[AI Refactoring] MediaCodec.GetCodecType/CheckMimeType 의 dynamic + Convert.ChangeType 제거 → DLR/박싱 제거 [Scope: src/Tizen.Multimedia.MediaCodec] (2026-06-07)

[JoonghyunCho]

[Type: Refactoring]
[Scope: src/Tizen.Multimedia.MediaCodec]
[Priority: 🟡 Improvement]
[Lens: Performance, Modernization, Clean Code]

Observation

MediaCodec.GetCodecType<T> and CheckMimeType<T> use dynamic + Convert.ChangeType purely to dispatch to the correct TypeConverter.ToNative overload, even though both public callers already pass a concrete enum type.

// src/Tizen.Multimedia.MediaCodec/MediaCodec/MediaCodec.cs : 421-443
private MediaCodecTypes GetCodecType<T>(T mimeType, Type type, bool isEncoder)
{
    dynamic changedType = Convert.ChangeType(mimeType, type);
    int codecType = TypeConverter.ToNative(changedType);
    Native.GetSupportedType(_handle, codecType, isEncoder, out int value)
        .ThrowIfFailed("Failed to get supported media codec type.");
    return (MediaCodecTypes)value;
}

private bool CheckMimeType<T>(Type mimeType, T value)
{
    if (!Enum.IsDefined(mimeType, value))
    {
        throw new ArgumentException($"The mime type value is invalid : { value }.");
    }
    dynamic changedType = Convert.ChangeType(value, mimeType);
    var codecType = TypeConverter.ToNative(changedType);
    return Enum.IsDefined(typeof(SupportedCodecType), codecType);
}

The two public entry points already know the concrete type:

public MediaCodecTypes GetCodecType(bool encoder, MediaFormatVideoMimeType type) { ... GetCodecType(type, typeof(MediaFormatVideoMimeType), encoder); }
public MediaCodecTypes GetCodecType(bool encoder, MediaFormatAudioMimeType type) { ... GetCodecType(type, typeof(MediaFormatAudioMimeType), encoder); }

Problem

• Performance: dynamic pulls in the DLR / Microsoft.CSharp call-site infrastructure, incurs first-call binding cost, and Convert.ChangeType boxes the enum on every call — all to re-select an overload the caller already knows statically. (Convert.ChangeType(mimeType, type) here is essentially an identity conversion: type == typeof(T).)
• Clean Code / Modernization: dynamic obscures which TypeConverter.ToNative overload runs and adds a needless generic + Type parameter that merely mirrors typeof(T).

This is a query/config-time API (not a per-frame path), so the win is correctness/clarity + removing the DLR dependency rather than a per-frame hot-path saving.

Proposed Improvement

Drop dynamic/Convert.ChangeType and call the concrete TypeConverter.ToNative overload directly from each strongly-typed public method (or via non-generic private helpers taking the already-resolved int codecType).

Before

return GetCodecType(type, typeof(MediaFormatVideoMimeType), encoder);
// ...
private MediaCodecTypes GetCodecType<T>(T mimeType, Type type, bool isEncoder)
{
    dynamic changedType = Convert.ChangeType(mimeType, type);
    int codecType = TypeConverter.ToNative(changedType);
    ...
}

After

// strongly-typed call sites compute codecType directly:
int codecType = TypeConverter.ToNative(type);   // overload resolved at compile time
return GetCodecType(codecType, encoder);
// ...
private MediaCodecTypes GetCodecType(int codecType, bool isEncoder)
{
    Native.GetSupportedType(_handle, codecType, isEncoder, out int value)
        .ThrowIfFailed("Failed to get supported media codec type.");
    return (MediaCodecTypes)value;
}

CheckMimeType similarly validates with Enum.IsDefined(typeof(SupportedCodecType), TypeConverter.ToNative(type)).

Target Files

• src/Tizen.Multimedia.MediaCodec/MediaCodec/MediaCodec.cs

Expected Impact (Quantitative Metrics)

• DLR call-site init + boxing Convert.ChangeType per call: 2 dynamic sites → 0
• Removes the Microsoft.CSharp dynamic dependency from this call graph.
• Allocation per GetCodecType/CheckMimeType call: 1 box → 0.

API Compatibility Check

• Public API signature change: none (only private helpers GetCodecType<T>/CheckMimeType<T> are reshaped; the public GetCodecType(bool, MediaFormat*MimeType) overloads are unchanged)
• Behavior change: none (same native codecType, same ArgumentException on invalid type)
• Tizen API Level floor: maintained

Impact Scope

• Private helpers: GetCodecType<T> and CheckMimeType<T> — used only inside MediaCodec.cs (2 callers each). No external/cross-assembly callers.
• Same-assembly only.

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Auto-generated by the TizenFX AI refactoring discovery pipeline (scan date 2026-06-07).