esri / swiftrtp

Swift implementation of RTP and the H264 RTP Profile

SwiftRTP

Swift 2 (iOS and Mac OS) implementation of RTP ("RTP: A Transport Protocol for Real-Time Applications") and the H264 RTP Profile ("RTP Payload Format for H.264 Video").

What Works

• Hardware acceleration of H264 decoding on (supported) iOS devices. (See the WWDC 2014 Session 513: "Direct Access to Video Encoding and Decoding).
• Live streaming of RTP H264 video from 3DRobotics Solo drone.
• Partial support of live streaming of ffmpeg rtp streams. Run a "test card" video stream using ffmpeg, the sample app will connect to it and display the card - (maybe with some corruption due to buggy STAP-A processing). (See Documentation/ folder for more info on ffmpeg)

ffmpeg -re -f lavfi -i smptebars -vcodec libx264 -tune zerolatency -vf scale=1920:1080 -b 900k -sdp_file stream.sdp -f rtp "rtp://127.0.0.1:5600"

What Does Not Work

• Check the liberal amount of // TODOs in the code.
• RTP padding, extensions and csrcs are not supported yet. If a RTP packet contains any of these elements it will be dropped.
• The STAP-A RTP H264 packet type is not tested well and doesn't seem to be reliable. Further work is needed.
• The following RTP H264 packet types are not yet supported:
  • FU-B
  • STAP-B
  • MTAP-A
  • MTAP-B

Future

• Fix items in the "What Does Not Work" section. The extra packet types are low priority. They're generally not seen coming either from 3DR Solo or from ffmpeg.
• Better support for handling SPS and PPS packets. It would be nice if the DecompressionSession class could handle changed parameters better.
• Preload SPS and PPS packets for "fast starts".
• Configure the RTP packet type. 96 (the first user-available type) is hard-coded.
• SDP file reader?
• Hooks for logging (don't log to println)
• For STAP and MTAP packets we should be calling CMSampleBufferCreate once for all samples in the packet.