I need to detect VP8 Key Frame in RTP packet. I know how to remove RTP header and get the payload.
Does it have a specific signature/header?
There is an RFC for VP8 which explains how to do detect if a frame is a key frame. See section 19.1.
| Frame Tag | Type |
| ------------------------------------------------- | ----- |
| frame_tag | f(24) |
| if (key_frame) { | |
| start_code | f(24) |
| horizontal_size_code | f(16) |
| vertical_size_code | f(16) |
| } | |
The 3-byte frame tag can be parsed as follows:
---- Begin code block --------------------------------------
unsigned char *c = pbi->source;
unsigned int tmp;
tmp = (c[2] << 16) | (c[1] << 8) | c[0];
key_frame = tmp & 0x1;
version = (tmp >> 1) & 0x7;
show_frame = (tmp >> 4) & 0x1;
first_part_size = (tmp >> 5) & 0x7FFFF;
---- End code block ----------------------------------------
Related
When I use Function_graph to trace the do_sys_open () function, I find it doesn't work.
Linux version 4.4.194
echo function_graph > current_tracer
echo do_sys_open > set_graph_function
echo 1 > tracing_on
cat trace
root#firefly:/sys/kernel/debug/tracing# cat set_ftrace_filter | grep do_sys_open
do_sys_open
root#firefly:/sys/kernel/debug/tracing# cat trace
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |
1) 0.583 us | } /* cpu_needs_another_gp */
1) 0.583 us | rcu_all_qs();
1) + 29.750 us | } /* rcu_check_callbacks */
1) | scheduler_tick() {
1) | _raw_spin_lock() {
1) 0.583 us | do_raw_spin_lock();
1) 5.833 us | }
1) 0.875 us | update_rq_clock();
1) | task_tick_fair() {
1) | update_curr() {
1) 0.583 us | update_min_vruntime();
1) 0.875 us | cpuacct_charge();
1) + 11.375 us | }
1) 0.583 us | cpufreq_scale_freq_capacity();
1) | scale_cpu_capacity() {
1) 0.583 us | cpufreq_scale_max_freq_capacity();
1) 5.541 us | }
1) 0.583 us | __compute_runnable_contrib();
1) 0.583 us | cpufreq_scale_freq_capacity();
1) | scale_cpu_capacity() {
1) 0.291 us | cpufreq_scale_max_freq_capacity();
1) 5.542 us | }
1) 0.583 us | update_cfs_shares();
1) 0.583 us | hrtimer_active();
1) | sched_slice.isra.8() {
1) 0.584 us | __calc_delta();
1) 5.833 us | }
1) 0.583 us | __cpu_overutilized.constprop.22();
It seems that it outputs all the tracking functions.
Function_graph and function tracker are found to be ineffective on the ARM64 development board of Linux version 4.4.194.
After echo do_sys_open > set_graph_function, all functions will still be tracked.
But it is effective in Linux version 5.4.0-135 Ubuntu 18.04. I wonder if it's the kernel version.
It's well-documented how to use ftrace to find the function graph starting from a certain function, e.g.
# echo nop > current_tracer
# echo 100 > max_graph_depth
# echo ksys_dup3 > set_graph_function
# echo function_graph > current_tracer
# cat trace
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |
7) | ksys_dup3() {
7) 0.533 us | expand_files();
7) | do_dup2() {
7) | filp_close() {
7) 0.405 us | dnotify_flush();
7) 0.459 us | locks_remove_posix();
7) | fput() {
7) | fput_many() {
7) | task_work_add() {
7) 0.533 us | kick_process();
7) 1.558 us | }
7) 2.475 us | }
7) 3.382 us | }
7) 6.122 us | }
7) 7.104 us | }
7) + 10.763 us | }
But this only returns the function graph starting at ksys_dup3. It omits the full function graph that leads to ksys_dup3:
7) | el0_svc_handler() {
7) | el0_svc_common() {
7) | __arm64_sys_dup3() {
7) | ksys_dup3() {
7) 0.416 us | expand_files();
7) | do_dup2() {
7) | filp_close() {
7) 0.405 us | dnotify_flush();
7) 0.406 us | locks_remove_posix();
7) | fput() {
7) 0.416 us | fput_many();
7) 1.269 us | }
7) 3.819 us | }
7) 4.746 us | }
7) 6.475 us | }
7) 7.381 us | }
7) 8.362 us | }
7) 9.205 us | }
Is there a way to use ftrace to filter a full function graph?
