAL	25	25
TV Video	PAL	30	30

Thursday, August 22, 2013

browser agents

Category: Webdev — SkyHi @ Thursday, August 22, 2013

Firefox

Mozilla/5.0 (Windows NT 6.1; rv:10.0.2) Gecko/20100101 Firefox/10.0.2

Chrome

Mozilla/5.0 (Windows NT 6.1) AppleWebKit/535.19 (KHTML, like Gecko) Chrome/18.0.1025.162 Safari/535.19

Safari

Mozilla/5.0 (Windows NT 6.1) AppleWebKit/534.50 (KHTML, like Gecko) Version/5.1 Safari/534.50

Opera

Opera/9.80 (Windows NT 6.1; U; en) Presto/2.9.168 Version/11.50

Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)

I'm interested to know why Mozilla/5.0 is prefixed when I echo it in IE, Safari And Chrome?

REFERENCES
http://stackoverflow.com/questions/12288452/what-does-mozilla-5-0-in-user-agent-string-signify

Sunday, August 18, 2013

yum The requested URL returned error 404

— SkyHi @ Sunday, August 18, 2013

ERROR:

[Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404"

Solution:

#yum clean all

Friday, July 26, 2013

What is this .nfs file and why can I not remove it?

Category: NFS — SkyHi @ Friday, July 26, 2013

Under linux/unix, if you remove a file that a currently running process still has open, the file isn't really removed. Once the process closes the file, the OS then removes the file handle and frees up the disk blocks. This process is complicated slightly when the file that is open and removed is on an NFS mounted filesystem. Since the process that has the file open is running on one machine (such as a workstation in your office or lab) and the files are on the file server, there has to be some way for the two machines to communicate information about this file. The way NFS does this is with the .nfsNNNN files. If you try to remove one of these file, and the file is still open, it will just reappear with a different number. So, in order to remove the file completely you must kill the process that has it open.

If you want to know what process has this file open, you can use 'lsof .nfs1234'. Note, however, this will only work on the machine where the processes that has the file open is running. So, if your process is running on one machine (eg. bobac) and you run the lsof on some other burrow machine (eg. silo or prairiedog), you won't see anything.

Here is an example that demonstrates the issue:

% echo test> foo

% tail -f foo

test

^Z

Suspended

% rm foo

% ls -A

.nfsB23D

% rm .nfsB23D

% ls -A

.nfsC23D

% lsof .nfsC23D

COMMAND  PID USER   FD   TYPE DEVICE SIZE/OFF    NODE NAME

tail    1257 robh    0r  VREG  176,6        5 3000753 .nfsC23D

%

Once you have located and killed the process that has the file open, the .nfs file will go away automatically. In the above example, when you kill the tail process, the .nfsC23D file will disappear.

REFERENCES

https://uisapp2.iu.edu/confluence-prd/pages/viewpage.action?pageId=123962105

Saturday, July 20, 2013

HOWTO: add disk to VMware Ubuntu guest without reboot using LVM

Category: Ubuntu — SkyHi @ Saturday, July 20, 2013

This howto is mostly built on the great tutorial available athttp://www.comnetslash.com/…hout-reboot/. My spot tries to be more Ubuntu and LVM specific. This manual was tested on Ubuntu 9.04 (jaunty) Server edition guest OS.

Add Virtual Hard Disk

A new hard disk can be added easily to a running virtual machine in VMWare Infrastructure Web Access by clicking Add Hardware and following the wizard.

Note: I assume that all of the commands given are run under superuser (root) rights. To become root type

sudo su root

Detect new SCSI Disk

The package scsitools provides the script rescan-scsi-bus.sh, which does exacly what we need. Install it and run it:

apt-get install scsitools
rescan-scsi-bus.sh

This should detect the newly added hard disk and make it available in /dev/ – /dev/sdb in the case you are adding a new drive for the first time. The output of fdisk -l should include the newly detected disk.

Format the new disk

Format the newly detected drive using fdisk

fdisk /dev/sdb
    n (for new partition)
    p (for primary partition)
    1 (partition number)
    (keep the other values default)
    w (write changes)

Change the type of the partition to LVM Linux:

fdisk /dev/sdb
    t (change the partition type)
    8e (for Linux LVM)
    w (write changes)

LVM

Initialize LVM Physical Volume

pvcreate /dev/sdb1

Add Physical Volume to Volume Group

List the Volume groups available at your machine.

vgdisplay

Replace VolGroupName with what you read from the output of the last command.

vgextend VolGroupName /dev/sdb1

You should see the newly aquired free space in the output of

vgdisplay

Resize Logical Volumes

After adding some free space to your Volume Group, you can distribute it to the Logical Volumes. The list of Logical Volumes can be obtained by running

lvdisplay

Run the following commands for each Logical Volume you want to resize (add space to). Again – replace /dev/VolGroupName/Namewith the Logical Volume name you can read from the output of the last command. The +10G means Add 10 GB

lvextend -L +10G /dev/VolGroupName/Name

The last step is to resize the ext3 filesystem (use different tool is you use different filesystem):

resize2fs /dev/VolGroupName/Name

REFERENCES
http://blog.stastnarodina.com/honza-en/spot/howto-add-disk-to-vmware-ubuntu-guest-without-reboot-using-lvm/

Thursday, June 20, 2013

Stop Ubuntu / Debian Linux From Deleting /tmp Files on Boot

Category: Ubuntu — SkyHi @ Thursday, June 20, 2013

Q. I know /tmp as it named is a temporary dircory, Debian policy is to clean /tmp at boot. However, I'd like to configure my Ubuntu Server to stop deleting files from /tmp on boot due to custom configuration issue. How do I configure behavior of boot scripts to stop deleting files on boot?

