RTC Client API Video Codec Registry Settings
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8/28/2008
Applies to Windows Embedded CE 6.0 R2
The RTC Client API uses the registry to configure pluggable video codecs. All registry keys are required unless specified as optional.
The HKEY_LOCAL_MACHINE\Comm\RTC\Video\Codecs registry key must have a value for each codec that needs to be supported. If a codec can send multiple format specific parameters (FMTP) options to the remote party, a different registry subkey along with a unique RTP Payload type must be specified for each FMTP.
Note
Each registry key can contain no more than seven lines.
| Name | Type | Description |
|---|---|---|
CodecType |
REG_SZ |
Specifies the codec type. Always set the data to |
EncoderPlugin |
REG_SZ |
Specifies the COM CLSID of the IRTCPluggableVideoEncoder interface. Set H.263 to {A7D8A6EF-575B-4750-A727-04234A70D9DE} to use the Microsoft provided implementation of this interface. Set H.264 to {92A200F8-0981-11DC-813E-B77255D89593} to use the Microsoft provided implementation of this interface. |
DecoderPlugin |
REG_SZ |
Specifies the COM CLSID of the IRTCPluggableVideoDecoder interface. Set H.263 to {0CE193DF-27F0-48c7-92F7-75CA7A5965E6} to use the Microsoft provided implementation of this interface. Set H.264 to {86546C00-0981-11DC-88BE-AE7255D89593} to use the Microsoft provided implementation of this interface. |
CodecRank |
REG_DWORD |
Sets the relative priority of the codec. The data is an integer between 0 and 100. The highest priority is 0 and the lowest is 100. |
CodecName |
REG_SZ |
Specifies the name of the codec sent in the Session Description Protocol (SDP) payload. For example, the codec name could be |
PayloadType |
REG_DWORD |
Specifies the RTP payload type associated with the codec. For example … |
ClockRate |
REG_DWORD |
Indicates the clock rate of the codec as it appears in the |
SDPFmtp |
REG_SZ |
Indicates the format specific parameters FMTP of the codec as it appears in the SDP This data indicates only the parameters themselves. SDP automatically fills in the following text: |
If a codec can support multiple FMTP options, the codec can be represented with multiple RTP payload types. The following SDP shows an example of multiple FMTP for the H264 codec.
m=video 49170 RTP/AVP 100 99 98
a=rtpmap:98 H264/90000
a=fmtp:98 profile-level-id=42A01E; packetization-mode=0;
sprop-parameter-sets=Z0IACpZTBYmI,aMljiA==
a=rtpmap:99 H264/90000
a=fmtp:99 profile-level-id=42A01E; packetization-mode=1;
sprop-parameter-sets=Z0IACpZTBYmI,aMljiA==
a=rtpmap:100 H264/90000
a=fmtp:100 profile-level-id=42A01E; packetization-mode=2;
sprop-parameter-sets=Z0IACpZTBYmI,aMljiA==;
sprop-interleaving-depth=45; sprop-deint-buf-req=64000;
sprop-init-buf-time=102478; deint-buf-cap=128000
To store the FMTP lines, RTP payload types, and configuration options in this example, create three registry keys for the H264 codec.
Each of the following HKEY_LOCAL_MACHINE\Comm\RTC\Video\Codecs values is filter-specific.
| Name | Type | Description |
|---|---|---|
EncoderFilter |
REG_SZ |
Specifies the COM CLSID of the encoding IBaseFilter. |
DecoderFilter |
REG_SZ |
Specifies the COM CLSID of the decoding IBaseFilter. |
DecoderMediaSubtype |
REG_SZ |
Specifies the media subtype GUID of the format of the incoming data. Examples of incoming data format include H263 and H264. |
A value under the HKEY_LOCAL_MACHINE\Comm\RTC\Video\SdpValidators registry key can specify optional IRTCSDPValidator interfaces for a codec. If a value is present, the codec uses the interface to validate the incoming SDP. This can be particular useful for validating the FMTP line in the SDP. For each name and data pair under the key, the name represents the codec string from the RTP packet, such as H263-1998, and the value represents the CLSID that implements the object.
An IRTCSDPValidator registry value is not required. If a codec does not implement this registry key, the codec accepts all SDP.
| Name | Type | Description |
|---|---|---|
<Codec Name> |
REG_SZ |
Specifies the CLSID that implements this object. |
This following table shows examples of SdpValidators keys.
| Name | Description |
|---|---|
H263-1998 |
|
H263-2000 |
|