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Rename variables to match standard, Add more comments refering to standard

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This commit is contained in:
Pierre-Hugues Husson 2020-02-18 15:23:48 +01:00
parent 90601267e6
commit 46e342bf3e
1 changed files with 20 additions and 18 deletions
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38
library/core/src/main/java/com/google/android/exoplayer2/metadata/dvbsi/AitDecoder.java
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@ -14,11 +14,11 @@ import java.util.ArrayList;
// Unless mentioned explicitly, every references here are to // Unless mentioned explicitly, every references here are to
// https://www.etsi.org/deliver/etsi_ts/102800_102899/102809/01.01.01_60/ts_102809v010101p.pdf // https://www.etsi.org/deliver/etsi_ts/102800_102899/102809/01.01.01_60/ts_102809v010101p.pdf
// Specification of AIT can be found in 5.3.4 of TS 102 809 v1.1.1
public class AitDecoder implements MetadataDecoder { public class AitDecoder implements MetadataDecoder {
// Specification of AIT can be found in 5.3.4 of TS 102 809 v1.1.1 // This value and descriptor is described in section 5.3.6
private final static int DESCRIPTOR_TRANSPORT_PROTOCOL = 0x02; private final static int DESCRIPTOR_TRANSPORT_PROTOCOL = 0x02;
// This value and descriptor is described in section 5.3.7
private final static int DESCRIPTOR_SIMPLE_APPLICATION_LOCATION = 0x15; private final static int DESCRIPTOR_SIMPLE_APPLICATION_LOCATION = 0x15;
private final static int TRANSPORT_PROTOCOL_HTTP = 3; private final static int TRANSPORT_PROTOCOL_HTTP = 3;
@ -101,40 +101,42 @@ public class AitDecoder implements MetadataDecoder {
sectionData.skipBits(4); sectionData.skipBits(4);
int applicationDescriptorsLoopLength = sectionData.readBits(12); int applicationDescriptorsLoopLength = sectionData.readBits(12);
int positionOfNextSection = sectionData.getBytePosition() + applicationDescriptorsLoopLength; int positionOfNextApplication = sectionData.getBytePosition() + applicationDescriptorsLoopLength;
while(sectionData.getBytePosition() < positionOfNextSection) { while(sectionData.getBytePosition() < positionOfNextApplication) {
int type = sectionData.readBits(8); int descriptorTag = sectionData.readBits(8);
int l = sectionData.readBits(8); int descriptorLen = sectionData.readBits(8);
int positionOfNextSection2 = sectionData.getBytePosition() + l; int positionOfNextDescriptor = sectionData.getBytePosition() + descriptorLen;
if(type == DESCRIPTOR_TRANSPORT_PROTOCOL) { if(descriptorTag == DESCRIPTOR_TRANSPORT_PROTOCOL) {
// See section 5.3.6 // This descriptor is defined in section 5.3.6
int protocolId = sectionData.readBits(16); int protocolId = sectionData.readBits(16);
// label // label
sectionData.skipBits(8); sectionData.skipBits(8);
if(protocolId == TRANSPORT_PROTOCOL_HTTP) { if(protocolId == TRANSPORT_PROTOCOL_HTTP) {
while (sectionData.getBytePosition() < positionOfNextSection2) { // This selector is defined in section 5.3.6.2
while (sectionData.getBytePosition() < positionOfNextDescriptor) {
int urlBaseLength = sectionData.readBits(8); int urlBaseLength = sectionData.readBits(8);
String urlBase = sectionData.readString(urlBaseLength, Charset.forName("ASCII")); String urlBase = sectionData.readString(urlBaseLength, Charset.forName("ASCII"));
int extensionCount = sectionData.readBits(8); int extensionCount = sectionData.readBits(8);
aitUrlBase = urlBase; aitUrlBase = urlBase;
for (int i = 0; i < extensionCount; i++) { for (int urlExtensionIdx = 0; urlExtensionIdx < extensionCount; urlExtensionIdx++) {
int len = sectionData.readBits(8); int urlExtensionLength = sectionData.readBits(8);
sectionData.skipBytes(len); sectionData.skipBytes(urlExtensionLength);
} }
} }
} }
} else if(type == DESCRIPTOR_SIMPLE_APPLICATION_LOCATION) { } else if(descriptorTag == DESCRIPTOR_SIMPLE_APPLICATION_LOCATION) {
String url = sectionData.readString(l, Charset.forName("ASCII")); // This descriptor is defined in section 5.3.7
String url = sectionData.readString(descriptorLen, Charset.forName("ASCII"));
aitUrlExtension = url; aitUrlExtension = url;
} }
sectionData.setPosition(positionOfNextSection2*8); sectionData.setPosition(positionOfNextDescriptor*8);
} }
sectionData.setPosition(positionOfNextSection*8); sectionData.setPosition(positionOfNextApplication*8);
if(aitControlCode != -1 && aitUrlBase != null && aitUrlExtension != null) { if(aitControlCode != -1 && aitUrlBase != null && aitUrlExtension != null) {
aits.add(new Ait(aitControlCode, aitUrlBase + aitUrlExtension)); aits.add(new Ait(aitControlCode, aitUrlBase + aitUrlExtension));