fn read_av1c()

in mp4parse/src/lib.rs [4884:4931]

• 45 lines of code
• 4 McCabe index (conditional complexity)

fn read_av1c<T: Read>(src: &mut BMFFBox<T>) -> Result<AV1ConfigBox> {
    // We want to store the raw config as well as a structured (parsed) config, so create a copy of
    // the raw config so we have it later, and then parse the structured data from that.
    let raw_config = src.read_into_try_vec()?;
    let mut raw_config_slice = raw_config.as_slice();
    let marker_byte = raw_config_slice.read_u8()?;
    if marker_byte & 0x80 != 0x80 {
        return Err(Error::Unsupported("missing av1C marker bit"));
    }
    if marker_byte & 0x7f != 0x01 {
        return Err(Error::Unsupported("missing av1C marker bit"));
    }
    let profile_byte = raw_config_slice.read_u8()?;
    let profile = (profile_byte & 0xe0) >> 5;
    let level = profile_byte & 0x1f;
    let flags_byte = raw_config_slice.read_u8()?;
    let tier = (flags_byte & 0x80) >> 7;
    let bit_depth = match flags_byte & 0x60 {
        0x60 => 12,
        0x40 => 10,
        _ => 8,
    };
    let monochrome = flags_byte & 0x10 == 0x10;
    let chroma_subsampling_x = (flags_byte & 0x08) >> 3;
    let chroma_subsampling_y = (flags_byte & 0x04) >> 2;
    let chroma_sample_position = flags_byte & 0x03;
    let delay_byte = raw_config_slice.read_u8()?;
    let initial_presentation_delay_present = (delay_byte & 0x10) == 0x10;
    let initial_presentation_delay_minus_one = if initial_presentation_delay_present {
        delay_byte & 0x0f
    } else {
        0
    };

    Ok(AV1ConfigBox {
        profile,
        level,
        tier,
        bit_depth,
        monochrome,
        chroma_subsampling_x,
        chroma_subsampling_y,
        chroma_sample_position,
        initial_presentation_delay_present,
        initial_presentation_delay_minus_one,
        raw_config,
    })
}