chromium/media/base/audio_parameters.h

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_BASE_AUDIO_PARAMETERS_H_
#define MEDIA_BASE_AUDIO_PARAMETERS_H_

#include <stdint.h>

#include <optional>
#include <string>
#include <vector>

#include "base/compiler_specific.h"
#include "base/numerics/checked_math.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "media/base/audio_latency.h"
#include "media/base/audio_point.h"
#include "media/base/channel_layout.h"
#include "media/base/media_shmem_export.h"
#include "media/base/sample_format.h"

namespace media {

// Use a struct-in-struct approach to ensure that we can calculate the required
// size as sizeof(Audio{Input,Output}BufferParameters) + #(bytes in audio
// buffer) without using packing. Also align Audio{Input,Output}BufferParameters
// instead of in Audio{Input,Output}Buffer to be able to calculate size like so.
// Use a constexpr for the alignment value that's the same as
// AudioBus::kChannelAlignment, since MSVC doesn't accept the latter to be used.
#if BUILDFLAG(IS_WIN)
#pragma warning(push)
#pragma warning(disable : 4324)  // Disable warning for added padding.
#endif
constexpr int kParametersAlignment = …;

// ****WARNING****: Do not change the field types or ordering of these fields
// without checking that alignment is correct. The structs may be concurrently
// accessed by both 32bit and 64bit process in shmem. http://crbug.com/781095.
struct MEDIA_SHMEM_EXPORT alignas(kParametersAlignment)
    AudioInputBufferParameters { … };
struct MEDIA_SHMEM_EXPORT alignas(kParametersAlignment)
    AudioOutputBufferParameters { … };
#if BUILDFLAG(IS_WIN)
#pragma warning(pop)
#endif

struct MEDIA_SHMEM_EXPORT AudioInputBuffer { … };
struct MEDIA_SHMEM_EXPORT AudioOutputBuffer { … };

struct MEDIA_SHMEM_EXPORT AudioRendererAlgorithmParameters { … };

class AudioParameters;

// These convenience function safely computes the size required for
// |shared_memory_count| AudioInputBuffers, with enough memory for AudioBus
// data, using |parameters| (or alternatively |channels| and |frames|). The
// functions not returning a CheckedNumeric will CHECK on overflow.
MEDIA_SHMEM_EXPORT base::CheckedNumeric<uint32_t>
ComputeAudioInputBufferSizeChecked(const AudioParameters& parameters,
                                   uint32_t audio_bus_count);

MEDIA_SHMEM_EXPORT uint32_t
ComputeAudioInputBufferSize(const AudioParameters& parameters,
                            uint32_t audio_bus_count);

MEDIA_SHMEM_EXPORT uint32_t
ComputeAudioInputBufferSize(int channels, int frames, uint32_t audio_bus_count);

// These convenience functions safely computes the size required for an
// AudioOutputBuffer with enough memory for AudioBus data using |parameters| (or
// alternatively |channels| and |frames|). The functions not returning a
// CheckedNumeric will CHECK on overflow.
MEDIA_SHMEM_EXPORT base::CheckedNumeric<uint32_t>
ComputeAudioOutputBufferSizeChecked(const AudioParameters& parameters);

MEDIA_SHMEM_EXPORT uint32_t
ComputeAudioOutputBufferSize(const AudioParameters& parameters);

MEDIA_SHMEM_EXPORT uint32_t ComputeAudioOutputBufferSize(int channels,
                                                         int frames);

// Channel count and ChannelLayout pair, with helper methods to enforce safe
// construction.
class MEDIA_SHMEM_EXPORT ChannelLayoutConfig { … };

// For |CHANNEL_LAYOUT_DISCRETE|, we have to explicitly set the number of
// channels, so we need to use the normal constructor.
template <>
ChannelLayoutConfig ChannelLayoutConfig::FromLayout<CHANNEL_LAYOUT_DISCRETE>() =
    delete;

class MEDIA_SHMEM_EXPORT AudioParameters { … };

// Comparison is useful when AudioParameters is used with std structures.
inline bool operator<(const AudioParameters& a, const AudioParameters& b) { … }

}  // namespace media

#endif  // MEDIA_BASE_AUDIO_PARAMETERS_H_