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USB Host 开发中支持数码相机的源码。即Picture To Picture协议的完整实现

libptp2 (c)2001-2004 Mariusz Woloszyn <[e-mail]>
ptpcam  (c)2001-2004 Mariusz Woloszyn <[e-mail]>

=====================
*About this software*
=====================

You may find new versions of this software at:
http://sf.net/projects/libptp

This folder contains following code:
ptp.c		- the main libptp2 code
ptp.h		- libptp2 header files
ptp-pack.c	- this file is included into ptp.c (internal code)
ptpcam.c	- the software to manipulate PTP cameras
		  (currently get/set properties); it does things that
		  you can't do with gphoto2

The libptp2 library is under development yet, but is considered to be
functional and quite stable.
It was written to be used with gphoto2, but can be easily used with any other
software.

==============
*Requirements*
==============

Currently this package requires libusb to build ptpcam.
The libptp2 library itself is transport layer independent and does not require
libusb, however no other transport layer has been tested due to lack
of PTP non-USB devices.
You can obtain libusb at http://libusb.sf.net/
If you want to build this library (for test purposes) on a box without
libusb pass --disable-ptpcam option to configure script.


==================
*What is libptp2?*
==================

libptp2 is a library used to communicate with PTP devices like still
imaging cameras or MP3 players (KODAK mc3).
At the current stage if you want to download your pictures from your PTP
camera all you need is libgphoto2 (which contains libptp2 code) and gphoto2
frontend (visit http://www.gphoto.org). This package contains only the
developers version of libptp2 and the ptpcam program used for tweaking
PTP camera properties.


===================
*Supported Cameras*
===================

NOTE that if your camera is not on the list it DOES NOT mean that it is not
supported! Most of USB cameras designed after 2002 are PTP or USB Mass
Storage. In both cases the camera is supported under Linux!

Below the list of cameras explicitly supported by gphoto2 ptp driver:
(THIS TABLE IS OUTDATED!!! Maintaining the constantly growing list of
supported cameras is harder than developing the driver ;)

=============================================+
Model			|Vendor ID|Product ID|
========================|=========|==========|
Kodak DC240 (PTP)	| 0x040a  |  0x0121  |
Kodak DC4800		| 0x040a  |  0x0160  |
Kodak DX3215		| 0x040a  |  0x0525  |
Kodak DX3500		| 0x040a  |  0x0500  |
Kodak DX3600		| 0x040a  |  0x0510  |
Kodak DX3700		| 0x040a  |  0x0530  |
Kodak DX3900		| 0x040a  |  0x0170  |
Kodak DX4330		| 0x040a  |  0x0555  |
Kodak DX4900		| 0x040a  |  0x0550  |
Kodak MC3		| 0x040a  |  0x0400  |
Kodak LS420		| 0x040a  |  0x0540  |
Kodak LS443		| 0x040a  |  0x0568  |
Kodak CX4200		| 0x040a  |  0x0560  |
Kodak CX4210		| 0x040a  |  0x0560  |
Kodak CX4230		| 0x040a  |  0x0535  |
Kodak CX4300		| 0x040a  |  0x0566  |
------------------------+---------+----------+
HP PhotoSmart 120	| 0x03f0  |  0x6502  |
HP PhotoSmart 318	| 0x03f0  |  0x6302  |
HP PhotoSmart 320	| 0x03f0  |  0x6602  |
HP PhotoSmart 612	| 0x03f0  |  0x6302  |
HP PhotoSmart 620	| 0x03f0  |  0x6802  |
HP PhotoSmart 715	| 0x03f0  |  0x6402  |
HP PhotoSmart 720	| 0x03f0  |  0x6702  |
HP PhotoSmart 735	| 0x03f0  |  0x6a02  |
HP PhotoSmart 812	| 0x03f0  |  0x4202  |
HP PhotoSmart 850	| 0x03f0  |  0x4302  |
------------------------+---------+----------+
Sony DSC-CD300		| 0x054c  |  0x004e  |
Sony DSC-F505		| 0x054c  |  0x004e  |
Sony DSC-F505V		| 0x054c  |  0x004e  |
Sony DSC-F707		| 0x054c  |  0x004e  |
Sony DSC-F707V		| 0x054c  |  0x004e  |
Sony DSC-P5		| 0x054c  |  0x004e  |
Sony DSC-P30		| 0x054c  |  0x004e  |
Sony DSC-P50		| 0x054c  |  0x004e  |
Sony DSC-P71		| 0x054c  |  0x004e  |
Sony DSC-S75		| 0x054c  |  0x004e  |
Sony DSC-S85		| 0x054c  |  0x004e  |
Sony MVC-CD300		| 0x054c  |  0x004e  |
------------------------+---------+----------+
Nikon DSC D100		| 0x04b0  |  0x0402  |
Nikon Coolpix 2000	| 0x04b0  |  0x0302  |
Nikon Coolpix SQ	| 0x04b0  |  0x0202  |
Nikon Coolpix 2500	| 0x04b0  |  0x0109  |
Nikon Coolpix 4500	| 0x04b0  |  0x010b  |
Nikon Coolpix 5700	| 0x04b0  |  0x010d  |
Nikon Coolpix 4300	| 0x04b0  |  0x010f  |
Nikon Coolpix 885	| 0x04b0  |  0x0112  |
Nikon Coolpix 5400	| 0x04b0  |  0x0119  |
------------------------+---------+----------+
Canon PowerShot S45	| 0x04a9  |  0x306d  |
Canon PowerShot G3	| 0x04a9  |  0x306f  |
Canon PowerShot S230	| 0x04a9  |  0x3071  |
Canon Digital IXUS v3	| 0x04a9  |  0x3071  |
Canon PowerShot A70	| 0x04a9  |  0x3073  |
==============================================

