This topic provides an outline of requirements for a head unit. The requirements are derived from a real life development project for in-vehicle infotainment platform. This is still work in progress--the content will be added gradually.
Some of the requirements below will be fulfilled outside of the MeeGo IVI based software. For example, the implementation of CAN network interface and early audio functions most probably falls into this category. The decisions about implementation of specific requirements in MeeGo IVI software will be made assuming a specific system architecture.
Constraints
Performance
- After power-on, the head unit displays a static splash screen within 200 ms.
- After power-on, the head unit displays an animated splash screen (pre-defined, fixed) within 200 ms and at the frame rate above 4 fps.
- After power-on, the head unit is able to play early audio (e.g. chimes and gongs--minimal set, best suited type, simple) within max. 1 s.
- After power-on, the head unit plays FM radio, resuming the last station before shut-down, within max. 2 s.
- After power-on, the head unit plays compressed audio from a connected media device (e.g. MP3 from USB stick), resuming the last track played before shut-down, within max. 2 s.
- After power-on, the head unit displays the rear view camera output within max. 2 s.
- After power-on, the head unit accepts first user input (e.g. HMI menu, screen, volume control) within max. 2 s.
- After power-on, the head unit displays the Navigation map and starts the route guidance, resuming the previous route, within max. 5 s.
- Head unit reacts to user input via HMI (touch screen events, button or switch presses) within max. 100 ms. Head unit displays interim response (e.g. sand glass) for all requests that cannot be completed within this time
- Head unit performs voice recognition for a single word against G2P vocabulary within max. 200 ms measured from the end of utterance (silence detection) to recognition result available (e.g. HMI display update or resulting voice prompt output).
- Head unit performs hand writing recognition against Chinese standard 2000 character set within max. 200 ms measured from end of entry to recognition result available (e.g. HMI display update or resulting voice prompt output).
- Head unit exhibits the refresh rate of min 15 fps for the navigation map in any scaling.
- Head unit exhibits a graphics rendering frame rate (for HMI animations and Navigation maps) of min. 15 fps.
Audio
Audio_Codecs_Playback
- Head unit supports the following codecs:
- AAC LC
- MP3
- WMA
- WAV
- Ogg Vorbis
- FLAC
Audio_Processing_And_Management
- Head unit supports up to 4 independent audio zones (sinks). One zone if 5.1 channels (e.g. cabin speakers) and others are stereo. (Each zone might require its own independent audio processing and audio codec instances.)
- Head unit allows the user to adjust at least audio treble and bass level.
- Head unit allows the user to adjust balance and fade level.
- Head unit is capable of playing back any of its sources to any of 4 audio zones including simultaneous playback to up to 4 audio zones.
- Head unit uses pre-defined fader ramps when switching the audio source for any particular audio zone.
- For each audio zone, the head unit keeps track of the most recently played audio source and restores it upon startup. (For example, when the FM tuner was played to the cabin speakers and the head unit has been switched off, it would attempt tuning to the same FM station and putting it to the cabin speakers upon the next startup.)
- For each audio zone, all available audio sources are assigned a unique priority. When an audio source is being played back and a higher priority source becomes available (e.g. the phone application attempts to play a ring tone), the latter overrides the former.
- As a configuration option, overriding can be done either by muting the first source and playing back the second source, or by lowering the volume of the first source and mixing it with the second source.
Audio_Generation
- chimes and gongs
- calibration to interior
Audio_Recording
- voice
- radio
- podcasts
Audio_Volume_Control
- Volume level is adjustable by the user.
- Adjustments by the user are only accepted during actual audio playback. (In other words, any volume changes e.g. during start up phase and before the audio output can be heard will be ignored.)
- The volume level selection by the user is maintained for each audio source / sink pair individually.
- Volume level is adjusted by the head unit accordingly to the current vehicle speed.
- Volume level set by the user is preserved through shutdown cycle.
- Upon start up, the previous volume level is only restored up to a defined 'start up maximum' (as contrasted to the 'absolute maximum' that can be set after the head unit is up and running in its normal mode).
- Under limit volume need to be set as some low level NOT minimum just to make sure that at leaset user can recognize low level volume even though user set the volume to minimum "basically mute" before the power cycle
- Upper limit volume need to be set as some high level NOT maximum just to make sure that user can not be annoyed due to the previous maximum volume setting.
