Re: PTP read-out from Fuji X-T100 extremely slow

Hi,

On Thu, Jul 19, 2018 at 04:37:41PM +0200, Thomas A wrote:
> Hi,
> 
> I found that listing files or just trying to pull one file from my Fujifilm
> X-T100 using gphoto2 takes a very long time. (The same is true for whatever
> backend Gnome uses - I did notice it was faster when there were fewer
> images on the memory card of the camera).

(From your debuglogfile you seem to have 1430 images in just one directory.)

> I tried with both -L, to list all files, and --get-file=1. In both cases,
> gphoto2 seems to go through the info for each file (object?) (To get
> filenames?) and each read-out takes about 200ms. (Logs at [1]. Also tried
> with gphoto2 2.5.15 / libgphoto2 2.5.16 on another computer)
> 
> Is there any way to avoid these reads? I guess they are needed to map
> filename to object?

It is hard. We are doing the basic PTP directory retrieval, which should
be used by almost all PTP applications, so all of them will likely
be similar slow.

We have on-demand retrieval, but it always needs to pull full directories,
so this is is not useful in "all in one directory" scenarios.
 
> Is there a 200ms wait performed by gphoto or is it my camera?

This is the camera taking so long, not libgphoto2.
 
> I tried searching for the problem. The closest I got is that the Fuji
> PTP/IP protocol does not have unique object IDs [2]. Going by how
> consecutive the numbering in the debug output is, this might be true for
> PTP over USB as well?

The objectids should be considered opaque, so we cannot and should not guess them.

I think what happens is that the camera tries to access every file
individually on the GetObjectInfo call, and due to the 1400 files
it just takes long.

> What I ultimately like to do is pulling a number of images (not all) from
> the camera within a number of seconds. Getting previews is not necessary.
> If necessary, I could resort to some kind of cache file and not delete
> images from the camera (to avoid object remapping, if the non-uniqueness is
> true).
> 
> (In the long term I was thinking of only extracting images with a certain
> "star" rating in the Exif data)

Does the camera have a menu setting where it can create a new directory every
100 images? This would help the ondemand loading to make this quicker.

Or a faster SD card?

Ciao, Marcus

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot