android - NDK 未解析函数 : media_status_t AMediaCodec_createInputSurface(AMediaCodec *mData, ANativeWindow **surface)

Question

NDK 文档说此函数可用 ( https://developer.android.com/ndk/reference/group/media#group___media_1ga8eb3e60bb5c76e90d7652dff636dd17b )，实际上它可以从 java 代码调用，但它会从 C++ 代码生成“未解析的函数”[在 Android Studio 中] 错误。

我正在尝试将 MJPEG 流提供给 MediaCodec 并让 MediaMuxer 从中录制 MP4 视频。关于如何在 Java 代码中做类似的事情，我发现了有限的例子，但是关于如何在 native 代码中做任何类似的事情的例子却为零。所以我试图在 native 代码中复制 Java 示例。这个特定的函数调用似乎对实现我的目标相对重要，我可以从 java 代码成功调用:MediaCodec.createInputSurface()。我查看了 media/NdkMediaCodec.h 并且 createInputSurface() NOT 列出了。

我是不是用错了方法，有什么我不明白的地方吗？这是 native 代码:

jboolean Java_com_business_rky_tht_1app_MjpegView_StartMP4Record(JNIEnv *env, jclass clazz, jobject surface, jstring filename) {

AMediaCodec *Native_codec = AMediaCodec_createEncoderByType("video/avc");
if (Native_codec != NULL)
{
    AMediaFormat *Media_Format = AMediaFormat_new();
    if (Media_Format != NULL) 
    {
        AMediaCrypto *Media_Crypto = NULL;
        uint32_t Config_Flags = AMEDIACODEC_CONFIGURE_FLAG_ENCODE;
        ANativeWindow *Native_Window  = ANativeWindow_fromSurface(env, surface);

        if(Native_Window == NULL)
            return JNI_FALSE;

        int32_t Frame_Height = ANativeWindow_getHeight(Native_Window);
        int32_t Frame_Width  = ANativeWindow_getWidth(Native_Window);

        // Make the work area of the frame a multiple of 64
        int32_t Image_Height = (Frame_Height & (0xFFFFFFC0) );
        int32_t Image_Width = (Frame_Width & (0xFFFFFFC0) );
        int32_t Color_Format = ANativeWindow_getFormat(Native_Window);

        // No limits for input size
        // AMediaFormat_setInt32(format, "max-input-size", 0);
        AMediaFormat_setInt32(Media_Format, AMEDIAFORMAT_KEY_MAX_INPUT_SIZE, 0);
        AMediaFormat_setInt32(Media_Format, AMEDIAFORMAT_KEY_MAX_HEIGHT, Frame_Height);
        AMediaFormat_setInt32(Media_Format, AMEDIAFORMAT_KEY_MAX_WIDTH, Frame_Width);
        AMediaFormat_setString(Media_Format, AMEDIAFORMAT_KEY_MIME, "video/avc");
        AMediaFormat_setInt32(Media_Format, AMEDIAFORMAT_KEY_HEIGHT, Frame_Height);
        AMediaFormat_setInt32(Media_Format, AMEDIAFORMAT_KEY_WIDTH, Frame_Width);

        // ** For simplicity we just crop from right and bottom,
        // ** to center the image 1/2 the differences should be
        // ** cropped from all four sides
        AMediaFormat_setInt32(Media_Format, "crop-left" , 0);
        AMediaFormat_setInt32(Media_Format, "crop-top" , 0);
        AMediaFormat_setInt32(Media_Format, "crop-right" , (Image_Width - 1));
        AMediaFormat_setInt32(Media_Format, "crop-bottom" , (Image_Height - 1));
        AMediaFormat_setInt32(Media_Format,AMEDIAFORMAT_KEY_STRIDE,Frame_Width);

        AMediaFormat_setInt32(Media_Format, AMEDIAFORMAT_KEY_COLOR_FORMAT, Color_Format);

        media_status_t rc = AMediaCodec_configure(Native_codec, Media_Format, NULL, NULL, Config_Flags);

        if (AMEDIA_OK == rc) {

            AMediaCodec_createInputSurface(Native_codec, &Native_Window);
                            //  ^^^ UNRESOLVED - UNRESOLVED - UNRESOLVED ^^^


            // Would start codec and create muxer
            // .
            // .
            // .
            return JNI_TRUE;
        }else{
            AMediaCodec_delete(Native_codec);
            ANativeWindow_release(Native_Window);
            return JNI_FALSE;
        }
    } // End - if (Media_Format != NULL)
} // End - if (Native_codec != NULL)

}//结束 - StartMP4Rec

---

构建错误:

Build command failed. Error while executing process C:\Users\rky\AppData\Local\Android\Sdk\ndk-bundle\ndk-build.cmd with arguments {NDK_PROJECT_PATH=null APP_BUILD_SCRIPT=C:\Users\rky\AndroidStudioProjects\THT_App\app\src\main\jni\Android.mk NDK_APPLICATION_MK=C:\Users\rky\AndroidStudioProjects\THT_App\app\src\main\jni\Application.mk APP_ABI=arm64-v8a NDK_ALL_ABIS=arm64-v8a NDK_DEBUG=1 APP_PLATFORM=android-18 NDK_OUT=C:/Users/rky/AndroidStudioProjects/THT_App/app/build/intermediates/ndkBuild/debug/obj NDK_LIBS_OUT=C:\Users\rky\AndroidStudioProjects\THT_App\app\build\intermediates\ndkBuild\debug\lib C:/Users/rky/AndroidStudioProjects/THT_App/app/build/intermediates/ndkBuild/debug/obj/local/arm64-v8a/libMjpgToMP4.so} [arm64-v8a] Compile++ : MjpgToMP4 <= MjpgToMP4.cpp C:/Users/rky/AndroidStudioProjects/THT_App/app/src/main/jni/MjpgToMP4/MjpgToMP4.cpp:320:17: error: use of undeclared identifier 'AMediaCodec_createInputSurface'; did you mean 'AMediaCodec_setOutputSurface'? AMediaCodec_createInputSurface(Native_codec, &Native_Window); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ AMediaCodec_setOutputSurface C:/Users/rky/AppData/Local/Android/Sdk/ndk-bundle/build//../sysroot/usr/include\media/NdkMediaCodec.h:266:16: note: 'AMediaCodec_setOutputSurface' declared here media_status_t AMediaCodec_setOutputSurface(AMediaCodec*, ANativeWindow* surface) __INTRODUCED_IN(21); ^ C:/Users/rky/AndroidStudioProjects/THT_App/app/src/main/jni/MjpgToMP4/MjpgToMP4.cpp:320:62: error: cannot initialize a parameter of type 'ANativeWindow ' with an rvalue of type 'ANativeWindow ' AMediaCodec_createInputSurface(Native_codec, &Native_Window); ^~~~~~~~~~~~~~ C:/Users/rky/AppData/Local/Android/Sdk/ndk-bundle/build//../sysroot/usr/include\media/NdkMediaCodec.h:266:74: note: passing argument to parameter 'surface' here media_status_t AMediaCodec_setOutputSurface(AMediaCodec, ANativeWindow* surface) __INTRODUCED_IN(21); ^ 2 errors generated. make: * [C:/Users/rky/AndroidStudioProjects/THT_App/app/build/intermediates/ndkBuild/debug/obj/local/arm64-v8a/objs-debug/MjpgToMP4/MjpgToMP4.o] Error 1

Answer 1

这些功能是在 API 级别 21 26 引入的，但是您的构建指定了 APP_PLATFORM=android-18。确保您没有在 build.gradle 中将 minSdkVersion 设置得太低。