[poppler] [PATCH] JPEG support for pdftoppm

Leonard Rosenthol lrosenth at adobe.com
Fri Oct 9 07:03:14 PDT 2009

You need the read the section on linearization in the PDF Reference/ISO
32000-1 as those are the files that have been prepared for use with "http
byte streaming".  You are going ot need to add the necessary code to Poppler
to read/parse/understand that information so that you can more reasonably
fetch the information necessary to quickly display the first chunk of info.

After that, then doing dynamic reads is more in line.  However, be aware
that when dealing with documents that use object streams, the complexity
goes up...


On 10/8/09 7:49 PM, "Stefan Thomas" <moon at justmoon.net> wrote:

> Hey,
>> Commited, fixed a small thing (virtual destructor needed) myself.
> Woohoo! :)
>> Thanks for contributing! Stay around and code something else ;-)
> I'm planning to add HTTP streaming support to poppler. Similar to the
> way Adobe Reader does it. We need this functionality for a project, so I
> can't promise my patch will be suitable for mainline poppler. But I'll
> definitely post it and we'll see how hard it would be to get it ready
> for prime time and whether there is even a demand for it.
> My basic plan is to create a new class HttpStream, extending BaseStream,
> adding libcurl as an optional dependency and just do partial requests
> whenever a substream is created. That should work, but performance would
> be dreadful. To improve it I would add a cache of some sort and some way
> for higher level functions to request prefetching of larger chunks of
> the file in advance.
> If you have any thoughts on the matter or if there have been any
> previous efforts towards this I'd love to hear it!
> Cheers,
> Stefan
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Leonard Rosenthol
PDF Standards Architect
Adobe Systems

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