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/*
* Copyright (c) 2017 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/video/video_content_type.h"
// VideoContentType stored as a single byte, which is sent over the network.
// Structure:
//
// 0 1 2 3 4 5 6 7
// +---------------+
// |r r e e e s s c|
//
// where:
// r - reserved bits.
// e - 3-bit number of an experiment group counted from 1. 0 means there's no
// experiment ongoing.
// s - 2-bit simulcast stream id or spatial layer, counted from 1. 0 means that
// no simulcast information is set.
// c - content type. 0 means real-time video, 1 means screenshare.
//
namespace webrtc {
namespace videocontenttypehelpers {
namespace {
static constexpr uint8_t kScreenshareBitsSize = 1;
static constexpr uint8_t kScreenshareBitsMask =
(1u << kScreenshareBitsSize) - 1;
static constexpr uint8_t kSimulcastShift = 1;
static constexpr uint8_t kSimulcastBitsSize = 2;
static constexpr uint8_t kSimulcastBitsMask = ((1u << kSimulcastBitsSize) - 1)
<< kSimulcastShift; // 0b00000110
static constexpr uint8_t kExperimentShift = 3;
static constexpr uint8_t kExperimentBitsSize = 3;
static constexpr uint8_t kExperimentBitsMask =
((1u << kExperimentBitsSize) - 1) << kExperimentShift; // 0b00111000
static constexpr uint8_t kTotalBitsSize =
kScreenshareBitsSize + kSimulcastBitsSize + kExperimentBitsSize;
} // namespace
bool SetExperimentId(VideoContentType* content_type, uint8_t experiment_id) {
// Store in bits 2-4.
if (experiment_id >= (1 << kExperimentBitsSize))
return false;
*content_type = static_cast<VideoContentType>(
(static_cast<uint8_t>(*content_type) & ~kExperimentBitsMask) |
((experiment_id << kExperimentShift) & kExperimentBitsMask));
return true;
}
bool SetSimulcastId(VideoContentType* content_type, uint8_t simulcast_id) {
// Store in bits 5-6.
if (simulcast_id >= (1 << kSimulcastBitsSize))
return false;
*content_type = static_cast<VideoContentType>(
(static_cast<uint8_t>(*content_type) & ~kSimulcastBitsMask) |
((simulcast_id << kSimulcastShift) & kSimulcastBitsMask));
return true;
}
uint8_t GetExperimentId(const VideoContentType& content_type) {
return (static_cast<uint8_t>(content_type) & kExperimentBitsMask) >>
kExperimentShift;
}
uint8_t GetSimulcastId(const VideoContentType& content_type) {
return (static_cast<uint8_t>(content_type) & kSimulcastBitsMask) >>
kSimulcastShift;
}
bool IsScreenshare(const VideoContentType& content_type) {
return (static_cast<uint8_t>(content_type) & kScreenshareBitsMask) > 0;
}
bool IsValidContentType(uint8_t value) {
// Any 6-bit value is allowed.
return value < (1 << kTotalBitsSize);
}
const char* ToString(const VideoContentType& content_type) {
return IsScreenshare(content_type) ? "screen" : "realtime";
}
} // namespace videocontenttypehelpers
} // namespace webrtc
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