我有一个完全由C / C ++代码组成的Android NDK项目，它基本上处理图像而不使用任何外部库。
我正在使用Android Studio + Gradle NDK实验插件（0.7.0-alpha1）。
现在，我需要将ffmpeg集成为本机库，以便从C / C ++代码中使用它来解码H.264视频帧。
这些是我在这里找到的关于这个问题的问题：
Android - Integrating ffmpeg and android-ndk-r9c
Android NDK w/ ffmpeg library - error running project
Using FFmpeg native libraries with Android-NDK
Can not build with prebuilt static libraries using gradle-experimental
这是我的build.gradle文件：
apply plugin: 'com.android.model.application'
def ffmpeg_path = file(project(':ffmpeg').projectDir).absolutePath + "/ffmpeg-android"
model {
repositories {
libs(PrebuiltLibraries) {
libavcodec {
headers.srcDir "${ffmpeg_path}/include"
binaries.withType(StaticLibraryBinary) {
staticLibraryFile = file("${ffmpeg_path}/${targetPlatform.getName()}/lib/libavcodec.a")
}
}
libavutil {
headers.srcDir "${ffmpeg_path}/include"
binaries.withType(StaticLibraryBinary) {
staticLibraryFile = file("${ffmpeg_path}/${targetPlatform.getName()}/lib/libavutil.a")
}
}
libswresample {
headers.srcDir "${ffmpeg_path}/include"
binaries.withType(StaticLibraryBinary) {
staticLibraryFile = file("${ffmpeg_path}/${targetPlatform.getName()}/lib/libswresample.a")
}
}
libswscale {
headers.srcDir "${ffmpeg_path}/include"
binaries.withType(StaticLibraryBinary) {
staticLibraryFile = file("${ffmpeg_path}/${targetPlatform.getName()}/lib/libswscale.a")
}
}
libavformat {
headers.srcDir "${ffmpeg_path}/include"
binaries.withType(StaticLibraryBinary) {
staticLibraryFile = file("${ffmpeg_path}/${targetPlatform.getName()}/lib/libavformat.a")
}
}
libavdevice {
headers.srcDir "${ffmpeg_path}/include"
binaries.withType(StaticLibraryBinary) {
staticLibraryFile = file("${ffmpeg_path}/${targetPlatform.getName()}/lib/libavdevice.a")
}
}
libavfilter {
headers.srcDir "${ffmpeg_path}/include"
binaries.withType(StaticLibraryBinary) {
staticLibraryFile = file("${ffmpeg_path}/${targetPlatform.getName()}/lib/libavfilter.a")
}
}
libpostproc {
headers.srcDir "${ffmpeg_path}/include"
binaries.withType(StaticLibraryBinary) {
staticLibraryFile = file("${ffmpeg_path}/${targetPlatform.getName()}/lib/libpostproc.a")
}
}
}
}
android {
compileSdkVersion = 23
buildToolsVersion = "23.0.2"
defaultConfig.with {
applicationId = "com.example.hellojni"
minSdkVersion.apiLevel = 4
targetSdkVersion.apiLevel = 23
}
}
/*
* native build settings
*/
android.ndk {
moduleName = "hello-jni"
platformVersion = 9 //same as minSdkVersion.apiLevel for better compatibility
stl = "c++_static"
abiFilters.addAll(["armeabi", "armeabi-v7a", "x86"]) //filtering ABIs on the ones Google Play Games library is compatible with.
