[FFmpeg-devel] [PATCH v2 1/6] avcodec: add av_jni_{get, set}_android_app_ctx helper

[Matthieu Bouron]

On Mon, Mar 4, 2024 at 4:11 PM Matthieu Bouron
<matthieu.bouron at gmail.com> wrote:
>
> On Mon, Mar 4, 2024 at 12:29 PM Andreas Rheinhardt
> <andreas.rheinhardt at outlook.com> wrote:
> >
> > Matthieu Bouron:
> > > This will allow users to pass the Android ApplicationContext which is mandatory
> > > to retrieve the ContentResolver responsible to resolve/open Android content-uri.
> > > ---
> > >  libavcodec/jni.c | 40 ++++++++++++++++++++++++++++++++++++++++
> > >  libavcodec/jni.h | 17 +++++++++++++++++
> > >  2 files changed, 57 insertions(+)
> > >
> > > diff --git a/libavcodec/jni.c b/libavcodec/jni.c
> > > index ae6490de9d..7d04d0a268 100644
> > > --- a/libavcodec/jni.c
> > > +++ b/libavcodec/jni.c
> > > @@ -64,6 +64,36 @@ void *av_jni_get_java_vm(void *log_ctx)
> > >      return vm;
> > >  }
> > >
> > > +int av_jni_set_android_app_ctx(void *app_ctx, void *log_ctx)
> > > +{
> > > +    JNIEnv *env = avpriv_jni_get_env(c);
> >
> > Patch #1 won't compile on its own due to this; you fix this up in patch #2.
> >
> > > +    if (!env)
> > > +        return AVERROR(EINVAL);
> > > +
> > > +    jobjectRefType type = (*env)->GetObjectRefType(env, app_ctx);
> > > +    if (type != JNIGlobalRefType) {
> > > +        av_log(log_ctx, AV_LOG_ERROR, "Application context must be passed as a global reference");
> > > +        return AVERROR(EINVAL);
> > > +    }
> > > +
> > > +    pthread_mutex_lock(&lock);
> > > +    android_app_ctx = app_ctx;
> > > +    pthread_mutex_unlock(&lock);
> > > +
> > > +    return 0;
> > > +}
> > > +
> > > +void *av_jni_get_android_app_ctx(void)
> > > +{
> > > +    void *ctx;
> > > +
> > > +    pthread_mutex_lock(&lock);
> > > +    ctx = android_app_ctx;
> > > +    pthread_mutex_unlock(&lock);
> > > +
> > > +    return ctx;
> > > +}
> > > +
> > >  #else
> > >
> > >  int av_jni_set_java_vm(void *vm, void *log_ctx)
> > > @@ -76,4 +106,14 @@ void *av_jni_get_java_vm(void *log_ctx)
> > >      return NULL;
> > >  }
> > >
> > > +int av_jni_set_android_app_ctx(void *app_ctx, void *log_ctx)
> > > +{
> > > +    return AVERROR(ENOSYS);
> > > +}
> > > +
> > > +void *av_jni_get_android_app_ctx(void)
> > > +{
> > > +    return NULL;
> > > +}
> >
> > I am against adding stub functions on platforms where they are known to
> > be useless, i.e. everything except android.
>
> Ok. Will update the patch introducing a new header "jni_android.h".
> Unless we want to also scope avcodec/jni.h to Android only ?

Or maybe you mean adding a ifdef guard to it ?

>
> >
> > > +
> > >  #endif
> > > diff --git a/libavcodec/jni.h b/libavcodec/jni.h
> > > index dd99e92611..da8025f830 100644
> > > --- a/libavcodec/jni.h
> > > +++ b/libavcodec/jni.h
> > > @@ -43,4 +43,21 @@ int av_jni_set_java_vm(void *vm, void *log_ctx);
> > >   */
> > >  void *av_jni_get_java_vm(void *log_ctx);
> > >
> > > +/*
> > > + * Set the Android application context which will be used to retrieve the Android
> > > + * content resolver to resolve content uris.
> > > + *
> > > + * @param app_ctx global JNI reference to the Android application context
> > > + * @return 0 on success, < 0 otherwise
> > > + */
> > > +int av_jni_set_android_app_ctx(void *app_ctx, void *log_ctx);
> > > +
> > > +/*
> > > + * Get the Android application context that has been set with
> > > + * av_jni_set_android_app_ctx.
> > > + *
> > > + * @return a pointer the the Android application context
> > > + */
> > > +void *av_jni_get_android_app_ctx(void);
> > > +
> > >  #endif /* AVCODEC_JNI_H */
> >
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