【Symbian】改變錄影格式

在Nokia官網裡提供的錄影程式，預設是使用QCIF(176x144)錄影，解析度似乎低了些，加入及修改下述的程式片段來提高錄影的品質。

使用mp4格式，CIF(352x288)

_LIT8(KMimeTypeMPEG4VSPL3, "video/mp4v-es; profile-level-id=3");

使用mp4格式，CIF(640x480, 30 fps, Nokia N95 & N93Support)

_LIT8(KMimeTypeMPEG4VSPL4, "video/mp4v-es; profile-level-id=4");

在程式片段中，在寫入檔案的部份要定義格式

iUtility->OpenFileL( iFilename,
iCameraHandle,
iControllerUid,
iFormatUid,
KMimeTypeMPEG4VSPL4);

在Prepare()之前，必需要錄影格式設定好

TRAP_IGNORE( iUtility->SetVideoFrameSizeL( iUtility ));
TRAP_IGNORE( iUtility->SetVideoBitRateL( KMMFVariableVideoBitRate ));
......
iUtility->Prepare();

Naming Conventions for Symbian

最近比賽告一段落了，要開始學習Symbian的學習，發現....還蠻多東西要看的，像是基本的Coding conventions更為重要啊。以下是在Symbain上Coding時需要注意的convention：

(此資料轉載於Blue119's blog)

Function Convention

• Trailing "D" indicates the deletion of an object
• Trailing "L" means function may leave
• Trailing "C" means an item is placed on the cleanup stack

-------------------------------------------

Variable Convention

• Member variables' names begin with 'i'
• Arguments' names begin with 'a'
• Automatics' (local variables) names have no initial letter, but start in lower case
• Constants' names begin with 'K'
• Global variables are usually avoided, but when used, their names begin with a capital letter.

-----------------------------------

Class Convention

'T' Classes

• Classes that don't own external objects/resources and so can be declared on the stack 'T'types contain their value.
• They do not own any external object, either directly (by pointer) or indirectly (by handle).
• they do not need a destructor to cleanup resources.
• 'T' types may be allocated either on the stack (that is locally as C++ automatic variables) or as members of other classes.
• note that the default stack size is 8KB in Symbian OS.
• Structure types mostly begin with 'T'.

'C' Classes
If a class needs to dynamically allocate any memory or own another class, it should derive, directly or indirectly, from CBase (a built-in Symbian OS class), and its class name should begin with 'C'. CBase-derived classes have the following properties:

• They are allocated on the heap (dynamically allocated) — not on the stack, and not as members of other classes.
• The allocator used for this class hierarchy initializes all member data to binary zeroes.
• They are passed by pointer, or reference, and so do not need an explicit copy constructor or assignment operator unless there is clear intention that a particular class supports copying.
• They have a virtual destructor, which is used for standard cleanup processing.
• They support two-phased construction – this will be covered later in the section.

'R' Classes
These classes are used to access system resources, for example files, via handles. The following are characteristics of ‘R’ classes:

• They contain a handle that is used to pass on requests to other objects.
• They are opened using an "Open()" function particular to the ‘R’ class, and closed using a "Close()" function particular to the class. An ‘R’ object must be closed once if it has been opened.
• They may be freely bit-wise copied.
• They have no explicit constructor, destructor, copy constructor or assignment operator.

'M' Classes
Characteristic:

• Abstract
• Pure virtual functions
• No member data

Purpose:

• define an interface

Advantage:

• reduce dependencies between classes

Rule:

• the only use of multiple inheritance
• A C class derive from one other C class and zero or more M classes

'M'classes have the following restrictions:

• They should contain no member data.
• They should not contain constructors or destructors, or overloaded operators.

'M' classes usually contain pure virtual functions that define a fully abstract interface.

轉載自Blue119's blog:Symbian Coding Conventions:Class

Symbian C++第一次的接觸

因為計劃的關係，要開始接觸從大學時就想玩的Symbian C++程式開發。
開始前必須要先把環境set up起來，所以開始找尋開發相關的資料，直接從google下手？當然不嘍，直接前往Forum Nokia，就可以找到Series 60 SDK Tools，裡面的資料相當的豐富，甚至develop documents也相當的多。

如果要使用Symbian C++作為開發工具必須要先安裝好開發環境，在Forum Nokia網站中，可以發現目前Nokia兩大主要的平台：

Series 40
└以低階切入市場，所以Series 40 platforms推出的手機價格約在2000~8000左右。在開發方面，Series 40只提供使用者J2ME develop，目前Series 40已經更新到5th Edition。
Series 60
└主要提供高階市場使用，有較完善的軟體支援與開發工具。除了提供J2ME develop之外，在Forum Nokia網站中，可以下載到Series 60 Symbian C++2的developments Tools and SDKs，使用者可以直接使用Symbian OS API撰寫Series 60上的程式。

以上為Nokia主推的Symbian platforms。當然，Symbian platforms不只有以上兩種，Nokia早期時還有Series 80(Nokia 9210)，另外也有SonyEricsson主推的Symbian UIQ platforms(p800, p900)。

下圖為Series platform structure

(取自於Forum Nokia Platforms)

--------------------------------------------------------------------------------------------

在這次的計劃中，主要是使用Series 60 platforms，並利用C++進行開發，當然對我而言是一個新的挑戰，畢竟之前沒有摸過C++與MFC，所以可能需要花一點時間在基本工上。

下載開發工具
需下載之工具
└ IDE開發工具(MS Visual Studio .NET或Carbide C++)
└ S60 Platform SDKs for Symbian OS, for C++
└ ActivePerl (http://www.activestate.com/)

直接連上Forum Nokia(http://www.forum.nokia.com/)下載工具，在網頁左邊Menu選單可以看到Platforms，點選後可以選擇Series 40 & 60 platforms。在下載SDKs前，必需要先選定所要開始的IDE工具，可以使用MS Visual Studio .NET進行開發(請下載Carbide.vs)，或是使用Carbide C++工具進行開發(很像Eclipse IDE)。

在這邊我直接使用Carbide C++進行開發。

安裝流程
1. S60 Platform SDKs for Symbian OS, for C++
2. ActivePerl
3. Carbide C++
4. 重開機

重開機完成後，直接執行Carbide C++，第一次執行時，會詢問設定workspaces，就依照自己的習慣設定吧。

(Carbide C++ IDE畫面)

參考網站
Forum Nokia Series 60
Wikipedia - Synbian OS