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<TITLE>sane-devel: Re: SANE API & file format</TITLE>
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<META NAME="Author" CONTENT="Stephen Williams (steve@icarus.com)">
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<META NAME="Subject" CONTENT="Re: SANE API & file format">
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<H1>Re: SANE API & file format</H1>
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<!-- received="Thu May 3 13:33:15 2001" -->
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<!-- sent="Thu, 03 May 2001 13:42:38 -0700" -->
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<!-- isosent="20010503204238" -->
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<!-- name="Stephen Williams" -->
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<!-- subject="Re: SANE API & file format" -->
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<STRONG>From:</STRONG> Stephen Williams (<A HREF="mailto:steve@icarus.com?Subject=Re:%20SANE%20API%20&%20file%20format&In-Reply-To=<200105032042.f43Kgdt04394@icarus.com>"><EM>steve@icarus.com</EM></A>)<BR>
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<STRONG>Date:</STRONG> Thu May 03 2001 - 13:42:38 PDT
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<P>
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<LI><STRONG>Next message:</STRONG> <A HREF="0054.html">Henning Meier-Geinitz: "Re: Canon backend"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0052.html">EdHamrick@aol.com: "Re: HP 7400c info / Minolta Scan Dual II"</A>
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<LI><STRONG>In reply to:</STRONG> <A HREF="0050.html">Henning Meier-Geinitz: "Re: SANE API & file format"</A>
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0055.html">Nick Lamb: "Re: SANE API & file format"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0055.html">Nick Lamb: "Re: SANE API & file format"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0056.html">Oliver Rauch: "Re: SANE API & file format"</A>
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<A HREF="mailto:henning@meier-geinitz.de?Subject=Re:%20SANE%20API%20&%20file%20format&In-Reply-To=<200105032042.f43Kgdt04394@icarus.com>">henning@meier-geinitz.de</A> said:
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<BR>
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<EM>> So somebody must go on and write an new standard for SANE 2 (see
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</EM><BR>
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<EM>> LEVEL2 in SANE distribution).
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</EM><BR>
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<P>Here are some ramblings on the matter. It doesn't seem all that
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<BR>
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hard...
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<BR>
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<P>The problem is that a JFIF stream (for example) does not sit well
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<BR>
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with the SANE_Parameters structure. In particular, the pixels_per_line
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<BR>
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and bytes_per_line values are not defines.
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<BR>
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<P>I suppose the right thing to do is simply ignore these for all but the
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<BR>
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5 core frame format types.
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<BR>
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<P>Other then that, supporting new formats should be easy and backwards
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<BR>
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compatible. Just create a well-known-type "transfer-type" with the
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<BR>
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default always set to TRANSFER_TYPE_SANE that acts like the existing
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<BR>
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in-memory transfer. Existing tools that are not aware of transfer types
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<BR>
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will automatically get this. A scanner driver that only supports the
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<BR>
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TRANSFER_TYPE_SANE type need not even implement type type.
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<BR>
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<P>If an application is aware of transfer types, it can ask the driver
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<BR>
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for the word list constraint to get a list of the transfer types that
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<BR>
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the driver supports. If the driver does not support "transfer-type"
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<BR>
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then the application supports TRANSFER_TYPE_SANE.
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<BR>
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<P>If the driver supports "transfer-type", then the list includes
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<BR>
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TRANSFER_TYPE_SANE and any other formats it supports, which should
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<BR>
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at least include TRANSFER_TYPE_JFIF and others that hardware can
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<BR>
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produce. The application can then compare the list of formats that
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<BR>
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the driver supports along with its own (implicit) list of supported
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<BR>
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types, then do whatever seems natural for the application with the
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<BR>
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types. For example, scanimage_ex may choose to support JFIF images
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<BR>
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by writing them to a file foo.jpg.
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<BR>
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<P>Most formats will be variable size streams. To account for that, the
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<BR>
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application should always read to the EOF to get everything that is
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<BR>
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the format.
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<BR>
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<PRE>
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--
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Steve Williams "The woods are lovely, dark and deep.
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<A HREF="mailto:steve@icarus.com?Subject=Re:%20SANE%20API%20&%20file%20format&In-Reply-To=<200105032042.f43Kgdt04394@icarus.com>">steve@icarus.com</A> But I have promises to keep,
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<A HREF="mailto:steve@picturel.com?Subject=Re:%20SANE%20API%20&%20file%20format&In-Reply-To=<200105032042.f43Kgdt04394@icarus.com>">steve@picturel.com</A> and lines to code before I sleep,
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<A HREF="http://www.picturel.com">http://www.picturel.com</A> And lines to code before I sleep."
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<P><P><P>--
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Source code, list archive, and docs: <A HREF="http://www.mostang.com/sane/">http://www.mostang.com/sane/</A>
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To unsubscribe: echo unsubscribe sane-devel | mail <A HREF="mailto:majordomo@mostang.com?Subject=Re:%20SANE%20API%20&%20file%20format&In-Reply-To=<200105032042.f43Kgdt04394@icarus.com>">majordomo@mostang.com</A>
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</PRE>
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<!-- next="start" -->
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<LI><STRONG>Next message:</STRONG> <A HREF="0054.html">Henning Meier-Geinitz: "Re: Canon backend"</A>
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<LI><STRONG>Previous message:</STRONG> <A HREF="0052.html">EdHamrick@aol.com: "Re: HP 7400c info / Minolta Scan Dual II"</A>
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<LI><STRONG>In reply to:</STRONG> <A HREF="0050.html">Henning Meier-Geinitz: "Re: SANE API & file format"</A>
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<!-- nextthread="start" -->
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<LI><STRONG>Next in thread:</STRONG> <A HREF="0055.html">Nick Lamb: "Re: SANE API & file format"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0055.html">Nick Lamb: "Re: SANE API & file format"</A>
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<LI><STRONG>Reply:</STRONG> <A HREF="0056.html">Oliver Rauch: "Re: SANE API & file format"</A>
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<EM>
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This archive was generated by <A HREF="http://www.hypermail.org/">hypermail 2b29</A>
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: <EM>Thu May 03 2001 - 13:34:26 PDT</EM>
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