2.7.1.1 wfdx_video_formats

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The wfdx-video-formats parameter replaces the wfd-video-formats parameter as specified in [WF-DTS2.1] section 6.1.3.<10> The wfdx-video-formats parameter specifies:

  • Additional supported video resolutions that augment the video resolutions specified in [WF-DTS2.1] sections 5.1.5.1–5.1.5.3.

  • A codec profile that augments the codec profile specified in [WF-DTS2.1] section 5.1.5.5.

  • A level that augments the level specified in [WF-DTS2.1] section 5.1.5.5.

  • Decoder latency.

  • Minimum slice size.

  • Slice encoding parameters and support for video frame rate control, including explicit frame rate change and implicit video frame skipping.

A Wi-Fi Display Sink can send both wfd-video-formats and wfdx-video-formats in an M3 response. If an M3 response contains both wfd-video-formats and wfdx-video-formats, the Wi-Fi Display Source MUST NOT use the wfd-video-formats parameter.

The M4 request MUST NOT contain both wfd-video-formats and wfdx-video-formats. If the M4 request contains both wfd-video-formats and wfdx-video-formats, the Wi-Fi Display Sink MUST NOT use the wfd-video-formats parameter.

The parameters definitions in the following ABNF syntax are different than those specified in [WF-DTS2.1] section 6.1.3: wfd-video-formats, native, profile, level, CEA-Support, and VESA-Support.

The ABNF syntax is as follows:

 wfdx-video-formats = "wfdx_video_formats:" SP sink-video-list CRLF
 sink-video-list = "none" / (native SP preferred-display-mode-supported SP H264-codec);
 native = 4*4HEXDIG;
 preferred-display-mode-supported = 2*2HEXDIG; 0-not supported, 1-supported, 2-255 reserved
 H264-codec  = profile SP level SP misc-params SP max-hres SP max-vres *("," SP
           H264-codec)
 profile = 4*4HEXDIG; 
 level = 4*4HEXDIG; 
 max-hres = "none" / (4*4HEXDIG); 
 max-vres = "none" / (4*4HEXDIG); 
 misc-params       = CEA-Support SP VESA-Support SP HH-Support SP latency SP min-slice-size SP slice-enc-params SP frame-rate-control-support
 CEA-Support       = 10*10HEXDIG; 
 VESA-Support = 10*10HEXDIG; 
 HH-Support = 8*8HEXDIG; 
 latency = 2*2HEXDIG; 
 min-slice-size = 4*4HEXDIG; 
 slice-enc-params = 4*4HEXDIG; 
 frame-rate-control-support = 2*2HEXDIG;

The codec is a list of one or more profile, level, misc-params, max-hres, or max-vres tuples for each codec profile, corresponding to the maximum level, miscellaneous parameters, maximum horizontal resolution, and maximum vertical resolution that are supported when included in an RTSP M3 response messages. The level parameter indicates the maximum level support for the specified profile. Tuples can appear in any order in an RTSP M3 response message.

A Wi-Fi Display Sink MUST set the Video Frame Rate Change Support bit in the frame-rate-control-support field to 1 in the RTSP M3 response message, if it supports this functionality. If the Wi-Fi Display Sink does not set this bit to 1, then the Wi-Fi Display Source MUST NOT set this bit to 1 in the RTSP M4 request message. If the Wi-Fi Display Source does not support the functionality, it MUST set this bit to 0.

A Wi-Fi Display Source MUST set the min-slice-size value to 0 in the RTSP M4 request message and MUST NOT transmit an encoded picture constructed by multiple slices to a Wi-Fi Display Sink that does not support decoding a picture constructed by multiple slices (the Wi-Fi Display Sink sets the min-slice-size value to 0 in the RTSP M3 response message).