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mp4a: Support DecoderSpecificDescriptor profiles > 30 #125

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mp4a: Support DecoderSpecificDescriptor profiles > 30 #125

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32674a6
mp4a: Make Descriptor::desc_size non-static
petzeb Oct 17, 2023
0a3973b
mp4a: Support DecoderSpecificDescriptor profiles > 30
petzeb Oct 17, 2023
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103 changes: 80 additions & 23 deletions src/mp4box/mp4a.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -181,11 +181,12 @@ impl Mp4Box for EsdsBox {
}

fn box_size(&self) -> u64 {
let es_desc_size = self.es_desc.desc_size();
HEADER_SIZE
+ HEADER_EXT_SIZE
+ 1
+ size_of_length(ESDescriptor::desc_size()) as u64
+ ESDescriptor::desc_size() as u64
+ size_of_length(es_desc_size) as u64
+ es_desc_size as u64
}

fn to_json(&self) -> Result<String> {
Expand Down Expand Up @@ -247,7 +248,7 @@ impl<W: Write> WriteBox<&mut W> for EsdsBox {

trait Descriptor: Sized {
fn desc_tag() -> u8;
fn desc_size() -> u32;
fn desc_size(&self) -> u32;
}

trait ReadDesc<T>: Sized {
Expand Down Expand Up @@ -325,13 +326,15 @@ impl Descriptor for ESDescriptor {
0x03
}

fn desc_size() -> u32 {
fn desc_size(&self) -> u32 {
let dec_config_size = self.dec_config.desc_size();
let sl_config_size = self.sl_config.desc_size();
3 + 1
+ size_of_length(DecoderConfigDescriptor::desc_size())
+ DecoderConfigDescriptor::desc_size()
+ size_of_length(dec_config_size)
+ dec_config_size
+ 1
+ size_of_length(SLConfigDescriptor::desc_size())
+ SLConfigDescriptor::desc_size()
+ size_of_length(sl_config_size)
+ sl_config_size
}
}

Expand Down Expand Up @@ -373,7 +376,7 @@ impl<R: Read + Seek> ReadDesc<&mut R> for ESDescriptor {

impl<W: Write> WriteDesc<&mut W> for ESDescriptor {
fn write_desc(&self, writer: &mut W) -> Result<u32> {
let size = Self::desc_size();
let size = self.desc_size();
write_desc(writer, Self::desc_tag(), size)?;

writer.write_u16::<BigEndian>(self.es_id)?;
Expand Down Expand Up @@ -417,10 +420,9 @@ impl Descriptor for DecoderConfigDescriptor {
0x04
}

fn desc_size() -> u32 {
13 + 1
+ size_of_length(DecoderSpecificDescriptor::desc_size())
+ DecoderSpecificDescriptor::desc_size()
fn desc_size(&self) -> u32 {
let dec_specific_size = self.dec_specific.desc_size();
13 + 1 + size_of_length(dec_specific_size) + dec_specific_size
}
}

Expand Down Expand Up @@ -467,7 +469,7 @@ impl<R: Read + Seek> ReadDesc<&mut R> for DecoderConfigDescriptor {

impl<W: Write> WriteDesc<&mut W> for DecoderConfigDescriptor {
fn write_desc(&self, writer: &mut W) -> Result<u32> {
let size = Self::desc_size();
let size = self.desc_size();
write_desc(writer, Self::desc_tag(), size)?;

writer.write_u8(self.object_type_indication)?;
Expand Down Expand Up @@ -504,15 +506,19 @@ impl Descriptor for DecoderSpecificDescriptor {
0x05
}

fn desc_size() -> u32 {
2
fn desc_size(&self) -> u32 {
if self.profile < 31 {
2
} else {
3
}
}
}

fn get_audio_object_type(byte_a: u8, byte_b: u8) -> u8 {
let mut profile = byte_a >> 3;
if profile == 31 {
profile = 32 + ((byte_a & 7) | (byte_b >> 5));
profile = 32 + ((byte_a & 7) << 3 | (byte_b >> 5));
}

