The dynamics of video networking solutions have changed significantly in recent years thanks to two key factors.
- Network heterogeneity: Coexistence of traditional Ethernet with pervasive wireless technologies like Wi-Fi.
- Device heterogeneity: Rise of multiple types of networked devices that exchange media and information – desktop, embedded, and mobile that includes laptops, smartphones and tablets.
Given this context, streaming servers, transcoders, and network cameras or DVRs need to overcome several challenges to enable quality video streaming to embedded/mobile clients over wireless networks.
Challenges in Video Streaming Over Wireless Networks
Take a look at some of the main concerns around video streaming over wireless networks.
- Wi-Fi networks offer lower bandwidth (theoretical maximum of 900Mbps for 802.11ac, <50% of that practically achievable) as compared to wired networks (1000Mbps for GbE).
- Wireless applications are sometimes unable to utilize the maximum available bandwidth due to channel utilization by other users and re-transmissions.
- Interference from other wireless devices affects the signal quality and prevents such networks from achieving their full capacity.
- The key impact is in terms of increased packet loss and hence higher re-transmissions.
Variable Channel Conditions
- Mobility increases the variations in channel and signal conditions between the transmitter and receiver.
- Signal strength in relation to distance between the transmitter and receiver is subjected to inverse-square law (Eg: If distance grows by 2x, the signal strength drops by 4x). This affects the available bandwidth and eventually the achievable video quality.
So how do we tackle these challenges to drive seamless video streaming over wireless networks? By carefully addressing the following three key aspects.
1. Network Aware Encoding and Rate Control
- Improve error resilience and lower latency with sub-frame video processing.
- Use network-aware media rate control for Constant Bit Rate (CBR) and Constrained Variable Bit Rat (CVBR) modes of streaming. Write to us to explore more about our patented rate control technology.
- Enable dynamic adaptation of video bit rate, frame rate & resolution based on available bandwidth for UDP/TCP streaming through intelligent adaptation to network characteristics.
- Adopt adaptive jitter handling to counter packet reordering and network jitter.
2. Error Concealment and Correction Mechanisms
- Use special encoding features such as Adaptive Intra Refresh (AIR) and Long Term Reference Picture (LTRP) encoding for better concealment of error due to packet losses.
- Recover from losses at the decoder by utilizing Forward Error Correction (FEC) schemes.
- Leverage packet loss concealment algorithms for audio and video at the decoder.
- Use on-request IDR generation to recover from losses.
3. Traffic Prioritization
- Use protocols and QoS mechanisms such as RSVP and other popular DiffServ and IntServ to prioritize audio video traffic for live streaming.
Explore Ittiam’s Networking Solutions
Ittiam has a long history of delivering solutions for wireless streaming to worldwide customers across multiple market segments. A few cases in point are illustrated below.