Note that for some HP, Nikon, Canon and Sony cameras you have to switch
them to PTP mode as in most cases the camera is dual mode:
PTP and USB Mass Storage or PTP and native.
For some cameras it even changes the Product ID number, so don't panic if
it does not match the one listed above, just switch the mode.
Don't ask me how to do it. Refer to camera documentation.


=============
*Quick Start*
=============

First of all you need kernel USB support. Please refer to your OS
documentation for more info!
For Linux users you need "Preliminary USB device filesystem" and "USB Host
Controller" (the one for your hardware: EHCI, OHCI or UHCI) support in your
kernel.
CAUTION: there was a bug in Linux Kernel 2.4.18 UHCI driver so make sure you
use more recent kernel!
If you got a kernel support, make sure that your usbdevfs is mounted under
/proc/bus/usb. In my case the fstab entry looks like this:

usb     /proc/bus/usb   usbdevfs        defaults,user 0 0

(NO, the entry in fstab isn't enough, you have to type: mount /proc/bus/usb).
If you want to run ptpcam as regular user read this:
http://gphoto.sourceforge.net/doc/manual/permissions-usb.html
although I suggest performing all tests as root unless you're security
paranoid.

If you have a PTP camera connected to your computer it should be detected by
invoking "ptpcam --list-devices".
In my case the output looks like this:

root@emsi(chroot):~# ptpcam --list-devices
Listing devices...
bus/dev vendorID/prodID device model
002/035 0x040A/0x0400   Kodak mc3
002/036 0x040A/0x0500   DX3500 Digital Camera
001/027 0x040A/0x0160   DC4800 Zoom Digital Camera

If you get something like this:

emsi@emsi(chroot):~> ptpcam --list-devices
Listing devices...
bus/dev vendorID/prodID device model
ERROR: Could not open session!
Try to reset the camera.

it means that you did not read carefully what I wrote above about running
ptpcam as regular user or your camera has stalled (needs reset).

If you need some more debug try --verbose or --verbose=2 thus increasing the
verbose level.

