src/add-ons/media/media-add-ons/video_mixer/BufferMixer.cpp

   1 /*
   2  * Copyright (C) 2010 David McPaul
   3  *
   4  * All rights reserved. Distributed under the terms of the MIT License.
   5  */
   6
   7 // This class merges buffers together
   8 // Merge is called everytime a primary buffer needs to be passed downstream
   9 // This should allow different framerates to be handled by buffering slower
  10 // buffer producers and discarding buffers from faster producers
  11 // TODO ColorConversion
  12
  13 #include "BufferMixer.h"
  14
  15 BufferMixer::BufferMixer() {
  16 }
  17
  18 BufferMixer::~BufferMixer() {
  19 }
  20
  21 bool
  22 BufferMixer::isBufferAvailable() {
  23         return groupedBuffers[0] != NULL;
  24 }
  25
  26 // Should only be called after checking with isBufferAvailable
  27 BBuffer *
  28 BufferMixer::GetOutputBuffer() {
  29         // Do the merging of all buffers in the groupedBuffers map
  30         // into the primary buffer and return that buffer.
  31         // The primary buffer is removed;
  32
  33         BBuffer *outputBuffer = groupedBuffers[0];
  34         groupedBuffers[0] = NULL;
  35
  36         std::map<int32, BBuffer*>::iterator each;
  37
  38         for (each=groupedBuffers.begin(); each != groupedBuffers.end(); each++) {
  39                 if (each->second != outputBuffer) {
  40                         if (each->second != NULL) {
  41                                 Merge(each->second, outputBuffer);
  42                         }
  43                 }
  44         }
  45
  46         return outputBuffer;
  47 }
  48
  49 #define ALPHABLEND(source, destination, alpha) (((destination) * (256 - (alpha)) + (source) * (alpha)) >> 8)
  50
  51 void
  52 BufferMixer::Merge(BBuffer *input, BBuffer *output) {
  53         // Currently only deals with RGBA32
  54
  55         uint8 *source = (uint8 *)input->Data();
  56         uint8 *destination = (uint8 *)output->Data();
  57         uint32 size = input->Header()->size_used / 4;
  58         uint8 alpha = 0;
  59         uint8 c1, c2, c3;
  60
  61         for (uint32 i=0; i<size; i++) {
  62                 c1    = *source++;
  63                 c2    = *source++;
  64                 c3    = *source++;
  65                 alpha = *source++;
  66                 destination[0] = ALPHABLEND(c1, destination[0], alpha);
  67                 destination[1] = ALPHABLEND(c2, destination[1], alpha);
  68                 destination[2] = ALPHABLEND(c3, destination[2], alpha);
  69                 destination[3] = 0x00;
  70                 destination += 4;
  71         }
  72 }
  73
  74 void
  75 BufferMixer::AddBuffer(int32 id, BBuffer *buffer, bool isPrimary) {
  76         BBuffer *oldBuffer;
  77
  78         if (isPrimary) {
  79                 oldBuffer = groupedBuffers[0];
  80                 groupedBuffers[0] = buffer;
  81         } else {
  82                 oldBuffer = groupedBuffers[id];
  83                 groupedBuffers[id] = buffer;
  84         }
  85
  86         if (oldBuffer != NULL) {
  87                 oldBuffer->Recycle();
  88         }
  89 }
  90
  91 void
  92 BufferMixer::RemoveBuffer(int32 id) {
  93         BBuffer *oldBuffer;
  94
  95         if (uint32(id) < groupedBuffers.size()) {
  96                 oldBuffer = groupedBuffers[id];
  97                 groupedBuffers[id] = NULL;
  98
  99                 if (oldBuffer != NULL) {
 100                         oldBuffer->Recycle();
 101                 }
 102         }
 103 }