Mp4Utils.java
/*
* Copyright 2022 The Android Open Source Project
*
* 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.
*/
package androidx.media3.muxer;
/** Utilities for MP4 files. */
/* package */ final class Mp4Utils {
/**
* The maximum length of boxes which have fixed sizes.
*
* <p>Technically, we'd know how long they actually are; this upper bound is much simpler to
* produce though and we'll throw if we overflow anyway.
*/
public static final int MAX_FIXED_LEAF_BOX_SIZE = 200;
/**
* The per-video timebase, used for durations in MVHD and TKHD even if the per-track timebase is
* different (e.g. typically the sample rate for audio).
*/
public static final long MVHD_TIMEBASE = 10_000L;
private Mp4Utils() {}
/** Converts microseconds to video units, using the provided timebase. */
public static long vuFromUs(long timestampUs, long videoUnitTimebase) {
return timestampUs * videoUnitTimebase / 1_000_000L; // (division for us to s conversion)
}
/** Converts video units to microseconds, using the provided timebase. */
public static long usFromVu(long timestampVu, long videoUnitTimebase) {
return timestampVu * 1_000_000L / videoUnitTimebase;
}
}