1

WiFi Display Standard

2

Protocol Methods Proprietary

Over TCP (what’s inside?)

Standard WFD Over UDP, WFD Header, MP2TS packets with

3

Standard WFD Stream

4

Architectural view

5

Media The Media Types supported by WFD:

H264 MPEG2 AAC Dolby AC3 LPCM (uncompressed audio)

6

MP2TS packetization in WFD WFD carries media (H264, AAC) in MP2TS packets

7 MP2TS are carried in a single RTP packet

RTP TS is derived from MP2TS and sent according to WLAN sync

7

Media Encapsulation Encapsulation of H264V into NAL/PES/MP2TS/RTP

8

Media Transport Stack Encoded audio/video streams are carried in MPEG2 Transport stream

The MP2TS packets are carried in RTP packets

9

H264 Profiles WFD supports two H264 profiles:

Constraint Base Profile Base profile without FMO, ASO

Constraint High Profile High profile without CABAC, 4x4

10

PAT & PMT PAT Should indicate PMT PID 0x100

PMT Should indicate PCR PID at 0x1000

PMT Should indicate video PID at 0x1011

PMT Should indicate Audio PID at 0x1100 (additional audio streams PID are consecutive)

The above tables (PCR,PAT/PMT…)should be sent at intervals smaller than 100mS

11

PMT Table

PMT Media Type Media Type

0x1B H.264

0X83 LPCM

0X81 AC3

0X0F AAC

12

Compression parameters changes Parameter compression change can follow changes in:

Device usage (Game, Video) Power (low battery) WLAN bandwidth changes

When changing compression parameters Source could: Change parameters without announcement Declare parameter changes using M4 RTSP request message

13

Frame Skipping WFD Frame skipping refers to removal of ALREADY

encoded video frames

Skipping is done AFTER the encoder

Frame number in slice header are sequential even when frames are skipped -> requires stream changing after encoder

The maximum skip interval is defined in bits B1:B3 of the wfd-video-formats parameters in M3 response

Frame skipping allowed only on non-referenced streams

->Skipping complete GOPs

Not recommended

14

Frame Refresh / Recovery In case of video streams errors (duo to packet loss), the

decoder may detect those errors

The Sink may decide that the errors are request a frame refresh (IDR Frame)

Request is done using the SET_PARAMETERS message with wfd_idr_request param