I can't work out how to get error concealment working in OpenH264. My initialisation code looks like this:
SDecodingParam sDecParam = {0};
sDecParam.sVideoProperty.eVideoBsType = VIDEO_BITSTREAM_SVC;
sDecParam.bParseOnly = false;
sDecParam.eEcActiveIdc = ERROR_CON_SLICE_MV_COPY_CROSS_IDR_FREEZE_RES_CHANGE;
if ( 0 == WelsCreateDecoder ( &decoder ) && decoder != nullptr && 0 == decoder->Initialize(&sDecParam) )
Obviously I've tried every possible option for concealment type, without much success
Finally worked this out by stepping through the source of OpenH264:
in decoder setup set eEcActiveIdc to one of the concealment types (e.g. ERROR_CON_SLICE_MV_COPY_CROSS_IDR)
decode with DecodeFrame2 and NOT DecodeFrameNoDelay
Ignore the result code and only look at iBufferStatus in the info block, to see if a buffer is available.
Downside is that this introduces extra latency, so definitely not useful for all applications
Related
I use C++ Builder (Delphi 10.2 and C++Builder 10.2 Update 2) and I need a method that, in case there is no particular table, creates it using TADO objects (ADODB)?
I mean TADOQuery, TADOTable, TADOConnection, etc.
How can I do this?
I tried looking at the methods of TADOConncection, of TADOTable, but none of them seem to be useful.
I also tried this route (https://docwiki.embarcadero.com/Libraries/Alexandria/en/Bde.DBTables.TTable.Exists) but there are compatibility problems.
Does this help ?
TADOConnection *YOUR_TADOCONNECTION; // your connection defined earlier in your code
TStringList *TableList = new TStringList;
bool WithSystemTables = true; // or false according to your requirements
YOUR_TADOCONNECTION->GetTableNames(TableList, WithSystemTables);
for (int i = 0 i < TableList->Count(); i++) {
String NextTableName = TableList->Strings[i];
/*.... your check for the table name being the one you want goes here .... */
}
delete TableList;
I'm trying to follow chisel3 materials(jupyter)
and i'm wondering why ready signals are always 0 in arbiter.
Here is the code below:
test(new Module {
// Example circuit using a priority arbiter
val io = IO(new Bundle {
val in = Flipped(Vec(2, Decoupled(UInt(8.W))))
val out = Decoupled(UInt(8.W))
})
// Arbiter doesn't have a convenience constructor, so it's built like any Module
val arbiter = Module(new Arbiter(UInt(8.W), 2)) // 2 to 1 Priority Arbiter
arbiter.io.in <> io.in
io.out <> arbiter.io.out
}) { c =>
c.io.in(0).valid.poke(false.B)
c.io.in(1).valid.poke(false.B)
println(s"Start:")
println(s"\tin(0).ready=${c.io.in(0).ready.peek().litValue}, in(1).ready=${c.io.in(1).ready.peek().litValue}")
println(s"\tout.valid=${c.io.out.valid.peek().litValue}, out.bits=${c.io.out.bits.peek().litValue}")
c.io.in(1).valid.poke(true.B) // Valid input 1
c.io.in(1).bits.poke(42.U)
// What do you think the output will be?
println(s"valid input 1:")
println(s"\tin(0).ready=${c.io.in(0).ready.peek().litValue}, in(1).ready=${c.io.in(1).ready.peek().litValue}")
println(s"\tout.valid=${c.io.out.valid.peek().litValue}, out.bits=${c.io.out.bits.peek().litValue}")
c.io.in(0).valid.poke(true.B) // Valid inputs 0 and 1
c.io.in(0).bits.poke(43.U)
// What do you think the output will be? Which inputs will be ready?
println(s"valid inputs 0 and 1:")
println(s"\tin(0).ready=${c.io.in(0).ready.peek().litValue}, in(1).ready=${c.io.in(1).ready.peek().litValue}")
println(s"\tout.valid=${c.io.out.valid.peek().litValue}, out.bits=${c.io.out.bits.peek().litValue}")
c.io.in(1).valid.poke(false.B) // Valid input 0
// What do you think the output will be?
