Android本地视频播放器开发--SDL编译

在上一章

Android本地视频播放器开发--ffmpeg解码视频文件中的音频(2)中使用OpenSL ES来播放视频的声音，遗留的问题是声音的不同步，由于视频实现部分也要同步，而且音视频也要同步，所以音频部分就不单独同步问题，当同时播放音视频的时候进行两者的同步问题，对于视频显示部分最后是要使用OpenGL
es来实现，由于SDL可以和OpenGL ES进行搭配，所以使用SDL+OpenGL ES进行显示视频，所以这章将要讲解的是SDL的交叉编译.

一、到官网下载http://www.libsdl.org/hg.php 下载2.0的源码也可以通过hg来clone最新的源码
hg clone http://hg.libsdl.org/SDL 二、其实1.3以后的版本就添加了android的支持，所以下载完源码后，在SDL目录下创建一个jni的目录，然后将原先SDL目录下面的文件以及文件夹都拷贝到jni目录下面，在jni目录下面我们会看见一个android.mk的文件,这就是官方给我们编写的编译文件，由于手机基本上都是使用的arm编译器，所以我在里面添加了LOCAL_ARM_MODE=arm，模块的编译使用arm编译器来编译，具体的内容如下:

###########################
#
# SDL shared library
#
###########################

include $(CLEAR_VARS)

LOCAL_MODULE := SDL2
LOCAL_ARM_MODE=arm
LOCAL_C_INCLUDES := $(LOCAL_PATH)/include

LOCAL_SRC_FILES := \
        $(subst $(LOCAL_PATH)/,, \
        $(wildcard $(LOCAL_PATH)/src/*.c) \
        $(wildcard $(LOCAL_PATH)/src/audio/*.c) \
        $(wildcard $(LOCAL_PATH)/src/audio/android/*.c) \
        $(wildcard $(LOCAL_PATH)/src/audio/dummy/*.c) \
        $(LOCAL_PATH)/src/atomic/SDL_atomic.c \
        $(LOCAL_PATH)/src/atomic/SDL_spinlock.c.arm \
        $(wildcard $(LOCAL_PATH)/src/core/android/*.cpp) \
        $(wildcard $(LOCAL_PATH)/src/cpuinfo/*.c) \
        $(wildcard $(LOCAL_PATH)/src/events/*.c) \
        $(wildcard $(LOCAL_PATH)/src/file/*.c) \
        $(wildcard $(LOCAL_PATH)/src/haptic/*.c) \
        $(wildcard $(LOCAL_PATH)/src/haptic/dummy/*.c) \
        $(wildcard $(LOCAL_PATH)/src/joystick/*.c) \
        $(wildcard $(LOCAL_PATH)/src/joystick/android/*.c) \
        $(wildcard $(LOCAL_PATH)/src/loadso/dlopen/*.c) \
        $(wildcard $(LOCAL_PATH)/src/power/*.c) \
        $(wildcard $(LOCAL_PATH)/src/power/android/*.c) \
        $(wildcard $(LOCAL_PATH)/src/render/*.c) \
        $(wildcard $(LOCAL_PATH)/src/render/*/*.c) \
        $(wildcard $(LOCAL_PATH)/src/stdlib/*.c) \
        $(wildcard $(LOCAL_PATH)/src/thread/*.c) \
        $(wildcard $(LOCAL_PATH)/src/thread/pthread/*.c) \
        $(wildcard $(LOCAL_PATH)/src/timer/*.c) \
        $(wildcard $(LOCAL_PATH)/src/timer/unix/*.c) \
        $(wildcard $(LOCAL_PATH)/src/video/*.c) \
        $(wildcard $(LOCAL_PATH)/src/video/android/*.c))

LOCAL_CFLAGS += -DGL_GLEXT_PROTOTYPES
LOCAL_LDLIBS := -ldl -lGLESv1_CM -lGLESv2 -llog

include $(BUILD_SHARED_LIBRARY)

三、如果直接编译的话会提示如下错误

/home/SDL/jni/src/core/android/SDL_android.cpp:30:21: fatal error: EGL/egl.h: No such file or directory

查看EGL的支持是在2.3版本以上，所以我们需要添加平台的支持，所以需要在jni目录下面创建一个Application.mk文件来指定编译平台，内容如下:

APP_ABI := armeabi
APP_PLATFORM := android-9

四、在jni目录终端下运行ndk-build，就会编译出libSDL2.so，编译过程如下:

