dominant - logical 0 / actively driven to a voltage

recessive - logical 1/ passively return


왜이리 어려운 단어를 썼나 했더니

전기적으로 신호를 설계해서

0과 1이 충돌되면 0이 우세(우성)하게 판결되어 1을 씹어먹는다.

그래서 0 이 우선권을 가지고 데이터를 전송하여 "실시간 전송" 성격에 적합하다는 말씀(?)


CAN data transmission uses a lossless bit-wise arbitration method of contention resolution. This arbitration method requires all nodes on the CAN network to be synchronized to sample every bit on the CAN network at the same time. This is why some call CAN synchronous. Unfortunately the term synchronous is imprecise since the data is transmitted without a clock signal in an asynchronous format.
The CAN specifications use the terms "dominant" bits and "recessive" bits where dominant is a logical 0 (actively driven to a voltage by the transmitter) and recessive is a logical 1 (passively returned to a voltage by a resistor). The idle state is represented by the recessive level (Logical 1). If one node transmits a dominant bit and another node transmits a recessive bit then there is a collision and the dominant bit "wins". The means there is no delay to the higher priority message, and the node transmitting the lower priority message automatically attempts to re-transmit six bit clocks after the end of the dominant message. This makes CAN very suitable as a real time prioritized communications system.

[링크 : http://en.wikipedia.org/wiki/CAN_bus#Data_transmission]


dominant / 우성의

[링크 : http://endic.naver.com/enkrEntry.nhn?sLn=kr&entryId=7371ab1c34a84fab8bc699af491763d4&query=dominant]


recessive / 열성의

[링크 : http://endic.naver.com/enkrEntry.nhn?sLn=kr&entryId=087f00309f264a60ab6d787e5792a02a&query=recessive]

'이론 관련 > 네트워크 관련' 카테고리의 다른 글

i2c ...  (0) 2016.05.03
Gigabit / Terabit Ethernet  (0) 2015.05.18
FEC - Forwarding equivalence class  (0) 2015.01.09
CIDR - Classless Inter-Domain Routing  (0) 2013.08.07
802.11n 108Mbps 150Mbps  (0) 2012.12.22
Posted by 구차니

SBR은 aacPlus/aacp/aac+ 를 위한 코덱이다.

mpeg-2 aac 에서 aacplus가 나오고

mpeg-4 HE-AAC는 그럼.. 어디서 나온 놈이지? -_-


 A Swedish company Coding Technologies (acquired by Dolby in 2007) developed and pioneered the use of SBR in its MPEG-2 AAC derived codec called aacPlus, which first appeared in 2001. This codec was submitted to MPEG and formed the basis of MPEG-4 High-Efficiency AAC (HE-AAC), standardized in 2003. Coding Technologies' SBR method has been used with WMA 10 Professional to create WMA 10 Pro LBR, and with MP3 to create mp3PRO.


[링크 : http://en.wikipedia.org/wiki/Spectral_band_replication]


2003년 이후부터 SBR이 MPEG-4 HE-AAC에 포함 되었다 라고 해야하려나?


[링크 : http://en.wikipedia.org/wiki/High-Efficiency_Advanced_Audio_Coding]

[링크 : https://software.intel.com/en-us/node/503067]


라이센스 문제가 있는거 같은데..

[링크 : https://code.google.com/p/aacplayer-android/]


일단 규모에 따라 다르지만 $1000 이나 $15000 달러 정도는 필요할 것으로 보인다.

[링크 : http://www.vialicensing.kr/licensing/aac-faq.aspx]

'이론 관련 > 컴퓨터 관련' 카테고리의 다른 글

IrDA  (0) 2015.04.01
MPEG4 HE-AAC 관련  (0) 2015.01.29
ntp / ptp  (0) 2014.11.26
네트워크 지연시간 설정 및 측정  (0) 2014.11.26
동기 비동기  (0) 2014.11.26
Posted by 구차니

예전에 본거 같긴한데..

한 기억은 없네? ㅋㅋ



Posted by 구차니
Linux API2015. 1. 22. 19:55

크게 제한은 없다.

