Home | History | Annotate | Download | only in source 
      1 /*
      2  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #include <string.h>
     12 
     13 #include "webrtc/base/logging.h"
     14 #include "webrtc/modules/include/module_common_types.h"
     15 #include "webrtc/modules/rtp_rtcp/source/byte_io.h"
     16 #include "webrtc/modules/rtp_rtcp/source/h264_sps_parser.h"
     17 #include "webrtc/modules/rtp_rtcp/source/rtp_format_h264.h"
     18 
     19 namespace webrtc {
     20 namespace {
     21 
     22 enum Nalu {
     23   kSlice = 1,
     24   kIdr = 5,
     25   kSei = 6,
     26   kSps = 7,
     27   kPps = 8,
     28   kStapA = 24,
     29   kFuA = 28
     30 };
     31 
     32 static const size_t kNalHeaderSize = 1;
     33 static const size_t kFuAHeaderSize = 2;
     34 static const size_t kLengthFieldSize = 2;
     35 static const size_t kStapAHeaderSize = kNalHeaderSize + kLengthFieldSize;
     36 
     37 // Bit masks for FU (A and B) indicators.
     38 enum NalDefs { kFBit = 0x80, kNriMask = 0x60, kTypeMask = 0x1F };
     39 
     40 // Bit masks for FU (A and B) headers.
     41 enum FuDefs { kSBit = 0x80, kEBit = 0x40, kRBit = 0x20 };
     42 
     43 // TODO(pbos): Avoid parsing this here as well as inside the jitter buffer.
     44 bool VerifyStapANaluLengths(const uint8_t* nalu_ptr, size_t length_remaining) {
     45   while (length_remaining > 0) {
     46     // Buffer doesn't contain room for additional nalu length.
     47     if (length_remaining < sizeof(uint16_t))
     48       return false;
     49     uint16_t nalu_size = nalu_ptr[0] << 8 | nalu_ptr[1];
     50     nalu_ptr += sizeof(uint16_t);
     51     length_remaining -= sizeof(uint16_t);
     52     if (nalu_size > length_remaining)
     53       return false;
     54     nalu_ptr += nalu_size;
     55     length_remaining -= nalu_size;
     56   }
     57   return true;
     58 }
     59 
     60 bool ParseSingleNalu(RtpDepacketizer::ParsedPayload* parsed_payload,
     61                      const uint8_t* payload_data,
     62                      size_t payload_data_length) {
     63   parsed_payload->type.Video.width = 0;
     64   parsed_payload->type.Video.height = 0;
     65   parsed_payload->type.Video.codec = kRtpVideoH264;
     66   parsed_payload->type.Video.isFirstPacket = true;
     67   RTPVideoHeaderH264* h264_header =
     68       &parsed_payload->type.Video.codecHeader.H264;
     69 
     70   const uint8_t* nalu_start = payload_data + kNalHeaderSize;
     71   size_t nalu_length = payload_data_length - kNalHeaderSize;
     72   uint8_t nal_type = payload_data[0] & kTypeMask;
     73   if (nal_type == kStapA) {
     74     // Skip the StapA header (StapA nal type + length).
     75     if (payload_data_length <= kStapAHeaderSize) {
     76       LOG(LS_ERROR) << "StapA header truncated.";
     77       return false;
     78     }
     79     if (!VerifyStapANaluLengths(nalu_start, nalu_length)) {
     80       LOG(LS_ERROR) << "StapA packet with incorrect NALU packet lengths.";
     81       return false;
     82     }
     83 
     84     nal_type = payload_data[kStapAHeaderSize] & kTypeMask;
     85     nalu_start += kStapAHeaderSize;
     86     nalu_length -= kStapAHeaderSize;
     87     h264_header->packetization_type = kH264StapA;
     88   } else {
     89     h264_header->packetization_type = kH264SingleNalu;
     90   }
     91   h264_header->nalu_type = nal_type;
     92 
     93   // We can read resolution out of sps packets.