I'd say all of ftrace is well documented (here). There is no way to do what you want though, because the filtering ability of ftrace is implemented through triggers that can start/stop tracing exactly when an event happens. Setting set_graph_function will trigger a trace start when the function is entered and a trace stop when it's exited. Since when you enter el0_svc_handler you cannot know beforehand if ksys_dup3 is going to be called, there is no way to write a trigger to start the trace on such a condition (that would require being able to "predict the future").
You can however do fine grained filtering with the set_ftrace_pid parameter writing a program that only does what you need, running a full trace on that program or filtering on the parent el0_svc_handler.
In case you don't actually know which parent functions are being called before the one you want, you can do a single targeted run with the func_stack_trace option enabled to get an idea about what the entire call chain is, and then use that output to set the appropriate filter for a "normal" run.
For example, let's say I want to trace do_dup2, but as you say I want to start from one of the parent functions. I'll first write a dummy test program like the following one:
int main(void) {
printf("My PID is %d, press ENTER to go...\n", getpid());
getchar();
dup2(0, 1);
return 0;
}
I'll compile and start the above program in one shell:
$ ./test
My PID is 1234, press ENTER to go...
Then in another root shell, configure tracing as follows:
cd /sys/kernel/tracing
echo function > current_tracer
echo 1 > options/func_stack_trace
echo do_dup2 > set_ftrace_filter
echo PID_OF_THE_PROGRAM_HERE > set_ftrace_pid
Note: echo do_dup2 > set_ftrace_filter is very important otherwise you will trace and dump the stack for every single kernel function, which would be a huge performance hit and can make the system unresponsive. For the same reason doing echo PID_OF_THE_PROGRAM_HERE > set_ftrace_pid is also important if you don't want to trace every single dup2 syscall done by the system.
Now I can do one trace:
echo 1 > tracing_on
# ... press ENTER in the other shell ...
echo 0 > tracing_on
cat trace
And the result will be something like this (my machine is x86 so the syscall entry functions have different names):
# tracer: function
#
# entries-in-buffer/entries-written: 2/2 #P:20
#
# _-----=> irqs-off
# / _----=> need-resched
# | / _---=> hardirq/softirq
# || / _--=> preempt-depth
# ||| / delay
# TASK-PID CPU# |||| TIMESTAMP FUNCTION
# | | | |||| | |
a.out-6396 [000] .... 1455.370160: do_dup2 <-__x64_sys_dup2
a.out-6396 [000] .... 1455.370174: <stack trace>
=> 0xffffffffc322006a
=> do_dup2
=> __x64_sys_dup2
=> do_syscall_64
=> entry_SYSCALL_64_after_hwframe
I can now see the entire call chain that led to do_dup2 (printed in reverse order above) and then do another normal trace from one of the parent functions (remember to disable options/func_stack_trace first).
I am getting the below error while connecting to IBM MQ using library pymqi.
Its a clustered MQ channel
Traceback (most recent call last):
File "postToQueue.py", line 432, in <module>
qmgr = pymqi.connect(queue_manager, channel, conn_info)
File "C:\Python\lib\site-packages\pymqi\__init__.py", line 2608, in connect
qmgr.connect_tcp_client(queue_manager or '', CD(), channel, conn_info, user, password)
File "C:\Python\lib\site-packages\pymqi\__init__.py", line 1441, in connect_tcp_client
self.connect_with_options(name, cd, user=user, password=password)
File "C:\Python\lib\site-packages\pymqi\__init__.py", line 1423, in connect_with_options
raise MQMIError(rv[1], rv[2])
pymqi.MQMIError: MQI Error. Comp: 2, Reason 2012: FAILED: MQRC_ENVIRONMENT_ERROR'
Please see my code below.
