better mpeg2 TS elementary stream Access Unit parsing
mpeg2 es stream access units have a 3 byte prefix and a 1 byte start
code. Searching for the next access unit started after the prefix
instead of after the start byte.
Bug: 74114680
Test: ran POC before/after
(cherry picked from commit 371066d073c5db289b0f38b9d2bfd3e326c78c66)
Change-Id: I3c51c62355c810e1b8dbc644cad3de335b7d8108
diff --git a/media/libstagefright/mpeg2ts/ESQueue.cpp b/media/libstagefright/mpeg2ts/ESQueue.cpp
index 1cf9744..11f3ed1 100644
--- a/media/libstagefright/mpeg2ts/ESQueue.cpp
+++ b/media/libstagefright/mpeg2ts/ESQueue.cpp
@@ -1486,7 +1486,9 @@
const uint8_t *data, size_t size) {
static const char kStartCode[] = "\x00\x00\x01";
- if (size < 3) {
+ // per ISO/IEC 14496-2 6.2.1, a chunk has a 3-byte prefix + 1-byte start code
+ // we need at least <prefix><start><next prefix> to successfully scan
+ if (size < 3 + 1 + 3) {
return -EAGAIN;
}
@@ -1494,7 +1496,7 @@
return -EAGAIN;
}
- size_t offset = 3;
+ size_t offset = 4;
while (offset + 2 < size) {
if (!memcmp(&data[offset], kStartCode, 3)) {
return offset;
@@ -1545,6 +1547,9 @@
state = EXPECT_VISUAL_OBJECT_START;
} else {
discard = true;
+ offset += chunkSize;
+ ALOGW("b/74114680, advance to next chunk");
+ android_errorWriteLog(0x534e4554, "74114680");
}
break;
}
