Add H264 bitstream rewriting to limit frame reordering marker in header

webrtc/modules/rtp_rtcp/source/h264/sps_parser.cc

 /*
- *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "webrtc/modules/rtp_rtcp/source/h264_sps_parser.h"
+#include "webrtc/modules/rtp_rtcp/source/h264/sps_parser.h"
 
+#include "webrtc/modules/rtp_rtcp/source/h264/h264_common.h"
 #include "webrtc/base/bitbuffer.h"
 #include "webrtc/base/bytebuffer.h"
 #include "webrtc/base/logging.h"
 
+typedef rtc::Optional<webrtc::SpsParser::SpsState> Sps;

[stefan-webrtc, 2016/05/22 23:11:50]

Call this OptionalSps, or remove it and write the full type name.

[sprang_webrtc, 2016/05/25 09:06:03]

Done.

+
 #define RETURN_FALSE_ON_FAIL(x) \
   if (!(x)) {                   \
-    return false;               \
+    return Sps();               \
   }
 
 namespace webrtc {
 
-H264SpsParser::H264SpsParser(const uint8_t* sps, size_t byte_length)
-    : sps_(sps), byte_length_(byte_length), width_(), height_() {
+// General note: this is based off the 02/2014 version of the H.264 standard.
+// You can find it on this page:
+// http://www.itu.int/rec/T-REC-H.264
+
+// Unpack RBSP and parse SPS state from the supplied buffer.
+rtc::Optional<SpsParser::SpsState> SpsParser::ParseSps(const uint8_t* data,
+                                                       size_t length) {
+  std::unique_ptr<rtc::Buffer> unpacked_buffer =
+      H264Common::ParseRbsp(data, length);
+  rtc::BitBuffer bit_buffer(unpacked_buffer->data(), unpacked_buffer->size());
+  return ParseSpsUpToVui(&bit_buffer);
 }
 
-bool H264SpsParser::Parse() {
-  // General note: this is based off the 02/2014 version of the H.264 standard.
-  // You can find it on this page:
-  // http://www.itu.int/rec/T-REC-H.264
-
-  const char* sps_bytes = reinterpret_cast<const char*>(sps_);
-  // First, parse out rbsp, which is basically the source buffer minus emulation
-  // bytes (the last byte of a 0x00 0x00 0x03 sequence). RBSP is defined in
-  // section 7.3.1 of the H.264 standard.
-  rtc::ByteBufferWriter rbsp_buffer;
-  for (size_t i = 0; i < byte_length_;) {
-    // Be careful about over/underflow here. byte_length_ - 3 can underflow, and
-    // i + 3 can overflow, but byte_length_ - i can't, because i < byte_length_
-    // above, and that expression will produce the number of bytes left in
-    // the stream including the byte at i.
-    if (byte_length_ - i >= 3 && sps_[i] == 0 && sps_[i + 1] == 0 &&
-        sps_[i + 2] == 3) {
-      // Two rbsp bytes + the emulation byte.
-      rbsp_buffer.WriteBytes(sps_bytes + i, 2);
-      i += 3;
-    } else {
-      // Single rbsp byte.
-      rbsp_buffer.WriteBytes(sps_bytes + i, 1);
-      i++;
-    }
-  }
-
+rtc::Optional<SpsParser::SpsState> SpsParser::ParseSpsUpToVui(
+    rtc::BitBuffer* buffer) {
   // Now, we need to use a bit buffer to parse through the actual AVC SPS
   // format. See Section 7.3.2.1.1 ("Sequence parameter set data syntax") of the
   // H.264 standard for a complete description.
   // Since we only care about resolution, we ignore the majority of fields, but
   // we still have to actively parse through a lot of the data, since many of
   // the fields have variable size.
   // We're particularly interested in:
   // chroma_format_idc -> affects crop units
   // pic_{width,height}_* -> resolution of the frame in macroblocks (16x16).
   // frame_crop_*_offset -> crop information
-  rtc::BitBuffer parser(reinterpret_cast<const uint8_t*>(rbsp_buffer.Data()),
-                        rbsp_buffer.Length());
+
+  SpsState sps;
 
   // The golomb values we have to read, not just consume.
   uint32_t golomb_ignored;
 
