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LibAudio: New error propagation API in Loader and Buffer

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Previously, a libc-like out-of-line error information was used in the
loader and its plugins. Now, all functions that may fail to do their job
return some sort of Result. The universally-used error type ist the new
LoaderError, which can contain information about the general error
category (such as file format, I/O, unimplemented features), an error
description, and location information, such as file index or sample
index.

Additionally, the loader plugins try to do as little work as possible in
their constructors. Right after being constructed, a user should call
initialize() and check the errors returned from there. (This is done
transparently by Loader itself.) If a constructor caused an error, the
call to initialize should check and return it immediately.

This opportunity was used to rework a lot of the internal error
propagation in both loader classes, especially FlacLoader. Therefore, a
couple of other refactorings may have sneaked in as well.

The adoption of LibAudio users is minimal. Piano's adoption is not
important, as the code will receive major refactoring in the near future
anyways. SoundPlayer's adoption is also less important, as changes to
refactor it are in the works as well. aplay's adoption is the best and
may serve as an example for other users. It also includes new buffering
behavior.

Buffer also gets some attention, making it OOM-safe and thereby also
propagating its errors to the user.
This commit is contained in:
kleines Filmröllchen 2021-11-27 17:00:19 +01:00 • committed by Brian Gianforcaro
parent ec8bd8116d
commit 96d02a3e75
19 changed files with 406 additions and 397 deletions
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39
Userland/Libraries/LibAudio/FlacLoader.h
View file

@ -11,6 +11,7 @@
#include "Loader.h"
#include <AK/BitStream.h>
#include <AK/Buffered.h>
#include <AK/Error.h>
#include <AK/Stream.h>
#include <AK/Types.h>
#include <AK/Variant.h>
@ -81,15 +82,12 @@ public:
m_stream->handle_any_error();
}
virtual bool sniff() override;
virtual MaybeLoaderError initialize() override;
virtual bool has_error() override { return !m_error_string.is_null(); }
virtual const String& error_string() override { return m_error_string; }
virtual LoaderSamples get_more_samples(size_t max_bytes_to_read_from_input = 128 * KiB) override;
virtual RefPtr<Buffer> get_more_samples(size_t max_bytes_to_read_from_input = 128 * KiB) override;
virtual void reset() override;
virtual void seek(const int position) override;
virtual MaybeLoaderError reset() override;
virtual MaybeLoaderError seek(const int position) override;
virtual int loaded_samples() override { return static_cast<int>(m_loaded_samples); }
virtual int total_samples() override { return static_cast<int>(m_total_samples); }
@ -102,32 +100,31 @@ public:
bool sample_count_unknown() const { return m_total_samples == 0; }
private:
bool parse_header();
MaybeLoaderError parse_header();
// Either returns the metadata block or sets error message.
// Additionally, increments m_data_start_location past the read meta block.
FlacRawMetadataBlock next_meta_block(InputBitStream& bit_input);
ErrorOr<FlacRawMetadataBlock, LoaderError> next_meta_block(InputBitStream& bit_input);
// Fetches and sets the next FLAC frame
void next_frame();
MaybeLoaderError next_frame();
// Helper of next_frame that fetches a sub frame's header
FlacSubframeHeader next_subframe_header(InputBitStream& bit_input, u8 channel_index);
ErrorOr<FlacSubframeHeader, LoaderError> next_subframe_header(InputBitStream& bit_input, u8 channel_index);
// Helper of next_frame that decompresses a subframe
Vector<i32> parse_subframe(FlacSubframeHeader& subframe_header, InputBitStream& bit_input);
ErrorOr<Vector<i32>, LoaderError> parse_subframe(FlacSubframeHeader& subframe_header, InputBitStream& bit_input);
// Subframe-internal data decoders (heavy lifting)
Vector<i32> decode_fixed_lpc(FlacSubframeHeader& subframe, InputBitStream& bit_input);
Vector<i32> decode_verbatim(FlacSubframeHeader& subframe, InputBitStream& bit_input);
Vector<i32> decode_custom_lpc(FlacSubframeHeader& subframe, InputBitStream& bit_input);
Vector<i32> decode_residual(Vector<i32>& decoded, FlacSubframeHeader& subframe, InputBitStream& bit_input);
ErrorOr<Vector<i32>, LoaderError> decode_fixed_lpc(FlacSubframeHeader& subframe, InputBitStream& bit_input);
ErrorOr<Vector<i32>, LoaderError> decode_verbatim(FlacSubframeHeader& subframe, InputBitStream& bit_input);
ErrorOr<Vector<i32>, LoaderError> decode_custom_lpc(FlacSubframeHeader& subframe, InputBitStream& bit_input);
ErrorOr<Vector<i32>, LoaderError> decode_residual(Vector<i32>& decoded, FlacSubframeHeader& subframe, InputBitStream& bit_input);
// decode a single rice partition that has its own rice parameter
ALWAYS_INLINE Vector<i32> decode_rice_partition(u8 partition_type, u32 partitions, u32 partition_index, FlacSubframeHeader& subframe, InputBitStream& bit_input);
// Converters for special coding used in frame headers
ALWAYS_INLINE u32 convert_sample_count_code(u8 sample_count_code);
ALWAYS_INLINE u32 convert_sample_rate_code(u8 sample_rate_code);
ALWAYS_INLINE PcmSampleFormat convert_bit_depth_code(u8 bit_depth_code);
ALWAYS_INLINE ErrorOr<u32, LoaderError> convert_sample_count_code(u8 sample_count_code);
ALWAYS_INLINE ErrorOr<u32, LoaderError> convert_sample_rate_code(u8 sample_rate_code);
ALWAYS_INLINE ErrorOr<PcmSampleFormat, LoaderError> convert_bit_depth_code(u8 bit_depth_code);
bool m_valid { false };
RefPtr<Core::File> m_file;
String m_error_string;
Optional<LoaderError> m_error {};
// Data obtained directly from the FLAC metadata: many values have specific bit counts
u32 m_sample_rate { 0 }; // 20 bit