Fix an issue in Audio transcoding where target-sample-rate is less than the source-sample-rate #111
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,55 @@ | ||
| /* | ||
| * Copyright (C) 2021 natario1 Transcoder | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| // from: https://github.com/natario1/Transcoder/blob/main/lib/src/main/java/com/otaliastudios/transcoder/resample/AudioResampler.java | ||
| // modified: removed all constant fields from this interface | ||
| // modified: changed the signature of resample() method | ||
| // modified: added two other default methods, getSampleRate() and getChannels() | ||
| package com.linkedin.android.litr.resample; | ||
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| import android.media.MediaFormat; | ||
| import androidx.annotation.NonNull; | ||
| import java.nio.ByteBuffer; | ||
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| /** | ||
| * Resamples audio data. See {@link DownsampleAudioResampler} for concrete implementations. | ||
| */ | ||
| public interface AudioResampler { | ||
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| /** | ||
| * Resamples input audio from input buffer into the output buffer. | ||
| * | ||
| * @param inputBuffer the input buffer | ||
| * @param outputBuffer the output buffer | ||
| * @param sourceMediaFormat the source media format | ||
| * @param targetMediaFormat the target media format | ||
| */ | ||
| void resample(@NonNull final ByteBuffer inputBuffer, @NonNull final ByteBuffer outputBuffer, | ||
| @NonNull MediaFormat sourceMediaFormat, @NonNull MediaFormat targetMediaFormat); | ||
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| /** | ||
| * Return the sample rate of an audio format | ||
| */ | ||
| default int getSampleRate(MediaFormat format) { | ||
| return format.getInteger(MediaFormat.KEY_SAMPLE_RATE); | ||
| } | ||
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| /** | ||
| * Return the width of the content in a video format. | ||
| */ | ||
| default int getChannels(MediaFormat format) { | ||
| return format.getInteger(MediaFormat.KEY_CHANNEL_COUNT); | ||
| } | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,73 @@ | ||
| /* | ||
| * Copyright (C) 2021 natario1 Transcoder | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| // from: https://github.com/natario1/Transcoder/blob/main/lib/src/main/java/com/otaliastudios/transcoder/resample/DownsampleAudioResampler.java | ||
| // modified: changed the signature of resample() method | ||
| // modified: small modification for "outputBuffer.put(inputBuffer.get());" logic | ||
| // modified: small modification for "inputBuffer.position(inputBuffer.position() + 1);" logic | ||
| package com.linkedin.android.litr.resample; | ||
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| import android.media.MediaFormat; | ||
| import androidx.annotation.NonNull; | ||
| import java.nio.ByteBuffer; | ||
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| /** | ||
| * An {@link AudioResampler} that downsamples from a higher sample rate to a lower sample rate. | ||
| */ | ||
| public class DownsampleAudioResampler implements AudioResampler { | ||
|
There was a problem hiding this comment. Is this adapted code from a different open source project? In that case we have to keep their copyright notice and add a note that we made modifications (feel free to add your name as author of modifications) |
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| private float ratio(int remaining, int all) { | ||
| return (float) remaining / all; | ||
| } | ||
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| @Override | ||
| public void resample(@NonNull ByteBuffer inputBuffer, @NonNull ByteBuffer outputBuffer, | ||
| @NonNull MediaFormat sourceMediaFormat, @NonNull MediaFormat targetMediaFormat) { | ||
| int inputSampleRate = getSampleRate(sourceMediaFormat); | ||
| int outputSampleRate = getSampleRate(targetMediaFormat); | ||
| int channels = getChannels(targetMediaFormat); | ||
| if (inputSampleRate < outputSampleRate) { | ||
| throw new IllegalArgumentException("Illegal use of DownsampleAudioResampler"); | ||
| } | ||
| if (channels != 1 && channels != 2) { | ||
| throw new IllegalArgumentException("Illegal use of DownsampleAudioResampler. Channels:" + channels); | ||
| } | ||
| final int inputSamples = inputBuffer.remaining() / channels; | ||
| final int outputSamples = (int) Math.ceil(inputSamples * ((double) outputSampleRate / inputSampleRate)); | ||
| final int dropSamples = inputSamples - outputSamples; | ||
| int remainingOutputSamples = outputSamples; | ||
| int remainingDropSamples = dropSamples; | ||
| float remainingOutputSamplesRatio = ratio(remainingOutputSamples, outputSamples); | ||
| float remainingDropSamplesRatio = ratio(remainingDropSamples, dropSamples); | ||
| while (remainingOutputSamples > 0 || remainingDropSamples > 0) { | ||
| // Will this be an input sample or a drop sample? | ||
| // Choose the one with the bigger ratio. | ||
| if (remainingOutputSamplesRatio >= remainingDropSamplesRatio) { | ||
| for (int i = 0; i < channels; i++) { | ||
| outputBuffer.put(inputBuffer.get()); | ||
| } | ||
| remainingOutputSamples--; | ||
| remainingOutputSamplesRatio = ratio(remainingOutputSamples, outputSamples); | ||
| } else { | ||
| // Drop this - read from input without writing. | ||
| for (int i = 0; i < channels; i++) { | ||
| inputBuffer.position(inputBuffer.position() + 1); | ||
| } | ||
| remainingDropSamples--; | ||
| remainingDropSamplesRatio = ratio(remainingDropSamples, dropSamples); | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,36 @@ | ||
| /* | ||
| * Copyright (C) 2021 natario1 Transcoder | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
| // from: https://github.com/natario1/Transcoder/blob/main/lib/src/main/java/com/otaliastudios/transcoder/resample/PassThroughAudioResampler.java | ||
| // modified: changed the signature of resample() method | ||
| // modified: removed the first if-condition in resample() method | ||
| package com.linkedin.android.litr.resample; | ||
|
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| import android.media.MediaFormat; | ||
| import androidx.annotation.NonNull; | ||
| import java.nio.ByteBuffer; | ||
|
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| /** | ||
| * An {@link AudioResampler} that does nothing, meant to be used when sample | ||
| * rates are identical. | ||
| */ | ||
| public class PassThroughAudioResampler implements AudioResampler { | ||
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| @Override | ||
| public void resample(@NonNull ByteBuffer inputBuffer, @NonNull ByteBuffer outputBuffer, | ||
| @NonNull MediaFormat sourceMediaFormat, @NonNull MediaFormat targetMediaFormat) { | ||
| outputBuffer.put(inputBuffer); | ||
| } | ||
| } |
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For all new classes that are not modified classes from other project please add LinkedIn copyright notice