Re-Compile JNI DJIVIDEOSTREAMDECODE

[lillogoal]

Hello to all, I'm trying to re-compile the source C ++, using the latest Android NDK builder. The code is posted here: https://github.com/DJI-Mobile-SDK-Tutorials/Android-VideoStreamDecodingSample/tree/master/android-videostreamdecodingsample/jni

I have this problem, this is the log:

[armeabi-v7a] Compile thumb : djivideojni <= dji_video_jni.c jni/dji_video_jni.c:65:51: warning: passing 'uint8_t ' (aka 'unsigned char ') to parameter of type 'const jbyte ' (aka 'const signed char ') converts between pointers to integer types with different sign [-Wpointer-sign] (*env)->SetByteArrayRegion(env, jarray, 0, size, buf); ^~~ 1 warning generated. [armeabi-v7a] Prebuilt : libffmpeg.so <= jni/ [armeabi-v7a] SharedLibrary : libdjivideojni.so D:/Users/Lorenzo/AppData/Local/Android/sdk/ndk-bundle/build//../toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin\ld: error: ./obj/local/armeabi-v7a/libffmpeg.so:1:9: syntax er ror, unexpected STRING D:/Users/Lorenzo/AppData/Local/Android/sdk/ndk-bundle/build//../toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/../../../../arm-linux-androideabi/bin\ld: error: ./obj/local/armeabi-v7a/libffmpeg.so: not an object or archive jni/dji_video_jni.c:43: error: undefined reference to 'av_register_all' jni/dji_video_jni.c:45: error: undefined reference to 'av_codec_next' jni/dji_video_jni.c:78: error: undefined reference to 'avcodec_register_all' jni/dji_video_jni.c:79: error: undefined reference to 'av_register_all' jni/dji_video_jni.c:82: error: undefined reference to 'avcodec_find_decoder' jni/dji_video_jni.c:83: error: undefined reference to 'avcodec_alloc_context3' jni/dji_video_jni.c:84: error: undefined reference to 'av_parser_init' jni/dji_video_jni.c:97: error: undefined reference to 'avcodec_open2' jni/dji_video_jni.c:103: error: undefined reference to 'av_frame_alloc' jni/dji_video_jni.c:127: error: undefined reference to 'av_init_packet' jni/dji_video_jni.c:132: error: undefined reference to 'av_parser_parse2' jni/dji_video_jni.c:165: error: undefined reference to 'av_free_packet' jni/dji_video_jni.c:223: error: undefined reference to 'avcodec_close' jni/dji_video_jni.c:227: error: undefined reference to 'av_free' jni/dji_video_jni.c:228: error: undefined reference to 'av_free' jni/dji_video_jni.c:229: error: undefined reference to 'av_parser_close' clang++.exe: error: linker command failed with exit code 1 (use -v to see invocation) make: *** [obj/local/armeabi-v7a/libdjivideojni.so] Error 1

[pisarik]

I have stepped into the same problem and found a solution. This happened, because I didn't notice in readme the important section.

I noticed that libffmpeg.so takes only 1KB of memory. Meanwhile original libffmpeg.so takes about 60MB of memory and therefore it was stored with help of special module . That is why your linking failed.

In that case you can complete linking without dipping into git lfs (but I am sure, that it is pretty simple). You can just download this original libffmpeg.so and replace the "placeholder" libffmpeg.so which located in app/jni

Also don't forget to change package names in dji_video_jni.c functions, which tagged as JNI_EXPORT

[lillogoal]

@pisarik thank you so much :)

[giannisergente]

Hi @lillogoal, we have the same issue (https://github.com/DJI-Mobile-SDK-Tutorials/Android-VideoStreamDecodingSample/issues/12). Did you solve also for arm64-v8a e x86 ABI? Because in those cases compilation fails :(

[dji-dev]

Will go ahead and close this ticket as current version should have a fix for v8a and x86 already. Please feel free to reopen if the problem still exists. Thanks!