Re: clean/smudge filters for pdf files

From: Leo Razoumov <slonik.az@gmail.com>
Date: Oct 24, 2008, 01:40 UTC
Message-ID: <ee2a733e0810231840u1aed8455w7e4c461e2565ad08@mail.gmail.com>
In-Reply-To: <20081023213203.GB26104@artemis.corp>

On 10/23/08, Pierre Habouzit <madcoder@debian.org> wrote:

Show 26 quoted lines

> On Thu, Oct 23, 2008 at 07:44:39PM +0000, Leo Razoumov wrote:
>  > I am trying to improve storage efficiency for PDF files in a git repo.
>  > Following earlier discussions in this list I am trying to set up
>  > proper clean/smudge filters. What follows is my current setup
>  >
>  > # in ~/.gitconfig
>  > [filter "pdf"]
>  >       clean  = "pdftk - output - uncompress"
>  >       smudge = "pdftk - output - compress"
>  >
>  > # in .gitattributes
>  > *.pdf filter=pdf
>  >
>  > Unfortunately, it seems as though that pdftk uncompress followed by
>  > pdftk compress do not leave the file invariant. I tried several
>  > uncompress+compress iterations and the file still keep changing (the
>  > size though stays the same).
>  > Is there any other alternative way to store PDF files in git repo more
>  > efficiently?
>  > Any alternative to pdftk on Linux?
>
>
> actually it uses some kind of zlib algorithm so that's pretty normal you
>  don't have the same result with a packer. Maybe one could write a tool
>  like pristine-tar for that purpose.
>

With zlib you get the same deterministic result as long as you use the same zlib packer and unpacker. With pdftk compress/uncompress seem not to form a bijection pair. This issue was briefly discussed on this list back in April 2008 but no resolution emerged.

--Leo--