RE: [libmicrohttpd] JPEG Streaming with libmicrohttpd

[David J Myers]

Ok, thanks again, Christian.
Just to get this straight then. In the Access Handler Callback, I call
'MHD_create_response_from_callback' with 
MHD_SIZE_UNKNOWN. Then call MHD_add_response_header to add my headers. Then
in the Content Reader Callback, I can fill in the JPEG data, but what about
subsequent frames? Do I create another response_from_callback and repeat for
each frame, or do I return zero from the Content Reader Callback so that it
calls me again for the same response? Can you add headers within the Content
Reader Callback?
Best regards
David


-----Original Message-----
From: Christian Grothoff [mailto:address@hidden 
Sent: 11 November 2010 16:12
To: David J Myers
Cc: 'libmicrohttpd development and user mailinglist'
Subject: Re: [libmicrohttpd] JPEG Streaming with libmicrohttpd

Dear David,

You must use 'MHD_create_response_from_callback', not 'from_data'; use 
MHD_SIZE_UNKNOWN for the size argument and your data will be transmitted
while 
you're still (incrementally) creating the response.

Happy hacking,

Christian


On Thursday, November 11, 2010 04:35:06 pm David J Myers wrote:
> Hi Christian,
> Thanks for the response. The infinite method is the one I need, but could
> you give me a bit more detail on the MHD calls I need to make.
> 
> I don't understand how to send each response part ie how to make an
> incremental response. In my callback, I can call
> MHD_Create_response_from_Data then MHD_queue_response, multiple times, but
> these responses won't be sent until the callback returns which won't work.
> 
> Thanks again,
> David
> 
> -----Original Message-----
> From: Christian Grothoff [mailto:address@hidden
> Sent: 11 November 2010 15:04
> To: libmicrohttpd development and user mailinglist
> Cc: David J Myers
> Subject: Re: [libmicrohttpd] JPEG Streaming with libmicrohttpd
> 
> Dear David,
> 
> MHD does very little for you here.  You'll need to set the content type
> header
> (MHD_add_response_header) and then somehow create the response with the
> boundaries yourself.  Depending on the requirements of your application,
> you
> 
> can either create it in-memory a-priori (if the stream is fixed size and
> small) or incrementally with the possibility of making the stream infinite
> in
> size (choose there respective MHD method to create the response object).
> 
> Either case will work, and in either case MHD will not help with the
> formatting of the response.
> 
> I hope this helps a bit.
> 
> Best,
> 
> Christian
> 
> On Thursday, November 11, 2010 01:30:52 pm David J Myers wrote:
> > Hi, I'm new to libmicrohttpd and I want to implement a motion JPEG
> > stream. Could someone please show me how to build the following
> > responses ie. A multipart response stream. This is what I want to send
> > back to the client when I receive the GET :-
> > 
> > 
> > 
> > HTTP Code: 200 OK
> > Content-Type: multipart/x-mixed-replace; boundary=myboundary
> > 
> > --myboundary
> > Content-Type: image/jpeg
> > 
> > <JPEG Image data>
> > --myboundary
> > Content-Type: image/jpeg
> > 
> > <JPEG Image data>
> > --myboundary
> > .
> > 
> > 
> > 
> > Thanks for your time
> > 
> > David
> 
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