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/*
* Copyright 2003-2020 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 "Order.hxx"
#include "Buffer.hxx"
#include "util/ConstBuffer.hxx"
/*
* According to:
* - https://xiph.org/flac/format.html#frame_header
* - https://github.com/nu774/qaac/wiki/Multichannel--handling
* the source channel order (after decoding, e.g., flac, alac) is for
* - 1ch: mono
* - 2ch: left, right
* - 3ch: left, right, center
* - 4ch: front left, front right, back left, back right
* - 5ch: front left, front right, front center, back/surround left, back/surround right
* - 6ch (aka 5.1): front left, front right, front center, LFE, back/surround left, back/surround right
* - 7ch: front left, front right, front center, LFE, back center, side left, side right
* - 8ch: (aka 7.1): front left, front right, front center, LFE, back left, back right, side left, side right
*
* The ALSA default channel map is (see /usr/share/alsa/pcm/surround71.conf):
* - front left, front right, back left, back right, front center, LFE, side left, side right
*
* Hence, in case of the following source channel orders 3ch, 5ch, 6ch (aka
* 5.1), 7ch and 8ch the channel order has to be adapted
*/
template<typename V>
struct TwoPointers {
V *dest;
const V *src;
TwoPointers<V> &CopyOne() noexcept {
*dest++ = *src++;
return *this;
}
TwoPointers<V> &CopyTwo() noexcept {
return CopyOne().CopyOne();
}
TwoPointers<V> &SwapTwoPairs() noexcept {
*dest++ = src[2];
*dest++ = src[3];
*dest++ = src[0];
*dest++ = src[1];
src += 4;
return *this;
}
TwoPointers<V> &ToAlsa50() noexcept {
*dest++ = src[0]; // front left
*dest++ = src[1]; // front right
*dest++ = src[3]; // surround left
*dest++ = src[4]; // surround right
*dest++ = src[2]; // front center
src += 5;
return *this;
}
TwoPointers<V> &ToAlsa51() noexcept {
return CopyTwo() // left+right
.SwapTwoPairs(); // center, LFE, surround left+right
}
TwoPointers<V> &ToAlsa70() noexcept {
*dest++ = src[0]; // front left
*dest++ = src[1]; // front right
*dest++ = src[5]; // side left
*dest++ = src[6]; // side right
*dest++ = src[2]; // front center
*dest++ = src[3]; // LFE
*dest++ = src[4]; // back center
src += 7;
return *this;
}
TwoPointers<V> &ToAlsa71() noexcept {
return ToAlsa51()
.CopyTwo(); // side left+right
}
};
template<typename V>
static void
ToAlsaChannelOrder50(V *dest, const V *src, size_t n) noexcept
{
TwoPointers<V> p{dest, src};
for (size_t i = 0; i != n; ++i)
p.ToAlsa50();
}
template<typename V>
static inline ConstBuffer<V>
ToAlsaChannelOrder50(PcmBuffer &buffer, ConstBuffer<V> src) noexcept
{
auto dest = buffer.GetT<V>(src.size);
ToAlsaChannelOrder50(dest, src.data, src.size / 5);
return { dest, src.size };
}
template<typename V>
static void
ToAlsaChannelOrder51(V *dest, const V *src, size_t n) noexcept
{
TwoPointers<V> p{dest, src};
for (size_t i = 0; i != n; ++i)
p.ToAlsa51();
}
template<typename V>
static inline ConstBuffer<V>
ToAlsaChannelOrder51(PcmBuffer &buffer, ConstBuffer<V> src) noexcept
{
auto dest = buffer.GetT<V>(src.size);
ToAlsaChannelOrder51(dest, src.data, src.size / 6);
return { dest, src.size };
}
template<typename V>
static void
ToAlsaChannelOrder70(V *dest, const V *src, size_t n) noexcept
{
TwoPointers<V> p{dest, src};
for (size_t i = 0; i != n; ++i)
p.ToAlsa70();
}
template<typename V>
static inline ConstBuffer<V>
ToAlsaChannelOrder70(PcmBuffer &buffer, ConstBuffer<V> src) noexcept
{
auto dest = buffer.GetT<V>(src.size);
ToAlsaChannelOrder70(dest, src.data, src.size / 7);
return { dest, src.size };
}
template<typename V>
static void
ToAlsaChannelOrder71(V *dest, const V *src, size_t n) noexcept
{
TwoPointers<V> p{dest, src};
for (size_t i = 0; i != n; ++i)
p.ToAlsa71();
}
template<typename V>
static inline ConstBuffer<V>
ToAlsaChannelOrder71(PcmBuffer &buffer, ConstBuffer<V> src) noexcept
{
auto dest = buffer.GetT<V>(src.size);
ToAlsaChannelOrder71(dest, src.data, src.size / 8);
return { dest, src.size };
}
template<typename V>
static ConstBuffer<V>
ToAlsaChannelOrderT(PcmBuffer &buffer, ConstBuffer<V> src,
unsigned channels) noexcept
{
switch (channels) {
case 5: // 5.0
return ToAlsaChannelOrder50(buffer, src);
case 6: // 5.1
return ToAlsaChannelOrder51(buffer, src);
case 7: // 7.0
return ToAlsaChannelOrder70(buffer, src);
case 8: // 7.1
return ToAlsaChannelOrder71(buffer, src);
default:
return src;
}
}
ConstBuffer<void>
ToAlsaChannelOrder(PcmBuffer &buffer, ConstBuffer<void> src,
SampleFormat sample_format, unsigned channels) noexcept
{
switch (sample_format) {
case SampleFormat::UNDEFINED:
case SampleFormat::S8:
case SampleFormat::DSD:
return src;
case SampleFormat::S16:
return ToAlsaChannelOrderT(buffer,
ConstBuffer<int16_t>::FromVoid(src),
channels).ToVoid();
case SampleFormat::S24_P32:
case SampleFormat::S32:
case SampleFormat::FLOAT:
return ToAlsaChannelOrderT(buffer,
ConstBuffer<int32_t>::FromVoid(src),
channels).ToVoid();
}
gcc_unreachable();
}
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