+ auto result = audio_buffer(format_desc_.audio_samples_per_frame, 0);\r
+\r
+ std::map<const void*, core::frame_transform> next_frame_transforms;\r
+\r
+ BOOST_FOREACH(auto& item, items)\r
+ { \r
+ const auto next = item.transform;\r
+ auto prev = next;\r
+\r
+ const auto it = prev_frame_transforms_.find(item.tag);\r
+ if(it != prev_frame_transforms_.end())\r
+ prev = it->second;\r
+ \r
+ next_frame_transforms[item.tag] = next; // Store all active tags, inactive tags will be removed at the end.\r
+ \r
+ if(next.volume < 0.001 && prev.volume < 0.001)\r
+ continue;\r
+ \r
+ if(static_cast<size_t>(item.audio_data.size()) != format_desc_.audio_samples_per_frame)\r
+ continue;\r
+\r
+ CASPAR_ASSERT(format_desc_.audio_channels == 2);\r
+ \r
+ const float prev_volume = static_cast<float>(prev.volume);\r
+ const float next_volume = static_cast<float>(next.volume);\r
+ const float delta = 1.0f/static_cast<float>(format_desc_.audio_samples_per_frame/2);\r
+ \r
+ tbb::parallel_for\r
+ (\r
+ tbb::blocked_range<size_t>(0, format_desc_.audio_samples_per_frame/2),\r
+ [&](const tbb::blocked_range<size_t>& r)\r
+ {\r
+ for(size_t n = r.begin(); n < r.end(); ++n)\r
+ {\r
+ const float alpha = n * delta;\r
+ const float volume = prev_volume * (1.0f - alpha) + next_volume * alpha;\r
+\r
+ auto sample_epi32 = _mm_loadl_epi64(reinterpret_cast<__m128i*>(&item.audio_data[n*2]));\r
+\r
+ auto sample_ps = _mm_cvtepi32_ps(sample_epi32); \r
+ sample_ps = _mm_mul_ps(sample_ps, _mm_set1_ps(volume)); \r
+\r
+ auto res_sample_epi32 = _mm_loadl_epi64(reinterpret_cast<__m128i*>(&result[n*2]));\r
+ auto res_sample_ps = _mm_cvtepi32_ps(res_sample_epi32); \r
+\r
+ res_sample_ps = _mm_add_ps(sample_ps, res_sample_ps);\r
+ res_sample_epi32 = _mm_cvtps_epi32(res_sample_ps);\r
+ \r
+ _mm_storel_epi64(reinterpret_cast<__m128i*>(&result[n*2]), res_sample_epi32);\r
+ }\r
+ }\r
+ );\r
+ }\r
+\r
+ items.clear();\r
+ prev_frame_transforms_ = std::move(next_frame_transforms); \r
+\r
+ result.resize(format_desc_.audio_samples_per_frame);\r
+ return std::move(result);\r