From 2b1614cc7bcc4d0b7dbd2a247a424d266a3b3c55 Mon Sep 17 00:00:00 2001 From: olly Date: Wed, 12 Jul 2017 04:47:31 -0700 Subject: [PATCH] Don't use ParsableBitArray to parse TS packet headers Really low hanging fruit optimization for TS extraction. ParsableBitArray is quite expensive. In particular readBits contains at least 2 if blocks and a for loop, and was being called 5 times per 188 byte packet (4 times via readBit). A separate change will follow that optimizes readBit, but for this particular case there's no real value to using a ParsableBitArray anyway; use of ParsableBitArray IMO only really becomes useful when you need to parse a bitstream more than 4 bytes long, or where parsing the bitstream requires some control flow (if/for) to parse. There are probably other places where we're using ParsableBitArray over-zealously. I'll roll that into a tracking bug for looking in more detail at all extractors. Issue: #3040 ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=161650940 --- .../exoplayer2/extractor/ts/TsExtractor.java | 24 ++++++++----------- 1 file changed, 10 insertions(+), 14 deletions(-) diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/TsExtractor.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/TsExtractor.java index 7b63ce813c..1149856649 100644 --- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/TsExtractor.java +++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/TsExtractor.java @@ -111,7 +111,6 @@ public final class TsExtractor implements Extractor { @Mode private final int mode; private final List timestampAdjusters; private final ParsableByteArray tsPacketBuffer; - private final ParsableBitArray tsScratch; private final SparseIntArray continuityCounters; private final TsPayloadReader.Factory payloadReaderFactory; private final SparseArray tsPayloadReaders; // Indexed by pid @@ -164,7 +163,6 @@ public final class TsExtractor implements Extractor { timestampAdjusters.add(timestampAdjuster); } tsPacketBuffer = new ParsableByteArray(BUFFER_SIZE); - tsScratch = new ParsableBitArray(new byte[3]); trackIds = new SparseBooleanArray(); tsPayloadReaders = new SparseArray<>(); continuityCounters = new SparseIntArray(); @@ -250,24 +248,23 @@ public final class TsExtractor implements Extractor { return RESULT_CONTINUE; } - tsPacketBuffer.skipBytes(1); - tsPacketBuffer.readBytes(tsScratch, 3); - if (tsScratch.readBit()) { // transport_error_indicator + int tsPacketHeader = tsPacketBuffer.readInt(); + if ((tsPacketHeader & 0x800000) != 0) { // transport_error_indicator // There are uncorrectable errors in this packet. tsPacketBuffer.setPosition(endOfPacket); return RESULT_CONTINUE; } - boolean payloadUnitStartIndicator = tsScratch.readBit(); - tsScratch.skipBits(1); // transport_priority - int pid = tsScratch.readBits(13); - tsScratch.skipBits(2); // transport_scrambling_control - boolean adaptationFieldExists = tsScratch.readBit(); - boolean payloadExists = tsScratch.readBit(); + boolean payloadUnitStartIndicator = (tsPacketHeader & 0x400000) != 0; + // Ignoring transport_priority (tsPacketHeader & 0x200000) + int pid = (tsPacketHeader & 0x1FFF00) >> 8; + // Ignoring transport_scrambling_control (tsPacketHeader & 0xC0) + boolean adaptationFieldExists = (tsPacketHeader & 0x20) != 0; + boolean payloadExists = (tsPacketHeader & 0x10) != 0; // Discontinuity check. boolean discontinuityFound = false; - int continuityCounter = tsScratch.readBits(4); if (mode != MODE_HLS) { + int continuityCounter = tsPacketHeader & 0xF; int previousCounter = continuityCounters.get(pid, continuityCounter - 1); continuityCounters.put(pid, continuityCounter); if (previousCounter == continuityCounter) { @@ -276,7 +273,7 @@ public final class TsExtractor implements Extractor { tsPacketBuffer.setPosition(endOfPacket); return RESULT_CONTINUE; } - } else if (continuityCounter != (previousCounter + 1) % 16) { + } else if (continuityCounter != ((previousCounter + 1) & 0xF)) { discontinuityFound = true; } } @@ -296,7 +293,6 @@ public final class TsExtractor implements Extractor { } tsPacketBuffer.setLimit(endOfPacket); payloadReader.consume(tsPacketBuffer, payloadUnitStartIndicator); - Assertions.checkState(tsPacketBuffer.getPosition() <= endOfPacket); tsPacketBuffer.setLimit(limit); } }