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Add comments for DTSUtil.java

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Cedric T 2023-05-05 13:44:21 +08:00 committed by Tianyi Feng
parent c0e03f14a8
commit 3b9d680914
1 changed files with 13 additions and 4 deletions
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17
libraries/extractor/src/main/java/androidx/media3/extractor/DtsUtil.java
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@ -41,7 +41,15 @@ public final class DtsUtil {
private static final int SYNC_VALUE_14B_BE = 0x1FFFE800;
private static final int SYNC_VALUE_LE = 0xFE7F0180;
private static final int SYNC_VALUE_14B_LE = 0xFF1F00E8;
/**
* DTS Extension Substream Syncword (in different Endianness) is defined in Section 7.4.1 of:
* https://www.etsi.org/deliver/etsi_ts/102100_102199/102114/01.06.01_60/ts_102114v010601p.pdf
*/
private static final int SYNC_EXT_SUB_LE = 0x25205864;
/**
* The two DTS FTOC Sync words below (in different Endianness) is defined in Section 6.4.4.1 of
* https://www.etsi.org/deliver/etsi_ts/103400_103499/103491/01.02.01_60/ts_103491v010201p.pdf
*/
private static final int SYNC_FTOC_LE = 0xF21B4140;
private static final int SYNC_FTOC_NON_SYNC_LE = 0xE842C471;
private static final byte FIRST_BYTE_BE = (byte) (SYNC_VALUE_BE >>> 24);
@ -153,14 +161,15 @@ public final class DtsUtil {
*/
public static int parseDtsAudioSampleCount(ByteBuffer buffer) {
// Check for sync or non sync word for DTS:X Profile 2.
// DTS:X Profile 2's FrameSize = 1024.
// Check for DTS:X Profile 2 sync or non sync word and return
// 1024 if found. This is the only audio sample count that is used by DTS:X Streaming Encoder.
if ((buffer.getInt(0) == SYNC_FTOC_LE) ||
(buffer.getInt(0) == SYNC_FTOC_NON_SYNC_LE)) {
return 1024;
}
// Check for sync word for DTS Express.
// DTS Express's FrameSize = 4096.
// Check for DTS Express sync word and return 4096 if found. This is the only audio
// sample count that is used by DTS Streaming Encoder.
else if (buffer.getInt(0) == SYNC_EXT_SUB_LE) {
return 4096;
}