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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-19 00:47:55 +0000 |
commit | 26a029d407be480d791972afb5975cf62c9360a6 (patch) | |
tree | f435a8308119effd964b339f76abb83a57c29483 /third_party/libwebrtc/modules/audio_coding/neteq/dtmf_buffer.cc | |
parent | Initial commit. (diff) | |
download | firefox-26a029d407be480d791972afb5975cf62c9360a6.tar.xz firefox-26a029d407be480d791972afb5975cf62c9360a6.zip |
Adding upstream version 124.0.1.upstream/124.0.1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | third_party/libwebrtc/modules/audio_coding/neteq/dtmf_buffer.cc | 246 |
1 files changed, 246 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/audio_coding/neteq/dtmf_buffer.cc b/third_party/libwebrtc/modules/audio_coding/neteq/dtmf_buffer.cc new file mode 100644 index 0000000000..115bfcf97b --- /dev/null +++ b/third_party/libwebrtc/modules/audio_coding/neteq/dtmf_buffer.cc @@ -0,0 +1,246 @@ +/* + * Copyright (c) 2012 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/audio_coding/neteq/dtmf_buffer.h" + +#include <algorithm> // max + +#include "rtc_base/checks.h" +#include "rtc_base/logging.h" + +// Modify the code to obtain backwards bit-exactness. Once bit-exactness is no +// longer required, this #define should be removed (and the code that it +// enables). +#define LEGACY_BITEXACT + +namespace webrtc { + +DtmfBuffer::DtmfBuffer(int fs_hz) { + SetSampleRate(fs_hz); +} + +DtmfBuffer::~DtmfBuffer() = default; + +void DtmfBuffer::Flush() { + buffer_.clear(); +} + +// The ParseEvent method parses 4 bytes from `payload` according to this format +// from RFC 4733: +// +// 0 1 2 3 +// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +// | event |E|R| volume | duration | +// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +// +// Legend (adapted from RFC 4733) +// - event: The event field is a number between 0 and 255 identifying a +// specific telephony event. The buffer will not accept any event +// numbers larger than 15. +// - E: If set to a value of one, the "end" bit indicates that this +// packet contains the end of the event. For long-lasting events +// that have to be split into segments, only the final packet for +// the final segment will have the E bit set. +// - R: Reserved. +// - volume: For DTMF digits and other events representable as tones, this +// field describes the power level of the tone, expressed in dBm0 +// after dropping the sign. Power levels range from 0 to -63 dBm0. +// Thus, larger values denote lower volume. The buffer discards +// values larger than 36 (i.e., lower than -36 dBm0). +// - duration: The duration field indicates the duration of the event or segment +// being reported, in timestamp units, expressed as an unsigned +// integer in network byte order. For a non-zero value, the event +// or segment began at the instant identified by the RTP timestamp +// and has so far lasted as long as indicated by this parameter. +// The event may or may not have ended. If the event duration +// exceeds the maximum representable by the duration field, the +// event is split into several contiguous segments. The buffer will +// discard zero-duration events. +// +int DtmfBuffer::ParseEvent(uint32_t rtp_timestamp, + const uint8_t* payload, + size_t payload_length_bytes, + DtmfEvent* event) { + RTC_CHECK(payload); + RTC_CHECK(event); + if (payload_length_bytes < 4) { + RTC_LOG(LS_WARNING) << "ParseEvent payload too short"; + return kPayloadTooShort; + } + + event->event_no = payload[0]; + event->end_bit = ((payload[1] & 0x80) != 0); + event->volume = (payload[1] & 0x3F); + event->duration = payload[2] << 8 | payload[3]; + event->timestamp = rtp_timestamp; + return kOK; +} + +// Inserts a DTMF event into the buffer. The event should be parsed from the +// bit stream using the ParseEvent method above before inserting it in the +// buffer. +// DTMF events can be quite long, and in most cases the duration of the event +// is not known when the first packet describing it is sent. To deal with that, +// the RFC 4733 specifies that multiple packets are sent for one and the same +// event as it is being created (typically, as the user is pressing the key). +// These packets will all share the same start timestamp and event number, +// while the duration will be the cumulative duration from the start. When +// inserting a new event, the InsertEvent method tries to find a matching event +// already in the buffer. If so, the new event is simply merged with the +// existing one. +int DtmfBuffer::InsertEvent(const