FFmpeg-based audio file decoder for audio-reactive shaders. More...

#include "file_audio.hpp"
#include "audio.hpp"
#include <RtAudio.h>
#include <algorithm>
#include <atomic>
#include <cctype>
#include <cmath>
#include <cstring>
#include <filesystem>
#include <fstream>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/opt.h>
#include <libswresample/swresample.h>

Classes
class	anonymous_namespace{file_audio.cpp}::FileAudioOutput

Namespaces
namespace	anonymous_namespace{file_audio.cpp}

Functions
static void	closeDecoderResources ()
static bool	decodeAllSamples ()
	Decode every audio packet from the open format context.
static bool	decodeAudioFile (const std::string &filepath)
void	file_audio_close ()
	Stop file-audio playback and release decoder/sample resources.
std::string	file_audio_current_source_path ()
	Return the source track at the current playback position.
bool	file_audio_enable_output (int output_device)
	Configure real-time playback of the decoded file through an output device.
bool	file_audio_has_output_clock ()
	Check whether real-time output playback can provide the master clock.
bool	file_audio_is_active ()
	Return true while decoded file-audio samples remain.
bool	file_audio_open (const std::string &filepath)
	Open and fully decode an audio file or M3U playlist to mono float PCM at 44.1 kHz.
double	file_audio_playback_time ()
	Return the current output-device playback timestamp in seconds.
void	file_audio_process_frame (double video_fps, acmx2::audio::AudioAnalyzer &analyzer)
	Advance one video-frame worth of samples and update audio analysis.
void	file_audio_set_repeat (bool enabled)
	Enable or disable looping of the currently decoded audio file.
std::vector< std::string >	file_audio_source_paths ()
	Return the successfully decoded source tracks in playback order.
static bool	isM3uPath (const std::string &filepath)
static std::vector< std::string >	readM3uPlaylist (const std::string &filepath)
static std::string	trimPlaylistLine (std::string line)

Variables
static int	audioStreamIndex = -1
static AVCodecContext *	codecCtx = nullptr
static std::vector< float >	decodedSamples
constexpr unsigned int	anonymous_namespace{file_audio.cpp}::FILE_AUDIO_SAMPLE_RATE = 44100
static std::atomic< bool >	fileAudioActive {false}
std::unique_ptr< FileAudioOutput >	anonymous_namespace{file_audio.cpp}::fileAudioOutput
static std::atomic< bool >	fileAudioRepeat {false}
static std::vector< std::size_t >	fileAudioSourceEndPositions
static std::vector< std::string >	fileAudioSourcePaths
static AVFormatContext *	fmtCtx = nullptr
static double	framePlaybackPos = 0.0
static size_t	playbackPos = 0
static SwrContext *	swrCtx = nullptr

Detailed Description

FFmpeg-based audio file decoder for audio-reactive shaders.

Decodes an entire audio file upfront into a mono float buffer at 44 100 Hz using FFmpeg's libavformat / libavcodec / libswresample. Each video frame, file_audio_process_frame() advances through the buffer and feeds the shared AudioAnalyzer used by the shader uniform pipeline.

Definition in file ACMX2/file_audio.cpp.

Function Documentation

◆ closeDecoderResources()

void closeDecoderResources ( )

static

Definition at line 252 of file ACMX2/file_audio.cpp.

References audioStreamIndex, closeDecoderResources(), codecCtx, fmtCtx, and swrCtx.

Referenced by closeDecoderResources(), decodeAudioFile(), and file_audio_close().

◆ decodeAllSamples()

bool decodeAllSamples ( )

static

Decode every audio packet from the open format context.

Reads packets from fmtCtx, sends them through the codec, and resamples the output to mono float 44 100 Hz via swrCtx. Decoded samples are appended to the module-level decodedSamples vector. The resampler is flushed at the end to capture trailing samples.

Returns: true if decoding completed without fatal errors.

Definition at line 329 of file ACMX2/file_audio.cpp.

References audioStreamIndex, codecCtx, decodeAllSamples(), decodedSamples, fmtCtx, and swrCtx.

Referenced by decodeAllSamples(), and decodeAudioFile().

◆ decodeAudioFile()

bool decodeAudioFile ( const std::string & filepath )

static

Definition at line 384 of file ACMX2/file_audio.cpp.

References audioStreamIndex, closeDecoderResources(), codecCtx, decodeAllSamples(), decodeAudioFile(), decodedSamples, fmtCtx, and swrCtx.

Referenced by decodeAudioFile(), and file_audio_open().

◆ file_audio_close()

void file_audio_close ( )

Stop file-audio playback and release decoder/sample resources.

