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#[cfg(test)]
extern crate bitstream_io;
#[derive(Debug)]
pub enum AdtsHeaderError {
BadSyncWord(u16),
NotEnoughData {
expected: usize,
actual: usize,
}
}
#[derive(Debug,PartialEq)]
pub struct PayloadError {
pub expected: usize,
pub actual: usize,
}
#[derive(Debug,PartialEq)]
pub enum MpegVersion {
Mpeg2,
Mpeg4,
}
#[derive(Debug,PartialEq)]
pub enum AudioObjectType {
AacMain,
AacLC,
AacSSR,
AacLTP,
}
#[derive(Debug,PartialEq)]
pub enum ProtectionIndicator {
CrcPresent,
CrcAbsent,
}
#[derive(Debug,PartialEq)]
pub enum SamplingFrequency {
Freq96000 = 0x0,
Freq88200 = 0x1,
Freq64000 = 0x2,
Freq48000 = 0x3,
Freq44100 = 0x4,
Freq32000 = 0x5,
Freq24000 = 0x6,
Freq22050 = 0x7,
Freq16000 = 0x8,
Freq12000 = 0x9,
Freq11025 = 0xa,
Freq8000 = 0xb,
FreqReserved0xc = 0xc,
FreqReserved0xd = 0xd,
FreqReserved0xe = 0xe,
FreqReserved0xf = 0xf,
}
impl SamplingFrequency {
fn from(value: u8) -> SamplingFrequency {
match value {
0x0 => SamplingFrequency::Freq96000,
0x1 => SamplingFrequency::Freq88200,
0x2 => SamplingFrequency::Freq64000,
0x3 => SamplingFrequency::Freq48000,
0x4 => SamplingFrequency::Freq44100,
0x5 => SamplingFrequency::Freq32000,
0x6 => SamplingFrequency::Freq24000,
0x7 => SamplingFrequency::Freq22050,
0x8 => SamplingFrequency::Freq16000,
0x9 => SamplingFrequency::Freq12000,
0xa => SamplingFrequency::Freq11025,
0xb => SamplingFrequency::Freq8000,
0xc => SamplingFrequency::FreqReserved0xc,
0xd => SamplingFrequency::FreqReserved0xd,
0xe => SamplingFrequency::FreqReserved0xe,
0xf => SamplingFrequency::FreqReserved0xf,
_ => panic!("invalud value {:x}", value),
}
}
pub fn freq(&self) -> Option<u32> {
match self {
&SamplingFrequency::Freq96000 => Some(96000),
&SamplingFrequency::Freq88200 => Some(88200),
&SamplingFrequency::Freq64000 => Some(64000),
&SamplingFrequency::Freq48000 => Some(48000),
&SamplingFrequency::Freq44100 => Some(44100),
&SamplingFrequency::Freq32000 => Some(32000),
&SamplingFrequency::Freq24000 => Some(24000),
&SamplingFrequency::Freq22050 => Some(22050),
&SamplingFrequency::Freq16000 => Some(16000),
&SamplingFrequency::Freq12000 => Some(12000),
&SamplingFrequency::Freq11025 => Some(11025),
&SamplingFrequency::Freq8000 => Some(8000),
&SamplingFrequency::FreqReserved0xc => None,
&SamplingFrequency::FreqReserved0xd => None,
&SamplingFrequency::FreqReserved0xe => None,
&SamplingFrequency::FreqReserved0xf => None,
}
}
}
#[derive(Debug,PartialEq)]
pub enum ChannelConfiguration {
ObjectTypeSpecificConfig = 0x0,
Mono = 0x1,
Stereo = 0x2,
Three = 0x3,
Four = 0x4,
Five = 0x5,
FiveOne = 0x6,
SevenOne = 0x7,
}
impl ChannelConfiguration {
fn from(value: u8) -> ChannelConfiguration {
match value {
0x0 => ChannelConfiguration::ObjectTypeSpecificConfig,
0x1 => ChannelConfiguration::Mono,
0x2 => ChannelConfiguration::Stereo,
0x3 => ChannelConfiguration::Three,
0x4 => ChannelConfiguration::Four,
0x5 => ChannelConfiguration::Five,
0x6 => ChannelConfiguration::FiveOne,
0x7 => ChannelConfiguration::SevenOne,
_ => panic!("invalid value {}", value),
}
}
}
#[derive(Debug,PartialEq)]
pub enum Originality {
Original,
Copy,
}
#[derive(Debug,PartialEq)]
pub enum CopyrightIdentificationStart {
Start,
Other,
}
pub struct AdtsHeader<'buf> {
buf: &'buf[u8],
}
impl<'buf> AdtsHeader<'buf> {
pub fn from_bytes(buf: &'buf[u8]) -> Result<AdtsHeader, AdtsHeaderError> {
let header_len = 7;
Self::check_len(header_len, buf.len())?;
let header = AdtsHeader {
buf,
};
if header.sync_word() != 0xfff {
return Err(AdtsHeaderError::BadSyncWord(header.sync_word()));
}
let crc_len = 2;
if header.protection() == ProtectionIndicator::CrcPresent {
Self::check_len(header_len+crc_len, buf.len())?;
}
Ok(header)
}
fn check_len(expected: usize, actual: usize) -> Result<(), AdtsHeaderError> {
if actual < expected {
Err(AdtsHeaderError::NotEnoughData{
expected,
actual,
})
} else {
Ok(())
}
}
fn header_length(&self) -> u16 {
let fixed_len = 7;
