DirectShow Graph File Format (Windows CE 3.0 Graphics and Multimedia)

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This article describes the format of a saved Microsoft DirectShow graph file (.grf) created by GraphEdit.

The docfile (storage file) contains a stream called ActiveMovieGraph. This single stream contains within it all the filters, filter names, file names, connections, and so on.

To load such a graph, either:

Pass the storage file name to RenderFile. It will recognize that this is not a media file but a saved graph, and will restore the graph.

- or -

Open the storage file (by using StgOpenStorage).
Query the filter graph manager for IPersistStream.
Open the L"ActiveMovieGraph" stream (by using IStorage::OpenStream).

Pass the stream to the filter graph (by using IPersistStream::Load).

The syntax of the graph within the stream follows:

<graph> ::=
<version3><filters><connections><clock>END
| <version2><filters><connections>END
<version3> ::= 0003\r\n <version2> ::= 0002\r\n
<clock> ::= CLOCK <b>
<required><b><clockid>\r\n <required> ::=
1|0 <clockid> ::= <n>|<class id> <filters ::=
FILTERS <b>[<filter list><b>] <connections>
::= CONNECTIONS [<b> <connection list>] <filter
list> ::= [<filter> <b>] <filter list>
<connection list> ::=
[<connection><b>]<connection list> <filter>
::= <n><b>"<name>"<b><class
id><b>[<file>]<length><b1><filter
data> <file> ::= SOURCE "<name>"<b> | SINK
"<name>"<b> <class id> ::= class id of the filter
in standard string form <name> ::= any sequence of characters
NOT including " <length> ::= character string representing
unsigned decimal number, for example, 23 this is the number of
bytes of data that follow the following space. <b> ::= any
combination of space, \t, \r, or \n <b1> ::= exactly one
space character <n> ::= an identifier that will in fact be an
integer, 0001, 0002, 0003, etc. <connection> ::=
<n1><b>"<pin1
id>"<b><n2><b>"<pin2 id>" <media
type> <n1> ::= identifier of first filter <n2> ::=
identifier of second filter <pin1 id> ::= <name>
<pin2 id> ::= <name> <media type> ::= <major
type><b><sub
type><b><flags><length><b1><format>
<major type> ::= <class id> <sub type> ::=
<class id> <flags> ::=
<FixedSizeSamples><b><TemporalCompression><b>
<FixedSizeSamples> ::= 1|0 <TemporalCompression> ::=
1|0 <Format> ::=
<SampleSize><b><FormatType><b><FormatLength><b1><FormatData>
<FormatType> ::= class id of the format in standard string
form <FormatLength> ::= character string representing
unsigned decimal number this is the number of bytes of data that
follow the following space. <FormatData> ::= binary
data

On output there will be a new line (\r\n) per filter, one per connection, and one for each of the keywords FILTERS and CONNECTIONS. Each other case of <B> will be a single space. The keywords FILTERS, CONNECTIONS, and END are not localizable. Note also that the filter data and the format data are binary, so they might contain incorrect line breaks, null values, and so on.

The following approximates what the output looks like (a connection line is long and so has been split for presentation here, <with comments enclosed like this>).

0002 <version 2 of the syntax> FILTERS 0001
"Source" {00000000-0000-0000-0000-000000000001} SOURCE "MyFile.mpg"
0000000000 <id name guid of the filter (need this to load it)
source file name no private data> 0002 "another filter"
{00000000-0000-0000-0000-000000000002} 0000000008 XXXXXXXX <id
name guid (this one is not a file source or sink) 8 bytes private
data> CONNECTIONS 0001 "Output pin" 0002 "In" <no line break
here> <filter id pin id filter id pin id (output pin is
first, then input pin)> 0000000172
{00000000-0000-0000-0000-000000000003} <no line break here>
<sample size, media type major-type>
{00000000-0000-0000-0000-000000000004} 1 0 <no line break
here> <media type sub-type, fixed size samples, no temporal
compression> 0000000093 {00000000-0000-0000-0000-000000000005}
18 YYYYYYYYYYYYYYYYYY <length of format format type 18 bytes of
binary format data> END where:

XXX... represents filter data