A. Users should not store files in /tmp, use /home or other partition, if you would like to keep the files. The behavior of boot scripts is controlled via a special configuration file called /etc/default/rcS. Open this file and modify TMPTIME variable.

On boot the files in /tmp will be deleted if their modification time is more than TMPTIME days ago. A value of 0 means that files are removed regardless of age. If you don't want the system to clean /tmp then set TMPTIME to a negative value(-1) or to the word infinite.

Configuration /etc/default/rcS

Open /etc/default/rcS file, enter:
$ sudo vi /etc/default/rcS
Set TMPTIME to 60 so that files in /tmp will deleted if their modification time is more than 60 days ago.
TMPTIME=60
Close and save the file. This configuration is used by /etc/init.d/bootclean script on boot to clean /tmp and other directories under all Debian based Linux distros.

A note about RHEL / CentOS / Fedora / Redhat Linux

Redhat and friends use /etc/cron.daily/tmpwatch cron job to clean files which haven’t been accessed for a period of time from /tmp. The default is 720 hours. If the file has not been accessed for 720 hours, the file is removed from /tmp. You can modify this script as per your requirements:

# cp /etc/cron.daily/tmpwatch /etc/cron.daily/tmpwatch.bak
# vi /etc/cron.daily/tmpwatch

REFERENCES
http://www.cyberciti.biz/faq/debian-ubuntu-removes-files-at-boot-time/

Tuesday, June 11, 2013

IP_CONNTRACK: TABLE FULL, DROPPING PACKET

Category: iptables, Kernel — SkyHi @ Tuesday, June 11, 2013

Last week, I found myself with a server under low load, but it couldn’t make or receive network connections. When I ran dmesg, I found the following line repeating over and over:

ip_conntrack: table full, dropping packet

I’d seen this message before, but I headed over to Red Hat’s site for more details. It turns out that the server was running iptables, but it was under a very heavy load and also handling a high volume of network connections. Generally, the ip_conntrack_max is set to the total MB of RAM installed multiplied by 16. However, this server had 4GB of RAM, but ip_conntrack_max was set to 65536:

# cat /proc/sys/net/ipv4/ip_conntrack_max
65536

I logged into another server with 1GB of RAM (RHES 5, 32-bit) and another with 2GB of RAM (RHES 4, 64-bit), and both had ip_conntrack_max set to 65536. I’m not sure if this is a known Red Hat issue, or if it’s just set to a standard value out of the box.

If you want to check your server’s current tracked connections, just run the following:

# cat /proc/sys/net/ipv4/netfilter/ip_conntrack_count

If you want to adjust it (as I did), just run the following as root:

# echo 131072 > /proc/sys/net/ipv4/ip_conntrack_max

REFERENCES

http://major.io/2008/01/24/ip_conntrack-table-full-dropping-packet/

default	fastfirstpass	lossless_ultrafast	lossless_slower
baseline	slowfirstpass	lossless_fast	lossless_max
normal	hq	lossless_medium	ipod320
main	max	lossless_slow	ipod640

-threads	thread count, 0 means all threads available
-y	overwrite output files
-ss	time_off set the start time offset
-t	duration record or transcode "duration" seconds of audio/video
-ildct	Interlaced

8x8dct	high
cabac+bframes	main
-level	#

Monday, August 26, 2013

Video Size and Aspect Ratios

iPhone 3 (480x320):

iPhone 4 (960x640):

iPhone 5 (1136x640):

DV NTSC Video

Youtube and Vimeo Upload

HD, Blu-Ray, AVCHD

Frame Rates

FFmpeg Encoding

X264Presets

High quality 2 Pass

iPod-iPhone 320 width

iPod-iPhone 640 width

Hight quality, 2 pass without presset

iPod-iPhone 320 width, without presset

iPod-iPhone 640 width, without presset

iPod-iPhone, 2 pass custom

DV Video

To DV

From DV To Microsoft AVI DV

Audio

AAC Stereo HQ

AAC Stereo SQ

AAC 5.1 HQ

AAC 5.1 LQ

Eac3To

AC3 5.1 Channel Mapping Fix

AAC to AC3

AC3 to AAC

Other FFmpeg Options

FFmpeg Information Sources

Download

Win32 Binary Builds

FFmpeg x264 encoding guide by Robert Swain

H.264 Profiles and Levels

Getting infos from a video file

Turn X images to a video sequence

Turn a video to X images

Encode a video sequence for the iPpod/iPhone

Encode video for the PSP

Extracting sound from a video, and save it as Mp3

Convert a wav file to Mp3

Convert .avi video to .mpg

Convert .mpg to .avi

Convert .avi to animated gif(uncompressed)

Mix a video with a sound file

Convert .avi to .flv

Convert .avi to dv

Convert .avi to mpeg for dvd players

Compress .avi to divx

Compress Ogg Theora to Mpeg dvd

Compress .avi to SVCD mpeg2

Compress .avi to VCD mpeg2

Multi-pass encoding with ffmpeg

REFERENCES