diff options
Diffstat (limited to 'Source/Sound/AudioFilters/transition_mixer.cpp')
| -rw-r--r-- | Source/Sound/AudioFilters/transition_mixer.cpp | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/Source/Sound/AudioFilters/transition_mixer.cpp b/Source/Sound/AudioFilters/transition_mixer.cpp new file mode 100644 index 00000000..19d2f97b --- /dev/null +++ b/Source/Sound/AudioFilters/transition_mixer.cpp @@ -0,0 +1,141 @@ +//----------------------------------------------------------------------------- +// Name: transition_mixer.cpp +// Developer: Wolfire Games LLC +// Description: +// License: Read below +//----------------------------------------------------------------------------- +// +// Copyright 2022 Wolfire Games LLC +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. +// +//----------------------------------------------------------------------------- +#include "transition_mixer.h" + +#include <Logging/logdata.h> +#include <Utility/assert.h> + +#include <cmath> +#include <algorithm> + +#define PI 3.141592653589793238462643383279502884197169399375105820974944592308 + +TransitionMixer::TransitionMixer( TransitionType trans_type, float transition_length_seconds ) : +transition_type( trans_type ), +transition_length_sec( transition_length_seconds ), +transition_position(0) +{ + +} + +bool TransitionMixer::Step( HighResBufferSegment* out, const HighResBufferSegment* first, const HighResBufferSegment* second ) +{ + LOG_ASSERT( first->sample_rate == second->sample_rate ); + LOG_ASSERT( first->channels == second->channels ); + + out->sample_rate = first->sample_rate; + out->channels = first->channels; + out->data_size = out->SampleSize() * std::max(first->FlatSampleCount(),second->FlatSampleCount()); + + size_t start = transition_position; + //How many bytes for a second of transition times the time of transition. + size_t end = (size_t) (transition_length_sec * first->sample_rate * first->channels); + + size_t i = 0; + + //This casting union is possible because we take endianess into account when we get the first from the underlying loader. + //If we use architecture inspecific endianess we have to bitshift this data instead. + //Also note that use of a union for aliasing is not strictly allowed until C99, but generally implemented and faster than shifting. + union casterunion + { + int32_t full; + char part[4]; + }; + + casterunion out1; + casterunion buf1; + casterunion buf2; + + //Crossfade the two firsts together. + for( i = 0; i < out->FlatSampleCount(); i++ ) + { + float d = (float)(start+i)/(float)(end); + if( d > 1.0f ) { + d = 1.0f; + } + + float dl; + float dr; + if( transition_type == Sinusoid ) + { + //Crossfade in a sinusoid to preserve the energy. + float dp = d*(float)PI/2; + dl = sin(dp); + dr = cos(dp); + } + else if( transition_type == Linear ) + { + dl = d; + dr = 1.0f-d; + } + else + { + LOGE << "No transition function used" << std::endl; + + dl = 1.0f; + dr = 0.0f; + } + + if( i < first->FlatSampleCount() ) { + buf1.part[0] = first->buf[i*4+0]; + buf1.part[1] = first->buf[i*4+1]; + buf1.part[2] = first->buf[i*4+2]; + buf1.part[3] = first->buf[i*4+3]; + } else { + buf1.full = 0; + } + + if( i < second->FlatSampleCount() ) { + buf2.part[0] = second->buf[i*4+0]; + buf2.part[1] = second->buf[i*4+1]; + buf2.part[2] = second->buf[i*4+2]; + buf2.part[3] = second->buf[i*4+3]; + } else { + buf2.full = 0; + } + + out1.full = (int32_t) (buf1.full*dr+buf2.full*dl); + + out->buf[i*4+0] = out1.part[0]; + out->buf[i*4+1] = out1.part[1]; + out->buf[i*4+2] = out1.part[2]; + out->buf[i*4+3] = out1.part[3]; + } + + //If it happened that the second first had more data than the first, indicate that + // we continued writing into the main first so we don't miss that segment of audio + // that was streamed. + transition_position += i; + + if( transition_position >= end ) + { + transition_position = end; + return true; + } + return false; +} + +void TransitionMixer::Reset() +{ + transition_position = 0; +} |