diff --git a/api/audio_codecs/BUILD.gn b/api/audio_codecs/BUILD.gn index f730260015..fb033f2cef 100644 --- a/api/audio_codecs/BUILD.gn +++ b/api/audio_codecs/BUILD.gn @@ -15,12 +15,16 @@ if (is_android) { rtc_source_set("audio_codecs_api") { visibility = [ "*" ] sources = [ + "audio_codec_pair_id.cc", + "audio_codec_pair_id.h", "audio_decoder.cc", "audio_decoder.h", + "audio_decoder_factory.cc", "audio_decoder_factory.h", "audio_decoder_factory_template.h", "audio_encoder.cc", "audio_encoder.h", + "audio_encoder_factory.cc", "audio_encoder_factory.h", "audio_encoder_factory_template.h", "audio_format.cc", diff --git a/api/audio_codecs/audio_codec_pair_id.cc b/api/audio_codecs/audio_codec_pair_id.cc new file mode 100644 index 0000000000..ac84107eda --- /dev/null +++ b/api/audio_codecs/audio_codec_pair_id.cc @@ -0,0 +1,90 @@ +/* + * Copyright (c) 2018 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 "api/audio_codecs/audio_codec_pair_id.h" + +#include + +#include "rtc_base/checks.h" + +namespace webrtc { + +namespace { + +// Returns a new value that it has never returned before. You may call it at +// most 2^63 times in the lifetime of the program. Note: The returned values +// may be easily predictable. +uint64_t GetNextId() { + static std::atomic next_id(0); + + // Atomically increment `next_id`, and return the previous value. Relaxed + // memory order is sufficient, since all we care about is that different + // callers return different values. + const uint64_t new_id = next_id.fetch_add(1, std::memory_order_relaxed); + + // This check isn't atomic with the increment, so if we start 2^63 + 1 + // invocations of GetNextId() in parallel, the last one to do the atomic + // increment could return the ID 0 before any of the others had time to + // trigger this DCHECK. We blithely assume that this won't happen. + RTC_DCHECK_LT(new_id, uint64_t{1} << 63) << "Used up all ID values"; + + return new_id; +} + +// Make an integer ID more unpredictable. This is a 1:1 mapping, so you can +// feed it any value, but the idea is that you can feed it a sequence such as +// 0, 1, 2, ... and get a new sequence that isn't as trivially predictable, so +// that users won't rely on it being consecutive or increasing or anything like +// that. +constexpr uint64_t ObfuscateId(uint64_t id) { + // Any nonzero coefficient that's relatively prime to 2^64 (that is, any odd + // number) and any constant will give a 1:1 mapping. These high-entropy + // values will prevent the sequence from being trivially predictable. + // + // Both the multiplication and the addition going to overflow almost always, + // but that's fine---we *want* arithmetic mod 2^64. + return uint64_t{0x85fdb20e1294309a} + uint64_t{0xc516ef5c37462469} * id; +} + +// The first ten values. Verified against the Python function +// +// def f(n): +// return (0x85fdb20e1294309a + 0xc516ef5c37462469 * n) % 2**64 +// +// Callers should obviously not depend on these exact values... +// +// (On Visual C++, we have to disable warning C4307 (integral constant +// overflow), even though unsigned integers have perfectly well-defined +// overflow behavior.) +#ifdef _MSC_VER +#pragma warning(push) +#pragma warning(disable : 4307) +#endif +static_assert(ObfuscateId(0) == uint64_t{0x85fdb20e1294309a}, ""); +static_assert(ObfuscateId(1) == uint64_t{0x4b14a16a49da5503}, ""); +static_assert(ObfuscateId(2) == uint64_t{0x102b90c68120796c}, ""); +static_assert(ObfuscateId(3) == uint64_t{0xd5428022b8669dd5}, ""); +static_assert(ObfuscateId(4) == uint64_t{0x9a596f7eefacc23e}, ""); +static_assert(ObfuscateId(5) == uint64_t{0x5f705edb26f2e6a7}, ""); +static_assert(ObfuscateId(6) == uint64_t{0x24874e375e390b10}, ""); +static_assert(ObfuscateId(7) == uint64_t{0xe99e3d93957f2f79}, ""); +static_assert(ObfuscateId(8) == uint64_t{0xaeb52cefccc553e2}, ""); +static_assert(ObfuscateId(9) == uint64_t{0x73cc1c4c040b784b}, ""); +#ifdef _MSC_VER +#pragma warning(pop) +#endif + +} // namespace + +AudioCodecPairId AudioCodecPairId::Create() { + return AudioCodecPairId(ObfuscateId(GetNextId())); +} + +} // namespace webrtc diff --git a/api/audio_codecs/audio_codec_pair_id.h b/api/audio_codecs/audio_codec_pair_id.h new file mode 100644 index 0000000000..b10f14ea66 --- /dev/null +++ b/api/audio_codecs/audio_codec_pair_id.h @@ -0,0 +1,74 @@ +/* + * Copyright (c) 2018 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. + */ + +#ifndef API_AUDIO_CODECS_AUDIO_CODEC_PAIR_ID_H_ +#define API_AUDIO_CODECS_AUDIO_CODEC_PAIR_ID_H_ + +#include + +#include + +namespace webrtc { + +class AudioCodecPairId final { + public: + // Copyable, but not default constructible. + AudioCodecPairId() = delete; + AudioCodecPairId(const AudioCodecPairId&) = default; + AudioCodecPairId(AudioCodecPairId&&) = default; + AudioCodecPairId& operator=(const AudioCodecPairId&) = default; + AudioCodecPairId& operator=(AudioCodecPairId&&) = default; + + friend void swap(AudioCodecPairId& a, AudioCodecPairId& b) { + using std::swap; + swap(a.id_, b.id_); + } + + // Creates a new ID, unequal to any previously created ID. + static AudioCodecPairId Create(); + + // IDs can be tested for equality. + friend bool operator==(AudioCodecPairId a, AudioCodecPairId b) { + return a.id_ == b.id_; + } + friend bool operator!=(AudioCodecPairId a, AudioCodecPairId b) { + return a.id_ != b.id_; + } + + // Comparisons. The ordering of ID values is completely arbitrary, but + // stable, so it's useful e.g. if you want to use IDs as keys in an ordered + // map. + friend bool operator<(AudioCodecPairId a, AudioCodecPairId b) { + return a.id_ < b.id_; + } + friend bool operator<=(AudioCodecPairId a, AudioCodecPairId b) { + return a.id_ <= b.id_; + } + friend bool operator>=(AudioCodecPairId a, AudioCodecPairId b) { + return a.id_ >= b.id_; + } + friend bool operator>(AudioCodecPairId a, AudioCodecPairId b) { + return a.id_ > b.id_; + } + + // Returns a numeric representation of the ID. The numeric values are + // completely arbitrary, but stable, collision-free, and reasonably evenly + // distributed, so they are e.g. useful as hash values in unordered maps. + uint64_t NumericRepresentation() const { return id_; } + + private: + explicit AudioCodecPairId(uint64_t id) : id_(id) {} + + uint64_t id_; +}; + +} // namespace webrtc + +#endif // API_AUDIO_CODECS_AUDIO_CODEC_PAIR_ID_H_ diff --git a/api/audio_codecs/audio_decoder_factory.cc b/api/audio_codecs/audio_decoder_factory.cc new file mode 100644 index 0000000000..08dbe788af --- /dev/null +++ b/api/audio_codecs/audio_decoder_factory.cc @@ -0,0 +1,26 @@ +/* + * Copyright (c) 2018 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 "api/audio_codecs/audio_decoder_factory.h" + +namespace webrtc { + +std::unique_ptr AudioDecoderFactory::MakeAudioDecoder( + const SdpAudioFormat& format, + rtc::Optional codec_pair_id) { + return MakeAudioDecoder(format); +} + +std::unique_ptr AudioDecoderFactory::MakeAudioDecoder( + const SdpAudioFormat& format) { + return MakeAudioDecoder(format, rtc::nullopt); +} + +} // namespace webrtc diff --git a/api/audio_codecs/audio_decoder_factory.h b/api/audio_codecs/audio_decoder_factory.h index ac0f4519d8..9954f314a6 100644 --- a/api/audio_codecs/audio_decoder_factory.h +++ b/api/audio_codecs/audio_decoder_factory.h @@ -14,8 +14,10 @@ #include #include +#include "api/audio_codecs/audio_codec_pair_id.h" #include "api/audio_codecs/audio_decoder.h" #include "api/audio_codecs/audio_format.h" +#include "api/optional.h" #include "rtc_base/refcount.h" namespace webrtc { @@ -28,8 +30,22 @@ class AudioDecoderFactory : public rtc::RefCountInterface { virtual bool IsSupportedDecoder(const SdpAudioFormat& format) = 0; + // Create a new decoder instance. The `codec_pair_id` argument is used to + // link encoders and decoders that talk to the same remote entity; if a + // MakeAudioEncoder() and a MakeAudioDecoder() call receive non-null IDs that + // compare equal, the factory implementations may assume that the encoder and + // decoder form a pair. + // + // Note: Implementations need to be robust against combinations other than + // one encoder, one decoder getting the same ID; such decoders must still + // work. virtual std::unique_ptr MakeAudioDecoder( - const SdpAudioFormat& format) = 0; + const SdpAudioFormat& format, + rtc::Optional codec_pair_id); + + // Deprecated version of the above. + virtual std::unique_ptr MakeAudioDecoder( + const SdpAudioFormat& format); }; } // namespace webrtc diff --git a/api/audio_codecs/audio_encoder_factory.cc b/api/audio_codecs/audio_encoder_factory.cc new file mode 100644 index 0000000000..b5c7110644 --- /dev/null +++ b/api/audio_codecs/audio_encoder_factory.cc @@ -0,0 +1,28 @@ +/* + * Copyright (c) 2018 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 "api/audio_codecs/audio_encoder_factory.h" + +namespace webrtc { + +std::unique_ptr AudioEncoderFactory::MakeAudioEncoder( + int payload_type, + const SdpAudioFormat& format, + rtc::Optional codec_pair_id) { + return MakeAudioEncoder(payload_type, format); +} + +std::unique_ptr AudioEncoderFactory::MakeAudioEncoder( + int payload_type, + const SdpAudioFormat& format) { + return MakeAudioEncoder(payload_type, format, rtc::nullopt); +} + +} // namespace webrtc diff --git a/api/audio_codecs/audio_encoder_factory.h b/api/audio_codecs/audio_encoder_factory.h index 43461f6b9a..02bdfd9234 100644 --- a/api/audio_codecs/audio_encoder_factory.h +++ b/api/audio_codecs/audio_encoder_factory.h @@ -14,8 +14,10 @@ #include #include +#include "api/audio_codecs/audio_codec_pair_id.h" #include "api/audio_codecs/audio_encoder.h" #include "api/audio_codecs/audio_format.h" +#include "api/optional.h" #include "rtc_base/refcount.h" namespace webrtc { @@ -33,12 +35,27 @@ class AudioEncoderFactory : public rtc::RefCountInterface { virtual rtc::Optional QueryAudioEncoder( const SdpAudioFormat& format) = 0; - // Creates an AudioEncoder for the specified format. The encoder will tags its - // payloads with the specified payload type. + // Creates an AudioEncoder for the specified format. The encoder will tags + // its payloads with the specified payload type. The `codec_pair_id` argument + // is used to link encoders and decoders that talk to the same remote entity; + // if a MakeAudioEncoder() and a MakeAudioDecoder() call receive non-null IDs + // that compare equal, the factory implementations may assume that the + // encoder and decoder form a pair. + // + // Note: Implementations need to be robust against combinations other than + // one encoder, one decoder getting the same ID; such encoders must still + // work. + // // TODO(ossu): Try to avoid audio encoders having to know their payload type. virtual std::unique_ptr MakeAudioEncoder( int payload_type, - const SdpAudioFormat& format) = 0; + const SdpAudioFormat& format, + rtc::Optional codec_pair_id); + + // Deprecated version of the above. + virtual std::unique_ptr MakeAudioEncoder( + int payload_type, + const SdpAudioFormat& format); }; } // namespace webrtc