root@zhangjie:/home/SDL/jni# ndk-build
Compile arm    : SDL2 <= SDL_assert.c
Compile arm    : SDL2 <= SDL.c
Compile arm    : SDL2 <= SDL_error.c
Compile arm    : SDL2 <= SDL_fatal.c
Compile arm    : SDL2 <= SDL_hints.c
Compile arm    : SDL2 <= SDL_log.c
Compile arm    : SDL2 <= SDL_audio.c
Compile arm    : SDL2 <= SDL_audiocvt.c
Compile arm    : SDL2 <= SDL_audiodev.c
Compile arm    : SDL2 <= SDL_audiotypecvt.c
Compile arm    : SDL2 <= SDL_mixer.c
Compile arm    : SDL2 <= SDL_wave.c
Compile arm    : SDL2 <= SDL_androidaudio.c
Compile arm    : SDL2 <= SDL_dummyaudio.c
Compile arm    : SDL2 <= SDL_atomic.c
Compile arm    : SDL2 <= SDL_spinlock.c
Compile++ arm    : SDL2 <= SDL_android.cpp
Compile arm    : SDL2 <= SDL_cpuinfo.c
Compile arm    : SDL2 <= SDL_clipboardevents.c
Compile arm    : SDL2 <= SDL_dropevents.c
Compile arm    : SDL2 <= SDL_events.c
Compile arm    : SDL2 <= SDL_gesture.c
Compile arm    : SDL2 <= SDL_keyboard.c
Compile arm    : SDL2 <= SDL_mouse.c
Compile arm    : SDL2 <= SDL_quit.c
Compile arm    : SDL2 <= SDL_touch.c
Compile arm    : SDL2 <= SDL_windowevents.c
Compile arm    : SDL2 <= SDL_rwops.c
Compile arm    : SDL2 <= SDL_haptic.c
Compile arm    : SDL2 <= SDL_syshaptic.c
Compile arm    : SDL2 <= SDL_gamecontroller.c
Compile arm    : SDL2 <= SDL_joystick.c
Compile arm    : SDL2 <= SDL_sysjoystick.c
Compile arm    : SDL2 <= SDL_sysloadso.c
Compile arm    : SDL2 <= SDL_power.c
Compile arm    : SDL2 <= SDL_syspower.c
Compile arm    : SDL2 <= SDL_render.c
Compile arm    : SDL2 <= SDL_yuv_mmx.c
Compile arm    : SDL2 <= SDL_yuv_sw.c
Compile arm    : SDL2 <= SDL_render_d3d.c
Compile arm    : SDL2 <= SDL_render_gles2.c
Compile arm    : SDL2 <= SDL_shaders_gles2.c
Compile arm    : SDL2 <= SDL_render_gles.c
Compile arm    : SDL2 <= SDL_render_gl.c
Compile arm    : SDL2 <= SDL_shaders_gl.c
Compile arm    : SDL2 <= SDL_render_psp.c
Compile arm    : SDL2 <= SDL_blendfillrect.c
Compile arm    : SDL2 <= SDL_blendline.c
Compile arm    : SDL2 <= SDL_blendpoint.c
Compile arm    : SDL2 <= SDL_drawline.c
Compile arm    : SDL2 <= SDL_drawpoint.c
Compile arm    : SDL2 <= SDL_render_sw.c
Compile arm    : SDL2 <= SDL_rotate.c
Compile arm    : SDL2 <= SDL_getenv.c
Compile arm    : SDL2 <= SDL_iconv.c
Compile arm    : SDL2 <= SDL_malloc.c
Compile arm    : SDL2 <= SDL_qsort.c
Compile arm    : SDL2 <= SDL_stdlib.c
Compile arm    : SDL2 <= SDL_string.c
Compile arm    : SDL2 <= SDL_thread.c
Compile arm    : SDL2 <= SDL_syscond.c
Compile arm    : SDL2 <= SDL_sysmutex.c
Compile arm    : SDL2 <= SDL_syssem.c
Compile arm    : SDL2 <= SDL_systhread.c
Compile arm    : SDL2 <= SDL_timer.c
Compile arm    : SDL2 <= SDL_systimer.c
Compile arm    : SDL2 <= SDL_blit_0.c
Compile arm    : SDL2 <= SDL_blit_1.c
Compile arm    : SDL2 <= SDL_blit_A.c
Compile arm    : SDL2 <= SDL_blit_auto.c
Compile arm    : SDL2 <= SDL_blit.c
Compile arm    : SDL2 <= SDL_blit_copy.c
Compile arm    : SDL2 <= SDL_blit_N.c
Compile arm    : SDL2 <= SDL_blit_slow.c
Compile arm    : SDL2 <= SDL_bmp.c
Compile arm    : SDL2 <= SDL_clipboard.c
Compile arm    : SDL2 <= SDL_fillrect.c
Compile arm    : SDL2 <= SDL_pixels.c
Compile arm    : SDL2 <= SDL_rect.c
Compile arm    : SDL2 <= SDL_RLEaccel.c
Compile arm    : SDL2 <= SDL_shape.c
Compile arm    : SDL2 <= SDL_stretch.c
Compile arm    : SDL2 <= SDL_surface.c
Compile arm    : SDL2 <= SDL_video.c
Compile arm    : SDL2 <= SDL_androidclipboard.c
Compile arm    : SDL2 <= SDL_androidevents.c
Compile arm    : SDL2 <= SDL_androidgl.c
Compile arm    : SDL2 <= SDL_androidkeyboard.c
Compile arm    : SDL2 <= SDL_androidtouch.c
Compile arm    : SDL2 <= SDL_androidvideo.c
Compile arm    : SDL2 <= SDL_androidwindow.c
StaticLibrary  : libstdc++.a
SharedLibrary  : libSDL2.so
Install        : libSDL2.so => libs/armeabi/libSDL2.so

编译出sdl库后，我们就可以调用它的相关函数来实现我们的功能了。

下一章将要使用ffmpeg来解码视频文件