DTV Software Infrastructure

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DTV Software Infrastructure

• Milton Chen

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Outline

• MPEG-2 Transport Stream
• Client
• Headend
• Examples

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MPEG-2 Transport Stream

• Packet
• 188 bytes (header plus payload)
• 13 bit packet ID (pid)
• 1 bit priority
• Filename ends in .ts (our convention)
• Which MPEG are you talking about ?

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Client Stack
DTV_MPEG API
DTV_Object API
DTV API
application
emulation
demand
driver
operation system
receiver card
disk
hardware
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DTV API

• int DTVInit( int channel, char tsfname,
  bool loop, double bitrate
  )
• int DTVClose()

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DTV API (2)

• class DTVConn DTVConn( int pid, int raw
  ) int RetrieveBuffer( DTVappbuf buf,
  int wait ) int ReturnBuffer( DTVappbuf buf
  ) int Flush()

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DTV API (3)

• typedef struct int filledsize unsigned char
  data DTVappbuf

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DTV_MPEG API

• Set a dozen global variables
• playbacklevel, texture size, etc.
• MyDtvDecoder()
• unsigned char RGBarray

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DTV_Object API

• class DtvObjStream DtvObjStream( int pid
  ) int GetObj( char objname, int
  waittime, dtvobject obj ) int CloseObj(
  dtvobject obj )

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DTV_Object API (2)

• typedef struct char name256 FILE data
  dtvobject

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Client Environment

• 1. Win 95
• 2. DirectX 5
• 3. ATI Rage Pro or Intel 740 Graphics Card
• Live reception requires 1
• MPEG decoder requires 2, 3
• Link with multi-threaded library in VC

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Headend - Video

• 1. Camera -gt
• 2. Video Capture Card -gt
• 3. capture.exe ( .ppm ) -gt
• 4. MPEG2 Encoder ( .m2v ) -gt
• 5. pespacketizer.exe ( .pes ) -gt
• 6. dynamux.exe ( .ts )
• Step 4, 5, and 6 are not real-time
• tools to manipulate .m2v files (clip, cat, )

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Headend - Object

• Object Parameter File
• file obj. name insert time
  magicidobj1.exe obj1 0.0 1obj2.zip obj2 0.5
  2obj3.html obj3 1.0 3
• Run dynamux.exe

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Headend - Arbitrary data

• Write it to a file
• Run dynamux.exe

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Headend - Multiplexer

• dynamux.exe
• Convert video, audio, object, and arbitrary data
  from different sources into one transport stream

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Examples

• MyDtvReceiver (DTV API)
• count the number of bytes received
• MyDtvApp (DTV_MPEG API)
• one thread decode to shared memory
• one thread display the decoded frames with OpenGL
  texture mapping
• MyDtvWeb (DTV_Object API)
• receive one html file and launch netscape to
  display that file

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Source Tree

• C\Dtv_public
• content
• headend
• receiver
• bin
• include
• lib
• sample