VoIP on the iphone. Dr. Jan Linden, VP of Engineering. iphone Developer Summit

Transcription

1 VoIP on the iphone Imagine the Possibilities! Dr. Jan Linden, VP of Engineering iphone Developer Summit

2 Evolution of IP Voice and Video Processing Advanced Mobile and Multimedia Capabilities Solutions Designed Specifically for VoIP PSTN Solutions Adapted for VoIP

3 Mobile Market Trends Fixed Mobile Convergence Mobile phone increasingly perceived as a computer Advanced doperating systems such as Apple OSX are making this a reality Users expect to access the same applications available across multiple platforms Increased accessibility and affordability Network operators are introducing new pricing models dlto encourage uptake of data driven services and applications IP networks enable more cost effective transport Handset prices declining iphone 3G half the price of 1 st Generation

4 Mobile Technology Trends Migration from legacy cellular to next gen networks Allows for faster data connection Growth of Smartphone adoption iphone and other dual mode phones provide greater flexibility in connecting to available lbl networks All in one devices able to run multiple applications efficiently Consumers can place calls and receive data simultaneously Development of 3 rd Party Applications Operating systems, like the Apple OS X, more conducive to advanced 3 rd party applications VoIP over mobile in high demand

5 The iphone as a VoIP Platform iphone most VoIP friendly phone on market Open APIs for easy development Sufficient CPU resources Support of wideband codecs Intuitive UI makes for simple navigation between applications Demand for 3 rd party apps is higher than other phones but strengths present unique challenges Running too many applications can drain resources Usage scenarios can negatively impact voice quality With the right voice processing software, developing VoIP applications is a cinch!

6 Technology Challenges Network Connections IP Networks Lt Latency Jitter Packet loss Wireless connections Low signal strength Interference from users in same or neighboring frequencies Available bandwidth varies Wi Fi access point bottlenecks

7 Technology Challenges Device Limitations Limited processing gpower Battery life Data intensive applications can cause jitter Mobile Environments Tend to have excessive background noise Hands Free operation enhances acoustic echo

8 Impact of IP Networks Delay Packet Loss Network Jitter

9 Impact of IP Networks Latency Major effect is stepping on each other s talk Usage scenario affects annoyance factor higher delay can be tolerated for mobile devices Long delays make echo more annoying

10 Sources of Latency Codec Capture Playout Network delay Jitter buffer OS interactioni Transcoding A/D D/A Preprocessin Pre Speech IP IP Processing encoding Encoding interface Interface g Post Post Speech Jitter processin Processing Decoding decoding Butter buffer g IP Network IP Network

11 Impact of Latency on Voice Quality 4 Mean Opinion Sco ore One-w ay transmission time [ms] Data from ITU T G.114 ITU T (G.114) recommends: Less than 150 ms one way delay for most applications (up to 400 ms acceptable tbl in special il cases) Users have got used to longer delays Still, low delay very important for high quality

12 Impact of IP Networks Packet Loss and Jitter Packet Loss Occurs due to flushed buffers in network nodes Same effect if packets are too late to be used Smooth concealment necessary Network Jitter Transmission time differs for each packet Jitter buffer necessary to ensure continuous playout Trade off between delay and quality

13 Technology Challenges Mobile Environments Acoustic Echo Speakerphone operation common for iphones Microphone and speaker close High delay in VoIP makes echo more prominent Background Noise Environments inherently noisy Usage scenarios can make differentiating between speech and noise difficult

14 Technology Challenges Devices Limited Resources Size limits processing power Battery life also limited VoIP Friendliness Many smartphones limit access to soundcard Device buffers add latency Clock drift Too much of a Good Thing Running toomanyapplications applications can drain resources Multiple applications accessing network can result in jitter

15 VoIP Design Considerations Speech Quality Time to Market Ease of Use Flexibility Network Impairments Power Consumption Quality Cost Cost Signaling Infrastructure Features Device Considerations

16 Mobile VoIP Design Considerations Speech Codec Coping withnetwork Degredation Echo Cancellation Echo Network Codec VoIP Design Challenges Additional Voice Processing Components Voice Environment Hardware Power Hardware Issues (Processor, OS, Acoustics, etc.) Power Consumption Environment Background Noise, Room Acoustics, etc.

17 Speech Codec Many conflicting parameters affect choice of codec Complexity Packet loss Robustness Determines upper limit of quality Delay Memory Support of several codecs necessary Interoperability Bit rate Speech Codec Input Signal Robutness Usage scenario IPR issues a significant concern Quality Sampling Rate

18 Audio Bandwidth Effect on Quality Quality CD Audio GIPS Wideband Speech GIPS Narrowband Speech Std Wideband Speech (e.g. G.722.2) Std Narrowband Speech Implementation (PSTN) Hz 3,4 4 khz khz 8 khz 22.1 khz Better than PSTN quality is achievable in VoIP Utilizing full 0 4 khz band in narrowband Wideband coding offers more natural and crispier voice Frequency

19 Recommendations IP Networks No need for dedicated ddi tdbandwidth idthifif solution includes high h performance: Bandwidth management Robust codec framework Low latency achieved by efficient jitter buffer Audio High quality audio is crucial Users expect the same quality they experience on the PC Optimized Solutions p Efficiency for ARM processors on iphones Reduce CPU constraint and increase battery life

20 Recommendations Adaptive Jitter Buffer and PLC Manage up to 30% packet loss Adapt to network busts and excessive mobile jitter Codecs Designed for IP Networks Work in tandem with jitter buffer to overcome packet loss Can deliver Wideband experience Robust and bit rate adaptive codecs necessary Efficient use of the total available bandwidth GIPS ilbc already in the iphone, GIPS isac and other wideband codecs provide even better user experience Aggressive Voice Quality Enhancement Detect and cancel background noise Suppress acoustic echo

21 Recommendations VoiceEngine Mobile for iphone Comprehensive package of voice processing components Handles delay, jitter, packet loss and mobile environments Optimized for iphone and Smartphones Efficient solution reduces CPU demands Flexible and easy to integrate