scte35/src/info.rs

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Rust
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use crate::commands::{SpliceCommand, SpliceCommandType};
use crate::descriptors::SpliceDescriptor;
use crate::{CueError, TransportPacketWrite};
use bitstream_io::{BigEndian, BitWrite, BitWriter};
use crc::{Crc, CRC_32_MPEG_2};
use std::fmt;
use std::fmt::{Display, Formatter};
pub const MPEG_2: Crc<u32> = Crc::<u32>::new(&CRC_32_MPEG_2);
#[derive(Debug, Clone, PartialEq)]
pub struct SpliceInfoSection<C, S>
where
C: SpliceCommand,
S: EncodingState,
{
state: SpliceInfoState<C>,
encoded: S,
}
#[derive(Debug, Clone, PartialEq)]
struct SpliceInfoState<C>
where
C: SpliceCommand,
{
/// This is an 8-bit field. Its value shall be 0xFC.
table_id: u8,
/// The section_syntax_indicator is a 1-bit field that should always be set to 0, indicating
/// that MPEG short sections are to be used.
section_syntax_indicator: bool,
/// This is a 1-bit flag that shall be set to 0.
private_indicator: bool,
/// A two-bit field that indicates if the content preparation system has created a Stream
/// Access Point (SAP) at the signaled point in the stream. SAP types are defined in
/// ISO 14496-12, Annex I. The semantics of SAP types are further informatively elaborated
/// in ISO/IEC 23009-1 DASH, Section 4.5.2.
sap_type: SAPType, // 2 bits
protocol_version: u8,
encrypted_packet: bool,
encryption_algorithm: EncryptionAlgorithm,
pts_adjustment: u64, // 33 bits
cw_index: u8,
tier: u16, // 12 bits
splice_command: C,
descriptors: Vec<SpliceDescriptor>,
}
pub trait EncodingState {}
#[derive(Debug, Clone, Copy, PartialEq)]
struct NotEncoded;
impl EncodingState for NotEncoded {}
#[derive(Debug, Clone, PartialEq)]
struct EncodedData {
section_length: u16,
splice_command_length: u16,
splice_command_type: SpliceCommandType,
descriptor_loop_length: u16,
crc32: u32,
final_data: Vec<u8>,
}
impl EncodingState for EncodedData {}
impl<C> SpliceInfoSection<C, NotEncoded>
where
C: SpliceCommand,
{
fn new(splice_command: C) -> Self {
Self {
state: SpliceInfoState {
table_id: 0xFC,
section_syntax_indicator: false,
private_indicator: false,
sap_type: SAPType::NotSpecified,
protocol_version: 0,
encrypted_packet: false,
encryption_algorithm: EncryptionAlgorithm::NotEncrypted,
pts_adjustment: 0,
cw_index: 0,
tier: 0xFFF,
splice_command,
descriptors: Vec::new(),
},
encoded: NotEncoded,
}
}
pub fn set_sap_type(&mut self, sap_type: SAPType) {
self.state.sap_type = sap_type;
}
pub fn set_pts_adjustment(&mut self, pts_adjustment: u64) {
self.state.pts_adjustment = pts_adjustment;
}
pub fn set_tier(&mut self, tier: u16) {
self.state.tier = tier;
}
pub fn set_cw_index(&mut self, cw_index: u8) {
self.state.cw_index = cw_index;
}
pub fn add_descriptor(&mut self, descriptor: SpliceDescriptor) {
self.state.descriptors.push(descriptor);
}
pub fn remove_descriptor(&mut self, index: usize) {
self.state.descriptors.remove(index);
}
pub fn descriptor_index(&self, descriptor: &SpliceDescriptor) -> Option<usize> {
self.state.descriptors.iter().position(|d| d == descriptor)
}
pub fn get_descriptor_mut(&mut self, index: usize) -> Option<&mut SpliceDescriptor> {
self.state.descriptors.get_mut(index)
}
}
impl<C> SpliceInfoSection<C, NotEncoded>
where
C: SpliceCommand,
{
pub fn into_encoded(self) -> anyhow::Result<SpliceInfoSection<C, EncodedData>> {
// Write splice command to a temporary buffer
let mut splice_data = Vec::new();
self.state.splice_command.write_to(&mut splice_data)?;
// Write the descriptors to a temporary buffer