println(s"valid input 0:")
println(s"\tin(0).ready=${c.io.in(0).ready.peek().litValue}, in(1).ready=${c.io.in(1).ready.peek().litValue}")
println(s"\tout.valid=${c.io.out.valid.peek().litValue}, out.bits=${c.io.out.bits.peek().litValue}")
}
and the result is:
Start:
in(0).ready=0, in(1).ready=0
out.valid=0, out.bits=0
valid input 1:
in(0).ready=0, in(1).ready=0
out.valid=1, out.bits=42
valid inputs 0 and 1:
in(0).ready=0, in(1).ready=0
out.valid=1, out.bits=43
valid input 0:
in(0).ready=0, in(1).ready=0
out.valid=1, out.bits=43
The material is explaining about ready signal like this:
Ready signal should only be dependent on whether the sink is able to receive data
So I thought that when valid signal comes to input, c.io.in.ready signal should be 1(or true)
but ready signal is always 0 here, even when both in(0) and in(1) is valid
Thanks for answering and actually this is the first time for me to ask a question here, so if there is any problem(or something that i have to know when i write a question here), please let me know.
Thank you!
Your code looks good, but you are just missing a couple of small things.
The Arbiter will not say it is ready until it's output ready is high. Thus you need to add a
c.io.out.ready.poke(true.B)
and that will pass the ready along to the inputs.
You also need to advance the clock after you add poke values into the arbiter.
Add the following after each block of pokes:
c.clock.step()
I am trying to set properties of captured image in linux.
For example:
format, width, height, that could be achieved by:
VIDIOC_S_FMT/VIDIOC_G_FMT + struct v4l2_format fmt;
But, I am blocked in getting/setting more detail parameters:
like H264 key-frame period.
I found there are api to reach the goal.
that are v4l2_ext_controls, v4l2-ext-control and VIDIOC_G_EXT_CTRLS.
I have tried that, but that did not work in my example code.
My code is like this :
struct v4l2_ext_control extCtrl;
memset(&extCtrl, 0, sizeof(struct v4l2_ext_control));
extCtrl.id = V4L2_CID_MPEG_VIDEO_H264_I_PERIOD;
extCtrl.size = 0;
extCtrl.value = 2;
struct v4l2_ext_controls extCtrls;
extCtrls.controls = &extCtrl;
extCtrls.count = 1;
extCtrls.ctrl_class = V4L2_CTRL_CLASS_MPEG;
ret = ioctl(fd, VIDIOC_S_EXT_CTRLS, &extCtrls);
if (0 < ret)
{
printf("VIDIOC_S_EXT_CTRLS setting (%s)\n", strerror(errno));
return -3;
}/*if*/
ret = ioctl(fd, VIDIOC_G_EXT_CTRLS, &extCtrls);
if (0 < ret)
{
printf("VIDIOC_G_EXT_CTRLS setting (%s)\n", strerror(errno));
return -4;
}/*if*/
printf("extCtrl.value = %d\n", extCtrl.value );
That seems well, the key frame period be 2 (extCtrl.value).
But when I used
ffplay -skip_frame nokey -i saved_raw_h264
The key frame period is obviously much greater than 2.
May anyone help me?
By the way: The Logitech C920, is the only one camera I know, supports h264 output in consumer market.
Does any know other camera supporting h264?
Assuming you are setting the parameters correctly, it's very possible that the Logitech C920 Linux driver is ignoring some, if not many, of the control parameters you are passing in via V4L2. Do you have the driver source for the C920? Or is it using a generic Linux USB camera driver? You could at least see which V4L2 controls are supported by the driver.
edit:
Have you seen these threads which talk about adding C920 support to gstreamer?