DtmfEvent& event) { + if (event.event_no < 0 || event.event_no > 15 || event.volume < 0 || + event.volume > 63 || event.duration <= 0 || event.duration > 65535) { + RTC_LOG(LS_WARNING) << "InsertEvent invalid parameters"; + return kInvalidEventParameters; + } + DtmfList::iterator it = buffer_.begin(); + while (it != buffer_.end()) { + if (MergeEvents(it, event)) { + // A matching event was found and the new event was merged. + return kOK; + } + ++it; + } + buffer_.push_back(event); + // Sort the buffer using CompareEvents to rank the events. + buffer_.sort(CompareEvents); + return kOK; +} + +bool DtmfBuffer::GetEvent(uint32_t current_timestamp, DtmfEvent* event) { + DtmfList::iterator it = buffer_.begin(); + while (it != buffer_.end()) { + // `event_end` is an estimate of where the current event ends. If the end + // bit is set, we know that the event ends at `timestamp` + `duration`. + uint32_t event_end = it->timestamp + it->duration; +#ifdef LEGACY_BITEXACT + bool next_available = false; +#endif + if (!it->end_bit) { + // If the end bit is not set, we allow extrapolation of the event for + // some time. + event_end += max_extrapolation_samples_; + DtmfList::iterator next = it; + ++next; + if (next != buffer_.end()) { + // If there is a next event in the buffer, we will not extrapolate over + // the start of that new event. + event_end = std::min(event_end, next->timestamp); +#ifdef LEGACY_BITEXACT + next_available = true; +#endif + } + } + if (current_timestamp >= it->timestamp && + current_timestamp <= event_end) { // TODO(hlundin): Change to <. + // Found a matching event. + if (event) { + event->event_no = it->event_no; + event->end_bit = it->end_bit; + event->volume = it->volume; + event->duration = it->duration; + event->timestamp = it->timestamp; + } +#ifdef LEGACY_BITEXACT + if (it->end_bit && current_timestamp + frame_len_samples_ >= event_end) { + // We are done playing this. Erase the event. + buffer_.erase(it); + } +#endif + return true; + } else if (current_timestamp > event_end) { // TODO(hlundin): Change to >=. +// Erase old event. Operation returns a valid pointer to the next element +// in the list. +#ifdef LEGACY_BITEXACT + if (!next_available) { + if (event) { + event->event_no = it->event_no; + event->end_bit = it->end_bit; + event->volume = it->volume; + event->duration = it->duration; + event->timestamp = it->timestamp; + } + it = buffer_.erase(it); + return true; + } else { + it = buffer_.erase(it); + } +#else + it = buffer_.erase(it); +#endif + } else { + ++it; + } + } + return false; +} + +size_t DtmfBuffer::Length() const { + return buffer_.size(); +} + +bool DtmfBuffer::Empty() const { + return buffer_.empty(); +} + +int DtmfBuffer::SetSampleRate(int fs_hz) { + if (fs_hz != 8000 && + fs_hz != 16000 && + fs_hz != 32000 && + fs_hz != 44100 && + fs_hz != 48000) { + return kInvalidSampleRate; + } + max_extrapolation_samples_ = 7 * fs_hz / 100; + frame_len_samples_ = fs_hz / 100; + return kOK; +} + +// The method returns true if the two events are considered to be the same. +// The are defined as equal if they share the same timestamp and event number. +// The special case with long-lasting events that have to be split into segments +// is not handled in this method. These will be treated as separate events in +// the buffer. +bool DtmfBuffer::SameEvent(const DtmfEvent& a, const DtmfEvent& b) { + return (a.event_no == b.event_no) && (a.timestamp == b.timestamp); +} + +bool DtmfBuffer::MergeEvents(DtmfList::iterator it, const DtmfEvent& event) { + if (SameEvent(*it, event)) { + if (!it->end_bit) { + // Do not extend the duration of an event for which the end bit was + // already received. + it->duration = std::max(event.duration, it->duration); + } + if (event.end_bit) { + it->end_bit = true; + } + return true; + } else { + return false; + } +} + +// Returns true if `a` goes before `b` in the sorting order ("`a` < `b`"). +// The events are ranked using their start timestamp (taking wrap-around into +// account). In the unlikely situation that two events share the same start +// timestamp, the event number is used to rank the two. Note that packets +// that belong to the same events, and therefore sharing the same start +// timestamp, have already been merged before the sort method is called. +bool DtmfBuffer::CompareEvents(const DtmfEvent& a, const DtmfEvent& b) { + if (a.timestamp == b.timestamp) { + return a.event_no < b.event_no; + } + // Take wrap-around into account. + return (static_cast<uint32_t>(b.timestamp - a.timestamp) < 0xFFFFFFFF / 2); +} +} // namespace webrtc |