if self.protection() == ProtectionIndicator::CrcPresent {
fixed_len + 2
} else {
fixed_len
}
}
fn sync_word(&self) -> u16 {
u16::from(self.buf[0]) << 4 | u16::from(self.buf[1] >> 4)
}
pub fn mpeg_version(&self) -> MpegVersion {
if self.buf[1] & 0b0000_1000 != 0 {
MpegVersion::Mpeg2
} else {
MpegVersion::Mpeg4
}
}
pub fn protection(&self) -> ProtectionIndicator {
if self.buf[1] & 0b0000_0001 != 0 {
ProtectionIndicator::CrcAbsent
} else {
ProtectionIndicator::CrcPresent
}
}
pub fn audio_object_type(&self) -> AudioObjectType {
match self.buf[2] & 0b1100_0000 {
0b0000_0000 => AudioObjectType::AacMain,
0b0100_0000 => AudioObjectType::AacLC,
0b1000_0000 => AudioObjectType::AacSSR,
0b1100_0000 => AudioObjectType::AacLTP,
v => panic!("impossible value {:#b}", v),
}
}
pub fn sampling_frequency(&self) -> SamplingFrequency {
SamplingFrequency::from(self.buf[2] >> 2 & 0b1111)
}
pub fn private_bit(&self) -> u8 {
self.buf[2] & 1
}
pub fn channel_configuration(&self) -> ChannelConfiguration {
ChannelConfiguration::from(self.buf[2] << 2 & 0b0100 | self.buf[3] >> 6)
}
pub fn originality(&self) -> Originality {
if self.buf[3] & 0b0010_0000 != 0 {
Originality::Copy
} else {
Originality::Original
}
}
pub fn home(&self) -> u8 {
self.buf[3] >> 4 & 1
}
pub fn copyright_identification_bit(&self) -> u8 {
self.buf[3] >> 3 & 1
}
pub fn copyright_identification_start(&self) -> CopyrightIdentificationStart {
if self.buf[3] & 0b0000_0100 != 0 {
CopyrightIdentificationStart::Start
} else {
CopyrightIdentificationStart::Other
}
}
pub fn frame_length(&self) -> u16 {
u16::from(self.buf[3] & 0b11) << 11 |
u16::from(self.buf[4] ) << 3 |
u16::from(self.buf[5] ) >> 5
}
pub fn payload_length(&self) -> Option<u16> {
let diff = self.frame_length() as i16 - self.header_length() as i16;
if diff >= 0 {
Some(diff as u16)
} else {
None
}
}
pub fn adts_buffer_fullness(&self) -> u16 {
u16::from(self.buf[5] & 0b00000011) << 6 |
u16::from(self.buf[6]) >> 2
}
pub fn number_of_raw_data_blocks_in_frame(&self) -> u8 {
(self.buf[6] & 0b11) + 1
}
pub fn payload(&self) -> Result<&'buf[u8], PayloadError> {
let len = self.frame_length() as usize;
if self.buf.len() < len {
Err(PayloadError { expected: len, actual: self.buf.len() })
} else {
Ok(&self.buf[self.header_length() as usize..len])
}
}
}
#[cfg(test)]
mod tests {
use std::io;
use bitstream_io::{BE, BitWriter};
use AdtsHeader;
use MpegVersion;
use AudioObjectType;
use ProtectionIndicator;
use SamplingFrequency;
use ChannelConfiguration;
use *;
fn make_test_data<F>(builder: F) -> Vec<u8>
where
F: Fn(BitWriter<BE>)->Result<(), io::Error>
{
let mut data: Vec<u8> = Vec::new();
builder(BitWriter::<BE>::new(&mut data)).unwrap();
data
}
#[test]
fn no_crc() {
let header_data = make_test_data(|mut w| {
w.write(12, 0xfff)?;
w.write(1, 0)?;
w.write(2, 0)?;
w.write(1, 1)?;
w.write(2, 0)?;
w.write(4, 0b0011)?;
w.write(1, 1)?;
w.write(3, 2)?;
w.write(1, 1)?;
w.write(1, 0)?;
w.write(1, 0)?;
w.write(1, 1)?;
w.write(13, 8)?;
w.write(11, 123)?;
w.write(2, 0)?;
w.write(8, 0b10000001)
});
let header = AdtsHeader::from_bytes(&header_data[..]).unwrap();
assert_eq!(header.mpeg_version(), MpegVersion::Mpeg4);
assert_eq!(header.protection(), ProtectionIndicator::CrcAbsent);
assert_eq!(header.audio_object_type(), AudioObjectType::AacMain);
assert_eq!(header.sampling_frequency(), SamplingFrequency::Freq48000);
assert_eq!(header.sampling_frequency().freq(), Some(48000));
assert_eq!(header.channel_configuration(), ChannelConfiguration::Stereo);
assert_eq!(header.originality(), Originality::Copy);
assert_eq!(header.home(), 0);
assert_eq!(header.copyright_identification_bit(), 0);
assert_eq!(header.copyright_identification_start(), CopyrightIdentificationStart::Start);
assert_eq!(header.frame_length(), 8);
assert_eq!(header.payload_length(), Some(8 - 7));
assert_eq!(header.adts_buffer_fullness(), 123);
assert_eq!(header.number_of_raw_data_blocks_in_frame(), 1);
assert_eq!(header.payload(), Ok(&[0b10000001][..]));
}
}