For example we might want to compile gst-omx with omx-il-1.2.0 headers but still be able to load Bellagio components which are 1.1.2

But currently in gst-omx/omx/gstomx.h there is:

#define GST_OMX_INIT_STRUCT(st) G_STMT_START { \
  memset ((st), 0, sizeof (*(st))); \
  (st)->nSize = sizeof (*(st)); \
  (st)->nVersion.s.nVersionMajor = OMX_VERSION_MAJOR; \
  (st)->nVersion.s.nVersionMinor = OMX_VERSION_MINOR; \
  (st)->nVersion.s.nRevision = OMX_VERSION_REVISION; \
  (st)->nVersion.s.nStep = OMX_VERSION_STEP; \
} G_STMT_END

which prevents the use the same libgstomx.so binary to load OpenMAX components with different versions. For example Bellagio returns OMX_ErrorVersionMismatch if nVersionMajor and nVersionMinor are not set to exactly 1 and 1

One solution is to call OMX_GetComponentVersion(&gstomxcomp->nVersion) when loading a component, and change GST_OMX_INIT_STRUCT to:

#define GST_OMX_INIT_STRUCT(st,comp) G_STMT_START { \
  memset ((st), 0, sizeof (*(st))); \
  (st)->nSize = sizeof (*(st)) + sizeof(OMX_STRING); \
  (st)->nVersion = comp->nVersion; \
} G_STMT_END