From 184a9e7e67542faccd6a054b5c4d50f2916cd0d4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?kleines=20Filmr=C3=B6llchen?= <malu.bertsch@gmail.com>
Date: Fri, 25 Jun 2021 13:37:38 +0200
Subject: LibAudio: Make ResampleHelper templated for different sample types

Previously, ResampleHelper was fixed on handling double's, which makes
it unsuitable for the upcoming FLAC loader that needs to resample
integers. For this reason, ResampleHelper is templated to support
theoretically any type of sample, though only the necessary i32 and
double are templated right now.

The ResampleHelper implementations are moved from WavLoader.cpp to
Buffer.cpp.

This also improves some imports in the WavLoader files.
---
 Userland/Libraries/LibAudio/Buffer.cpp | 58 +++++++++++++++++++++++++++++++---
 1 file changed, 54 insertions(+), 4 deletions(-)

(limited to 'Userland/Libraries/LibAudio/Buffer.cpp')

diff --git a/Userland/Libraries/LibAudio/Buffer.cpp b/Userland/Libraries/LibAudio/Buffer.cpp
index 86a51aa7ac..efe6945a5f 100644
--- a/Userland/Libraries/LibAudio/Buffer.cpp
+++ b/Userland/Libraries/LibAudio/Buffer.cpp
@@ -5,10 +5,10 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include "Buffer.h"
 #include <AK/Atomic.h>
 #include <AK/Debug.h>
 #include <AK/String.h>
-#include <LibAudio/Buffer.h>
 
 namespace Audio {
 
@@ -44,7 +44,7 @@ i32 Buffer::allocate_id()
 }
 
 template<typename SampleReader>
-static void read_samples_from_stream(InputMemoryStream& stream, SampleReader read_sample, Vector<Frame>& samples, ResampleHelper& resampler, int num_channels)
+static void read_samples_from_stream(InputMemoryStream& stream, SampleReader read_sample, Vector<Frame>& samples, ResampleHelper<double>& resampler, int num_channels)
 {
     double norm_l = 0;
     double norm_r = 0;
@@ -127,13 +127,13 @@ static double read_norm_sample_8(InputMemoryStream& stream)
     return double(sample) / NumericLimits<u8>::max();
 }
 
-RefPtr<Buffer> Buffer::from_pcm_data(ReadonlyBytes data, ResampleHelper& resampler, int num_channels, PcmSampleFormat sample_format)
+RefPtr<Buffer> Buffer::from_pcm_data(ReadonlyBytes data, ResampleHelper<double>& resampler, int num_channels, PcmSampleFormat sample_format)
 {
     InputMemoryStream stream { data };
     return from_pcm_stream(stream, resampler, num_channels, sample_format, data.size() / (pcm_bits_per_sample(sample_format) / 8));
 }
 
-RefPtr<Buffer> Buffer::from_pcm_stream(InputMemoryStream& stream, ResampleHelper& resampler, int num_channels, PcmSampleFormat sample_format, int num_samples)
+RefPtr<Buffer> Buffer::from_pcm_stream(InputMemoryStream& stream, ResampleHelper<double>& resampler, int num_channels, PcmSampleFormat sample_format, int num_samples)
 {
     Vector<Frame> fdata;
     fdata.ensure_capacity(num_samples);
@@ -166,4 +166,54 @@ RefPtr<Buffer> Buffer::from_pcm_stream(InputMemoryStream& stream, ResampleHelper
     return Buffer::create_with_samples(move(fdata));
 }
 
+template<typename SampleType>
+ResampleHelper<SampleType>::ResampleHelper(double source, double target)
+    : m_ratio(source / target)
+{
+}
+template ResampleHelper<i32>::ResampleHelper(double, double);
+template ResampleHelper<double>::ResampleHelper(double, double);
+
+template<typename SampleType>
+Vector<SampleType> ResampleHelper<SampleType>::resample(Vector<SampleType> to_resample)
+{
+    Vector<SampleType> resampled;
+    resampled.ensure_capacity(to_resample.size() * m_ratio);
+    for (auto sample : to_resample) {
+        process_sample(sample, sample);
+
+        while (read_sample(sample, sample))
+            resampled.unchecked_append(sample);
+    }
+
+    return resampled;
+}
+template Vector<i32> ResampleHelper<i32>::resample(Vector<i32>);
+template Vector<double> ResampleHelper<double>::resample(Vector<double>);
+
+template<typename SampleType>
+void ResampleHelper<SampleType>::process_sample(SampleType sample_l, SampleType sample_r)
+{
+    m_last_sample_l = sample_l;
+    m_last_sample_r = sample_r;
+    m_current_ratio += 1;
+}
+template void ResampleHelper<i32>::process_sample(i32, i32);
+template void ResampleHelper<double>::process_sample(double, double);
+
+template<typename SampleType>
+bool ResampleHelper<SampleType>::read_sample(SampleType& next_l, SampleType& next_r)
+{
+    if (m_current_ratio > 0) {
+        m_current_ratio -= m_ratio;
+        next_l = m_last_sample_l;
+        next_r = m_last_sample_r;
+        return true;
+    }
+
+    return false;
+}
+template bool ResampleHelper<i32>::read_sample(i32&, i32&);
+template bool ResampleHelper<double>::read_sample(double&, double&);
+
 }
-- 
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