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Diffstat (limited to 'third_party/libwebrtc/modules/rtp_rtcp/source/forward_error_correction_internal.h')
| -rw-r--r-- | third_party/libwebrtc/modules/rtp_rtcp/source/forward_error_correction_internal.h | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/rtp_rtcp/source/forward_error_correction_internal.h b/third_party/libwebrtc/modules/rtp_rtcp/source/forward_error_correction_internal.h new file mode 100644 index 0000000000..31acf73e3e --- /dev/null +++ b/third_party/libwebrtc/modules/rtp_rtcp/source/forward_error_correction_internal.h @@ -0,0 +1,121 @@ +/* + * 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. + */ + +#ifndef MODULES_RTP_RTCP_SOURCE_FORWARD_ERROR_CORRECTION_INTERNAL_H_ +#define MODULES_RTP_RTCP_SOURCE_FORWARD_ERROR_CORRECTION_INTERNAL_H_ + +#include <stddef.h> +#include <stdint.h> + +#include "api/array_view.h" +#include "modules/include/module_fec_types.h" + +namespace webrtc { + +// Maximum number of media packets that can be protected +// by these packet masks. +constexpr size_t kUlpfecMaxMediaPackets = 48; + +// Packet mask size in bytes (given L bit). +constexpr size_t kUlpfecPacketMaskSizeLBitClear = 2; +constexpr size_t kUlpfecPacketMaskSizeLBitSet = 6; + +// Packet code mask maximum length. kFECPacketMaskMaxSize = MaxNumFECPackets * +// (kUlpfecMaxMediaPackets / 8), and MaxNumFECPackets is equal to maximum number +// of media packets (kUlpfecMaxMediaPackets) +constexpr size_t kFECPacketMaskMaxSize = 288; + +// Convenience constants. +constexpr size_t kUlpfecMinPacketMaskSize = kUlpfecPacketMaskSizeLBitClear; +constexpr size_t kUlpfecMaxPacketMaskSize = kUlpfecPacketMaskSizeLBitSet; + +namespace internal { + +class PacketMaskTable { + public: + PacketMaskTable(FecMaskType fec_mask_type, int num_media_packets); + ~PacketMaskTable(); + + rtc::ArrayView<const uint8_t> LookUp(int num_media_packets, + int num_fec_packets); + + private: + static const uint8_t* PickTable(FecMaskType fec_mask_type, + int num_media_packets); + const uint8_t* table_; + uint8_t fec_packet_mask_[kFECPacketMaskMaxSize]; +}; + +rtc::ArrayView<const uint8_t> LookUpInFecTable(const uint8_t* table, + int media_packet_index, + int fec_index); + +// Returns an array of packet masks. The mask of a single FEC packet +// corresponds to a number of mask bytes. The mask indicates which +// media packets should be protected by the FEC packet. + +// \param[in] num_media_packets The number of media packets to protect. +// [1, max_media_packets]. +// \param[in] num_fec_packets The number of FEC packets which will +// be generated. [1, num_media_packets]. +// \param[in] num_imp_packets The number of important packets. +// [0, num_media_packets]. +// num_imp_packets = 0 is the equal +// protection scenario. +// \param[in] use_unequal_protection Enables unequal protection: allocates +// more protection to the num_imp_packets. +// \param[in] mask_table An instance of the `PacketMaskTable` +// class, which contains the type of FEC +// packet mask used, and a pointer to the +// corresponding packet masks. +// \param[out] packet_mask A pointer to hold the packet mask array, +// of size: num_fec_packets * +// "number of mask bytes". +void GeneratePacketMasks(int num_media_packets, + int num_fec_packets, + int num_imp_packets, + bool use_unequal_protection, + PacketMaskTable* mask_table, + uint8_t* packet_mask); + +// Returns the required packet mask size, given the number of sequence numbers +// that will be covered. +size_t PacketMaskSize(size_t num_sequence_numbers); + +// Inserts `num_zeros` zero columns into `new_mask` at position +// `new_bit_index`. If the current byte of `new_mask` can't fit all zeros, the +// byte will be filled with zeros from `new_bit_index`, but the next byte will +// be untouched. +void InsertZeroColumns(int num_zeros, + uint8_t* new_mask, + int new_mask_bytes, + int num_fec_packets, + int new_bit_index); + +// Copies the left most bit column from the byte pointed to by +// `old_bit_index` in `old_mask` to the right most column of the byte pointed +// to by `new_bit_index` in `new_mask`. `old_mask_bytes` and `new_mask_bytes` +// represent the number of bytes used per row for each mask. `num_fec_packets` +// represent the number of rows of the masks. +// The copied bit is shifted out from `old_mask` and is shifted one step to +// the left in `new_mask`. `new_mask` will contain "xxxx xxn0" after this +// operation, where x are previously inserted bits and n is the new bit. +void CopyColumn(uint8_t* new_mask, + int new_mask_bytes, + uint8_t* old_mask, + int old_mask_bytes, + int num_fec_packets, + int new_bit_index, + int old_bit_index); + +} // namespace internal +} // namespace webrtc + +#endif // MODULES_RTP_RTCP_SOURCE_FORWARD_ERROR_CORRECTION_INTERNAL_H_ |