queue_manager = 'quename here'
channel = 'channel name here'
host ='host-name here'
port = '2333'
queue_name = 'queue name here'
message = 'my message here'
conn_info = '%s(%s)' % (host, port)
print(conn_info)
qmgr = pymqi.connect(queue_manager, channel, conn_info)
queue = pymqi.Queue(qmgr, queue_name)
queue.put(message)
print("message sent")
queue.close()
qmgr.disconnect()
Getting error at the line below
qmgr = pymqi.connect(queue_manager, channel, conn_info)
Added the IBM client to scripts folder as well , using Windows 10 , Python 3.8.1 and IBM Client 9.1 windows client installation image, Below is the header
-----------------------------------------------------------------------------+
| |
| WebSphere MQ First Failure Symptom Report |
| ========================================= |
| |
| Date/Time :- Tue January 28 2020 16:27:51 Eastern Standard Time |
| UTC Time :- 1580246871.853000 |
| UTC Time Offset :- -300 (Eastern Standard Time) |
| Host Name :- CA-LDLD0SQ2 |
| Operating System :- Windows 10 Enterprise x64 Edition, Build 17763 |
| PIDS :- 5724H7251 |
| LVLS :- 8.0.0.11 |
| Product Long Name :- IBM MQ for Windows (x64 platform) |
| Vendor :- IBM |
| O/S Registered :- 0 |
| Data Path :- C:\Python\Scripts\IBM |
| Installation Path :- C:\Python |
| Installation Name :- MQNI08000011 (126) |
| License Type :- Unknown |
| Probe Id :- XC207013 |
| Application Name :- MQM |
| Component :- xxxInitialize |
| SCCS Info :- F:\build\slot1\p800_P\src\lib\cs\amqxeida.c, |
| Line Number :- 5085 |
| Build Date :- Dec 12 2018 |
| Build Level :- p800-011-181212.1 |
| Build Type :- IKAP - (Production) |
| UserID :- alekhya.machiraju |
| Process Name :- C:\Python\python.exe |
| Arguments :- |
| Addressing mode :- 32-bit |
| Process :- 00010908 |
| Thread :- 00000001 |
| Session :- 00000001 |
| UserApp :- TRUE |
| Last HQC :- 0.0.0-0 |
| Last HSHMEMB :- 0.0.0-0 |
| Last ObjectName :- |
| Major Errorcode :- xecF_E_UNEXPECTED_SYSTEM_RC |
| Minor Errorcode :- OK |
| Probe Type :- INCORROUT |
| Probe Severity :- 2 |
| Probe Description :- AMQ6090: MQM could not display the text for error |
| 536895781. |
| FDCSequenceNumber :- 0 |
| Comment1 :- WinNT error 1082155270 from Open ccsid.tbl. |
| |
+-----------------------------------------------------------------------------+
I am currently trying to learn the syntax of Rust by solving little tasks. I compare the execution time as sanity-checks if I am using the language the right way.
One task is:
Create an array of 10000000 random integers in the range 0 - 1000000000
Sort it and measure the time
Print the time for sorting it
I got the following results:
| # | Language | Speed | LOCs |
| --- | -------------------- | ------ | ---- |
| 1 | C++ (with -O3) | 1.36s | 1 |
| 2 | Python (with PyPy) | 3.14s | 1 |
| 3 | Ruby | 5.04s | 1 |
| 4 | Go | 6.17s | 1 |
| 5 | C++ | 7.95s | 1 |
| 6 | Python (with Cython) | 11.51s | 1 |
| 7 | PHP | 36.28s | 1 |
Now I wrote the following Rust code:
rust.rs
extern crate rand;
extern crate time;
use rand::Rng;
use time::PreciseTime;
fn main() {
let n = 10000000;
let mut array = Vec::new();
let mut rng = rand::thread_rng();
for _ in 0..n {
//array[i] = rng.gen::<i32>();
array.push(rng.gen::<i32>());
}
// Sort
let start = PreciseTime::now();
array.sort();
let end = PreciseTime::now();
println!("{} seconds for sorting {} integers.", start.to(end), n);
}
with the following Cargo.toml:
[package]
name = "hello_world" # the name of the package
version = "0.0.1" # the current version, obeying semver
authors = [ "you#example.com" ]
[[bin]]
name = "rust"
path = "rust.rs"
[dependencies]
rand = "*" # Or a specific version
time = "*"
I compiled it with cargo run rust.rs and ran the binary. It outputs
PT18.207168155S seconds for sorting 10000000 integers.
Note that this is much slower than Python. I guess I am doing something wrong. (The complete code of rust and of the other languages is here if you are interested.)
Why does it take so long to sort with Rust? How can I make it faster?
I Tried your code on my computer, running it with cargo run gives:
PT11.634640178S seconds for sorting 10000000 integers.
And with cargo run --release (turning on optimizations) gives:
PT1.004434739S seconds for sorting 10000000 integers.
My assumption is that any module tested using Intern will automatically be covered by Istanbul's code coverage. For reasons unknown to me, my module is not being included.
