The ESDescriptor conveys all information related to a particular elementary
stream and has three major parts:
The first part consists of the ES_ID which is a unique reference to the
elementary stream within its name scope, a mechanism to group elementary
streams within this Descriptor and an optional URL String.
The second part is a set of optional extension descriptors that support the
inclusion of future extensions as well as the transport of private data in a
backward compatible way.
The third part consists of the DecoderConfigDescriptor, SLConfigDescriptor,
IPIDescriptor and QoSDescriptor which convey the parameters and requirements
of the elementary stream.
author  Alexander Simm

The ES_ID provides a unique label for each elementary stream within its
name scope. The value should be within 0 and 65535 exclusively. The
values 0 and 65535 are reserved.
return  the elementary stream's ID

Indicates if an ID of another stream is present, on which this stream
depends.
return  true if the dependingOnES_ID is present

The dependingOnES_ID is the ES_ID of another elementary
stream on which this elementary stream depends. The stream with the
dependingOnES_ID shall also be associated to this
Descriptor. If no value is present (if hasStreamDependency()
returns false) this method returns -1.

@return the dependingOnES_ID value, or -1 if none is present

A flag that indicates the presence of a URL.
return  true if a URL is present

A URL String that shall point to the location of an SL-packetized stream
by name. The parameters of the SL-packetized stream that is retrieved
from the URL are fully specified in this ESDescriptor.
If no URL is present (if isURLPresent() returns false) this
method returns null.
return  a URL String or null if none is present

The stream priority indicates a relative measure for the priority of this
elementary stream. An elementary stream with a higher priority is more
important than one with a lower priority. The absolute values are not
normatively defined.
return  the stream priority