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Refactor TS Extractor.

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Refactor sniff(), and extract a few methods out from read() to make it look clearer. This CL does not change any functionality.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=201933207
This commit is contained in:
hoangtc 2018-06-25 04:12:26 -07:00 committed by Oliver Woodman
parent 24c21a292f
commit de57f09801
1 changed files with 77 additions and 42 deletions
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119
library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/TsExtractor.java
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@ -178,16 +178,19 @@ public final class TsExtractor implements Extractor {
public boolean sniff(ExtractorInput input) throws IOException, InterruptedException {
byte[] buffer = tsPacketBuffer.data;
input.peekFully(buffer, 0, TS_PACKET_SIZE * SNIFF_TS_PACKET_COUNT);
for (int j = 0; j < TS_PACKET_SIZE; j++) {
for (int i = 0; true; i++) {
if (i == SNIFF_TS_PACKET_COUNT) {
input.skipFully(j);
return true;
}
if (buffer[j + i * TS_PACKET_SIZE] != TS_SYNC_BYTE) {
for (int startPosCandidate = 0; startPosCandidate < TS_PACKET_SIZE; startPosCandidate++) {
// Try to identify at least SNIFF_TS_PACKET_COUNT packets starting with TS_SYNC_BYTE.
boolean isSyncBytePatternCorrect = true;
for (int i = 0; i < SNIFF_TS_PACKET_COUNT; i++) {
if (buffer[startPosCandidate + i * TS_PACKET_SIZE] != TS_SYNC_BYTE) {
isSyncBytePatternCorrect = false;
break;
}
}
if (isSyncBytePatternCorrect) {
input.skipFully(startPosCandidate);
return true;
}
}
return false;
}
@ -219,46 +222,17 @@ public final class TsExtractor implements Extractor {
@Override
public int read(ExtractorInput input, PositionHolder seekPosition)
throws IOException, InterruptedException {
byte[] data = tsPacketBuffer.data;
// Shift bytes to the start of the buffer if there isn't enough space left at the end.
if (BUFFER_SIZE - tsPacketBuffer.getPosition() < TS_PACKET_SIZE) {
int bytesLeft = tsPacketBuffer.bytesLeft();
if (bytesLeft > 0) {
System.arraycopy(data, tsPacketBuffer.getPosition(), data, 0, bytesLeft);
}
tsPacketBuffer.reset(data, bytesLeft);
if (!fillBufferWithAtLeastOnePacket(input)) {
return RESULT_END_OF_INPUT;
}
// Read more bytes until we have at least one packet.
while (tsPacketBuffer.bytesLeft() < TS_PACKET_SIZE) {
int limit = tsPacketBuffer.limit();
int read = input.read(data, limit, BUFFER_SIZE - limit);
if (read == C.RESULT_END_OF_INPUT) {
return RESULT_END_OF_INPUT;
}
tsPacketBuffer.setLimit(limit + read);
int endOfPacket = findEndOfFirstTsPacketInBuffer();
int limit = tsPacketBuffer.limit();
if (endOfPacket > limit) {
return RESULT_CONTINUE;
}
// Note: See ISO/IEC 13818-1, section 2.4.3.2 for details of the header format.
int limit = tsPacketBuffer.limit();
int position = tsPacketBuffer.getPosition();
int searchStart = position;
while (position < limit && data[position] != TS_SYNC_BYTE) {
position++;
}
tsPacketBuffer.setPosition(position);
int endOfPacket = position + TS_PACKET_SIZE;
if (endOfPacket > limit) {
bytesSinceLastSync += position - searchStart;
if (mode == MODE_HLS && bytesSinceLastSync > TS_PACKET_SIZE * 2) {
throw new ParserException("Cannot find sync byte. Most likely not a Transport Stream.");
}
return RESULT_CONTINUE;
}
bytesSinceLastSync = 0;
int tsPacketHeader = tsPacketBuffer.readInt();
if ((tsPacketHeader & 0x800000) != 0) { // transport_error_indicator
// There are uncorrectable errors in this packet.
@ -310,6 +284,67 @@ public final class TsExtractor implements Extractor {
// Internals.
private boolean fillBufferWithAtLeastOnePacket(ExtractorInput input)
throws IOException, InterruptedException {
byte[] data = tsPacketBuffer.data;
// Shift bytes to the start of the buffer if there isn't enough space left at the end.
if (BUFFER_SIZE - tsPacketBuffer.getPosition() < TS_PACKET_SIZE) {
int bytesLeft = tsPacketBuffer.bytesLeft();
if (bytesLeft > 0) {
System.arraycopy(data, tsPacketBuffer.getPosition(), data, 0, bytesLeft);
}
tsPacketBuffer.reset(data, bytesLeft);
}
// Read more bytes until we have at least one packet.
while (tsPacketBuffer.bytesLeft() < TS_PACKET_SIZE) {
int limit = tsPacketBuffer.limit();
int read = input.read(data, limit, BUFFER_SIZE - limit);
if (read == C.RESULT_END_OF_INPUT) {
return false;
}
tsPacketBuffer.setLimit(limit + read);
}
return true;
}
/**
* Returns the position of the end of the first TS packet (exclusive) in the packet buffer.
*
* <p>This may be a position beyond the buffer limit if the packet has not been read fully into
* the buffer, or if no packet could be found within the buffer.
*/
private int findEndOfFirstTsPacketInBuffer() throws ParserException {
int searchStart = tsPacketBuffer.getPosition();
int limit = tsPacketBuffer.limit();
int syncBytePosition = findSyncBytePosition(tsPacketBuffer.data, searchStart, limit);
// Discard all bytes before the sync byte.
// If sync byte is not found, this means discard the whole buffer.
tsPacketBuffer.setPosition(syncBytePosition);
int endOfPacket = syncBytePosition + TS_PACKET_SIZE;
if (endOfPacket > limit) {
bytesSinceLastSync += syncBytePosition - searchStart;
if (mode == MODE_HLS && bytesSinceLastSync > TS_PACKET_SIZE * 2) {
throw new ParserException("Cannot find sync byte. Most likely not a Transport Stream.");
}
} else {
// We have found a packet within the buffer.
bytesSinceLastSync = 0;
}
return endOfPacket;
}
/**
* Returns the position of the first TS_SYNC_BYTE within the range [startPosition, limitPosition)
* from the provided data array, or returns limitPosition if sync byte could not be found.
*/
private static int findSyncBytePosition(byte[] data, int startPosition, int limitPosition) {
int position = startPosition;
while (position < limitPosition && data[position] != TS_SYNC_BYTE) {
position++;
}
return position;
}
private void resetPayloadReaders() {
trackIds.clear();
tsPayloadReaders.clear();