     94   if (nal_type == kSps) {
     95     H264SpsParser parser(nalu_start, nalu_length);
     96     if (parser.Parse()) {
     97       parsed_payload->type.Video.width = parser.width();
     98       parsed_payload->type.Video.height = parser.height();
     99     }
    100   }
    101   switch (nal_type) {
    102     case kSps:
    103     case kPps:
    104     case kIdr:
    105       parsed_payload->frame_type = kVideoFrameKey;
    106       break;
    107     default:
    108       parsed_payload->frame_type = kVideoFrameDelta;
    109       break;
    110   }
    111   return true;
    112 }
    113 
    114 bool ParseFuaNalu(RtpDepacketizer::ParsedPayload* parsed_payload,
    115                   const uint8_t* payload_data,
    116                   size_t payload_data_length,
    117                   size_t* offset) {
    118   if (payload_data_length < kFuAHeaderSize) {
    119     LOG(LS_ERROR) << "FU-A NAL units truncated.";
    120     return false;
    121   }
    122   uint8_t fnri = payload_data[0] & (kFBit | kNriMask);
    123   uint8_t original_nal_type = payload_data[1] & kTypeMask;
    124   bool first_fragment = (payload_data[1] & kSBit) > 0;
    125 
    126   uint8_t original_nal_header = fnri | original_nal_type;
    127   if (first_fragment) {
    128     *offset = kNalHeaderSize;
    129     uint8_t* payload = const_cast<uint8_t*>(payload_data + *offset);
    130     payload[0] = original_nal_header;
    131   } else {
    132     *offset = kFuAHeaderSize;
    133   }
    134 
    135   if (original_nal_type == kIdr) {
    136     parsed_payload->frame_type = kVideoFrameKey;
    137   } else {
    138     parsed_payload->frame_type = kVideoFrameDelta;
    139   }
    140   parsed_payload->type.Video.width = 0;
    141   parsed_payload->type.Video.height = 0;
    142   parsed_payload->type.Video.codec = kRtpVideoH264;
    143   parsed_payload->type.Video.isFirstPacket = first_fragment;
    144   RTPVideoHeaderH264* h264_header =
    145       &parsed_payload->type.Video.codecHeader.H264;
    146   h264_header->packetization_type = kH264FuA;
    147   h264_header->nalu_type = original_nal_type;
    148   return true;
    149 }
    150 }  // namespace
    151 
    152 RtpPacketizerH264::RtpPacketizerH264(FrameType frame_type,
    153                                      size_t max_payload_len)
    154     : payload_data_(NULL),
    155       payload_size_(0),
    156       max_payload_len_(max_payload_len) {
    157 }
    158 
    159 RtpPacketizerH264::~RtpPacketizerH264() {
    160 }
    161 
    162 void RtpPacketizerH264::SetPayloadData(
    163     const uint8_t* payload_data,
    164     size_t payload_size,
    165     const RTPFragmentationHeader* fragmentation) {
    166   assert(packets_.empty());
    167   assert(fragmentation);
    168   payload_data_ = payload_data;
    169   payload_size_ = payload_size;
    170   fragmentation_.CopyFrom(*fragmentation);
    171   GeneratePackets();
    172 }
    173 
    174 void RtpPacketizerH264::GeneratePackets() {
    175   for (size_t i = 0; i < fragmentation_.fragmentationVectorSize;) {
    176     size_t fragment_offset = fragmentation_.fragmentationOffset[i];
    177     size_t fragment_length = fragmentation_.fragmentationLength[i];
    178     if (fragment_length > max_payload_len_) {
    179       PacketizeFuA(fragment_offset, fragment_length);
    180       ++i;
    181     } else {
    182       i = PacketizeStapA(i, fragment_offset, fragment_length);
    183     }
    184   }
    185 }
    186 
    187 void RtpPacketizerH264::PacketizeFuA(size_t fragment_offset,
    188                                      size_t fragment_length) {
    189   // Fragment payload into packets (FU-A).
