src/add-ons/media/media-add-ons/usb_webcam/CamBufferingDeframer.cpp

   1 /*
   2  * Copyright 2004-2008, François Revol, <revol@free.fr>.
   3  * Distributed under the terms of the MIT License.
   4  */
   5
   6 /*
   7  * buffer based deframer
   8  * buffers all packet until it finds a complete frame.
   9  * simpler than StreamingDeframer, but doesn't work any better
  10  * and hogs the cpu intermitently :^)
  11  */
  12
  13 #define CD_COL "31"
  14 #include "CamBufferingDeframer.h"
  15 #include "CamDevice.h"
  16 #include "CamDebug.h"
  17 #include <Autolock.h>
  18 #define MAX_TAG_LEN CAMDEFRAMER_MAX_TAG_LEN
  19 #define MAXFRAMEBUF CAMDEFRAMER_MAX_QUEUED_FRAMES
  20
  21 #define IB fInputBuffs[fInputBuffIndex]
  22
  23
  24 CamBufferingDeframer::CamBufferingDeframer(CamDevice *device)
  25         : CamDeframer(device),
  26         fInputBuffIndex(0)
  27 {
  28 }
  29
  30
  31 CamBufferingDeframer::~CamBufferingDeframer()
  32 {
  33 }
  34
  35
  36 ssize_t
  37 CamBufferingDeframer::Write(const void *buffer, size_t size)
  38 {
  39         uint8 *b;
  40         int l;
  41         int i, s, e;
  42         int which;
  43         fMinFrameSize = fDevice->MinRawFrameSize();
  44         fMaxFrameSize = fDevice->MaxRawFrameSize();
  45         IB.Write(buffer, size);
  46         b = (uint8 *)IB.Buffer();
  47         l = IB.BufferLength();
  48
  49         PRINT((CH "(%p, %d), IB: %d" CT, buffer, size, IB.BufferLength()));
  50
  51         if (l < (int)(fMinFrameSize + fSkipSOFTags + fSkipEOFTags))
  52                 return size; // not enough data anyway
  53
  54         if (!fCurrentFrame) {
  55                 BAutolock l(fLocker);
  56                 if (fFrames.CountItems() < MAXFRAMEBUF)
  57                         fCurrentFrame = AllocFrame();
  58                 else {
  59                         PRINT((CH "DROPPED %d bytes! (too many queued frames)" CT, size));
  60                         return size; // drop XXX
  61                 }
  62         }
  63
  64         for (s = 0; (l - s > (int)fMinFrameSize) && ((i = FindSOF(b + s, l - fMinFrameSize - s, &which)) > -1); s++) {
  65                 s += i;
  66                 if ((int)(s + fSkipSOFTags + fMinFrameSize + fSkipEOFTags) > l)
  67                         break;
  68                 if (!fDevice->ValidateStartOfFrameTag(b + s, fSkipSOFTags))
  69                         continue;
  70
  71                 PRINT((CH ": SOF[%d] at offset %d" CT, which, s));
  72                 PRINT((CH ": SOF: ... %02x %02x %02x %02x %02x %02x" CT, b[s+6], b[s+7], b[s+8], b[s+9], b[s+10], b[s+11]));
  73
  74                 for (e = s + fSkipSOFTags + fMinFrameSize;
  75                          ((e <= (int)(s + fSkipSOFTags + fMaxFrameSize)) &&
  76                           (e < l) && ((i = 0*FindEOF(b + e, l - e, &which)) > -1));
  77                          e++) {
  78                         e += i;
  79
  80                         //PRINT((CH ": EOF[%d] at offset %d" CT, which, s));
  81                         if (!fDevice->ValidateEndOfFrameTag(b + e, fSkipEOFTags, e - s - fSkipSOFTags))
  82                                 continue;
  83
  84
  85
  86                 PRINT((CH ": SOF= ... %02x %02x %02x %02x %02x %02x" CT, b[s+6], b[s+7], b[s+8], b[s+9], b[s+10], b[s+11]));
  87
  88                         // we have one!
  89                         s += fSkipSOFTags;
  90
  91                         // fill it
  92                         fCurrentFrame->Write(b + s, e - s);
  93
  94                         // queue it
  95                         BAutolock f(fLocker);
  96                         PRINT((CH ": Detaching a frame (%d bytes, %d to %d / %d)" CT, (size_t)fCurrentFrame->Position(), s, e, l));
  97                         fCurrentFrame->Seek(0LL, SEEK_SET);
  98                         fFrames.AddItem(fCurrentFrame);
  99                         release_sem(fFrameSem);
 100                         // next Write() will allocate a new one
 101                         fCurrentFrame = NULL;
 102                         // discard the frame and everything before it.
 103                         DiscardFromInput(e + fSkipEOFTags);
 104
 105                         return size;
 106                 }
 107         }
 108         return size;
 109 }
 110
 111
 112 size_t
 113 CamBufferingDeframer::DiscardFromInput(size_t size)
 114 {
 115         int next = (fInputBuffIndex+1)%2;
 116         PRINT((CH ": %d bytes of %d from buffs[%d] (%d left)" CT, size, IB.BufferLength(), fInputBuffIndex, IB.BufferLength() - size));
 117         fInputBuffs[next].Seek(0LL, SEEK_SET);
 118         fInputBuffs[next].SetSize(0);
 119         uint8 *buff = (uint8 *)IB.Buffer();
 120         if (IB.BufferLength() > size) {
 121                 buff += size;
 122                 fInputBuffs[next].Write(buff, IB.BufferLength() - size);
 123         }
 124         IB.Seek(0LL, SEEK_SET);
 125         IB.SetSize(0);
 126         fInputBuffIndex = next;
 127         return size;
 128 }