mirror of
https://github.com/oxen-io/session-android.git
synced 2024-12-28 02:37:46 +00:00
227 lines
8.6 KiB
C++
227 lines
8.6 KiB
C++
/*
|
|
* 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 "webrtc/modules/audio_coding/neteq/dtmf_buffer.h"
|
|
|
|
#include <assert.h>
|
|
#include <algorithm> // max
|
|
|
|
// 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 {
|
|
|
|
// 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,
|
|
int payload_length_bytes,
|
|
DtmfEvent* event) {
|
|
if (!payload || !event) {
|
|
return kInvalidPointer;
|
|
}
|
|
if (payload_length_bytes < 4) {
|
|
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 > 36 ||
|
|
event.duration <= 0 || event.duration > 65535) {
|
|
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;
|
|
}
|
|
|
|
int DtmfBuffer::SetSampleRate(int fs_hz) {
|
|
if (fs_hz != 8000 &&
|
|
fs_hz != 16000 &&
|
|
fs_hz != 32000 &&
|
|
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
|