mirror of
https://github.com/RGBCube/serenity
synced 2025-05-24 05:45:07 +00:00
8258618caf
We downsample multi-channel files into stereo for now, which at least makes the other channels listenable. The new multi-channel downmix helper is intended to be used for other formats with the same or similar channel arrangement, such as QOA.
87 lines
3.2 KiB
C++
87 lines
3.2 KiB
C++
/*
|
|
* Copyright (c) 2023, kleines Filmröllchen <filmroellchen@serenityos.org>
|
|
*
|
|
* SPDX-License-Identifier: BSD-2-Clause
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <AK/Concepts.h>
|
|
#include <AK/FixedArray.h>
|
|
#include <LibAudio/Sample.h>
|
|
|
|
namespace Audio {
|
|
|
|
// Downmixes any number of channels to stereo, under the assumption that standard channel layout is followed:
|
|
// 1 channel = mono
|
|
// 2 channels = stereo (left, right)
|
|
// 3 channels = left, right, center
|
|
// 4 channels = front left/right, back left/right
|
|
// 5 channels = front left/right, center, back left/right
|
|
// 6 channels = front left/right, center, LFE, back left/right
|
|
// 7 channels = front left/right, center, LFE, back center, side left/right
|
|
// 8 channels = front left/right, center, LFE, back left/right, side left/right
|
|
template<ArrayLike<float> ChannelType, ArrayLike<ChannelType> InputType>
|
|
ErrorOr<FixedArray<Sample>> downmix_surround_to_stereo(InputType input)
|
|
{
|
|
if (input.size() == 0)
|
|
return Error::from_string_view("Cannot resample from 0 channels"sv);
|
|
|
|
auto channel_count = input.size();
|
|
auto sample_count = input[0].size();
|
|
|
|
FixedArray<Sample> output = TRY(FixedArray<Sample>::create(sample_count));
|
|
|
|
// FIXME: We could figure out a better way to mix the channels, possibly spatially, but for now:
|
|
// - Center and LFE channels are added to both left and right.
|
|
// - All left channels are added together on the left, all right channels are added together on the right.
|
|
switch (channel_count) {
|
|
case 1:
|
|
for (auto i = 0u; i < sample_count; ++i)
|
|
output[i] = Sample { input[0][i] };
|
|
break;
|
|
case 2:
|
|
for (auto i = 0u; i < sample_count; ++i)
|
|
output[i] = Sample { input[0][i], input[1][i] };
|
|
break;
|
|
case 3:
|
|
for (auto i = 0u; i < sample_count; ++i)
|
|
output[i] = Sample { input[0][i] + input[2][i],
|
|
input[1][i] + input[2][i] };
|
|
break;
|
|
case 4:
|
|
for (auto i = 0u; i < sample_count; ++i)
|
|
output[i] = Sample { input[0][i] + input[2][i],
|
|
input[1][i] + input[3][i] };
|
|
break;
|
|
case 5:
|
|
for (auto i = 0u; i < sample_count; ++i)
|
|
output[i] = Sample { input[0][i] + input[3][i] + input[2][i],
|
|
input[1][i] + input[4][i] + input[2][i] };
|
|
break;
|
|
case 6:
|
|
for (auto i = 0u; i < sample_count; ++i) {
|
|
output[i] = Sample { input[0][i] + input[4][i] + input[2][i] + input[3][i],
|
|
input[1][i] + input[5][i] + input[2][i] + input[3][i] };
|
|
}
|
|
break;
|
|
case 7:
|
|
for (auto i = 0u; i < sample_count; ++i) {
|
|
output[i] = Sample { input[0][i] + input[5][i] + input[2][i] + input[3][i] + input[4][i],
|
|
input[1][i] + input[6][i] + input[2][i] + input[3][i] + input[4][i] };
|
|
}
|
|
break;
|
|
case 8:
|
|
for (auto i = 0u; i < sample_count; ++i) {
|
|
output[i] = Sample { input[0][i] + input[4][i] + input[6][i] + input[2][i] + input[3][i],
|
|
input[1][i] + input[5][i] + input[7][i] + input[2][i] + input[3][i] };
|
|
}
|
|
break;
|
|
default:
|
|
return Error::from_string_view("Invalid number of channels greater than 8"sv);
|
|
}
|
|
|
|
return output;
|
|
}
|
|
|
|
}
|