com.googlecode.mp4parser.boxes.mp4.samplegrouping.VisualRandomAccessEntry Maven / Gradle / Ivy

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A generic parser and writer for all ISO 14496 based files (MP4, Quicktime, DCF, PDCF, ...)
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/*
 * Copyright 2012 castLabs, Berlin
 *
 * 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 com.googlecode.mp4parser.boxes.mp4.samplegrouping;

import java.nio.ByteBuffer;

/**
 * 4cc = "{@value #TYPE}"
 * 
 * For some coding systems a sync sample is specified to be a random access point after which all samples in decoding
 * order can be correctly decoded. However, it may be possible to encode an “open” random access point, after which all
 * samples in output order can be correctly decoded, but some samples following the random access point in decoding
 * order and preceding the random access point in output order need not be correctly decodable. For example, an intra
 * picture starting an open group of pictures can be followed in decoding order by (bi-)predicted pictures that however
 * precede the intra picture in output order; though they possibly cannot be correctly decoded if the decoding starts
 * from the intra picture, they are not needed.
 * 
 * 
 * Such "open" random-access samples can be marked by being a member of this group. Samples marked by this group must
 * be random access points, and may also be sync points (i.e. it is not required that samples marked by the sync sample
 * table be excluded).
 * 
 */
public class VisualRandomAccessEntry extends GroupEntry {
    public static final String TYPE = "rap ";
    private boolean numLeadingSamplesKnown;
    private short numLeadingSamples;

    @Override
    public String getType() {
        return TYPE;
    }


    public boolean isNumLeadingSamplesKnown() {
        return numLeadingSamplesKnown;
    }

    public void setNumLeadingSamplesKnown(boolean numLeadingSamplesKnown) {
        this.numLeadingSamplesKnown = numLeadingSamplesKnown;
    }

    public short getNumLeadingSamples() {
        return numLeadingSamples;
    }

    public void setNumLeadingSamples(short numLeadingSamples) {
        this.numLeadingSamples = numLeadingSamples;
    }

    @Override
    public void parse(ByteBuffer byteBuffer) {
        final byte b = byteBuffer.get();
        numLeadingSamplesKnown = ((b & 0x80) == 0x80);
        numLeadingSamples = (short) (b & 0x7f);
    }

    @Override
    public ByteBuffer get() {
        ByteBuffer content = ByteBuffer.allocate(1);
        content.put((byte) ((numLeadingSamplesKnown ? 0x80 : 0x00) | (numLeadingSamples & 0x7f)));
        content.rewind();
        return content;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        VisualRandomAccessEntry that = (VisualRandomAccessEntry) o;

        if (numLeadingSamples != that.numLeadingSamples) return false;
        if (numLeadingSamplesKnown != that.numLeadingSamplesKnown) return false;

        return true;
    }

    @Override
    public int hashCode() {
        int result = (numLeadingSamplesKnown ? 1 : 0);
        result = 31 * result + (int) numLeadingSamples;
        return result;
    }

    @Override
    public String toString() {
        final StringBuilder sb = new StringBuilder();
        sb.append("VisualRandomAccessEntry");
        sb.append("{numLeadingSamplesKnown=").append(numLeadingSamplesKnown);
        sb.append(", numLeadingSamples=").append(numLeadingSamples);
        sb.append('}');
        return sb.toString();
    }
}