+static MXFPackage* mxf_resolve_source_package(MXFContext *mxf, UID package_uid)
+{
+ MXFPackage *package = NULL;
+ int i;
+
+ for (i = 0; i < mxf->packages_count; i++) {
+ package = mxf_resolve_strong_ref(mxf, &mxf->packages_refs[i], SourcePackage);
+ if (!package)
+ continue;
+
+ if (!memcmp(package->package_uid, package_uid, 16))
+ return package;
+ }
+ return NULL;
+}
+
+static MXFStructuralComponent* mxf_resolve_essence_group_choice(MXFContext *mxf, MXFEssenceGroup *essence_group)
+{
+ MXFStructuralComponent *component = NULL;
+ MXFPackage *package = NULL;
+ MXFDescriptor *descriptor = NULL;
+ int i;
+
+ if (!essence_group || !essence_group->structural_components_count)
+ return NULL;
+
+ /* essence groups contains multiple representations of the same media,
+ this return the first components with a valid Descriptor typically index 0 */
+ for (i =0; i < essence_group->structural_components_count; i++){
+ component = mxf_resolve_strong_ref(mxf, &essence_group->structural_components_refs[i], SourceClip);
+ if (!component)
+ continue;
+
+ if (!(package = mxf_resolve_source_package(mxf, component->source_package_uid)))
+ continue;
+
+ descriptor = mxf_resolve_strong_ref(mxf, &package->descriptor_ref, Descriptor);
+ if (descriptor){
+ /* HACK: force the duration of the component to match the duration of the descriptor */
+ if (descriptor->duration != AV_NOPTS_VALUE)
+ component->duration = descriptor->duration;
+ return component;
+ }
+ }
+ return NULL;
+}
+
+static MXFStructuralComponent* mxf_resolve_sourceclip(MXFContext *mxf, UID *strong_ref)
+{
+ MXFStructuralComponent *component = NULL;
+
+ component = mxf_resolve_strong_ref(mxf, strong_ref, AnyType);
+ if (!component)
+ return NULL;
+ switch (component->type) {
+ case SourceClip:
+ return component;
+ case EssenceGroup:
+ return mxf_resolve_essence_group_choice(mxf, (MXFEssenceGroup*) component);
+ default:
+ break;
+ }
+ return NULL;
+}
+