단, 메모리의 영향을 받기 때문에 메모리가 적을수록 쓰레드의 숫자도 적어질수 밖에 없다.



cat /proc/sys/kernel/threads-max


number of threads = total virtual memory / (stack size*1024*1024)

Total Virtual Memory: ulimit -v (default is unlimited, thus you need to increase swap memory to increase this)

Total Stack Size: ulimit -s (default is 8Mb)


[링크 : http://stackoverflow.com/questions/344203/maximum-number-of-threads-per-process-in-linux]

'Linux API' 카테고리의 다른 글

lirc - linux IR Remote control  (0) 2015.03.31
vaapi vdpau uvd  (6) 2015.03.26
getopt() / getopt_long()  (0) 2014.11.19
공유메모리  (0) 2014.09.02
timeval, gettimeofday()  (0) 2013.08.20
Posted by 구차니
Linux API/network2015. 1. 22. 19:49


TCP Connection

UDP Connectionless


그래서 UDP는

socket()

bind()

recvfrom()

sendto()

close()

----

socket()

gethostbyname()

sento()

recvfrom()

close()

로 진행되고


TCP는

socket()

bind()

listen()

accept()

select()

recv()

send()

close()

----

socket()

gethostbyname()

connect()

sen()

recv()

close()

로 진행된다.


[링크 : http://www-01.ibm.com/support/knowledgecenter/ssw_ibm_i_71/rzab6/connectionor.htm] TCP

[링크 : http://www-01.ibm.com/support/knowledgecenter/ssw_ibm_i_71/rzab6/connectionless.htm] UDP


소켓은

32K 정도는 열수 있을 듯.

[링크 : http://stackoverflow.com/questions/3430474/max-number-of-socket-on-linux]


recvfrom

[링크 : http://forum.falinux.com/zbxe/index.php?document_srl=441147&mid=C_LIB]


'Linux API > network' 카테고리의 다른 글

리눅스 TCP 소켓  (0) 2019.05.24
linux udp cpp example  (0) 2019.05.16
멀티캐스트 되는지 여부 확인  (0) 2014.11.21
net tools 소스코드  (0) 2011.11.07
INADDR_ANY/INADDR_BROADCAST/INADDR_NONE 매크로  (0) 2011.09.29
Posted by 구차니
Linux2015. 1. 22. 13:25

ntp의 목록 회람(?)기능으로 엄청난 udp 패킷을 생성시켜 DDoS로 사용되는 기능

물론 원래 그러라고 만든게 아니다~


[링크 : http://www.dailysecu.com/news_view.php?article_id=6121]

'Linux' 카테고리의 다른 글

LD_SHOW_AUXV  (0) 2015.02.10
cpu 활성화 기능 확인하기  (0) 2015.02.06
top manpage  (0) 2014.12.30
스크립트 상대경로를 절대경로로 변환하기  (0) 2014.12.30
lightdm 실행하지 않도록 하기  (0) 2014.12.24
Posted by 구차니
Programming/qt2015. 1. 21. 22:12

... 맨날 조사만 하네..


./configure -release -opengl es2 -device linux-rasp-pi-g++ -device-option CROSS_COMPILE=$TOOLCHAIN/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf- -sysroot $ROOTFS -prefix /usr/local/qt5


./configure -platform linux-clang

./configure -platform linux-g++

./configure -platform linux-g++-32


[링크 : http://doc.qt.io/qt-5/configure-options.html]


Embedded Platforms


You can develop with Qt for the following embedded platforms:


Embedded Android

Embedded Linux

Windows Embedded (Compact and Standard)

Real-Time Operating Systems, such as QNX, VxWorks and INTEGRITY


[링크 : http://doc.qt.io/qt-5/supported-platforms.html]


./configure -release -opengl es2 -device linux-rasp-pi-g++ -device-option CROSS_COMPILE=$TOOLCHAIN/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf- -sysroot $ROOTFS -prefix /usr/local/qt5


LinuxFB

This plugin writes directly to the framebuffer. Only software-rendered content is supported. Note that on some setups the display performance is expected to be limited.

The linuxfb plugin allows specifying additional settings by passing them in the QT_QPA_PLATFORM environment variable or -platform command-line option. For example, QT_QPA_PLATFORM=linuxfb:fb=/dev/fb1 specifies that the framebuffer device /dev/fb1 should be used instead of the default fb0. Multiple settings can be specfified by separating them with a colon.


Input

When no windowing system is present, the mouse, keyboard and touch input are read directly via evdev or using helper libraries like tslib. Note that this requires that devices nodes /dev/input/event* are readable by the user. eglfs has all the evdev input handling code built-in, while linuxfb relies on the traditional and somewhat limited -plugin command-line parameters.


Input on linuxfb

To enable keyboard, mouse, touch or tablet support with linuxfb, pass QT_QPA_GENERIC_PLUGINS=evdevkeyboard,evdevmouse,evdevtouch,... in the environment or, alternatively, -plugin evdevkeyboard, -plugin evdevmouse, -plugin evdevtouch, or -plugin evdevtablet on the command-line. Most of these can take a device node parameter, for example QT_QPA_GENERIC_PLUGINS=evdevmouse:/dev/event1, in case the Qt's automatic device discovery (based either on libudev or a walkthrough of /dev/input/event*) is not functional or misbehaving.


