Note
ამ გვერდზე წვდომა ავტორიზაციას მოითხოვს. შეგიძლიათ სცადოთ შესვლა ან დირექტორიების შეცვლა.
ამ გვერდზე წვდომა ავტორიზაციას მოითხოვს. შეგიძლიათ სცადოთ დირექტორიების შეცვლა.
The Microsoft MPEG Audio Decoder is a synchronous Media Foundation Transform (MFT) that enables decoding MPEG audio elementary stream formats using the Media Foundation (MF) pipeline.
The decoder supports the following MPEG elementary stream formats.
MPEG-1 audio layers I and II (ISO/IEC 11172-3). 2. MPEG-2 backward-compatible, layers I and II (ISO
MPEG-2 backward-compatible, layers I and II (ISO/IEC 13818-3), mono and stereo only
Class Identifier
The class identifier (CLSID) of the MPEG Audio decoder is CLSID_MSMPEGAudDecMFT, defined in the header file wmcodecdsp.h.
Input Media Types
The MPEG Audio decoder supports the following input media type attributes.
| Attribute | Value |
|---|---|
| MF_MT_MAJOR_TYPE | MFMediaType_Audio |
| MF_MT_SUBTYPE | MFAudioFormat_MPEG |
| MF_MT_AUDIO_NUM_CHANNELS | (Optional) Usually 1 for mono or 2 for stereo, but can be up to 6 channels. |
| MF_MT_AUDIO_CHANNEL_MASK | (Optional) Usually 0x4 for mono or 0x3 for stereo, but can also be any one of the channel masks associated with up to 6 channels (3/2/1, 3/2, 3/1, 2/2, 2/1). If present, the channel mask must be consistent with the specified input number of channels. |
| MF_MT_AUDIO_SAMPLES_PER_SECOND | (Optional) One of the following: 16000, 22050, 24000, 32000, 44100, 48000. If specified, the input sampling rate must be one of the valid MPEG sampling rates. |
Output Media Types
The MPEG Audio decoder will support up to four output media subtypes, in the following order.
- 1. Stereo, floating point.
2. Stereo, 16-bit PCM.
3. Mono, floating point (only if the input is mono or dual-mono).
4. Mono, 16-bit PCM (only if the input is mono or dual-mono).
The decoder always supports stereo output and it is enumerated as the first output media type.
The decoder supports the following output media type attributes.
| Attribute | Value |
|---|---|
| MF_MT_MAJOR_TYPE | MFMediaType_Audio |
| MF_MT_SUBTYPE | Either MFAudioFormat_PCM or MFAudioFormat_Float |
| MF_MT_AUDIO_BITS_PER_SAMPLE | 16 or 32 |
| MF_MT_AUDIO_NUM_CHANNELS | 1 or 2 |
| MF_MT_AUDIO_CHANNEL_MASK | 0x4 for mono or 0x3 for stereo |
| MF_MT_AUDIO_SAMPLES_PER_SECOND | One of the following: 16000, 22050, 24000, 32000, 44100, 48000. |
Transform Attributes
The MPEG Audio decoder implements the IMFTransform::GetAttributes method. Applications can use this method to get or set the following attributes.
| Attribute | Description |
|---|---|
| CODECAPI_AVDecAudioDualMono | Specifies whether 2-channel audio being decoded is dual mono or not. Read-only. Set by the MFT. For more information see eAVDecAudioDualMono. |
| CODECAPI_AVDecAudioDualMonoReproMode | Specifies how the decoder reproduces dual mono audio. The default value is eAVDecAudioDualMonoReproMode_LEFT_MONO. Read/Write. Applications can set this property to change the default behavior. For more information see eAVDecAudioDualMono. |
| CODECAPI_AVEncCommonMeanBitRate | Specifies the compressed stream bit rate. Read-only. Set by the MFT. |
See also