-  // separate_colour_plane_flag is optional (assumed 0), but has implications
-  // about the ChromaArrayType, which modifies how we treat crop coordinates.
-  uint32_t separate_colour_plane_flag = 0;
   // chroma_format_idc will be ChromaArrayType if separate_colour_plane_flag is
   // 0. It defaults to 1, when not specified.
   uint32_t chroma_format_idc = 1;
 
   // profile_idc: u(8). We need it to determine if we need to read/skip chroma
   // formats.
   uint8_t profile_idc;
-  RETURN_FALSE_ON_FAIL(parser.ReadUInt8(&profile_idc));
+  RETURN_FALSE_ON_FAIL(buffer->ReadUInt8(&profile_idc));
   // constraint_set0_flag through constraint_set5_flag + reserved_zero_2bits
   // 1 bit each for the flags + 2 bits = 8 bits = 1 byte.
-  RETURN_FALSE_ON_FAIL(parser.ConsumeBytes(1));
+  RETURN_FALSE_ON_FAIL(buffer->ConsumeBytes(1));
   // level_idc: u(8)
-  RETURN_FALSE_ON_FAIL(parser.ConsumeBytes(1));
+  RETURN_FALSE_ON_FAIL(buffer->ConsumeBytes(1));
   // seq_parameter_set_id: ue(v)
-  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
+  RETURN_FALSE_ON_FAIL(buffer->ReadExponentialGolomb(&golomb_ignored));
+  sps.separate_colour_plane_flag = 0;
   // See if profile_idc has chroma format information.
   if (profile_idc == 100 || profile_idc == 110 || profile_idc == 122 ||
       profile_idc == 244 || profile_idc == 44 || profile_idc == 83 ||
       profile_idc == 86 || profile_idc == 118 || profile_idc == 128 ||
       profile_idc == 138 || profile_idc == 139 || profile_idc == 134) {
     // chroma_format_idc: ue(v)
-    RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&chroma_format_idc));
+    RETURN_FALSE_ON_FAIL(buffer->ReadExponentialGolomb(&chroma_format_idc));
     if (chroma_format_idc == 3) {
       // separate_colour_plane_flag: u(1)
-      RETURN_FALSE_ON_FAIL(parser.ReadBits(&separate_colour_plane_flag, 1));
+      RETURN_FALSE_ON_FAIL(
+          buffer->ReadBits(&sps.separate_colour_plane_flag, 1));
     }
     // bit_depth_luma_minus8: ue(v)
-    RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
+    RETURN_FALSE_ON_FAIL(buffer->ReadExponentialGolomb(&golomb_ignored));
     // bit_depth_chroma_minus8: ue(v)
-    RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
+    RETURN_FALSE_ON_FAIL(buffer->ReadExponentialGolomb(&golomb_ignored));
     // qpprime_y_zero_transform_bypass_flag: u(1)
-    RETURN_FALSE_ON_FAIL(parser.ConsumeBits(1));
+    RETURN_FALSE_ON_FAIL(buffer->ConsumeBits(1));
     // seq_scaling_matrix_present_flag: u(1)
     uint32_t seq_scaling_matrix_present_flag;
-    RETURN_FALSE_ON_FAIL(parser.ReadBits(&seq_scaling_matrix_present_flag, 1));
+    RETURN_FALSE_ON_FAIL(buffer->ReadBits(&seq_scaling_matrix_present_flag, 1));
     if (seq_scaling_matrix_present_flag) {
       // seq_scaling_list_present_flags. Either 8 or 12, depending on
       // chroma_format_idc.
       uint32_t seq_scaling_list_present_flags;
       if (chroma_format_idc != 3) {
         RETURN_FALSE_ON_FAIL(
-            parser.ReadBits(&seq_scaling_list_present_flags, 8));
+            buffer->ReadBits(&seq_scaling_list_present_flags, 8));
       } else {
         RETURN_FALSE_ON_FAIL(
-            parser.ReadBits(&seq_scaling_list_present_flags, 12));
+            buffer->ReadBits(&seq_scaling_list_present_flags, 12));
       }
       // We don't support reading the sequence scaling list, and we don't really
       // see/use them in practice, so we'll just reject the full sps if we see
       // any provided.
       if (seq_scaling_list_present_flags > 0) {
         LOG(LS_WARNING) << "SPS contains scaling lists, which are unsupported.";
-        return false;
+        return Sps();
       }
     }
   }
   // log2_max_frame_num_minus4: ue(v)
-  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
+  RETURN_FALSE_ON_FAIL(
+      buffer->ReadExponentialGolomb(&sps.log2_max_frame_num_minus4));
   // pic_order_cnt_type: ue(v)
-  uint32_t pic_order_cnt_type;
-  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&pic_order_cnt_type));
-  if (pic_order_cnt_type == 0) {
+  RETURN_FALSE_ON_FAIL(buffer->ReadExponentialGolomb(&sps.pic_order_cnt_type));
+  if (sps.pic_order_cnt_type == 0) {
     // log2_max_pic_order_cnt_lsb_minus4: ue(v)
-    RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
