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/*
* Copyright 2003-2021 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "PcmChannels.hxx"
#include "ChannelDefs.hxx"
#include "Buffer.hxx"
#include "Silence.hxx"
#include "Traits.hxx"
#include "util/ConstBuffer.hxx"
#include "util/WritableBuffer.hxx"
#include <array>
#include <algorithm>
#include <cassert>
template<typename D, typename S>
static void
MonoToStereo(D dest, S src, S end) noexcept
{
while (src != end) {
const auto value = *src++;
*dest++ = value;
*dest++ = value;
}
}
template<SampleFormat F, class Traits=SampleTraits<F>>
static typename Traits::value_type
StereoToMono(typename Traits::value_type _a,
typename Traits::value_type _b) noexcept
{
typename Traits::sum_type a(_a);
typename Traits::sum_type b(_b);
return typename Traits::value_type((a + b) / 2);
}
template<SampleFormat F, class Traits=SampleTraits<F>>
static typename Traits::pointer
StereoToMono(typename Traits::pointer dest,
typename Traits::const_pointer src,
typename Traits::const_pointer end) noexcept
{
while (src != end) {
const auto a = *src++;
const auto b = *src++;
*dest++ = StereoToMono<F, Traits>(a, b);
}
return dest;
}
template<SampleFormat F, class Traits=SampleTraits<F>>
static typename Traits::pointer
NToStereo(typename Traits::pointer dest,
unsigned src_channels,
typename Traits::const_pointer src,
typename Traits::const_pointer end) noexcept
{
assert((end - src) % src_channels == 0);
while (src != end) {
typename Traits::sum_type sum = *src++;
for (unsigned c = 1; c < src_channels; ++c)
sum += *src++;
typename Traits::value_type value(sum / int(src_channels));
/* TODO: this is actually only mono ... */
*dest++ = value;
*dest++ = value;
}
return dest;
}
/**
* Convert stereo to N channels (where N > 2). Left and right map to
* the first two channels (front left and front right), and the
* remaining (surround) channels are filled with silence.
*/
template<SampleFormat F, class Traits=SampleTraits<F>>
static typename Traits::pointer
StereoToN(typename Traits::pointer dest,
unsigned dest_channels,
typename Traits::const_pointer src,
typename Traits::const_pointer end) noexcept
{
assert(dest_channels > 2);
assert((end - src) % 2 == 0);
std::array<typename Traits::value_type, MAX_CHANNELS - 2> silence;
PcmSilence({&silence.front(), sizeof(silence)}, F);
while (src != end) {
/* copy left/right to front-left/front-right, which is
the first two channels in all multi-channel
configurations **/
*dest++ = *src++;
*dest++ = *src++;
/* all other channels are silent */
dest = std::copy_n(silence.begin(), dest_channels - 2, dest);
}
return dest;
}
template<SampleFormat F, class Traits=SampleTraits<F>>
static typename Traits::pointer
NToM(typename Traits::pointer dest,
unsigned dest_channels,
unsigned src_channels,
typename Traits::const_pointer src,
typename Traits::const_pointer end) noexcept
{
assert((end - src) % src_channels == 0);
while (src != end) {
typename Traits::sum_type sum = *src++;
for (unsigned c = 1; c < src_channels; ++c)
sum += *src++;
typename Traits::value_type value(sum / int(src_channels));
/* TODO: this is actually only mono ... */
for (unsigned c = 0; c < dest_channels; ++c)
*dest++ = value;
}
return dest;
}
template<SampleFormat F, class Traits=SampleTraits<F>>
static ConstBuffer<typename Traits::value_type>
ConvertChannels(PcmBuffer &buffer,
unsigned dest_channels,
unsigned src_channels,
ConstBuffer<typename Traits::value_type> src) noexcept
{
assert(src.size % src_channels == 0);
const size_t dest_size = src.size / src_channels * dest_channels;
auto dest = buffer.GetT<typename Traits::value_type>(dest_size);
if (src_channels == 1 && dest_channels == 2)
MonoToStereo(dest, src.begin(), src.end());
else if (src_channels == 2 && dest_channels == 1)
StereoToMono<F>(dest, src.begin(), src.end());
else if (dest_channels == 2)
NToStereo<F>(dest, src_channels, src.begin(), src.end());
else if (src_channels == 2 && dest_channels > 2)
StereoToN<F, Traits>(dest, dest_channels,
src.begin(), src.end());
else
NToM<F>(dest, dest_channels,
src_channels, src.begin(), src.end());
return { dest, dest_size };
}
ConstBuffer<int16_t>
pcm_convert_channels_16(PcmBuffer &buffer,
unsigned dest_channels,
unsigned src_channels,
ConstBuffer<int16_t> src) noexcept
{
return ConvertChannels<SampleFormat::S16>(buffer, dest_channels,
src_channels, src);
}
ConstBuffer<int32_t>
pcm_convert_channels_24(PcmBuffer &buffer,
unsigned dest_channels,
unsigned src_channels,
ConstBuffer<int32_t> src) noexcept
{
return ConvertChannels<SampleFormat::S24_P32>(buffer, dest_channels,
src_channels, src);
}
ConstBuffer<int32_t>
pcm_convert_channels_32(PcmBuffer &buffer,
unsigned dest_channels,
unsigned src_channels,
ConstBuffer<int32_t> src) noexcept
{
return ConvertChannels<SampleFormat::S32>(buffer, dest_channels,
src_channels, src);
}
ConstBuffer<float>
pcm_convert_channels_float(PcmBuffer &buffer,
unsigned dest_channels,
unsigned src_channels,
ConstBuffer<float> src) noexcept
{
return ConvertChannels<SampleFormat::FLOAT>(buffer, dest_channels,
src_channels, src);
}
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