    190   // Strip out the original header and leave room for the FU-A header.
    191   fragment_length -= kNalHeaderSize;
    192   size_t offset = fragment_offset + kNalHeaderSize;
    193   size_t bytes_available = max_payload_len_ - kFuAHeaderSize;
    194   size_t fragments =
    195       (fragment_length + (bytes_available - 1)) / bytes_available;
    196   size_t avg_size = (fragment_length + fragments - 1) / fragments;
    197   while (fragment_length > 0) {
    198     size_t packet_length = avg_size;
    199     if (fragment_length < avg_size)
    200       packet_length = fragment_length;
    201     uint8_t header = payload_data_[fragment_offset];
    202     packets_.push(Packet(offset,
    203                          packet_length,
    204                          offset - kNalHeaderSize == fragment_offset,
    205                          fragment_length == packet_length,
    206                          false,
    207                          header));
    208     offset += packet_length;
    209     fragment_length -= packet_length;
    210   }
    211 }
    212 
    213 int RtpPacketizerH264::PacketizeStapA(size_t fragment_index,
    214                                       size_t fragment_offset,
    215                                       size_t fragment_length) {
    216   // Aggregate fragments into one packet (STAP-A).
    217   size_t payload_size_left = max_payload_len_;
    218   int aggregated_fragments = 0;
    219   size_t fragment_headers_length = 0;
    220   assert(payload_size_left >= fragment_length);
    221   while (payload_size_left >= fragment_length + fragment_headers_length) {
    222     assert(fragment_length > 0);
    223     uint8_t header = payload_data_[fragment_offset];
    224     packets_.push(Packet(fragment_offset,
    225                          fragment_length,
    226                          aggregated_fragments == 0,
    227                          false,
    228                          true,
    229                          header));
    230     payload_size_left -= fragment_length;
    231     payload_size_left -= fragment_headers_length;
    232 
    233     // Next fragment.
    234     ++fragment_index;
    235     if (fragment_index == fragmentation_.fragmentationVectorSize)
    236       break;
    237     fragment_offset = fragmentation_.fragmentationOffset[fragment_index];
    238     fragment_length = fragmentation_.fragmentationLength[fragment_index];
    239 
    240     fragment_headers_length = kLengthFieldSize;
    241     // If we are going to try to aggregate more fragments into this packet
    242     // we need to add the STAP-A NALU header and a length field for the first
    243     // NALU of this packet.
    244     if (aggregated_fragments == 0)
    245       fragment_headers_length += kNalHeaderSize + kLengthFieldSize;
    246     ++aggregated_fragments;
    247   }
    248   packets_.back().last_fragment = true;
    249   return fragment_index;
    250 }
    251 
    252 bool RtpPacketizerH264::NextPacket(uint8_t* buffer,
    253                                    size_t* bytes_to_send,
    254                                    bool* last_packet) {
    255   *bytes_to_send = 0;
    256   if (packets_.empty()) {
    257     *bytes_to_send = 0;
    258     *last_packet = true;
    259     return false;
    260   }
    261 
    262   Packet packet = packets_.front();
    263 
    264   if (packet.first_fragment && packet.last_fragment) {
    265     // Single NAL unit packet.
    266     *bytes_to_send = packet.size;
    267     memcpy(buffer, &payload_data_[packet.offset], packet.size);
    268     packets_.pop();
    269     assert(*bytes_to_send <= max_payload_len_);
    270   } else if (packet.aggregated) {
    271     NextAggregatePacket(buffer, bytes_to_send);
    272     assert(*bytes_to_send <= max_payload_len_);
    273   } else {
    274     NextFragmentPacket(buffer, bytes_to_send);
    275     assert(*bytes_to_send <= max_payload_len_);
    276   }
    277   *last_packet = packets_.empty();
    278   return true;
    279 }
    280 
    281 void RtpPacketizerH264::NextAggregatePacket(uint8_t* buffer,
    282                                             size_t* bytes_to_send) {
    283   Packet packet = packets_.front();
    284   assert(packet.first_fragment);
    285   // STAP-A NALU header.
