849c4012c0
This allows FilterPCM() to return more data, which some implementations may need to do (e.g. FFmpeg).
85 lines
1.9 KiB
C++
85 lines
1.9 KiB
C++
// SPDX-License-Identifier: GPL-2.0-or-later
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// Copyright The Music Player Daemon Project
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#ifndef MPD_FILTER_HXX
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#define MPD_FILTER_HXX
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#include "pcm/AudioFormat.hxx"
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#include <cassert>
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#include <cstddef>
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#include <span>
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class Filter {
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protected:
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AudioFormat out_audio_format;
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explicit Filter(AudioFormat _out_audio_format) noexcept
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:out_audio_format(_out_audio_format) {
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assert(out_audio_format.IsValid());
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}
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public:
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virtual ~Filter() noexcept = default;
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/**
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* Returns the #AudioFormat produced by FilterPCM().
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*/
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const AudioFormat &GetOutAudioFormat() const noexcept {
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return out_audio_format;
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}
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/**
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* Reset the filter's state, e.g. drop/flush buffers.
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*/
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virtual void Reset() noexcept {
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}
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/**
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* Filters a block of PCM data.
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*
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* Throws on error.
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*
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* @param src the input buffer
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* @return the output buffer (will be invalidated by deleting
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* this object or any call to Reset(), FilterPCM(), ReadMore()
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* or Flush()); may be empty if no output is currently
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* available
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*/
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virtual std::span<const std::byte> FilterPCM(std::span<const std::byte> src) = 0;
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/**
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* Read more result data from the filter. After each
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* FilterPCM() call, this should be called repeatedly until it
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* returns an empty span.
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*
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* Throws on error.
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*
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* @return the output buffer (will be invalidated by deleting
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* this object or any call to Reset(), FilterPCM(), ReadMore()
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* or Flush()); may be empty if no output is currently
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* available
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*/
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virtual std::span<const std::byte> ReadMore() {
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return {};
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}
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/**
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* Flush pending data and return it. This should be called
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* repeatedly until it returns an empty span.
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*
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* After calling this method, this object cannot be used again
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* (not even Reset() is allowed).
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*
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* Throws on error.
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*
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* @return pending data (will be invalidated by deleting this
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* object or by any call to Flush())
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*/
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virtual std::span<const std::byte> Flush() {
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return {};
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}
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};
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#endif
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