http://sourceforge.net/p/linux-uvc/mailman/linux-uvc-devel/thread/505D0DAE.7020907#collabora.co.uk/
http://kakaroto.homelinux.net/2012/09/uvc-h264-encoding-cameras-support-in-gstreamer/
If you write a simple object to a socket:
var o:Object = new Object();
o.type = e.type;
o.params = e.params;
_socket.writeObject(o);
_socket.flush();
Then on the client do you simply use:
private function onData(e:ProgressEvent):void
{
var o:Object = _clientSocket.readObject();
}
Or do you have to implement some way of checking all of the data has been received recieved before calling .readObject()
There's 2 approaches:
If you're confident that your object will fit into one packet, you can do something like:
var fromServer:ByteArray = new ByteArray;
while( socket.bytesAvailable )
socket.readBytes( fromServer );
fromServer.position = 0;
var myObj:* = fromServer.readObject();
If you have the possibility of having multiple packet messages, then a common usage is to prepend the message with the length of the message. Something like (pseudo code):
var fromServer:ByteArray = new ByteArray();
var msgLen:int = 0;
while ( socket.bytesAvailable > 0 )
{
// if we don't have a message length, read it from the stream
if ( msgLen == 0 )
msgLen = socket.readInt();
// if our message is too big for one push
var toRead:int = ( msgLen > socket.bytesAvailable ) ? socket.bytesAvailable : msgLen;
msgLen -= toRead; // msgLen will now be 0 if it's a full message
// read the number of bytes that we want.
// fromServer.length will be 0 if it's a new message, or if we're adding more
// to a previous message, it'll be appended to the end
socket.readBytes( fromServer, fromServer.length, toRead );
// if we still have some message to come, just break
if ( msgLen != 0 )
break;
// it's a full message, create your object, then clear fromServer
}
Having your socket able to read like this will mean that multiple packet messages will be read properly as well as the fact that you won't miss any messages where 2 small messages are sent almost simultaneously (as the first message will treat it all as one message, thereby missing the second one)
Rule # 1 when dealing with TCP: it is an octet stream transfer protocol. You may never ever assume anything about how many octets (8 bit long values, commonly called bytes) you get in one go, always write code that can deal with any amount, both too few and too many. There is no gurantee that the write will not be split into multiple reads. There is also no gurantee that a single read will be from a single write.
The way I handled it was to make a call back that the server tell the client that the null bit was received.
The null bit is appended to the end of the data string you are sending to the server.
String.fromCharCode(0)
Also in your case you are doing
_socket.writeObject(o);
You should be sending a string not an object.
So Like this.
_socket.writeUTFBytes( 'Hellow World" + String.fromCharCode(0) );
NOTE *************
And one thing that most first time socket creators over look is the
fact that the first request to from the client to the server over the
port that the socket is connected on is a request for the
crossdomainpolicy.xml
If you only wish to send Objects, the simplest solution is if you send an int(size) before every object. Its not important to send the exact size, you can send a bit less. In my case, I've sent a bitmapdata, and the width and height of the object. obviously the bitmapdata's size is so big, its okay if you send only that, and ignore the rest.
var toRead=0;
protected function onSocketData(event:ProgressEvent):void{
if(toRead==0) {
toRead=socket.readInt()
}
if(socket.bytesAvailable>toRead){
var recieved:Object=socket.readObject()
/*do stuff with recieved object*/
toRead=0
}
I'm new to Lua, so (naturally) I got stuck at the first thing I tried to program. I'm working with an example script provided with the Corona Developer package. Here's a simplified version of the function (irrelevant material removed) I'm trying to call:
function new( imageSet, slideBackground, top, bottom )
function g:jumpToImage(num)
print(num)
local i = 0
print("jumpToImage")
print("#images", #images)
for i = 1, #images do
if i < num then
images[i].x = -screenW*.5;
elseif i > num then
images[i].x = screenW*1.5 + pad
else
images[i].x = screenW*.5 - pad
end
end
imgNum = num
initImage(imgNum)
end
end
If I try to call that function like this:
local test = slideView.new( myImages )
test.jumpToImage(2)
I get this error:
attempt to compare number with nil
at line 225. It would seem that "num" is not getting passed into the function. Why is this?
Where are you declaring g? You're adding a method to g, which doesn't exist (as a local). Then you're never returning g either. But most likely those were just copying errors or something. The real error is probably the notation that you're using to call test:jumpToImage.
You declare g:jumpToImage(num). That colon there means that the first argument should be treated as self. So really, your function is g.jumpToImage(self, num)
Later, you call it as test.jumpToImage(2). That makes the actual arguments of self be 2 and num be nil. What you want to do is test:jumpToImage(2). The colon there makes the expression expand to test.jumpToImage(test, 2)
Take a look at this page for an explanation of Lua's : syntax.