profile
Expand All @@ -531,7 +537,7 @@ fn get_chan_conf<R: Read + Seek>(
chan_conf = ((sample_rate >> 4) & 0x0F) as u8;
} else if extended_profile {
let byte_c = reader.read_u8()?;
chan_conf = (byte_b & 1) | (byte_c & 0xE0);
chan_conf = (byte_b & 1) << 3 | (byte_c >> 5);
} else {
chan_conf = (byte_b >> 3) & 0x0F;
}
Expand Down Expand Up @@ -564,11 +570,18 @@ impl<R: Read + Seek> ReadDesc<&mut R> for DecoderSpecificDescriptor {

impl<W: Write> WriteDesc<&mut W> for DecoderSpecificDescriptor {
fn write_desc(&self, writer: &mut W) -> Result<u32> {
let size = Self::desc_size();
let size = self.desc_size();
write_desc(writer, Self::desc_tag(), size)?;

writer.write_u8((self.profile << 3) + (self.freq_index >> 1))?;
writer.write_u8((self.freq_index << 7) + (self.chan_conf << 3))?;
if self.profile < 31 {
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@petzeb petzeb Oct 17, 2023 •
edited
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A potential option could be to use some crate like:
https://docs.rs/bitstream-io/1.7.0/bitstream_io/
for this bit packing (and unpacking)

writer.write_u8((self.profile << 3) | (self.freq_index >> 1))?;
writer.write_u8((self.freq_index << 7) | (self.chan_conf << 3))?;
} else {
let profile_minus_32 = self.profile - 32;
writer.write_u8(31u8 << 3 | profile_minus_32 >> 3)?;
writer.write_u8(profile_minus_32 << 5 | self.freq_index << 1 | self.chan_conf >> 7)?;
writer.write_u8((self.chan_conf & 7) << 5)?;
}

Ok(size)
}
Expand All @@ -588,7 +601,7 @@ impl Descriptor for SLConfigDescriptor {
0x06
}

fn desc_size() -> u32 {
fn desc_size(&self) -> u32 {
1
}
}
Expand All @@ -603,7 +616,7 @@ impl<R: Read + Seek> ReadDesc<&mut R> for SLConfigDescriptor {

impl<W: Write> WriteDesc<&mut W> for SLConfigDescriptor {
fn write_desc(&self, writer: &mut W) -> Result<u32> {
let size = Self::desc_size();
let size = self.desc_size();
write_desc(writer, Self::desc_tag(), size)?;

writer.write_u8(2)?; // pre-defined
Expand Down Expand Up @@ -680,4 +693,48 @@ mod tests {
let dst_box = Mp4aBox::read_box(&mut reader, header.size).unwrap();
assert_eq!(src_box, dst_box);
}

#[test]
fn test_decoder_specific_descriptor() {
let test_dec_spec = |src_dec_spec: DecoderSpecificDescriptor| {
let mut buf = Vec::new();
let written = src_dec_spec.write_desc(&mut buf).unwrap();
// expect two extra bytes for the tag and size fields
assert_eq!(buf.len(), written as usize + 2);

let mut reader = Cursor::new(&buf);
let (tag, size) = read_desc(&mut reader).unwrap();
assert_eq!(5, tag);
assert_eq!(size, written);

let dst_dec_spec = DecoderSpecificDescriptor::read_desc(&mut reader, written).unwrap();
assert_eq!(src_dec_spec, dst_dec_spec);
};

test_dec_spec(DecoderSpecificDescriptor {
profile: 2, // LC
freq_index: 4, // 44100
chan_conf: 2, // Stereo
});
test_dec_spec(DecoderSpecificDescriptor {
profile: 5, // SpectralBandReplication (HEv1)
freq_index: 3, // 48000
chan_conf: 1, // Mono
});
test_dec_spec(DecoderSpecificDescriptor {
profile: 29, // ParametricStereo (HEv2)
freq_index: 2, // 64000
chan_conf: 7, // SevenOne
});
test_dec_spec(DecoderSpecificDescriptor {
profile: 34, // MpegLayer3
freq_index: 4, // 44100
chan_conf: 2, // Stereo
});
test_dec_spec(DecoderSpecificDescriptor {
profile: 42, // UnifiedSpeechAudioCoding (xHE)
freq_index: 11, // 8000
chan_conf: 6, // FiveOne
});
}
}
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