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	 488de12ed4
			
		
	
	
		488de12ed4
		
	
	
	
	
		
			
			Previously, error_string() returned char* which is bad Serenity style and caused issues when other error handling methods were tried. As both WavLoader and (future) FLAC loader store a String internally for the error message, it makes sense to return a String reference instead.
		
			
				
	
	
		
			87 lines
		
	
	
	
		
			2.8 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			87 lines
		
	
	
	
		
			2.8 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
| /*
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|  * Copyright (c) 2018-2021, the SerenityOS developers.
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|  *
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|  * SPDX-License-Identifier: BSD-2-Clause
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|  */
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| 
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| #pragma once
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| 
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| #include <AK/ByteBuffer.h>
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| #include <AK/RefCounted.h>
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| #include <AK/RefPtr.h>
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| #include <AK/StringView.h>
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| #include <LibAudio/Buffer.h>
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| #include <LibCore/File.h>
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| 
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| namespace Audio {
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| 
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| static const String empty_string = "";
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| static String no_plugin_error = "No loader plugin available";
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| 
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| class LoaderPlugin {
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| public:
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|     virtual ~LoaderPlugin() { }
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| 
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|     virtual bool sniff() = 0;
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| 
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|     virtual bool has_error() { return false; }
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|     virtual const String& error_string() { return empty_string; }
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| 
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|     virtual RefPtr<Buffer> get_more_samples(size_t max_bytes_to_read_from_input = 128 * KiB) = 0;
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| 
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|     virtual void reset() = 0;
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| 
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|     virtual void seek(const int sample_index) = 0;
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| 
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|     // total_samples() and loaded_samples() should be independent
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|     // of the number of channels.
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|     //
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|     // For example, with a three-second-long, stereo, 44.1KHz audio file:
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|     //    num_channels() should return 2
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|     //    sample_rate() should return 44100 (each channel is sampled at this rate)
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|     //    total_samples() should return 132300 (sample_rate * three seconds)
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|     virtual int loaded_samples() = 0;
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|     virtual int total_samples() = 0;
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|     virtual u32 sample_rate() = 0;
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|     virtual u16 num_channels() = 0;
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| 
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|     virtual PcmSampleFormat pcm_format() = 0;
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|     virtual RefPtr<Core::File> file() = 0;
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| };
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| 
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| class Loader : public RefCounted<Loader> {
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| public:
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|     static NonnullRefPtr<Loader> create(const StringView& path) { return adopt_ref(*new Loader(path)); }
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|     static NonnullRefPtr<Loader> create(const ByteBuffer& buffer) { return adopt_ref(*new Loader(buffer)); }
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| 
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|     bool has_error() const { return m_plugin ? m_plugin->has_error() : true; }
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|     const String& error_string() const { return m_plugin ? m_plugin->error_string() : no_plugin_error; }
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| 
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|     RefPtr<Buffer> get_more_samples(size_t max_bytes_to_read_from_input = 128 * KiB) const { return m_plugin ? m_plugin->get_more_samples(max_bytes_to_read_from_input) : nullptr; }
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| 
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|     void reset() const
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|     {
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|         if (m_plugin)
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|             m_plugin->reset();
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|     }
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|     void seek(const int position) const
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|     {
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|         if (m_plugin)
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|             m_plugin->seek(position);
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|     }
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| 
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|     int loaded_samples() const { return m_plugin ? m_plugin->loaded_samples() : 0; }
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|     int total_samples() const { return m_plugin ? m_plugin->total_samples() : 0; }
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|     u32 sample_rate() const { return m_plugin ? m_plugin->sample_rate() : 0; }
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|     u16 num_channels() const { return m_plugin ? m_plugin->num_channels() : 0; }
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|     u16 bits_per_sample() const { return m_plugin ? pcm_bits_per_sample(m_plugin->pcm_format()) : 0; }
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|     RefPtr<Core::File> file() const { return m_plugin ? m_plugin->file() : nullptr; }
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| 
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| private:
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|     Loader(const StringView& path);
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|     Loader(const ByteBuffer& buffer);
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| 
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|     mutable OwnPtr<LoaderPlugin> m_plugin;
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| };
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| 
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| }
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