On Nov 13, 2012, at 5:08 PM, [email protected] wrote:
> Hi Quincey
> I have tried this, the problem is the padding part is only partial of the
> element size, so the stride can only be set to be interger, which means
> if i have scan line like 00000000, 11111111, 00 here the element size is
> 8bit, but the padding bits is 2bit, if i select hyperslab, the stride can be
> only the interger, which means the padding bits at least 8bit. So it will
> cause problem.
*blah* What an awkward data layout :-) I suppose you could create the
packed, matrix-like dataset in the file and then write small pieces of your
buffer in memory to regions of the dataset in the file, with multiple I/O
calls. Not the best performance possibly, but if you use chunked dataset
stored for the dataset in the file, the chunk caching in the HDF5 library
should mitigate that performance issue significantly.
Quincey
> Thanks
> He Yang
>
>
>
> On Tue, Nov 13, 2012 at 4:45 PM, Quincey Koziol <[email protected]> wrote:
> Hi He,
> You can build up this sort of selection with the H5Sselect_hyperslab()
> routine by using the H5S_SELECT_OR operator (or another convenient operator).
>
> Quincey
>
>
> On Nov 13, 2012, at 1:06 PM, [email protected] wrote:
>
>> Hi
>> The problem is the hyperslab's strid is meaused by the number of pixels,
>> not bytes, so I i have a 8 16bit pixels, and a 4 padding bits,
>> the stride will not work. as if the stride is 1 it will be 16bit not 4bits.
>>
>> He Yang
>>
>>
>>
>> On Tue, Nov 13, 2012 at 12:24 PM, Quincey Koziol <[email protected]> wrote:
>>
>> On Nov 12, 2012, at 8:52 AM, [email protected] wrote:
>>
>> > Hi All
>> > I am trying to save image data to the dataset, the image data is
>> > allocated by other library, so the image's scanline length is not equal
>> > to the number
>> > of pixels, and will have the padding bytes. I want save it into hdf5 as a
>> > matrix, which don't have those padding bytes, as the image can be
>> > float, unsigned short, and come from other data, the scanline length(/
>> > step ) between each row may not be the multiples of the pixels. for
>> > example, the
>> > image has 9 unsigned short pixels, and the sacn line length is defined by
>> > allocate 9*(16/2)+4=76 bytes, the stride in hdf5 can only be the interger
>> > times the elements length. so it can not work. And I don't want use a
>> > temporary buffer to change the memory layout. I also want all other hdf5
>> > application can directly read the image out as matrix, so I don't want use
>> > raw data format. Is there a way which can directly use hdf5's api and it
>> > will automatically strip the padding bytes for image data.
>>
>> You should be able to use hyperslab or point selections to achieve
>> what you want.
>>
>> Quincey
>>
>>
>>
>> _______________________________________________
>> Hdf-forum is for HDF software users discussion.
>> [email protected]
>> http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
>>
>> _______________________________________________
>> Hdf-forum is for HDF software users discussion.
>> [email protected]
>> http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
>
>
> _______________________________________________
> Hdf-forum is for HDF software users discussion.
> [email protected]
> http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
>
>
> _______________________________________________
> Hdf-forum is for HDF software users discussion.
> [email protected]
> http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
_______________________________________________
Hdf-forum is for HDF software users discussion.
[email protected]
http://mail.hdfgroup.org/mailman/listinfo/hdf-forum_hdfgroup.org
