This chapter describes multimedia constants and functions related to codecs:
Multimedia Codec Constants
Multimedia Codec Functions and Macros
The header file MMCodecClass.h
declares the API that this chapter describes.
Multimedia Codec Constants
Codec Class Properties
Purpose
Defines property keys that can be used to access information in codec classes.
Declared In
MMCodecClass.h
Constants
-
#define P_MM_CODEC_CLASS_PROP_CREATOR (P_MM_CODEC_CLASS_PROP_BASE | 0x0003L)
- The codec class's creator ID.
-
#define P_MM_CODEC_CLASS_PROP_DEST_FORMAT (P_MM_CODEC_CLASS_PROP_BASE | 0x0005L)
- The codec's destination format if it is an encoder.
-
#define P_MM_CODEC_CLASS_PROP_NAME (P_MM_CODEC_CLASS_PROP_BASE | 0x0001L)
- The codec's name.
-
#define P_MM_CODEC_CLASS_PROP_SOURCE_FORMAT (P_MM_CODEC_CLASS_PROP_BASE | 0x0004L)
- The codec's source format if it is a decoder.
-
#define P_MM_CODEC_CLASS_PROP_VERSION (P_MM_CODEC_CLASS_PROP_BASE | 0x0002L)
- The codec's version number.
Multimedia Codec Functions and Macros
MMCodecClassEnumerate Function
Purpose
Iterates through the available codecs, both encoders and decoders.
Declared In
MMCodecClass.h
Prototype
status_t MMCodecClassEnumerate ( MMFormatTypetype
, int32_t*ioIterator
, MMCodecClassID*outCodecClassID
)
Parameters
-
→ type
- The type of codecs to enumerate. Specify one of the constants listed in "formatType," or specify
P_FORMAT_UNKNOWN
to enumerate codecs of all format types. -
↔ ioIterator
- Pointer to the value returned by the previous call to this function. On the first call to this function, set this value to
P_MM_ENUM_BEGIN
. When the set of iterated values is exhausted, this function sets this value toP_MM_ENUM_END
. -
← outCodecClassID
- Pointer to the ID of the next available codec.
Returns
-
errNone
- No error.
-
sysErrParamErr
- The iterator is invalid or the type doesn't match previous calls in the same iteration set.
-
sysErrBadIndex
- The iterator value is invalid or past the last item in the set.
MMFileFormatEnumerate Function
Purpose
Iterates through the supported file formats (these are distinct from codecs because a file format may encapsulate many kinds of encoded data).
Declared In
MMCodecClass.h
Prototype
status_t MMFileFormatEnumerate ( int32_t*ioIterator
, MMFormatType*outFormat
)
Parameters
-
↔ ioIterator
- Pointer to the value returned by the previous call to this function. On the first call to this function, set this value to
P_MM_ENUM_BEGIN
. When the set of iterated values is exhausted, this function sets this value toP_MM_ENUM_END
. -
← outFormat
- Pointer to the ID of the next available format.
Returns
-
errNone
- No error.
-
sysErrParamErr
- The iterator is invalid or the type doesn't match previous calls in the same iteration set.
-
sysErrBadIndex
- The iterator value is invalid or past the last item in the set.