[sane-devel] proposel for buffer size increase frontends scanimage ..
On Tuesday 18 January 2005 18:19, Johannes Berg wrote: gerard klaver schrieb: In this way the write cycle in sane_read will be reduced and is it possible to write a image from for example a 640 x 480 webcam in one cycle to the frontend buffer. What's the advantage? If there really is an advantage, I think it should probably be made dynamic instead. Using this much space on the stack isn't really a good thing IMHO. That would be my comment too. 1Mib on the stack - hmmm, I don't like this idea. If we really need such an amount of mem, use malloc! My 2 cents Gerhard
[sane-devel] proposel for buffer size increase frontends scanimage ..
On Wed, 2005-01-19 at 08:31 +0100, Gerhard Jaeger wrote: On Tuesday 18 January 2005 18:19, Johannes Berg wrote: gerard klaver schrieb: In this way the write cycle in sane_read will be reduced and is it possible to write a image from for example a 640 x 480 webcam in one cycle to the frontend buffer. What's the advantage? If there really is an advantage, I think it should probably be made dynamic instead. Using this much space on the stack isn't really a good thing IMHO. That would be my comment too. 1Mib on the stack - hmmm, I don't like this idea. If we really need such an amount of mem, use malloc! My 2 cents Gerhard IFAIK in the backend as in the frontend more and/or bigger buffers are used in general to do color correction, line skew correction etc. The idea of making it dynamic sounds good to me. How this should be done, i don't know yet. If somebody else has an idea, please let me know. I think it should be something like: Frontends defines a max. buffer value ( for example 1024 * 1024, default value is old value 32 * 1024) Backends defines a value ( for example 256 * 1024) if no backend value is present default value frontend will be used (so no existing backend is affected). if backend value max. frontend value, backend value will be used if backend value = max. frontend value, frontend value will be used -- m.vr.gr. Gerard Klaver
[sane-devel] proposel for buffer size increase frontends scanimage ..
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Hello,
Proposal to increase the buffersize of buffer[32 * 1024] to
buffer[1024 * 1024] for frontend scanimage for diff zie attachment.
In this way the write cycle in sane_read will be reduced and is it
possible to write a image from for example a 640 x 480 webcam in
one cycle to the frontend buffer.
For other frontends its the same but i tested only xscanimage at this
moment (patch (with other patches) is in sane/experimental but needs a
update)
For:
saned ??
scanadf ??
Others
??
Any comments?
--
m.vr.gr.
Gerard Klaver
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--- scanimage-orig.c2005-01-18 17:33:20.0 +0100
+++ scanimage.c 2005-01-18 17:34:03.0 +0100
@@ -1020,7 +1020,7 @@
scan_it (void)
{
int i, len, first_frame = 1, offset = 0, must_buffer = 0;
- SANE_Byte buffer[32 * 1024], min = 0xff, max = 0;
+ SANE_Byte buffer[1024 * 1024], min = 0xff, max = 0;
SANE_Parameters parm;
SANE_Status status;
Image image = { 0, 0, 0, 0, 0, 0 };
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[sane-devel] proposel for buffer size increase frontends scanimage ..
gerard klaver schrieb: In this way the write cycle in sane_read will be reduced and is it possible to write a image from for example a 640 x 480 webcam in one cycle to the frontend buffer. What's the advantage? If there really is an advantage, I think it should probably be made dynamic instead. Using this much space on the stack isn't really a good thing IMHO. johannes
