OpenShot Library | libopenshot 0.4.0
Loading...
Searching...
No Matches
AudioReaderSource.cpp
Go to the documentation of this file.
1
9// Copyright (c) 2008-2019 OpenShot Studios, LLC
10//
11// SPDX-License-Identifier: LGPL-3.0-or-later
12
13#include "AudioReaderSource.h"
14#include "Exceptions.h"
15#include "Frame.h"
16
17using namespace std;
18using namespace openshot;
19
20// Constructor that reads samples from a reader
21AudioReaderSource::AudioReaderSource(ReaderBase *audio_reader, int64_t starting_frame_number)
22 : reader(audio_reader), frame_position(starting_frame_number), videoCache(NULL), frame(NULL),
23 sample_position(0), speed(1), stream_position(0) {
24}
25
26// Destructor
30
31// Get the next block of audio samples
32void AudioReaderSource::getNextAudioBlock(const juce::AudioSourceChannelInfo& info)
33{
34 if (info.numSamples > 0) {
35 int remaining_samples = info.numSamples;
36 int remaining_position = info.startSample;
37
38 // Pause and fill buffer with silence (wait for pre-roll)
39 if (speed != 1 || !videoCache->isReady()) {
40 info.buffer->clear();
41 return;
42 }
43
44 while (remaining_samples > 0) {
45 try {
46 // Get current frame object
47 if (reader) {
48 frame = reader->GetFrame(frame_position);
49 }
50 }
51 catch (const ReaderClosed & e) { }
52 catch (const OutOfBoundsFrame & e) { }
53
54 // Get audio samples
55 if (reader && frame) {
56 if (sample_position + remaining_samples <= frame->GetAudioSamplesCount()) {
57 // Success, we have enough samples
58 for (int channel = 0; channel < frame->GetAudioChannelsCount(); channel++) {
59 if (channel < info.buffer->getNumChannels()) {
60 info.buffer->addFrom(channel, remaining_position, *frame->GetAudioSampleBuffer(),
61 channel, sample_position, remaining_samples);
62 }
63 }
64 sample_position += remaining_samples;
65 remaining_position += remaining_samples;
66 remaining_samples = 0;
67
68 } else if (sample_position + remaining_samples > frame->GetAudioSamplesCount()) {
69 // Not enough samples, take what we can
70 int amount_to_copy = frame->GetAudioSamplesCount() - sample_position;
71 for (int channel = 0; channel < frame->GetAudioChannelsCount(); channel++) {
72 if (channel < info.buffer->getNumChannels()) {
73 info.buffer->addFrom(channel, remaining_position, *frame->GetAudioSampleBuffer(), channel,
74 sample_position, amount_to_copy);
75 }
76 }
77 sample_position += amount_to_copy;
78 remaining_position += amount_to_copy;
79 remaining_samples -= amount_to_copy;
80 }
81
82 // Increment frame position (if samples are all used up)
83 if (sample_position == frame->GetAudioSamplesCount()) {
84 frame_position += speed;
85 sample_position = 0; // reset for new frame
86 }
87
88 }
89 }
90 }
91}
92
93// Prepare to play this audio source
95
96// Release all resources
98
99// Get the total length (in samples) of this audio source
101{
102 // Get the length
103 if (reader)
104 return reader->info.sample_rate * reader->info.duration;
105 else
106 return 0;
107}
Header file for AudioReaderSource class.
Header file for all Exception classes.
Header file for Frame class.
AudioReaderSource(ReaderBase *audio_reader, int64_t starting_frame_number)
The cache thread (for pre-roll checking)
void releaseResources()
Release all resources.
juce::int64 getTotalLength() const
Get the total length (in samples) of this audio source.
void prepareToPlay(int, double)
Prepare to play this audio source.
void getNextAudioBlock(const juce::AudioSourceChannelInfo &info)
Get the next block of audio samples.
Exception for frames that are out of bounds.
Definition Exceptions.h:301
This abstract class is the base class, used by all readers in libopenshot.
Definition ReaderBase.h:76
openshot::ReaderInfo info
Information about the current media file.
Definition ReaderBase.h:88
virtual std::shared_ptr< openshot::Frame > GetFrame(int64_t number)=0
Exception when a reader is closed, and a frame is requested.
Definition Exceptions.h:364
bool isReady()
Is cache ready for video/audio playback.
This namespace is the default namespace for all code in the openshot library.
Definition Compressor.h:29
float duration
Length of time (in seconds)
Definition ReaderBase.h:43
int sample_rate
The number of audio samples per second (44100 is a common sample rate)
Definition ReaderBase.h:60