// reserved = b1
// the first fragment of "buffer" follows
+ // Each transport packet (except for the last one contributing to the PES
+ // payload) must contain a multiple of 16 bytes of payload per HDCP spec.
+ bool alignPayload =
+ (mFlags & (EMIT_HDCP20_DESCRIPTOR | EMIT_HDCP21_DESCRIPTOR));
+
+ /*
+ a) The very first PES transport stream packet contains
+
+ 4 bytes of TS header
+ ... padding
+ 14 bytes of static PES header
+ PES_private_data_len + 1 bytes (only if PES_private_data_len > 0)
+ numStuffingBytes bytes
+
+ followed by the payload
+
+ b) Subsequent PES transport stream packets contain
+
+ 4 bytes of TS header
+ ... padding
+
+ followed by the payload
+ */
+
size_t PES_packet_length = accessUnit->size() + 8 + numStuffingBytes;
if (PES_private_data_len > 0) {
PES_packet_length += PES_private_data_len + 1;
}
- size_t numTSPackets;
- if (PES_packet_length <= 178) {
- numTSPackets = 1;
- } else {
- numTSPackets = 1 + ((PES_packet_length - 178) + 183) / 184;
+ size_t numTSPackets = 1;
+
+ {
+ // Make sure the PES header fits into a single TS packet:
+ size_t PES_header_size = 14 + numStuffingBytes;
+ if (PES_private_data_len > 0) {
+ PES_header_size += PES_private_data_len + 1;
+ }
+
+ CHECK_LE(PES_header_size, 188u - 4u);
+
+ size_t sizeAvailableForPayload = 188 - 4 - PES_header_size;
+ size_t numBytesOfPayload = accessUnit->size();
+
+ if (numBytesOfPayload > sizeAvailableForPayload) {
+ numBytesOfPayload = sizeAvailableForPayload;
+
+ if (alignPayload && numBytesOfPayload > 16) {
+ numBytesOfPayload -= (numBytesOfPayload % 16);
+ }
+ }
+
+ // size_t numPaddingBytes = sizeAvailableForPayload - numBytesOfPayload;
+ ALOGV("packet 1 contains %zd padding bytes and %zd bytes of payload",
+ numPaddingBytes, numBytesOfPayload);
+
+ size_t numBytesOfPayloadRemaining = accessUnit->size() - numBytesOfPayload;
+
+#if 0
+ // The following hopefully illustrates the logic that led to the
+ // more efficient computation in the #else block...
+
+ while (numBytesOfPayloadRemaining > 0) {
+ size_t sizeAvailableForPayload = 188 - 4;
+
+ size_t numBytesOfPayload = numBytesOfPayloadRemaining;
+
+ if (numBytesOfPayload > sizeAvailableForPayload) {
+ numBytesOfPayload = sizeAvailableForPayload;
+
+ if (alignPayload && numBytesOfPayload > 16) {
+ numBytesOfPayload -= (numBytesOfPayload % 16);
+ }
+ }
+
+ size_t numPaddingBytes = sizeAvailableForPayload - numBytesOfPayload;
+ ALOGI("packet %zd contains %zd padding bytes and %zd bytes of payload",
+ numTSPackets + 1, numPaddingBytes, numBytesOfPayload);
+
+ numBytesOfPayloadRemaining -= numBytesOfPayload;
+ ++numTSPackets;
+ }
+#else
+ // This is how many bytes of payload each subsequent TS packet
+ // can contain at most.
+ sizeAvailableForPayload = 188 - 4;
+ size_t sizeAvailableForAlignedPayload = sizeAvailableForPayload;
+ if (alignPayload) {
+ // We're only going to use a subset of the available space
+ // since we need to make each fragment a multiple of 16 in size.
+ sizeAvailableForAlignedPayload -=
+ (sizeAvailableForAlignedPayload % 16);
+ }
+
+ size_t numFullTSPackets =
+ numBytesOfPayloadRemaining / sizeAvailableForAlignedPayload;
+
+ numTSPackets += numFullTSPackets;
+
+ numBytesOfPayloadRemaining -=
+ numFullTSPackets * sizeAvailableForAlignedPayload;
+
+ // numBytesOfPayloadRemaining < sizeAvailableForAlignedPayload
+ if (numFullTSPackets == 0 && numBytesOfPayloadRemaining > 0) {
+ // There wasn't enough payload left to form a full aligned payload,
+ // the last packet doesn't have to be aligned.
+ ++numTSPackets;
+ } else if (numFullTSPackets > 0
+ && numBytesOfPayloadRemaining
+ + sizeAvailableForAlignedPayload > sizeAvailableForPayload) {
+ // The last packet emitted had a full aligned payload and together
+ // with the bytes remaining does exceed the unaligned payload
+ // size, so we need another packet.
