Using Pixotope Pocket

Pixotope pocket is a mobile app that uses your iPhone’s camera and ARKit to send tracking data and a live video feed into Pixotope Director via SRT connection.

Components

How to use

Installation

1. Download and install the app → Download from App store

2. On first launch, grant the app permission to use your camera and network

Setup

In Director

1. Create a camera system in SETUP > Configure > Camera tracking

2. Set the Camera tracking protocol to Pixotope Pocket

3. Route the camera system in SETUP > Configure > Routing using the + on the top right

4. Expand the camera item. Set the Input to SRT, and Mode to Listener

5. Match this camera’s Resolution and Frame rate to match Pocket’s formats

   • By default it should be Resolution 1080 and Frame rate 30

6. Note your camera’s Port number

   • By default it should be 16213

7. Note your machine’s IP address, visible on top, next to the machine name

In Pocket

1. Go to Settings > Connection settings using the cog icon

2. Input your Director machine’s IP address in the Send to field

3. If needed, input your camera system’s port number in the Port field

4. Go to Settings > Video

5. Ensure that Resolution and Frame rate match the configuration in Director

Going Live

1. Tap the home screen to set the origin point, shown as 3 colored axes

2. Check the status of your SRT and tracking connections

   

3. Press the big red button!

Additional settings

• (SRT) Connection
  

  

  
  

  • SRT latency

    • The value will depend on the RTT of your connection.

    • RTT (Round-Trip-Time) is the time it takes for a packet to travel from source to destination and back, and it is measured using the ping command on the destination IP (Director machine's IP).

    • SRT latency is a buffer that allows the destination to ask for missing packets to the source, for retransmission. Hence, this buffer must be larger than the measured RTT value.

    • The default value is 120 ms, which is typically suitable for local networks. Increase the value if you experience connection issues.

    • Set the same value on both ends of the connection. If there is a mismatch, the highest value prevails.

    • Increasing SRT latency increases end-to-end latency. Decrease this value to optimize latency, but ensure that the connection remains stable.

  • Password

    • Choose a password with a length between 10 and 79 characters.

    • Configure the same password both in Pocket and Director

• Video

  

  • Video must be compressed (encoded) in real-time to send it over the network using the SRT protocol. Compression can impact latency and video quality.

  • Adjust compression settings to optimize connection stability, video quality, and latency.

  • Bitrate

    • Adjust Bitrate based on available network bandwidth and WiFi capacity.

    • If you experience video streaming issues, decrease the bitrate to improve stability while maintaining good video quality. Lower Bitrate values may affect video quality.

  • Codec

    • For a given Bitrate value

      • Different codecs impact video quality, latency, and phone performance

      • H264 and MPEG4 should provide similar video quality results

      • H264 uses less CPU hence it uses less battery and heats up the phone less

      • HEVC provides better quality at low bitrates, at the cost of higher CPU usage

      • MPEG4 provides lower latency

  • GOP Size

    • Given a Bitrate and Codec, the value of GOP Size will impact the video quality and latency

    • Lower values will result in lower latency

    • Higher values will result in better video quality and low bitrates

Recommended settings

• (SRT) Connection

  • SRT Latency

    • Measure RTT and configure the value in 3 * RTT (milliseconds)

    • In local network, use the default value (120 ms)

• Video

  • Bitrate

    • As high as possible without exceeding your network/connection capacity

    • Start with 20-50 Mbps and only decrease if you see instabilities in the video on your composite output

  • Codec

    • Start with H264 and, if bitrate must be pushed down to a very low value (15 Mbps or lower), switch to HEVC.

    • Only try MPEG4 if you want to cut latency down to the minimum

  • GOP Size

    • Use default value (15 frames), decrease to optimize latency if needed

• Optimizing latency

  • Decrease SRT Latency, testing over time that connection stability is not affected. Remember to decrease on both ends: Pocket and Director

  • Decrease GOP Size. If video quality drops, increase Bitrate without exceeding your network capacity

  • Use MPEG4 codec

Debugging

• Network of Director machine is different from phone

  • Port forwarding

  • Router needs to be reconfigured