Video
Raw Video
RGBA format
Uncompressed 32 bit Alpha Red, Green, Blue.
On Windows Phone 7, the alpha channel is ignored.
YV12 format- YCrCb(4:2:0)
Uncompressed YCrCb(4:2:0).
Not supported on Windows Phone 7.
RGBA - 32 bit Alpha Red, Green, Blue
Windows Media Video and VC-1 formatsWMV1: Windows Media Video 7
Supports Simple, Main, and Advanced Profiles.
Supports only progressive (non-interlaced) content.
WMV2: Windows Media Video 8
WMV3: Windows Media Video 9
Supports Simple and Main Profiles.
Supports only progressive (non-interlaced) content.
WMVA: Windows Media Video Advanced Profile, non-VC-1
WVC1: Windows Media Video Advanced Profile, VC-1
Supports Advanced Profile.
Supports only progressive (non-interlaced) content.
H264 (ITU-T H.264 / ISO MPEG-4 AVC) formats
Supports H.264 and MP43 codecs.
Supports Base, Main, and High Profiles.
Windows Phone 7 supports up to Level 3.0.
Note that level 3.0 defines the maximum supported resolution for 30fps as 720x480. Other frame rates have different maximum supported resolutions.
Supports only progressive (non-interlaced) content.
Supports only 4:2:0 chroma subsampling profiles.
Desktop Silverlight only supports the Annex B NAL format (i.e. start codes).
Note, that media libraries, such as the SmoothStreamingMediaElement, support the AVC NAL format by programmatically converting AVC NALs to Annex B NALs. As Silverlight supports partial encryption of H.264 samples, this conversion can occur on encrypted content as well if the NAL headers are not encrypted. The Annex B NAL format is described in MPEG-4 Part 10.
Supports PlayReady DRM with Mp4 (H264 and AAC-LC)
H.263 format
Not supported by desktop versions of Silverlight.
Not supported by the MediaStreamSource class in Windows Phone 7.
MPEG-4 Part 2 format
Supports Simple and Advanced Profiles.

Audio
PCM / WAV format"1". This is Linear 8 or 16 bit Pulse Code Modulation. Roughly speaking, this is WAV format.
This is Linear 8 or 16 bit Pulse Code Modulation. Roughly speaking, this is WAV format.
Microsoft Windows Media Audio Standard formats."353" - Microsoft Windows Media Audio v7, v8 and v9.x Standard (WMA Standard)
Microsoft Windows Media Audio Professional formats."354" - Microsoft Windows Media Audio v9.x and v10 Professional (WMA Professional)
Supports full fidelity decoding of WMA 10 Professional Low Bit Rate (LBR) modes in the 32-96 kbps range.
Multichannel (5.1 and 7.1 surround) audio content is automatically mixed down to stereo.
24 bit audio will return silence.
Sampling Rates beyond 48000 return an invalid format error code in same-domain and a 4001 in cross-domain scenarios.
MP3 "85" -– (ISO MPEG-1 Layer III) format (MP3).
AAC"255" - (ISO Advanced Audio Coding) (AAC)format.
Supports Low Complexity (AAC-LC) decoding at full fidelity (up to 48 kHz).
High Efficiency (HE-AAC) encoded content. will decode only at half fidelity (up to 24 kHz).
HE-AAC v1 (AAC+) and HE-AAC v2 (eAAC+) supported.
Desktop Silverlight will decode only at half fidelity (up to 24 kHz).
Multichannel (5.1 surround) audio content is not supported.
AMR-NB (Adaptive Multi-Rate Narrow Band) format
Not supported by desktop versions of Silverlight.
Not supported by the MediaStreamSource class.