+ ++numTSPackets;
+ }
+#endif
}
if (flags & EMIT_PAT_AND_PMT) {
uint64_t PTS = (timeUs * 9ll) / 100ll;
- bool padding = (PES_packet_length < (188 - 10));
-
if (PES_packet_length >= 65536) {
// This really should only happen for video.
CHECK(track->isVideo());
PES_packet_length = 0;
}
+ size_t sizeAvailableForPayload = 188 - 4 - 14 - numStuffingBytes;
+ if (PES_private_data_len > 0) {
+ sizeAvailableForPayload -= PES_private_data_len + 1;
+ }
+
+ size_t copy = accessUnit->size();
+
+ if (copy > sizeAvailableForPayload) {
+ copy = sizeAvailableForPayload;
+
+ if (alignPayload && copy > 16) {
+ copy -= (copy % 16);
+ }
+ }
+
+ size_t numPaddingBytes = sizeAvailableForPayload - copy;
+
uint8_t *ptr = packetDataStart;
*ptr++ = 0x47;
*ptr++ = 0x40 | (track->PID() >> 8);
*ptr++ = track->PID() & 0xff;
- *ptr++ = (padding ? 0x30 : 0x10) | track->incrementContinuityCounter();
- if (padding) {
- size_t paddingSize = 188 - 10 - PES_packet_length;
- *ptr++ = paddingSize - 1;
- if (paddingSize >= 2) {
+ *ptr++ = (numPaddingBytes > 0 ? 0x30 : 0x10)
+ | track->incrementContinuityCounter();
+
+ if (numPaddingBytes > 0) {
+ *ptr++ = numPaddingBytes - 1;
+ if (numPaddingBytes >= 2) {
*ptr++ = 0x00;
- memset(ptr, 0xff, paddingSize - 2);
- ptr += paddingSize - 2;
+ memset(ptr, 0xff, numPaddingBytes - 2);
+ ptr += numPaddingBytes - 2;
}
}
*ptr++ = 0xff;
}
- // 18 bytes of TS/PES header leave 188 - 18 = 170 bytes for the payload
-
- size_t sizeLeft = packetDataStart + 188 - ptr;
- size_t copy = accessUnit->size();
- if (copy > sizeLeft) {
- copy = sizeLeft;
- }
-
memcpy(ptr, accessUnit->data(), copy);
ptr += copy;
- CHECK_EQ(sizeLeft, copy);
- memset(ptr, 0xff, sizeLeft - copy);
+ CHECK_EQ(ptr, packetDataStart + 188);
packetDataStart += 188;
size_t offset = copy;
while (offset < accessUnit->size()) {
- bool padding = (accessUnit->size() - offset) < (188 - 4);
-
// for subsequent fragments of "buffer":
// 0x47
// transport_error_indicator = b0
// continuity_counter = b????
// the fragment of "buffer" follows.
+ size_t sizeAvailableForPayload = 188 - 4;
+
+ size_t copy = accessUnit->size() - offset;
+
+ if (copy > sizeAvailableForPayload) {
+ copy = sizeAvailableForPayload;
+
+ if (alignPayload && copy > 16) {
+ copy -= (copy % 16);
+ }
+ }
+
+ size_t numPaddingBytes = sizeAvailableForPayload - copy;
+
uint8_t *ptr = packetDataStart;
*ptr++ = 0x47;
*ptr++ = 0x00 | (track->PID() >> 8);
*ptr++ = track->PID() & 0xff;
- *ptr++ = (padding ? 0x30 : 0x10) | track->incrementContinuityCounter();
+ *ptr++ = (numPaddingBytes > 0 ? 0x30 : 0x10)
+ | track->incrementContinuityCounter();
- if (padding) {
- size_t paddingSize = 188 - 4 - (accessUnit->size() - offset);
- *ptr++ = paddingSize - 1;
- if (paddingSize >= 2) {
+ if (numPaddingBytes > 0) {
+ *ptr++ = numPaddingBytes - 1;
+ if (numPaddingBytes >= 2) {
*ptr++ = 0x00;
- memset(ptr, 0xff, paddingSize - 2);
- ptr += paddingSize - 2;
+ memset(ptr, 0xff, numPaddingBytes - 2);
+ ptr += numPaddingBytes - 2;
}
}
- // 4 bytes of TS header leave 188 - 4 = 184 bytes for the payload
-
- size_t sizeLeft = packetDataStart + 188 - ptr;
- size_t copy = accessUnit->size() - offset;
- if (copy > sizeLeft) {
- copy = sizeLeft;
- }
-
memcpy(ptr, accessUnit->data() + offset, copy);
ptr += copy;
- CHECK_EQ(sizeLeft, copy);
- memset(ptr, 0xff, sizeLeft - copy);
+ CHECK_EQ(ptr, packetDataStart + 188);
offset += copy;
packetDataStart += 188;
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