-  } else if (pic_order_cnt_type == 1) {
+    RETURN_FALSE_ON_FAIL(
+        buffer->ReadExponentialGolomb(&sps.log2_max_pic_order_cnt_lsb_minus4));
+  } else if (sps.pic_order_cnt_type == 1) {
     // delta_pic_order_always_zero_flag: u(1)
-    RETURN_FALSE_ON_FAIL(parser.ConsumeBits(1));
+    RETURN_FALSE_ON_FAIL(
+        buffer->ReadBits(&sps.delta_pic_order_always_zero_flag, 1));
     // offset_for_non_ref_pic: se(v)
-    RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
+    RETURN_FALSE_ON_FAIL(buffer->ReadExponentialGolomb(&golomb_ignored));
     // offset_for_top_to_bottom_field: se(v)
-    RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
+    RETURN_FALSE_ON_FAIL(buffer->ReadExponentialGolomb(&golomb_ignored));
     // num_ref_frames_in_pic_order_cnt_cycle: ue(v)
     uint32_t num_ref_frames_in_pic_order_cnt_cycle;
     RETURN_FALSE_ON_FAIL(
-        parser.ReadExponentialGolomb(&num_ref_frames_in_pic_order_cnt_cycle));
+        buffer->ReadExponentialGolomb(&num_ref_frames_in_pic_order_cnt_cycle));
     for (size_t i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; ++i) {
       // offset_for_ref_frame[i]: se(v)
-      RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
+      RETURN_FALSE_ON_FAIL(buffer->ReadExponentialGolomb(&golomb_ignored));
     }
   }
   // max_num_ref_frames: ue(v)
-  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&golomb_ignored));
+  RETURN_FALSE_ON_FAIL(buffer->ReadExponentialGolomb(&sps.max_num_ref_frames));
   // gaps_in_frame_num_value_allowed_flag: u(1)
-  RETURN_FALSE_ON_FAIL(parser.ConsumeBits(1));
+  RETURN_FALSE_ON_FAIL(buffer->ConsumeBits(1));
   //
   // IMPORTANT ONES! Now we're getting to resolution. First we read the pic
   // width/height in macroblocks (16x16), which gives us the base resolution,
   // and then we continue on until we hit the frame crop offsets, which are used
   // to signify resolutions that aren't multiples of 16.
   //
   // pic_width_in_mbs_minus1: ue(v)
   uint32_t pic_width_in_mbs_minus1;
-  RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&pic_width_in_mbs_minus1));
+  RETURN_FALSE_ON_FAIL(buffer->ReadExponentialGolomb(&pic_width_in_mbs_minus1));
   // pic_height_in_map_units_minus1: ue(v)
   uint32_t pic_height_in_map_units_minus1;
   RETURN_FALSE_ON_FAIL(
-      parser.ReadExponentialGolomb(&pic_height_in_map_units_minus1));
+      buffer->ReadExponentialGolomb(&pic_height_in_map_units_minus1));
   // frame_mbs_only_flag: u(1)
-  uint32_t frame_mbs_only_flag;
-  RETURN_FALSE_ON_FAIL(parser.ReadBits(&frame_mbs_only_flag, 1));
-  if (!frame_mbs_only_flag) {
+  RETURN_FALSE_ON_FAIL(buffer->ReadBits(&sps.frame_mbs_only_flag, 1));
+  if (!sps.frame_mbs_only_flag) {
     // mb_adaptive_frame_field_flag: u(1)
-    RETURN_FALSE_ON_FAIL(parser.ConsumeBits(1));
+    RETURN_FALSE_ON_FAIL(buffer->ConsumeBits(1));
   }
   // direct_8x8_inference_flag: u(1)
-  RETURN_FALSE_ON_FAIL(parser.ConsumeBits(1));
+  RETURN_FALSE_ON_FAIL(buffer->ConsumeBits(1));
   //
   // MORE IMPORTANT ONES! Now we're at the frame crop information.
   //
   // frame_cropping_flag: u(1)
   uint32_t frame_cropping_flag;
   uint32_t frame_crop_left_offset = 0;
   uint32_t frame_crop_right_offset = 0;
   uint32_t frame_crop_top_offset = 0;
   uint32_t frame_crop_bottom_offset = 0;
-  RETURN_FALSE_ON_FAIL(parser.ReadBits(&frame_cropping_flag, 1));
+  RETURN_FALSE_ON_FAIL(buffer->ReadBits(&frame_cropping_flag, 1));
   if (frame_cropping_flag) {
     // frame_crop_{left, right, top, bottom}_offset: ue(v)
-    RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&frame_crop_left_offset));
     RETURN_FALSE_ON_FAIL(
-        parser.ReadExponentialGolomb(&frame_crop_right_offset));
-    RETURN_FALSE_ON_FAIL(parser.ReadExponentialGolomb(&frame_crop_top_offset));
+        buffer->ReadExponentialGolomb(&frame_crop_left_offset));
     RETURN_FALSE_ON_FAIL(
-        parser.ReadExponentialGolomb(&frame_crop_bottom_offset));
+        buffer->ReadExponentialGolomb(&frame_crop_right_offset));
+    RETURN_FALSE_ON_FAIL(buffer->ReadExponentialGolomb(&frame_crop_top_offset));
+    RETURN_FALSE_ON_FAIL(
+        buffer->ReadExponentialGolomb(&frame_crop_bottom_offset));
   }
+  // vui_parameters_present_flag: u(1)
+  RETURN_FALSE_ON_FAIL(buffer->ReadBits(&sps.vui_params_present, 1));
 