What if you get "Found no PTP devices"?
If you're sure that your camera is a PTP camera please check your OS usb
config. In case of Linux make sure that you have usbdevfs mounted under
/proc/bus/usb. If so read the output of 'cat /proc/bus/usb/devices' and check
if your camera is listed there.
It might be that your camera is not in PTP mode. To verify so, issue:

cat /proc/bus/usb/devices | grep "Cls=06"

If you find something like this:

I:  If#= 0 Alt= 0 #EPs= 3 Cls=06(still) Sub=01 Prot=01 Driver=(none)
                          ^^^^^^^^^^^^^
that means that your camera is in PTP mode and should be detected.
If there is no interface of Class 6 refer to camera documentation to find
how to switch it into PTP mode.

You may also try to use --force option while listing cameras or talking to
it, but don't use it unless you really know what you are doing!!!
--force forces ptpcam to talk to non PTP devices [which makes sense only in
case of PTP device with interface class other than 6 (PTP), like Kodak DC240
with PTP firmware]. BE AWARE that talking PTPish to non PTP devices may
cause harmful damage!!!


============
*What next?*
============

I guess that you'd like to tweak camera properties? ;)
Use "ptpcam --list-properties" to list all available camera properties.
Unfortunately if you have bought a high-end camera or a very expensive PTP
camera it DOES NOT mean that it supports setting any properties. The problem
is that manufacturers do not specify in documentation what properties or
operations are supported by the given camera. In most cases you never know
until you buy the camera. [I'll try to provide a list of supported camera
properties and operations on libptp.sf.net]
If ptpcam detects more than one camera you need to pass --bus=BUS-NUMBER and,
or --dev=DEV-NUMBER arguments otherwise ptpcam tries to talk to first detected
camera. If you specify only bus or dev number ptpcam talks to first matching
camera.

Let's say that you get something like this:

root@emsi(chroot):~# ptpcam --list-properties
Listing properties...
Querying: DX3500 Digital Camera
0x5001 : Battery Level

It means that your camera (in this case DX3500 Digital Camera) supports only
one property, which is "Battery Level" (property number 0x5001). Not much,
but you still can try to list its value:

root@emsi(chroot):~# ptpcam --show-property=5001
Camera: DX3500 Digital Camera
Property 'Battery Level'
Data type is 0x0002
Current value is 100
Factory default value is 100
The property is read only, enumerated. Allowed values are:
0
10
100

As you can see --show-property argument does not require 0x, that's for your
convenience. ;)
The output of this command is quite verbose. It tells you about the Data
type (in this case 0x0002 means UINT8, if you want to know what are those
numbers read ptp.h and look for PTP_DTC_* defines), current value, factory
default value and the property type. The property type may vary among
different cameras! In this camera 'Battery Level' is read only and
enumerated. Allowed values are 0, 10 and 100 which (more or less) means:
0 - low battery lever (may shut down immediately), 10 - medium battery
level, 100 - full battery level. However for a different camera this
property may be defined as range of 1 to 100 with step of 1.
That's just an example.

Now let's look at the list of properties of another camera:

root@emsi(chroot):~# ptpcam --list-properties
Listing properties...
Querying: DC4800 Zoom Digital Camera
0x5001 : Battery Level
0x5003 : Image Size
0x5004 : Compression Setting
0x5005 : White Balance
0x5006 : RGB Gain
0x5007 : F-Number
0x5008 : Focal Length
0x5009 : Focus Distance
0x500a : Focus Mode
0x500b : Exposure Metering Mode
0x500c : Flash Mode
0x500d : Exposure Time
0x500e : Exposure Program Mode
0x500f : Exposure Index (film speed ISO)
0x5010 : Exposure Bias Compensation
0x5011 : Date Time
0x5013 : Still Capture Mode
0x5015 : Sharpness
0x5016 : Digital Zoom
0x5017 : Effect Mode
0x5018 : Burst Number
0x501c : Focus Metering Mode
0xd001 : EK Color Temperature
0xd002 : EK Date Time Stamp Format
0xd003 : EK Beep Mode
0xd004 : EK Video Out
0xd005 : EK Power Saving
0xd006 : EK UI Language

All properties of numbers starting with 0x50 are standard PTP properties,
although for many of them the type (enumerated or range) and value meaning
are NOT specified by the PTP standard and may vary among different cameras!
The properties starting with 0xd0 are PTP extension (in this case EK means
Eastman Kodak extension) and in most cases are not known to public at all.