- In Emergency Case, volume should not be adjusted by the user, volume need to be fit as some very loud level as much as no sound is masked with ambient noisy backgroud,
Handfree Functionality
- Noise reduction
- Echo cancellation
- Residual echo cancellation
- Automatic gain control
- Programmable Equalization
- Performance Requirement
- objective testing : VDA 1.6
- subjective testing : In-Vehicle live testing
Connectivity
Wireless_Interfaces
Wireless_Infrared_IRDA
Wireless_WiFi_Connection
- access point
- client
Wireless_Bluetooth_Connection_and_Telephony
Wireless_Cellular_Mobile_Telephony
Wireless_BT_Hands-free_Telephony
- profiles
- Acoustic Echo Cancellation / Noise Reduction (AEC / NR)
- single and dual microphone
Wired_Interfaces
USB_Connection_to_CE_Devices
Removable_SD_Card_Connections
Internet_Access_and_Browser
- internet radio
- podcasts
- applications (e.g. google maps)
- social networks
Phone_Functionality
- internal phone book
- VoIP
Terminal_Mode_Functionality
Microsoft_Plays_From_Device
Configuration
Personalization
- user profiles
Driver_Assistance
- camera input processing
- electronic horizon
Diagnostics
HMI
User_Inputs_Support
UI_Devices_Support
UI_Touch_Sreen_Hand_Writing_Detection
UI_Speech_Recognition_Function
1. Recognition Category
1. discrete command - command, single digit ( e.g. "dial",'1','2',..etc )
2. continuous command - continuous digit ( e.g. "dial 555-1212", " 555-1212" )
3. natural language understaning - flexible recognition ( e.g. "I want to make a call to john",
"please route to the san franciso regency hyatt hotel",..etc)
2. Recognition Response time
1. discrete command - 300ms
2. continuous command - 1200ms
3. natural language understanding - 1500ms
3. Recognition performance measurement
1. overall accuracy measurement
Average Sentence Accuracy = (Total Number of Correct Sentences)/(Total Number of Sentence Attempted)
2. individual accuracy measurement
Average Word Accuracy = ((Total number of attempts) - (insertions) - (deletions) - (substitutions))/Total number of attempts
4. Regnition performance requirement
1. discrete command
IDLE SNR>20dB (98%>) , Middle noisy SNR>10dB ( 95%> ), Too much noisy SNR> 6dB ( 92%) , SNR <6dB (rejection )
2. continuous command
IDLE SNR>20dB (98%>) , Middle noisy SNR>10dB ( 95%> ), Too much noisy SNR> 6dB ( 92%) , SNR <6dB (rejection )
Multiple_HMI_Languages
Software_Support
Users_Manual_Integrated
Graphics_Functions
Media
Media_Player_and_Browser_Requirements
- number of player instances
- playlists
- ripping
Storage_Media_Support
Navigation
Navigation_Engine
Map_Function
- database
- map source
- 2D/3D representation (pitch)
- zooming (IN / OUT / auto-zoom)
- panning (NORTH / SOUTH / EAST / WEST / and combination of these 4 eg. NORTH-WEST)
- orientation / northing (ON - map oriented north / OFF - map oriented in travelling direction)
- follow gps signal ( ON - map cursor follows gps signal / OFF - map cursor does not follow gps signal / timeout - number of updates to wait before cursor follows gps signal on map; useful for panning)
- set / clear destination
- center the map
- set/change map layout (day / night / detailed - POIs / plain simple)
- bookmarks (see also Destination_Import)
- OSD (on-screen display) information
Real_Time_Traffic_Information
Speech_Support_for_Navigation
Positioning_Capabilities
Points_of_Interestes_POIs
Destination_Import
- from file (eg. USB)
- from web server / web service
- free input
- coordinate units conversion
Network
CAN_Network_Interface
MOST_Network_Interface
Ethernet_Network_Interface
- DLNA
- AVB
Serial_Network_Interfaces
- UART
- LIN
Gateway
Power
Power_Management_Master
Power_Modes
Wakeup_Conditions
Monitor_Voltage_Ranges
Telematics and Data Services
Emergency_and_Breakdown_Call
JAVA_Telematics_Client
Remote_Diagnostics
Vehicle_Tracking
Radio and Video Broadcast Tuner
Radio_Broadcast_Reception
Radio_AM_FM_Broadcast_Reception
Radio_SDARS_Broadcast_Reception
Radio_HD_Broadcast_Reception
Radio_DAB_Broadcast_Reception
Radio_DRM_Broadcast_Reception
Broadcast_Sources_Pause_Resume
- time shift
Radio_Further_Traffic_and_Data_Services
Video_Broadcast_Reception
Video
Video_Playback_Formats_and_Codecs
- containers
- codecs
- resolutions
- frame rates
Video_Decoding_Performance
Voice
Voice_Tag_Processing
Voice_Recognition_Capabilties
Voice_Output_Functionality
Software Services
Software_Architectural_Requirements
Software_Update
Office_Applications
Security_Features
- user privacy
- data storage security
- data access authorization
Gaming_Features
- pre-installed
- nomadic device