   // Far enough! We don't use the rest of the SPS.
 
   // Start with the resolution determined by the pic_width/pic_height fields.
-  int width = 16 * (pic_width_in_mbs_minus1 + 1);
-  int height =
-      16 * (2 - frame_mbs_only_flag) * (pic_height_in_map_units_minus1 + 1);
+  sps.width = 16 * (pic_width_in_mbs_minus1 + 1);
+  sps.height =
+      16 * (2 - sps.frame_mbs_only_flag) * (pic_height_in_map_units_minus1 + 1);
 
   // Figure out the crop units in pixels. That's based on the chroma format's
   // sampling, which is indicated by chroma_format_idc.
-  if (separate_colour_plane_flag || chroma_format_idc == 0) {
-    frame_crop_bottom_offset *= (2 - frame_mbs_only_flag);
-    frame_crop_top_offset *= (2 - frame_mbs_only_flag);
-  } else if (!separate_colour_plane_flag && chroma_format_idc > 0) {
+  if (sps.separate_colour_plane_flag || chroma_format_idc == 0) {
+    frame_crop_bottom_offset *= (2 - sps.frame_mbs_only_flag);
+    frame_crop_top_offset *= (2 - sps.frame_mbs_only_flag);
+  } else if (!sps.separate_colour_plane_flag && chroma_format_idc > 0) {
     // Width multipliers for formats 1 (4:2:0) and 2 (4:2:2).
     if (chroma_format_idc == 1 || chroma_format_idc == 2) {
       frame_crop_left_offset *= 2;
       frame_crop_right_offset *= 2;
     }
     // Height multipliers for format 1 (4:2:0).
     if (chroma_format_idc == 1) {
       frame_crop_top_offset *= 2;
       frame_crop_bottom_offset *= 2;
     }
   }
   // Subtract the crop for each dimension.
-  width -= (frame_crop_left_offset + frame_crop_right_offset);
-  height -= (frame_crop_top_offset + frame_crop_bottom_offset);
+  sps.width -= (frame_crop_left_offset + frame_crop_right_offset);
+  sps.height -= (frame_crop_top_offset + frame_crop_bottom_offset);
 
-  width_ = width;
-  height_ = height;
-  return true;
+  return Sps(sps);
 }
 
 }  // namespace webrtc