Close the file audio decoder and release all resources.

Stop file-audio playback and release decoder/sample resources.

Stops file playback, frees any remaining FFmpeg contexts (safe to call even if already closed), and releases the decoded sample buffer.

Definition at line 607 of file ACMX2/file_audio.cpp.

References closeDecoderResources(), decodedSamples, file_audio_close(), fileAudioActive, anonymous_namespace{file_audio.cpp}::fileAudioOutput, fileAudioRepeat, fileAudioSourceEndPositions, fileAudioSourcePaths, framePlaybackPos, and playbackPos.

Referenced by file_audio_close(), file_audio_open(), and ACView::~ACView().

◆ file_audio_current_source_path()

std::string file_audio_current_source_path ( )

Return the source track at the current playback position.

Returns: Current file/playlist entry path, or an empty string when inactive.

Definition at line 505 of file ACMX2/file_audio.cpp.

References file_audio_current_source_path(), fileAudioActive, fileAudioSourceEndPositions, fileAudioSourcePaths, and playbackPos.

Referenced by file_audio_current_source_path().

◆ file_audio_enable_output()

bool file_audio_enable_output ( int output_device )

Configure real-time playback of the decoded file through an output device.

The stream is opened immediately and starts when file_audio_process_frame() first advances the file, keeping audible playback aligned with visual analysis.

Parameters

output_device RtAudio device ID, or -1 for the default output.

Returns: true when the output stream was configured successfully.

Definition at line 519 of file ACMX2/file_audio.cpp.

References decodedSamples, file_audio_enable_output(), and anonymous_namespace{file_audio.cpp}::fileAudioOutput.

Referenced by file_audio_enable_output().

◆ file_audio_has_output_clock()

bool file_audio_has_output_clock ( )

Check whether real-time output playback can provide the master clock.

This remains true from output configuration until the decoded audio reaches its end. Before the stream starts, its timestamp is zero.

Definition at line 536 of file ACMX2/file_audio.cpp.

References file_audio_has_output_clock(), fileAudioActive, and anonymous_namespace{file_audio.cpp}::fileAudioOutput.

Referenced by ACView::draw(), file_audio_has_output_clock(), and file_audio_playback_time().

◆ file_audio_is_active()

bool file_audio_is_active ( )

Return true while decoded file-audio samples remain.

Check whether file audio playback is still active.

Return true while decoded file-audio samples remain.

Returns: true if a file is open and unplayed samples remain.

Definition at line 602 of file ACMX2/file_audio.cpp.

References file_audio_is_active(), and fileAudioActive.

Referenced by file_audio_is_active().

◆ file_audio_open()

bool file_audio_open ( const std::string & filepath )

Open and fully decode an audio file or M3U playlist to mono float PCM at 44.1 kHz.

Open and fully decode an audio file to mono float PCM at 44 100 Hz.

Open and fully decode an audio file or M3U playlist to mono float PCM at 44.1 kHz.

Uses FFmpeg to open filepath, locate the first audio stream, decode it, and resample all samples into an internal buffer. After this call the FFmpeg decoder contexts are freed; only the sample buffer remains in memory.

Parameters

filepath Path to an audio or video file containing an audio track.

Returns: true on success, false on any decoder or I/O error.

Definition at line 457 of file ACMX2/file_audio.cpp.

References decodeAudioFile(), decodedSamples, file_audio_close(), file_audio_open(), fileAudioActive, fileAudioSourceEndPositions, fileAudioSourcePaths, framePlaybackPos, isM3uPath(), playbackPos, and readM3uPlaylist().

Referenced by file_audio_open().

◆ file_audio_playback_time()

double file_audio_playback_time ( )

Return the current output-device playback timestamp in seconds.

Returns: Playback position measured by the RtAudio callback, or 0 when no output clock is available.

Definition at line 541 of file ACMX2/file_audio.cpp.

References file_audio_has_output_clock(), file_audio_playback_time(), anonymous_namespace{file_audio.cpp}::FILE_AUDIO_SAMPLE_RATE, and anonymous_namespace{file_audio.cpp}::fileAudioOutput.

Referenced by ACView::draw(), and file_audio_playback_time().

◆ file_audio_process_frame()

void file_audio_process_frame	(	double	video_fps,
		acmx2::audio::AudioAnalyzer &	analyzer )

Advance one video-frame worth of samples and update audio analysis.

Advance playback by one video frame and update the audio analyzer.

Advance one video-frame worth of samples and update audio analysis.

Without output playback, advances by exactly one video-frame duration using a fractional sample accumulator. With output playback, analyzes the sample window at the output device's current timestamp.

Parameters