    286   buffer[0] = (packet.header & (kFBit | kNriMask)) | kStapA;
    287   int index = kNalHeaderSize;
    288   *bytes_to_send += kNalHeaderSize;
    289   while (packet.aggregated) {
    290     // Add NAL unit length field.
    291     ByteWriter<uint16_t>::WriteBigEndian(&buffer[index], packet.size);
    292     index += kLengthFieldSize;
    293     *bytes_to_send += kLengthFieldSize;
    294     // Add NAL unit.
    295     memcpy(&buffer[index], &payload_data_[packet.offset], packet.size);
    296     index += packet.size;
    297     *bytes_to_send += packet.size;
    298     packets_.pop();
    299     if (packet.last_fragment)
    300       break;
    301     packet = packets_.front();
    302   }
    303   assert(packet.last_fragment);
    304 }
    305 
    306 void RtpPacketizerH264::NextFragmentPacket(uint8_t* buffer,
    307                                            size_t* bytes_to_send) {
    308   Packet packet = packets_.front();
    309   // NAL unit fragmented over multiple packets (FU-A).
    310   // We do not send original NALU header, so it will be replaced by the
    311   // FU indicator header of the first packet.
    312   uint8_t fu_indicator = (packet.header & (kFBit | kNriMask)) | kFuA;
    313   uint8_t fu_header = 0;
    314 
    315   // S | E | R | 5 bit type.
    316   fu_header |= (packet.first_fragment ? kSBit : 0);
    317   fu_header |= (packet.last_fragment ? kEBit : 0);
    318   uint8_t type = packet.header & kTypeMask;
    319   fu_header |= type;
    320   buffer[0] = fu_indicator;
    321   buffer[1] = fu_header;
    322 
    323   if (packet.last_fragment) {
    324     *bytes_to_send = packet.size + kFuAHeaderSize;
    325     memcpy(buffer + kFuAHeaderSize, &payload_data_[packet.offset], packet.size);
    326   } else {
    327     *bytes_to_send = packet.size + kFuAHeaderSize;
    328     memcpy(buffer + kFuAHeaderSize, &payload_data_[packet.offset], packet.size);
    329   }
    330   packets_.pop();
    331 }
    332 
    333 ProtectionType RtpPacketizerH264::GetProtectionType() {
    334   return kProtectedPacket;
    335 }
    336 
    337 StorageType RtpPacketizerH264::GetStorageType(
    338     uint32_t retransmission_settings) {
    339   return kAllowRetransmission;
    340 }
    341 
    342 std::string RtpPacketizerH264::ToString() {
    343   return "RtpPacketizerH264";
    344 }
    345 
    346 bool RtpDepacketizerH264::Parse(ParsedPayload* parsed_payload,
    347                                 const uint8_t* payload_data,
    348                                 size_t payload_data_length) {
    349   assert(parsed_payload != NULL);
    350   if (payload_data_length == 0) {
    351     LOG(LS_ERROR) << "Empty payload.";
    352     return false;
    353   }
    354 
    355   uint8_t nal_type = payload_data[0] & kTypeMask;
    356   size_t offset = 0;
    357   if (nal_type == kFuA) {
    358     // Fragmented NAL units (FU-A).
    359     if (!ParseFuaNalu(
    360             parsed_payload, payload_data, payload_data_length, &offset)) {
    361       return false;
    362     }
    363   } else {
    364     // We handle STAP-A and single NALU's the same way here. The jitter buffer
    365     // will depacketize the STAP-A into NAL units later.
    366     if (!ParseSingleNalu(parsed_payload, payload_data, payload_data_length))
    367       return false;
    368   }
    369 
    370   parsed_payload->payload = payload_data + offset;
    371   parsed_payload->payload_length = payload_data_length - offset;
    372   return true;
    373 }
    374 }  // namespace webrtc
    375