IMFMediaSourceTopologyProvider::GetMediaSourceTopology always fails, why? - ms-media-foundation

Under what circumstances the IMFMediaSourceTopologyProvider::GetMediaSourceTopology() does not fail? It always fails with code 0xc00d36e6 (MF_E_ATTRIBUTENOTFOUND).
Please do not answer with a link to MSDN.

Here is the solution after pissing blood for hours.
You have to call QueryInterface() on IMFSequencerSource object to get the IMFMediaSource like this:
hr = pMFSequencerSrc->QueryInterface( __uuidof( IMFMediaSource ), (void**)&pMediaSource );
Now on pMediaSource object call CreatePresentationDescriptor() to get the presentation descriptor required for the GetMediaSourceTopology() call.
voila...
P.S.
That MF_E_ATTRIBUTENOTFOUND error... nice work M$

Related

Sage TypeError positive characteristics not allowed in symbolic computations

I am new to sage and have got a code (link to code) which should run.
I am still getting an error message in the decoding part. The error trace looks like this:
in decode(y)
--> sigma[i+1+1] = sigma[i+1]*(z)\
-(delta[i+1]/delta[mu+1])*z^(i-mu)*sigma[mu+1]*(z);
in sage.structure.element.Element.__mul__
if BOTH_ARE_ELEMNT(cl):
--> return coercion_model.bin_op(left, right, mul)
in sage.structure.coerce.CoercionModel_cache_maps.bin_op
--> action = self.get_action(xp,yp,op,x,y)
...... some more traces (don't actually know if they are important)
TypeError: positive characteristics not allowed in symbolic computations
Does anybody know if there is something wrong in this code snipped? Due to previous errors, I changed the following to get to where I am at the moment:
.coeffs() changed to .coefficients(sparse=False) due to a warning message.
in the code line sigma[i+1+1] = sigma[i+1](z)\
-(delta[i+1]/delta[mu+1])*z^(i-mu)*sigma[mu+1](z); where the error occurs, i needed to insert * eg. sigma[i+1]*(z)
I would be grateful for any guess what could be wrong!
Your issue is that you are multiplying things not of characteristic zero (like elements related to Phi.<x> = GF(2^m)) with elements of symbolic computation like z which you have explicitly defined as a symbolic variable
Phi.<x> = GF(2^m)
PR = PolynomialRing(Phi,'z')
z = var('z')
Basically, the z you get from PR is not the same one as from var('z'). I recommend naming it something else. You should be able to access this with PR.gen() or maybe PR(z).
I'd be able to be more detailed, but I encourage you next time to paste a fully (non-)working example; trying to slog through a big worksheet is not the easiest thing to track all this down. Finally, good luck, hope Sage ends up being useful for you!

Airflow: set a default value in code when Variable doesn't exist without an exception

I have a little problem, I want to do the typical conditional like
setting_x = Variable.get('setting_x')
variable = setting_x if setting_x else 0
But since the Airflow model throws an exception when the key doesn't exist is impossible to do it without trycatching and that's not very cool.
Is there any solution that I'm missing to solve that case? I've searched in the whole internet of course, but without a solution yet.
Thanks,
Angel
You can set the default for the Variable if it doesn't exist when you're retrieving it with the get method.
variable = Variable.get('setting_x', default_var=0)
https://github.com/apache/airflow/blob/master/airflow/models/variable.py#L127
Shorter version of the previous answer (keyword default_var omitted):
variable = Variable.get('setting_x', 0)

