\section{Status Code Definitions}
\label{sec:status}

Where applicable, HTTP status [H10] codes are re-used.  Status codes
that have the same meaning are not repeated here.  See
Table~\ref{tab:status} for a listing of which status codes may be
returned by which request.

\subsection{Success 2xx}

\begin{changebar}
\subsubsection{250 Low on Storage Space}

The server returns this warning after receiving a {\sf RECORD} request
that it may not be able to fulfill completely due to insufficient
storage space. If possible, the server should use the {\sf Range} header
to indicate what time period it may still be able to record. Since other
processes on the server may be consuming storage space simultaneously, a
client should take this only as an estimate.
\end{changebar}

\subsection{Redirection 3xx}

See [H10.3].

Within RTSP, redirection may be used for load balancing or redirecting
stream requests to a server topologically closer to the client.
Mechanisms to determine topological proximity are beyond the scope of this
specification.

\subsection{Client Error 4xx}

\subsubsection{405 Method Not Allowed}

The method specified in the request is not allowed for the resource
identified by the request URI. The response MUST include an {\sf Allow}
header containing a list of valid methods for the requested resource.
This status code is also to be used if a request attempts to use a
method not indicated during {\sf SETUP}, e.g., if a {\sf RECORD} request
is issued even though the {\sf mode} parameter in the {\sf Transport}
header only specified {\sf PLAY}.

\subsubsection{451 Parameter Not Understood}

The recipient of the request does not support one or more parameters
contained in the request.

\subsubsection{452 Conference Not Found}

The conference indicated by a {\sf Conference} header field is unknown
to the media server.

\subsubsection{453 Not Enough Bandwidth}

The request was refused since there was insufficient bandwidth.  This
may, for example, be the result of a resource reservation failure.

\subsubsection{454 Session Not Found}

The RTSP session identifier in the {\sf Session} header is missing,
invalid or has timed out.

\subsubsection{455 Method Not Valid in This State}

The client or server cannot process this request in its current state. 

\subsubsection{456 Header Field Not Valid for Resource}

The server could not act on a required request header. For example, if
{\sf PLAY} contains the {\sf Range} header field, but the stream does
not allow seeking.

\subsubsection{457 Invalid Range}

The {\sf Range} value given is out of bounds, e.g., beyond the end of
the presentation.

\subsubsection{458 Parameter Is Read-Only}

The parameter to be set by {\sf SET\_PARAMETER} can only be read, but
not modified.

\subsubsection {459 Aggregate operation not allowed}
The requested method may not be applied  on the URL in question since it is
an aggregate(presentation) URL. The method may be applied on a stream URL.

\subsubsection {460 Only aggregate operation allowed}
The requested method may not be applied  on the URL in question since it is not
an aggregate(presentation) URL. The method may be applied on the 
presentation URL.
