<?xml version="1.0" encoding="UTF-8"?>
<xsd:schema targetNamespace="http://www.loc.gov/standards/AudioMD/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.loc.gov/standards/AudioMD/" elementFormDefault="qualified" attributeFormDefault="unqualified">
	<!--============================================================

	 AudioMD: Audio Technical Metadata Extension Schema
		
	============================================================-->
	<xsd:element name="AudioMD" type="AudioMDType"/>
	<xsd:annotation>
		<xsd:documentation>AudioMD: Digital Audio Archival Object Technical Metadata Element.
	                 AudioMD contains technical metadata that describe a digital audio archival object. 
	             </xsd:documentation>
	</xsd:annotation>
	<xsd:annotation>
		<xsd:documentation>AudioMD: Elements of a digital audio archival object.
                       	The AudioMD elements describe the characteristics of a digital audio archival object.
                       	AudioMD contains 6 top level elements:
				1. bits_per_sample	The number of bits in a digital audio sample  i.e. quantization   e.g. 16, 24;
				2. channel			Number and information about channels/tracks (e.g., 2-trk, 4-trk, 8-trk, etc.);
				3. data_rate			Information about the mode and data rate of audio files in Kb/s  e.g. 16, 44.1, 96 etc;
				4. duration			Duration of audio source material in time    i.e. HH:MM:SSSS format;
                          5. sampling_frequency	The rate at which the audio was sampled  e.g. 44.1KHz, 96KHz, etc...;                                 				6. sound_field		 Aural space on source recording, e.g., monaural, stereo, surround sound, etc....
              </xsd:documentation>
	</xsd:annotation>
	<xsd:element name="bits_per_sample" type="bits_per_sampleType"/>
	<xsd:element name="channel" type="channelType"/>
	<xsd:element name="data_rate" type="data_rateType"/>
	<xsd:element name="duration" type="durationType"/>
	<xsd:element name="sampling_frequency" type="sampling_frequencyType"/>
	<xsd:element name="sound_field" type="sound_fieldType"/>
	<xsd:complexType name="AudioMDType">
		<xsd:annotation>
			<xsd:documentation>AudioMDType: Complex Type for encapsulating within a single
                        parent element the individual digital audio archival object elements that describe an object or portion of an
                        object.  But note that the individual digital audio archival object elements that comprise the
                        AudioMD schema can be used independently of the schema element and  directly under a
                        METS mdSec.dmWrap element. The individual elements that comprise a digital audio archival object element
                        are documented under their corresponding types.
                        AudioMDType has a single attribute, ID (XML ID).
                    </xsd:documentation>
		</xsd:annotation>
		<xsd:sequence>
			<xsd:element ref="bits_per_sample" minOccurs="0" maxOccurs="unbounded"/>
			<xsd:element ref="channel" minOccurs="0" maxOccurs="unbounded"/>
			<xsd:element ref="data_rate" minOccurs="0" maxOccurs="unbounded"/>
			<xsd:element ref="duration" minOccurs="0" maxOccurs="unbounded"/>
			<xsd:element ref="sampling_frequency" minOccurs="0" maxOccurs="unbounded"/>
			<xsd:element ref="sound_field" minOccurs="0" maxOccurs="unbounded"/>
		</xsd:sequence>
		<xsd:attribute name="ID" type="xsd:ID"/>
	</xsd:complexType>
	<xsd:complexType name="bits_per_sampleType">
		<xsd:annotation>
			<xsd:documentation>bits_per_sampleType: Complex Type for recording sample size of
                        an item or portion of an item.  bits_per_sampleType has a single attribute, ID (XML ID).
                    </xsd:documentation>
		</xsd:annotation>
		<xsd:simpleContent>
			<xsd:restriction base="xsd:string">
				<xsd:attribute name="ID" type="xsd:ID"/>
			</xsd:restriction>
		</xsd:simpleContent>
	</xsd:complexType>
	<xsd:complexType name="channelType">
		<xsd:annotation>
			<xsd:documentation>channelType: Complex Type for recording the channel configuration used
                        in an item or portion of an item.  channelType has 2 attributes, 
                        ID: (XML ID)
                        FIELDTYPE: qualifier of the type of channel metadata contained in the element. 
                        	- channelTrackQuantity: the number of channels of audio  e.g. 1, 2, 4, 5 
                        	- channelTrackFormat: information about the track format  e.g. 1/4- trk, 1/2- trk, full-trk, etc... 
                        	- channelTrackInformation: information about the channel and track configuration
                    </xsd:documentation>
		</xsd:annotation>
		<xsd:simpleContent>
			<xsd:restriction base="xsd:string">
				<xsd:attribute name="ID" type="xsd:ID"/>
				<xsd:attribute name="FIELDTYPE" default="channelTrackQuantity">
					<xsd:simpleType>
						<xsd:restriction base="xsd:NMTOKEN">
							<xsd:enumeration value="channelTrackQuantity"/>
							<xsd:enumeration value="channelTrackFormat"/>
							<xsd:enumeration value="channelTrackInformation"/>
						</xsd:restriction>
					</xsd:simpleType>
				</xsd:attribute>
			</xsd:restriction>
		</xsd:simpleContent>
	</xsd:complexType>
	<xsd:complexType name="data_rateType">
		<xsd:annotation>
			<xsd:documentation>data-_rateType: Complex Type for recording the data rate (e.g. 1.5 Mbps, 4Mbps, etc...)
                        of an item or portion of an item.  data_rateType has 2 attributes,  
                        ID: (XML ID)
                        MODE: mode of data rate  i.e. Fixed or Variable.
                     </xsd:documentation>
		</xsd:annotation>
		<xsd:simpleContent>
			<xsd:restriction base="xsd:string">
				<xsd:attribute name="ID" type="xsd:ID"/>
				<xsd:attribute name="MODE" type="xsd:string"/>
			</xsd:restriction>
		</xsd:simpleContent>
	</xsd:complexType>
	<xsd:complexType name="durationType">
		<xsd:annotation>
			<xsd:documentation>durationType: Complex Type for recording the duration
                        of an item or portion of an item.  durationType has a single attribute, ID (XML ID).
                    </xsd:documentation>
		</xsd:annotation>
		<xsd:simpleContent>
			<xsd:restriction base="xsd:string">
				<xsd:attribute name="ID" type="xsd:ID"/>
			</xsd:restriction>
		</xsd:simpleContent>
	</xsd:complexType>
	<xsd:complexType name="sampling_frequencyType">
		<xsd:annotation>
			<xsd:documentation>sampling_frequencyType: Complex Type for recording the sampling frequency
                        of an item or portion of an item in pixels.  sampling_frequencyType has a 1 attribute, 
                        ID: (XML ID)
                    </xsd:documentation>
		</xsd:annotation>
		<xsd:simpleContent>
			<xsd:restriction base="xsd:string">
				<xsd:attribute name="ID" type="xsd:ID"/>
			</xsd:restriction>
		</xsd:simpleContent>
	</xsd:complexType>
	<xsd:complexType name="sound_fieldType">
		<xsd:annotation>
			<xsd:documentation>sound_fieldType: Complex Type for recording the aural space of the
                         item or portion of an item.  sound_fieldType has a single attribute, ID (XML ID).
                    </xsd:documentation>
		</xsd:annotation>
		<xsd:simpleContent>
			<xsd:restriction base="xsd:string">
				<xsd:attribute name="ID" type="xsd:ID"/>
			</xsd:restriction>
		</xsd:simpleContent>
	</xsd:complexType>
</xsd:schema>