readHTMLTable does not recognize URL

Okay guys, I have, what I'm sure, is an entry-level problem. Still, I cannot explain it. Here's my code and its error:
> sample1 = readHTMLTable(http://www.pro-football-reference.com/boxscores/201609150buf.htm, which = 16)
Error: unexpected '/' in "sample1 = readHTMLTable(http:/"
It's having a problem with the second front-slash? Not only does every URL have two front-slashes, but I've poured through countless examples of this function, both on this site and others, and they've all formatted this code in this way. So, what am I doing wrong?
Additionally, I've tried it without the back-slashes:
> sample1 = readHTMLTable(www.pro-football-reference.com/boxscores/201609150buf.htm, which = 16)
Error: unexpected symbol in "sample1 = readHTMLTable(www.pro-football-reference.com/boxscores/201609150buf.htm"
Here, I'm not even sure which symbol it's talking about.
Please explain.
The issue is that you need to place your url in quotes (""). The following does return the table from your specified url:
sample1 = readHTMLTable("www.pro-football-reference.com/boxscores/201609150buf.htm")
As you probably know, the "which=" parameter is used to select which of the tables in that page you would like to retrieve. However my own attempts show that only 1 and 2 work. Could you tell me which table you are attempted to read into R? If this method doesn't end up working you can also attempt to read in the entirety of the webpage and parse out the table in question.
Hope this helps get things started!

what does mean the command if(0) in r?

I have a question, I have been reviewing some code and in one script, the authors use:
if(0){
#do something
}
Any help in what if(0) means?
The author (most likely) put the block of code in an if statement so that they could easily remove it if necessary without having to comment it out (or remove it). Similar to if(true) or if(false), you just need to change one value and it would skip that code.
Upon reviewing the code, developers should remove these kinds of statements once they've finalized all their source code not to confuse others.
Looks like something that will never be executed, since 0 = FALSE. Most probably this is a manual switch to test some code in parenthesis.

XForms bind element error

I am changing my code to use binds in XForms (which is better practice than using nodesets everywhere!) but I am getting errors.
The error message I receive is: "Error: XForms Error (8): id (data_criterion) does not refer to a bind element..."
From tutorials/guides I have been using, it seems as though this should work, but clearly I am missing something! (btw, I was modeling my binding code after the examples here: http://en.wikibooks.org/wiki/XForms/Bind)
I originally thought the problem was due to the fact I was using xf:select controls as opposed to xf:input like the examples, but even once I dumbed down my code to the most simplistic code, I still receive errors!
This is the model code I am using:
<xf:model id="select_data">
<xf:instance id="criteria_data" xmlns="">
<file>
<criteria>
<criterion></criterion>
</criteria>
</file>
</xf:instance>
<bind id="data_criterion" nodeset="instance('criteria_data')/criteria/criterion"/>
</xf:model>
As for the ui code, this is what I have:
<xf:input bind="data_criterion">
<xf:label>Enter criteria:</xf:label>
</xf:input>
The error message I receive is: "Error: XForms Error (8): id (data_criterion) does not refer to a bind element..."
Anyone have any insight to what the problem is? Also, is there any special usage of bindings and xf:select (with xf:itemset) controls that I should be aware of? (I am ultimately using a lot of xf:select controls on my form..)
Thanks in advance!
EDIT:
I ran the code through this validator, and I got this message (refers to the bind line):
"Warning: Should the following element have the XForms namespace applied?: bind (line 66)"
A couple of things you might want to change:
Not sure of this is the reason for the error, but the nodeset expression should be instance('criteria_data')/criteria/..., without file. Remember: instance() returns the root element, not the document node. (This one you took care by updating the question; good)
You are missing the xf on the bind. It should be: <xf:bind id="data_criterion" nodeset="instance('criteria_data')/criteria/criterion"/>.
See below a full example with your code, which works fine for me under Orbeon Forms:
<xhtml:html xmlns:xhtml="http://www.w3.org/1999/xhtml"
xmlns:xforms="http://www.w3.org/2002/xforms"
xmlns:xf="http://www.w3.org/2002/xforms"
xmlns:xxforms="http://orbeon.org/oxf/xml/xforms"
xmlns:ev="http://www.w3.org/2001/xml-events"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:fr="http://orbeon.org/oxf/xml/form-runner">
<xhtml:head>
<xhtml:title>SO Bind</xhtml:title>
<xf:model id="select_data">
<xf:instance id="criteria_data" xmlns="">
<file>
<criteria>
<criterion>Gaga</criterion>
</criteria>
</file>
</xf:instance>
<xf:bind id="data_criterion" nodeset="instance('criteria_data')/criteria/criterion"/>
</xf:model>
</xhtml:head>
<xhtml:body>
<xf:input bind="data_criterion">
<xf:label>Enter criteria:</xf:label>
</xf:input>
</xhtml:body>
</xhtml:html>

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