let mut descriptor_data = Vec::new();
for descriptor in &self.state.descriptors {
descriptor.write_to(&mut descriptor_data)?;
}
// Start writing the final output to a temporary buffer
let mut data = Vec::new();
let mut buffer = BitWriter::endian(&mut data, BigEndian);
buffer.write(8, self.state.table_id)?;
buffer.write_bit(self.state.section_syntax_indicator)?;
buffer.write_bit(self.state.private_indicator)?;
buffer.write(2, self.state.sap_type as u8)?;
// We know the section length by computing all known fixed size elements from now plus the
// splice command length and descriptors which are also known by now
const FIXED_INFO_SIZE_BYTES: usize = (8 + 1 + 6 + 33 + 8 + 12 + 12 + 8 + 16 + 32) / 8;
let mut section_length =
(FIXED_INFO_SIZE_BYTES + splice_data.len() + descriptor_data.len()) as u16;
if self.state.encrypted_packet {
section_length += 4;
}
buffer.write(12, section_length)?;
buffer.write(8, self.state.protocol_version)?;
buffer.write_bit(self.state.encrypted_packet)?;
let encryption_algorithm: u8 = self.state.encryption_algorithm.into();
buffer.write(6, encryption_algorithm)?;
buffer.write(33, self.state.pts_adjustment)?;
buffer.write(8, self.state.cw_index)?;
buffer.write(12, self.state.tier)?;
let splice_command_length = splice_data.len() as u16;
buffer.write(12, splice_command_length)?;
let splice_command_type = self.state.splice_command.splice_command_type();
buffer.write(8, u8::from(splice_command_type))?;
buffer.write_bytes(splice_data.as_slice())?;
let descriptor_loop_length = descriptor_data.len() as u16;
buffer.write(16, descriptor_loop_length)?;
buffer.write_bytes(descriptor_data.as_slice())?;
buffer.flush()?;
// Finally, write to out
let mut final_data = Vec::new();
let mut buffer = BitWriter::endian(&mut final_data, BigEndian);
buffer.write_bytes(data.as_slice())?;
// CRC 32
if self.state.encrypted_packet {
// TODO: alignment stuffing here, in case of DES encryption this needs to be 8 bytes aligned
// encrypted_packet_crc32:
buffer.write(32, u32::MAX)?;
}
let crc32 = MPEG_2.checksum(data.as_slice());
buffer.write(32, crc32)?;
buffer.flush()?;
Ok(SpliceInfoSection {
state: self.state,
encoded: EncodedData {
section_length,
splice_command_length,
splice_command_type,
descriptor_loop_length,
crc32,
final_data,
},
})
}
}
impl<C> SpliceInfoSection<C, EncodedData>
where
C: SpliceCommand,
{
pub fn to_base64(&self) -> String {
base64::encode(self.as_bytes())
}
pub fn to_hex(&self) -> String {
format!("0x{}", hex::encode(self.as_bytes()))
}
pub fn as_bytes(&self) -> &[u8] {
self.encoded.final_data.as_slice()
}
}
#[derive(Copy, Clone, Debug, PartialEq)]
#[repr(u8)]
pub enum SAPType {
Type1 = 0x00,
Type2 = 0x01,
Type3 = 0x02,
NotSpecified = 0x03,
}
impl Display for SAPType {
fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
match self {
SAPType::Type1 => write!(f, "Type 1"),
SAPType::Type2 => write!(f, "Type 2"),
SAPType::Type3 => write!(f, "Type 3"),
SAPType::NotSpecified => write!(f, "Not Specified"),
}
}
}
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum EncryptionAlgorithm {
NotEncrypted,
DESECBMode,
DESCBCMode,
TripleDESEDE3ECBMode,
Reserved(u8), // 4-31
Private(u8), // 32-63
}
impl From<u8> for EncryptionAlgorithm {
fn from(value: u8) -> Self {
match value {
0x00 => EncryptionAlgorithm::NotEncrypted,
0x01 => EncryptionAlgorithm::DESECBMode,
0x02 => EncryptionAlgorithm::DESCBCMode,
0x03 => EncryptionAlgorithm::TripleDESEDE3ECBMode,
0x04..=0x1F => EncryptionAlgorithm::Reserved(value),
_ => EncryptionAlgorithm::Private(value),
}
}
}
impl From<EncryptionAlgorithm> for u8 {