I am:
running Intern 1.6.2 (installed with npm locally)
testing NodeJS code
using callbacks, not promises
using CommonJS modules, not AMD modules
Directory Structure (only showing relevant files):
plister
|
|--libraries
| |--file-type-support.js
|
|--tests
| |--intern.js
| |--unit
| |--file-type-support.js
|
|--node_modules
|--intern
plister/tests/intern.js
define({
useLoader: {
'host-node': 'dojo/dojo'
},
loader: {
packages: [
{name: 'libraries', location: 'libraries'}
]
},
reporters: ['console'],
suites: ['tests/unit/file-type-support'],
functionalSuites: [],
excludeInstrumentation: /^(tests|node_modules)\//
});
plister/tests/unit/file-type-support.js
define([
'intern!bdd',
'intern/chai!expect',
'intern/dojo/node!fs',
'intern/dojo/node!path',
'intern/dojo/node!stream-equal',
'intern/dojo/node!../../libraries/file-type-support'
], function (bdd, expect, fs, path, streamEqual, fileTypeSupport) {
'use strict';
bdd.describe('file-type-support', function doTest() {
bdd.it('should show that the example output.plist matches the ' +
'temp.plist generated by the module', function () {
var deferred = this.async(),
input = path.normalize('tests/resources/input.plist'),
output = path.normalize('tests/resources/output.plist'),
temporary = path.normalize('tests/resources/temp.plist');
// Test deactivate function by checking output produced by
// function against test output.
fileTypeSupport.deactivate(fs.createReadStream(input),
fs.createWriteStream(temporary),
deferred.rejectOnError(function onFinish() {
streamEqual(fs.createReadStream(output),
fs.createReadStream(temporary),
deferred.callback(function checkEqual(error, equal) {
expect(equal).to.be.true;
}));
}));
});
});
});
Output:
PASS: main - file-type-support - should show that the example output.plist matches the temp.plist generated by the module (29ms)
1/1 tests passed
1/1 tests passed
Output (on failure):
FAIL: main - file-type-support - should show that the example output.plist matches the temp.plist generated by the module (30ms)
AssertionError: expected true to be false
AssertionError: expected true to be false
0/1 tests passed
0/1 tests passed
npm ERR! Test failed. See above for more details.
npm ERR! not ok code 0
Output (after removing excludeInstrumentation):
PASS: main - file-type-support - should show that the example output.plist matches the temp.plist generated by the module (25ms)
1/1 tests passed
1/1 tests passed
------------------------------------------+-----------+-----------+-----------+-----------+
File | % Stmts |% Branches | % Funcs | % Lines |
------------------------------------------+-----------+-----------+-----------+-----------+
node_modules/intern/ | 70 | 50 | 100 | 70 |
chai.js | 70 | 50 | 100 | 70 |
node_modules/intern/lib/ | 79.71 | 42.86 | 72.22 | 79.71 |
Test.js | 79.71 | 42.86 | 72.22 | 79.71 |
node_modules/intern/lib/interfaces/ | 80 | 50 | 63.64 | 80 |
bdd.js | 100 | 100 | 100 | 100 |
tdd.js | 76.19 | 50 | 55.56 | 76.19 |
node_modules/intern/lib/reporters/ | 56.52 | 35 | 57.14 | 56.52 |
console.js | 56.52 | 35 | 57.14 | 56.52 |
node_modules/intern/node_modules/chai/ | 37.9 | 8.73 | 26.38 | 39.34 |
chai.js | 37.9 | 8.73 | 26.38 | 39.34 |
tests/unit/ | 100 | 100 | 100 | 100 |
file-type-support.js | 100 | 100 | 100 | 100 |
------------------------------------------+-----------+-----------+-----------+-----------+
All files | 42.14 | 11.35 | 33.45 | 43.63 |
------------------------------------------+-----------+-----------+-----------+-----------+
My module passes the test and I can make it fail too. It just will not show up in the code coverage. I have done the tutorial hosted on GitHub without any problems.
I tried dissecting the Istanbul and Intern dependencies. I place a console.log where it seems files to be covered go through, but my module doesn't get passed. I have tried every variation of deferred.callback and deferred.rejectOnError with no difference to the code coverage.
Also, any feedback on my use of deferred.callback and deferred.rejectOnError will be greatly appreciated. I am still a little uncertain on their usage.
Thanks!
As of Intern 1.6, only require('vm').runInThisContext is hooked to add code coverage data, not require. Instrumentation of require was added in Intern 2.0.
The use of callback/rejectOnError in the above code is correct.