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      1 /*
      2  * Copyright 2008 CoreMedia AG, Hamburg
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the License);
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *     http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an AS IS BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.coremedia.iso.boxes;
     18 
     19 import com.coremedia.iso.IsoTypeWriter;
     20 import com.coremedia.iso.boxes.sampleentry.SampleEntry;
     21 import com.googlecode.mp4parser.FullContainerBox;
     22 
     23 import java.nio.ByteBuffer;
     24 
     25 /**
     26  * The sample description table gives detailed information about the coding type used, and any initialization
     27  * information needed for that coding. <br>
     28  * The information stored in the sample description box after the entry-count is both track-type specific as
     29  * documented here, and can also have variants within a track type (e.g. different codings may use different
     30  * specific information after some common fields, even within a video track).<br>
     31  * For video tracks, a VisualSampleEntry is used; for audio tracks, an AudioSampleEntry. Hint tracks use an
     32  * entry format specific to their protocol, with an appropriate name. Timed Text tracks use a TextSampleEntry
     33  * For hint tracks, the sample description contains appropriate declarative data for the streaming protocol being
     34  * used, and the format of the hint track. The definition of the sample description is specific to the protocol.
     35  * Multiple descriptions may be used within a track.<br>
     36  * The 'protocol' and 'codingname' fields are registered identifiers that uniquely identify the streaming protocol or
     37  * compression format decoder to be used. A given protocol or codingname may have optional or required
     38  * extensions to the sample description (e.g. codec initialization parameters). All such extensions shall be within
     39  * boxes; these boxes occur after the required fields. Unrecognized boxes shall be ignored.
     40  * <br>
     41  * Defined in ISO/IEC 14496-12
     42  *
     43  * @see com.coremedia.iso.boxes.sampleentry.VisualSampleEntry
     44  * @see com.coremedia.iso.boxes.sampleentry.TextSampleEntry
     45  * @see com.coremedia.iso.boxes.sampleentry.AudioSampleEntry
     46  */
     47 public class SampleDescriptionBox extends FullContainerBox {
     48     public static final String TYPE = "stsd";
     49 
     50     public SampleDescriptionBox() {
     51         super(TYPE);
     52     }
     53 
     54     @Override
     55     protected long getContentSize() {
     56         return super.getContentSize() + 4;
     57     }
     58 
     59     @Override
     60     public void _parseDetails(ByteBuffer content) {
     61         parseVersionAndFlags(content);
     62         content.get(new byte[4]);
     63         parseChildBoxes(content);
     64     }
     65 
     66     @Override
     67     protected void getContent(ByteBuffer byteBuffer) {
     68         writeVersionAndFlags(byteBuffer);
     69         IsoTypeWriter.writeUInt32(byteBuffer, boxes.size());
     70         writeChildBoxes(byteBuffer);
     71     }
     72 
     73     public SampleEntry getSampleEntry() {
     74         for (Box box : boxes) {
     75             if (box instanceof SampleEntry) {
     76                 return (SampleEntry) box;
     77             }
     78         }
     79         return null;
     80     }
     81 }
     82