extern const ff_asf_guid ff_asf_content_encryption;
extern const ff_asf_guid ff_asf_ext_content_encryption;
extern const ff_asf_guid ff_asf_digital_signature;
extern const ff_asf_guid ff_asf_content_encryption;
extern const ff_asf_guid ff_asf_ext_content_encryption;
extern const ff_asf_guid ff_asf_digital_signature;