[링크 : http://doc.qt.io/qt-5/embedded-linux.html]


'Programming > qt' 카테고리의 다른 글

qt framebuffer에 출력하기  (0) 2021.02.09
qt - ts / qm  (0) 2015.02.24
qt 4.x/5.x INSTALL_PATH  (0) 2015.01.20
qt font path  (0) 2015.01.20
qt websocket support  (0) 2015.01.20
Posted by 구차니
프로그램 사용/winscp2015. 1. 20. 16:32

엄밀하게는 로컬로 받아서 다시 넣는것이긴 한데

그래도 아주 불편한건 아니라 쓸만해 보인다.





걍 scp -r 으로 바로 넣는게 나을지도 모르겠지만..

busybox는 -r을 지원하지 않는다 -_-


-r' Recursively copy entire directories. Note that scp follows symbolic links encountered in the tree traversal.

[링크 : http://linux.die.net/man/1/scp] 


'프로그램 사용 > winscp' 카테고리의 다른 글

winscp 암호화 변경  (0) 2016.02.03
winscp sftp 접속불가 문제  (0) 2013.02.09
winscp - passive/active mode  (0) 2012.04.28
winscp UTF-8 한글 적용하기  (2) 2012.01.16
winscp - 한글 사용에 주의하세요  (0) 2009.09.12
Posted by 구차니
Programming/qt2015. 1. 20. 10:42



Usually, to cross-compile autotools-based packages, one do:

./configure --prefix=/usr --host=arm-linux-gnueabi

make

make DESTDIR=/embedded/target install

make DESTDIR=/embedded/staging install


You typically install things twice because in /embedded/target you want

to have only the files useful for execution, completely stripped, while

in /embedded/staging you want to keep all debugging symbols to help in

debugging. /embedded/target goes in your target embedded system,

while /embedded/staging is kept on your development machine, and is

used to build more applications and to do remote debugging.


Within Qt5, this could be translated as:


./configure -prefix /usr -device <something>

make

make INSTALL_ROOT=/embedded/target install

make INSTALL_ROOT=/embedded/staging install


But Qt5 has host utilities, not only tools for the target. And instead

of having to build Qt twice, it nicely allows to do the build of host

tools and target libraries in just one build, which is really nice. So,

one typically does:


./configure -prefix /usr -hostprefix /embedded/host -device <something>

make

make INSTALL_ROOT=/embedded/target install

make INSTALL_ROOT=/embedded/staging install


Unfortunately, the INSTALL_ROOT does not only impact target libraries,

but also the host utilities. So they end up

in /embedded/target/embedded/host which obviously isn't correct.


For the moment, I am solving this by doing:


./configure -prefix /usr -hostprefix /embedded/host -sysroot /embedded/staging -device <something>

make

make install


[링크 : http://lists.qt-project.org/pipermail/interest/2013-January/005447.html] 


4.7 에서 hostprefix로는 안되었고

make INSTALL_ROOT install을 통해서 했다는 건데..

-hostprefix, but it doesn't work like I hoped. With "make install INSTALL_ROOT=..." it will install everything even the host tools under this install root


[링크 : http://www.qtcentre.org/.../30449-How-to-build-and-install-Qt-apps-on-cross-compiled-embedded-targets] 

'Programming > qt' 카테고리의 다른 글

qt - ts / qm  (0) 2015.02.24
qt 5.3 cross compile 조사  (0) 2015.01.21
qt font path  (0) 2015.01.20
qt websocket support  (0) 2015.01.20
xquery / qt  (0) 2015.01.19
Posted by 구차니
Programming/qt2015. 1. 20. 10:32

크로스 컴파일로 하는 바람에

prefix를 잘못 붙여서 QT에서 rootfs 경로 포함하여 찾는 바람에 헤매는데..

configure 옵션을 조금더 찾아 봐야 편하게 쓸 수 있을듯..



아무튼 환경변수는 QT_QWS_FONTDIR 로 정해줄수 있으며

:를 이용해 여러개의 디렉토리를 지정해 줄 수 는 없다.


export QT_QWS_FONTDIR=/usr/local/Qt/lib/fonts

[링크 : http://qt-project.org/forums/viewthread/30575]

'Programming > qt' 카테고리의 다른 글

qt 5.3 cross compile 조사  (0) 2015.01.21
qt 4.x/5.x INSTALL_PATH  (0) 2015.01.20
qt websocket support  (0) 2015.01.20
xquery / qt  (0) 2015.01.19
qt 4.8.5 neon / cross compile  (0) 2015.01.15
Posted by 구차니