fn from(value: EncryptionAlgorithm) -> Self {
match value {
EncryptionAlgorithm::NotEncrypted => 0x00,
EncryptionAlgorithm::DESECBMode => 0x01,
EncryptionAlgorithm::DESCBCMode => 0x02,
EncryptionAlgorithm::TripleDESEDE3ECBMode => 0x03,
EncryptionAlgorithm::Reserved(value) => value,
EncryptionAlgorithm::Private(value) => value,
}
}
}
#[cfg(feature = "serde")]
mod serde_serialization {
use super::*;
use crate::ticks_to_secs;
use serde::ser::{Serialize, SerializeStruct, Serializer};
use std::fmt::LowerHex;
impl<C> Serialize for SpliceInfoSection<C, EncodedData>
where
C: SpliceCommand + Serialize,
{
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: Serializer,
{
#[inline]
fn as_hex<T>(value: T) -> String
where
T: LowerHex,
{
format!("0x{:x}", value)
}
let mut state = serializer.serialize_struct("SpliceInfoSection", 18)?;
state.serialize_field("table_id", &as_hex(self.state.table_id))?;
state.serialize_field(
"section_syntax_indicator",
&self.state.section_syntax_indicator,
)?;
state.serialize_field("private_indicator", &self.state.private_indicator)?;
state.serialize_field("sap_type", &as_hex(self.state.sap_type as u8))?;
state.serialize_field("section_length", &self.encoded.section_length)?;
state.serialize_field("protocol_version", &self.state.protocol_version)?;
state.serialize_field("encrypted_packet", &self.state.encrypted_packet)?;
state.serialize_field(
"encryption_algorithm",
&u8::from(self.state.encryption_algorithm),
)?;
state.serialize_field("pts_adjustment", &ticks_to_secs(self.state.pts_adjustment))?;
state.serialize_field("cw_index", &as_hex(self.state.cw_index))?;
state.serialize_field("tier", &as_hex(self.state.tier))?;
state.serialize_field("splice_command_length", &self.encoded.splice_command_length)?;
state.serialize_field(
"splice_command_type",
&u8::from(self.encoded.splice_command_type),
)?;
state.serialize_field("splice_command_name", &self.encoded.splice_command_type)?;
state.serialize_field("splice_command", &self.state.splice_command)?;
state.serialize_field(
"descriptor_loop_length",
&self.encoded.descriptor_loop_length,
)?;
state.serialize_field("descriptors", &self.state.descriptors)?;
state.serialize_field("crc_32", &as_hex(self.encoded.crc32))?;
state.end()
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::commands::*;
use crate::descriptors::{SegmentationDescriptor, SegmentationType, SegmentationUpid};
use crate::ClockTimeExt;
use anyhow::Result;
use assert_json_diff::assert_json_eq;
use std::time::Duration;
#[test]
fn write_splice_null_as_base64() -> Result<()> {
let splice = SpliceInfoSection::new(SpliceNull::new());
assert_eq!(
splice.into_encoded()?.to_base64(),
"/DARAAAAAAAAAP/wAAAAAHpPv/8=".to_string()
);
Ok(())
}
#[test]
fn write_splice_null_as_hex() -> Result<()> {
let splice = SpliceInfoSection::new(SpliceNull::new());
assert_eq!(
splice.into_encoded()?.to_hex(),
"0xfc301100000000000000fff0000000007a4fbfff".to_string()
);
Ok(())
}
#[test]
fn compliance_spec_14_1_example_time_signal_as_base64() -> Result<()> {
let mut splice = SpliceInfoSection::new(TimeSignal::from_ticks(0x072bd0050));
splice.set_cw_index(0xff);
let mut descriptor = SegmentationDescriptor::default();
descriptor.set_segmentation_event_id(0x4800008e);
descriptor.set_program_segmentation_flag(true);
descriptor.set_segmentation_duration_flag(true);
descriptor.set_no_regional_blackout_flag(true);
descriptor.set_archive_allowed_flag(true);
descriptor.set_segmentation_duration(27630000);
descriptor.set_segmentation_upid(SegmentationUpid::AiringID(0x2ca0a18a));