}
android.buildTypes {
release {
minifyEnabled = false
proguardFiles.add(file('proguard-rules.txt'))
}
}
android.sources {
main {
jni {
dependencies {
library "libavcodec" linkage "static"
library "libavutil" linkage "static"
library "libswresample" linkage "static"
library "libswscale" linkage "static"
library "libavformat" linkage "static"
library "libavdevice" linkage "static"
library "libavfilter" linkage "static"
library "libpostproc" linkage "static"
}
}
}
}
}
我基于Google的this sample，它集成了一个外部本机库。
这是我在将它导入我的之前编译的ffmpeg项目：https://github.com/WritingMinds/ffmpeg-android
我已经添加了所有的.a和.h文件，我可以在我的C / C ++代码中导入标题，但是当我尝试编译它时，我收到以下错误：
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(utils.o):utils.c:function try_decode_frame: error: undefined reference to 'avpriv_h264_has_num_reorder_frames'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(utils.o):utils.c:function compute_pkt_fields: error: undefined reference to 'avpriv_h264_has_num_reorder_frames'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(utils.o):utils.c:function parse_packet: error: undefined reference to 'av_parser_parse2'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(utils.o):utils.c:function parse_packet: error: undefined reference to 'av_parser_close'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(utils.o):utils.c:function read_frame_internal: error: undefined reference to 'av_parser_init'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(utils.o):utils.c:function avformat_find_stream_info: error: undefined reference to 'av_parser_init'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(utils.o):utils.c:function avformat_find_stream_info: error: undefined reference to 'avcodec_pix_fmt_to_codec_tag'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(utils.o):utils.c:function avformat_find_stream_info: error: undefined reference to 'avpriv_get_raw_pix_fmt_tags'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(utils.o):utils.c:function ff_stream_add_bitstream_filter: error: undefined reference to 'av_bitstream_filter_init'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(utils.o):utils.c:function ff_stream_add_bitstream_filter: error: undefined reference to 'av_bitstream_filter_close'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(utils.o):utils.c:function av_apply_bitstream_filters: error: undefined reference to 'av_bitstream_filter_filter'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(aadec.o):aadec.c:function aa_read_packet: error: undefined reference to 'av_tea_init'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(aadec.o):aadec.c:function aa_read_packet: error: undefined reference to 'av_tea_crypt'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(aadec.o):aadec.c:function aa_read_header: error: undefined reference to 'av_tea_alloc'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(aadec.o):aadec.c:function aa_read_header: error: undefined reference to 'av_tea_init'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(aadec.o):aadec.c:function aa_read_header: error: undefined reference to 'av_tea_crypt'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(ac3dec.o):ac3dec.c:function ac3_eac3_probe.isra.0: error: undefined reference to 'avpriv_ac3_parse_header'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(adtsenc.o):adtsenc.c:function adts_write_header: error: undefined reference to 'avpriv_mpeg4audio_get_config'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(adtsenc.o):adtsenc.c:function adts_write_header: error: undefined reference to 'avpriv_copy_pce_data'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(asfcrypt.o):asfcrypt.c:function ff_asfcrypt_dec: error: undefined reference to 'av_rc4_alloc'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(asfcrypt.o):asfcrypt.c:function ff_asfcrypt_dec: error: undefined reference to 'av_rc4_init'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(asfcrypt.o):asfcrypt.c:function ff_asfcrypt_dec: error: undefined reference to 'av_rc4_crypt'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(asfcrypt.o):asfcrypt.c:function ff_asfcrypt_dec: error: undefined reference to 'av_rc4_init'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(asfcrypt.o):asfcrypt.c:function ff_asfcrypt_dec: error: undefined reference to 'av_rc4_crypt'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(matroska.o):matroska.c:function ff_mkv_stereo3d_conv: error: undefined reference to 'av_stereo3d_alloc'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(nut.o):nut.c:function ff_nut_add_sp: error: undefined reference to 'av_tree_node_alloc'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(nut.o):nut.c:function ff_nut_add_sp: error: undefined reference to 'av_tree_insert'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(nut.o):nut.c:function ff_nut_free_sp: error: undefined reference to 'av_tree_enumerate'
/Users/marcos/Documents/Android/fdecoder/ffmpeg/ffmpeg-android/armeabi-v7a/lib/libavformat.a(nut.o):nut.c:function ff_nut_free_sp: error: undefined reference to 'av_tree_destroy'
Error:error: ld returned 1 exit status
Error:Execution failed for task ':app:linkHello-jniArmeabi-v7aDebugSharedLibrary'.
> A build operation failed.
Linker failed while linking libhello-jni.so.
See the complete log at: file:///Users/marcos/Documents/Android/fdecoder/app/build/tmp/linkHello-jniArmeabi-v7aDebugSharedLibrary/output.txt
Information:BUILD FAILED
Information:Total time: 14.993 secs
Information:2 errors
Information:0 warnings
Information:See complete output in console
显然我没有正确导入，但无法确切地知道缺少什么。
下面的Makefile对我有用。 （对应于这个qazxsw poi）
code