1. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed. Multiprocessors zConsumer electronics systems. zCell phones. zCDs and DVDs. zAudio players. zDigital still cameras.

2. Consumer electronics use cases zMultimedia: stored in compressed form, uncompressed on viewing. zData storage and management: keep track of your multimedia, etc. zCommunication: download, upload, chat. © 2000 Morgan Kaufman Overheads for Computers as Components

3. Non-functional requirements for CE zOften battery-operated, strict power budget., zVery inexpensive. zUser interface must be capable but inexpensive. © 2000 Morgan Kaufman Overheads for Computers as Components

4. CE devices and hosts zMany devices talk to host system. yPC host does things that are hard to do on the device. zIncreasingly, CE devices communicate directly over the network, avoiding the host for access. © 2000 Morgan Kaufman Overheads for Computers as Components

5. Platforms and operating systems © 2000 Morgan Kaufman Overheads for Computers as Components z Many CE devices use a DSP for signal processing and a RISC CPU for other tasks. z I/O devices include buttons, screen, USB.

6. Flash file systems zFlash is widely used for mass storage. zFlash wears out on writing (up to 1 million cycles). yDirectory is most often written, wears out first. zFlash file system has layer that moves contents to levelize wear. yHides wear leveling from API. © 2000 Morgan Kaufman Overheads for Computers as Components

7. Cell phones zMost popular CE device in history; most widely used computing device. y1 billion sold per year. zHandset talks to cell. zCells hand off handset as it moves. © 2000 Morgan Kaufman Overheads for Computers as Components

8. Cell phone platforms zToday’s cell phones use analog front end, digital baseband processing. yFuture cell phones will perform IF processing with DSP. zBaseband processing in DSP: yVoice compression. yNetwork protocol. zOther processing: yMultimedia functions. yUser interface. yFile system. yApplications (contacts, etc.) © 2000 Morgan Kaufman Overheads for Computers as Components

9. CD/MP3 player Audio CPU amp Jog memory Error corrector Servo CPU Analog in Analog out FE, TE, amp focus, tracking, sled, motor head drive memory display DAC I2SI2S © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

10. CD medium zRotational speed: 1.2-1.4 m/s (CLV). zTrack pitch: 1.6 microns. zDiameter: 120 mm. zPit length: 0.8 -3 microns. zPit depth:.11 microns. zPit width: 0.5 microns. zLaser wavelength: 780 nm. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

11. CD mechanism zLaser, lens, sled: laser CD detectors diffraction grating sled track focus © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

12. Laser focus zFocus controlled by vertical position of lens. zUnfocused beam causes irregular spot: In focusOut of focus © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

13. Laser pickup A B C D F E Side spot detectors Level: A+B+C+D Focus error: (A+C)-(B+D) Tracking error: E-F © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

14. Servo control zFour main signals: yfocus (laser) @ 245 kHz; ytracking (laser) @ 245 kHz; ysled (motor): @ 800 Hz; yDisc motor. Optical pickup © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

15. EFM zEight-to-fourteen modulation: yFourteen-bit code guarantees a maximum distance between transitions. 0000001100100100000000 © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

16. Error correction zCD capacity: 6.99 GB raw, 700 MB formatted. zReed-Solomon code:  g(x) = (x-  ) (x-  2 ) … (x-  n-k-1 ) (x-  n-k ) zProduces data, erasure bits. zTime to solve varies greatly depending on noise. zCD interleaves Reed-Solomon blocks to reduce effects of large data gaps. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

17. Control and error correction zSkips caused by physical disturbance. yWait for disturbance to subside. yRetry. zRead errors caused by disc/servo problems. yDetect error. yChoose location for retry. yRetry. yFail and interpolate. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

18. MPEG audio standards zLayer 1: yLossless compression of subbands + optional simple masking model zLayer 2: yMore advanced masking model. zLayer 3: yAdditional processing for lower bit rates. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

19. MPEG audio rates zInput sampling rates: y32, 44.1, 48 kHz. zOutput bit rates: y23, 48, 64, 96, 112, 128, 192, 256, 384 kbits/sec. zOutput can be mono, dual-channel (bilingual, etc.), stereo. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

20. Other standards zDolby Digital (AC-3): yUses modified discrete cosine transform. zATRAC (MiniDisc): yUses subband + modified DCT. zMPEG-2 AAC. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

21. MPEG Layer 1 z384 samples/block at all frequencies. yEquals 8 ms at 48 kHz. zOptional masking model. yDriven by separate FFT for better accuracy. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

22. MPEG Layer 1 data frame zBit allocation codes specify word length in each subband. zScale factors give gain for each band. headerCRC bit allocation scale factors subband samples aux data © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

23. MPEG Layer 1 encoder Filter bank Choose Scale factor Masking model requantize * FFT mux 0101.. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

24. MPEG Layer 1 decoder 0101.. demux Scale factor ** Step size Inverse filter bank inverse quantize expand © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

25. MP3 zDecoding is easier than encoding, but requires: ydecompression; yfiltering. zBasic CD standard for data discs. zNo standards for MP3 disc file structure: player must understand Windows, Mac, Unix discs. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

26. Audio players zAudio players may use flash, hard disk, or CD for mass storage. zDecompression requires small amount of CPU: y10% of ARM7. zFile system must be compatible (FAT). © 2000 Morgan Kaufman Overheads for Computers as Components

27. Digital still cameras zDSC must determine exposure before taking picture. zAfter taking picture: yImprove image quality. yCompress. ySave as file. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

28. Digital still camera architecture © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed. z DSC uses CPU for general-purpose processing, DSP for image processing. z Internal memory buffers the passes on the image. z Display is lower resolution than image sensor. yImage must be downsampled.

29. Image capture zBefore taking picture: yDetermine exposure. yDetermine focus. yOptimize white balance. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed. Bayer pattern

30. Image processing zMust perform basic processing to get usable picture: yBayer->RGB interpolation. zDSCs perform many functions formerly performed by photoprocessors for film: yImage sharpening. yColor balance. © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.

31. File management zEXIF standard gives format for digital pictures: yFormat of data in a file. yDirectory structure. zEXIF file includes: yImage (JPEG, etc.) yThumbnail. yMetadata (camera type, date/time, etc.) © 2008 Wayne Wolf Overheads for Computers as Components 2 nd ed.