IMpegAudioDecoder Interface

Microsoft DirectShow 9.0

IMpegAudioDecoder Interface

The IMpegAudioDecoder interface is exposed on the MPEG-1 Audio Decoder filter and it enables applications to control decoding parameters. Most of these methods are useful only when an application is running on an older system and needs to sacrifice quality to increase performance. The default values provide the optimal decoding quality.

The two methods that are still useful in some scenarios are get_DualMode and put_DualMode. These methods enable applications to access either the right or left channel in VCD-based karaoke discs.

In addition to the methods inherited from IUnknown, the IMpegAudioDecoder interface exposes the following methods.

Method	Description
get_AudioFormat	Returns the audio format of the connected input pin.
get_DecoderAccuracy	Returns the decoder accuracy as a three-level quality setting.
get_DecoderWordSize	Returns the word size used to decode, either eight or 16 bit.
get_DualMode	Returns which channel is currently being decoded.
get_FrequencyDivider	Returns the frequency divider as a quality setting equal to CD Audio, FM Radio, or AM Radio.
get_IntegerDecode	Returns whether the decoder is currently using integer-based decoding as opposed to floating point decoding.
get_Stereo	Returns whether the decoder is decoding the encoded stream into stereo or mono PCM.
put_DecoderAccuracy	Specifies the quality as high, full or best.
put_DecoderWordSize	Specifies the word size used by the decoder.
put_DualMode	Specifies the channel to be decoded.
put_FrequencyDivider	Specifies the frequency divider as a three-level setting corresponding to the quality of CD Audio, FM Radio, or AM Radio.
put_IntegerDecode	Specifies whether the decoder will use integer-based decoding.
put_Stereo	Specifies whether the decoder will decode the encoded stream into stereo or mono PCM.

Requirements

Header: Include mpegtype.h.

Library: Use Strmiids.lib.