在带有 NDK 的 Android 上使用带有 FFmpeg 的 openssl

Question

I cross compiled FFmpeg with openssl support using the scripts from the Guardian project however my code crashes whenever I execute the following:

System.loadLibrary("crypto");    // loads OK
System.loadLibrary("ssl");       // loads OK
System.loadLibrary("avformat");  // crashes

The error:

dlopen("/data/data/wseemann.media.demo/lib/libavformat.so") failed: dlopen failed: cannot locate symbol "SSL_library_init" referenced by "libavformat.so"...

I build libavformat with a toolchain and then run ndk-build using the following Android.mk file to create the .so files:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE := libswscale
LOCAL_SRC_FILES := ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavcodec
LOCAL_SRC_FILES := ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavformat
LOCAL_SRC_FILES := ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libavutil
LOCAL_SRC_FILES := ffmpeg/$(TARGET_ARCH_ABI)/lib/$(LOCAL_MODULE).so
LOCAL_EXPORT_C_INCLUDES := $(LOCAL_PATH)/ffmpeg/$(TARGET_ARCH_ABI)/include
include $(PREBUILT_SHARED_LIBRARY)

LOCAL_PATH:= $(call my-dir)

It would seem that libavformat needs libcrypto and libssl when it is loaded but it can't find them or isn't loading them. Does anyone know how to fix this issue?

Answer 1

The problem is that there normally is libssl.so in /system/lib . The loader System.loadLibrary() prefers that path to your app lib directory ( /data/data/your.package.name/lib ), and this is what may cause confusion. The easiest fix is to use System.load("/data/data/your.package.name/lib/libssl.so") instead (there are correct ways to obtain the path, too).

Another fix could be to rename libssl.so that you prepared, to libavssl.so , and call System.loadLibrary("avssl") . Note that maybe you will be required to recompile libavformat so that it looks for libavssl.so .

Answer 2

This worked for me in FFmpegMediaPlayer.java line 614:

static {

    System.loadLibrary("crypto");    // loads OK
    System.loadLibrary("ssl");       // loads OK

    for (int i = 0; i < JNI_LIBRARIES.length; i++) {

        Log.d("TAG", JNI_LIBRARIES[i]);

        System.loadLibrary(JNI_LIBRARIES[i]);

    }

    native_init();

}