tor-browser

h264.cc (6318B)

---

/*
*  Copyright (c) 2015 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 "modules/video_coding/codecs/h264/include/h264.h"

#include <memory>
#include <optional>
#include <string>
#include <vector>

#include "absl/base/nullability.h"
#include "absl/container/inlined_vector.h"
#include "api/environment/environment.h"
#include "api/video_codecs/h264_profile_level_id.h"
#include "api/video_codecs/scalability_mode.h"
#include "api/video_codecs/sdp_video_format.h"
#include "api/video_codecs/video_encoder.h"
#include "media/base/media_constants.h"
#include "modules/video_coding/codecs/h264/include/h264_globals.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/trace_event.h"

#if defined(WEBRTC_USE_H264)
#include "modules/video_coding/codecs/h264/h264_decoder_impl.h"
#include "modules/video_coding/codecs/h264/h264_encoder_impl.h"
#endif

namespace webrtc {

namespace {

#if defined(WEBRTC_USE_H264)
bool g_rtc_use_h264 = true;
#endif

// If H.264 OpenH264/FFmpeg codec is supported.
bool IsH264CodecSupported() {
#if defined(WEBRTC_USE_H264)
 return g_rtc_use_h264;
#else
 return false;
#endif
}

constexpr ScalabilityMode kSupportedScalabilityModes[] = {
   ScalabilityMode::kL1T1, ScalabilityMode::kL1T2, ScalabilityMode::kL1T3};

}  // namespace

SdpVideoFormat CreateH264Format(H264Profile profile,
                               H264Level level,
                               const std::string& packetization_mode,
                               bool add_scalability_modes) {
 const std::optional<std::string> profile_string =
     H264ProfileLevelIdToString(H264ProfileLevelId(profile, level));
 RTC_CHECK(profile_string);
 absl::InlinedVector<ScalabilityMode, kScalabilityModeCount> scalability_modes;
 if (add_scalability_modes) {
   for (const auto scalability_mode : kSupportedScalabilityModes) {
     scalability_modes.push_back(scalability_mode);
   }
 }
 return SdpVideoFormat(kH264CodecName,
                       {{kH264FmtpProfileLevelId, *profile_string},
                        {kH264FmtpLevelAsymmetryAllowed, "1"},
                        {kH264FmtpPacketizationMode, packetization_mode}},
                       scalability_modes);
}

void DisableRtcUseH264() {
#if defined(WEBRTC_USE_H264)
 g_rtc_use_h264 = false;
#endif
}

std::vector<SdpVideoFormat> SupportedH264Codecs(bool add_scalability_modes) {
 TRACE_EVENT0("webrtc", __func__);
 if (!IsH264CodecSupported())
   return std::vector<SdpVideoFormat>();
 // We only support encoding Constrained Baseline Profile (CBP), but the
 // decoder supports more profiles. We can list all profiles here that are
 // supported by the decoder and that are also supersets of CBP, i.e. the
 // decoder for that profile is required to be able to decode CBP. This means
 // we can encode and send CBP even though we negotiated a potentially
 // higher profile. See the H264 spec for more information.
 //
 // We support both packetization modes 0 (mandatory) and 1 (optional,
 // preferred).
 return {CreateH264Format(H264Profile::kProfileBaseline, H264Level::kLevel3_1,
                          "1", add_scalability_modes),
         CreateH264Format(H264Profile::kProfileBaseline, H264Level::kLevel3_1,
                          "0", add_scalability_modes),
         CreateH264Format(H264Profile::kProfileConstrainedBaseline,
                          H264Level::kLevel3_1, "1", add_scalability_modes),
         CreateH264Format(H264Profile::kProfileConstrainedBaseline,
                          H264Level::kLevel3_1, "0", add_scalability_modes),
         CreateH264Format(H264Profile::kProfileMain, H264Level::kLevel3_1, "1",
                          add_scalability_modes),
         CreateH264Format(H264Profile::kProfileMain, H264Level::kLevel3_1, "0",
                          add_scalability_modes)};
}

std::vector<SdpVideoFormat> SupportedH264DecoderCodecs() {
 TRACE_EVENT0("webrtc", __func__);
 if (!IsH264CodecSupported())
   return std::vector<SdpVideoFormat>();

 std::vector<SdpVideoFormat> supportedCodecs = SupportedH264Codecs();

 // OpenH264 doesn't yet support High Predictive 4:4:4 encoding but it does
 // support decoding.
 supportedCodecs.push_back(CreateH264Format(
     H264Profile::kProfilePredictiveHigh444, H264Level::kLevel3_1, "1"));
 supportedCodecs.push_back(CreateH264Format(
     H264Profile::kProfilePredictiveHigh444, H264Level::kLevel3_1, "0"));

 return supportedCodecs;
}

H264EncoderSettings H264EncoderSettings::Parse(const SdpVideoFormat& format) {
 if (auto it = format.parameters.find(kH264FmtpPacketizationMode);
     it != format.parameters.end()) {
   if (it->second == "0") {
     return {.packetization_mode = H264PacketizationMode::SingleNalUnit};
   } else if (it->second == "1") {
     return {.packetization_mode = H264PacketizationMode::NonInterleaved};
   }
 }
 return {};
}

absl_nonnull std::unique_ptr<VideoEncoder> CreateH264Encoder(
   [[maybe_unused]] const Environment& env,
   [[maybe_unused]] H264EncoderSettings settings) {
#if defined(WEBRTC_USE_H264)
 RTC_CHECK(g_rtc_use_h264);
 RTC_LOG(LS_INFO) << "Creating H264EncoderImpl.";
 return std::make_unique<H264EncoderImpl>(env, settings);
#else
 RTC_CHECK_NOTREACHED();
#endif
}

bool H264Encoder::IsSupported() {
 return IsH264CodecSupported();
}

bool H264Encoder::SupportsScalabilityMode(ScalabilityMode scalability_mode) {
 for (const auto& entry : kSupportedScalabilityModes) {
   if (entry == scalability_mode) {
     return true;
   }
 }
 return false;
}

std::unique_ptr<H264Decoder> H264Decoder::Create() {
 RTC_DCHECK(H264Decoder::IsSupported());
#if defined(WEBRTC_USE_H264)
 RTC_CHECK(g_rtc_use_h264);
 RTC_LOG(LS_INFO) << "Creating H264DecoderImpl.";
 return std::make_unique<H264DecoderImpl>();
#else
 RTC_DCHECK_NOTREACHED();
 return nullptr;
#endif
}

bool H264Decoder::IsSupported() {
 return IsH264CodecSupported();
}

}  // namespace webrtc