descriptor.set_segmentation_type(SegmentationType::ProviderPlacementOpportunityStart);
descriptor.set_segment_num(2);
descriptor.set_sub_segment_num(154);
descriptor.set_sub_segments_expected(201);
splice.add_descriptor(descriptor.into());
assert_eq!(
splice.into_encoded()?.to_base64(),
"/DA2AAAAAAAA///wBQb+cr0AUAAgAh5DVUVJSAAAjn/PAAGlmbAICAAAAAAsoKGKNAIAmsm2waDx"
.to_string()
);
Ok(())
}
#[test]
fn compliance_spec_14_1_example_time_signal_as_hex() -> Result<()> {
let mut splice = SpliceInfoSection::new(TimeSignal::from_ticks(0x072bd0050));
splice.set_cw_index(0xff);
let mut descriptor = SegmentationDescriptor::default();
descriptor.set_segmentation_event_id(0x4800008e);
descriptor.set_program_segmentation_flag(true);
descriptor.set_segmentation_duration_flag(true);
descriptor.set_no_regional_blackout_flag(true);
descriptor.set_archive_allowed_flag(true);
descriptor.set_segmentation_duration(27630000);
descriptor.set_segmentation_upid(SegmentationUpid::AiringID(0x2ca0a18a));
descriptor.set_segmentation_type(SegmentationType::ProviderPlacementOpportunityStart);
descriptor.set_segment_num(2);
descriptor.set_sub_segment_num(154);
descriptor.set_sub_segments_expected(201);
splice.add_descriptor(descriptor.into());
assert_eq!(
splice.into_encoded()?.to_hex(),
"0xfc3036000000000000fffff00506fe72bd00500020021e435545494800008e7fcf0001a599b00808000000002ca0a18a3402009ac9b6c1a0f1".to_string()
);
Ok(())
}
#[cfg(feature = "serde")]
#[test]
fn compliance_spec_14_1_example_time_signal_as_json() -> Result<()> {
let mut splice = SpliceInfoSection::new(TimeSignal::from_ticks(0x072bd0050));
splice.set_cw_index(0xff);
let mut descriptor = SegmentationDescriptor::default();
descriptor.set_segmentation_event_id(0x4800008e);
descriptor.set_program_segmentation_flag(true);
descriptor.set_segmentation_duration_flag(true);
descriptor.set_no_regional_blackout_flag(true);
descriptor.set_archive_allowed_flag(true);
descriptor.set_segmentation_duration(27630000);
descriptor.set_segmentation_upid(SegmentationUpid::AiringID(0x2ca0a18a));
descriptor.set_segmentation_type(SegmentationType::ProviderPlacementOpportunityStart);
descriptor.set_segment_num(2);
descriptor.set_sub_segment_num(154);
descriptor.set_sub_segments_expected(201);
splice.add_descriptor(descriptor.into());
assert_json_eq!(
serde_json::to_value(&splice.into_encoded()?)?,
serde_json::json!({
"table_id": "0xfc",
"section_syntax_indicator": false,
"private_indicator": false,
"sap_type": "0x3",
"section_length": 22,
"protocol_version": 0,
"encrypted_packet": false,
"encryption_algorithm": 0,
"pts_adjustment": 0.0,
"cw_index": "0xff",
"tier": "0xfff",
"splice_command_length": 5,
"splice_command_type": 6,
"splice_command_name": "TimeSignal",
"splice_command": {
"time_specified_flag": true,
"pts_time": 21388.766756,
},
"descriptor_loop_length": 0,
"descriptors": [],
"crc_32": "0x2184b03d"
})
);
Ok(())
}
#[cfg(feature = "serde")]
#[test]
fn serialize_as_json() -> Result<()> {
let splice = SpliceInfoSection::new(SpliceNull::new());
assert_json_eq!(
serde_json::to_value(&splice.into_encoded()?)?,
serde_json::json!({
"table_id": "0xfc",
"section_syntax_indicator": false,
"private_indicator": false,
"sap_type": "0x3",
"section_length": 17,
"protocol_version": 0,
"encrypted_packet": false,
"encryption_algorithm": 0,
"pts_adjustment": 0.0,
"cw_index": "0x0",
"tier": "0xfff",
"splice_command_length": 0,
"splice_command_type": 0,
"splice_command_name": "SpliceNull",
"splice_command": {},
"descriptor_loop_length": 0,
"descriptors": [],
"crc_32": "0x7a4fbfff"
})
);
Ok(())
}
}