src/decoder/track.rs

// Copyright 2024 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use crate::internal_utils::*;
use crate::parser::mp4box::ItemProperty;
use crate::parser::mp4box::MetaBox;
use crate::*;

use std::num::NonZero;

#[derive(Clone, Copy, Debug, PartialEq)]
pub enum RepetitionCount {
    Unknown,
    Infinite,
    Finite(i32),
}

impl Default for RepetitionCount {
    fn default() -> Self {
        Self::Finite(0)
    }
}

#[derive(Debug, Default)]
pub struct Track {
    pub id: u32,
    pub aux_for_id: Option<u32>,
    pub prem_by_id: Option<u32>,
    pub media_timescale: u32,
    pub media_duration: u64,
    pub track_duration: u64,
    pub segment_duration: u64,
    pub is_repeating: bool,
    pub width: u32,
    pub height: u32,
    pub sample_table: Option<SampleTable>,
    pub elst_seen: bool,
    pub meta: Option<MetaBox>,
    pub handler_type: String,
}

impl Track {
    pub(crate) fn check_limits(
        &self,
        size_limit: Option<NonZero<u32>>,
        dimension_limit: Option<NonZero<u32>>,
    ) -> bool {
        check_limits(self.width, self.height, size_limit, dimension_limit)
    }

    fn has_av1_samples(&self) -> bool {
        if let Some(sample_table) = &self.sample_table {
            self.id != 0 && !sample_table.chunk_offsets.is_empty() && sample_table.has_av1_sample()
        } else {
            false
        }
    }
    pub(crate) fn is_video_handler(&self) -> bool {
        // Handler types known to be associated with video content.
        self.handler_type == "pict" || self.handler_type == "vide" || self.handler_type == "auxv"
    }
    pub(crate) fn is_aux(&self, primary_track_id: u32) -> bool {
        // Do not check the track's handler_type. It should be "auxv" according to
        // HEIF (ISO/IEC 23008-12:2022), Section 7.5.3.1, but old versions of libavif used to write
        // "pict" instead.
        self.has_av1_samples() && self.aux_for_id == Some(primary_track_id)
    }
    pub(crate) fn is_color(&self) -> bool {
        // Do not check the track's handler_type. It should be "pict" according to
        // HEIF (ISO/IEC 23008-12:2022), Section 7 but some existing files might be using "vide".
        self.has_av1_samples() && self.aux_for_id.is_none()
    }

    pub(crate) fn is_auxiliary_alpha(&self) -> bool {
        if let Some(properties) = self.get_properties() {
            if let Some(aux_type) = &find_property!(properties, AuxiliaryType) {
                return is_auxiliary_type_alpha(aux_type);
            }
        }
        true // Assume alpha if no type is present
    }

    pub(crate) fn get_properties(&self) -> Option<&Vec<ItemProperty>> {
        self.sample_table.as_ref()?.get_properties()
    }

    pub(crate) fn repetition_count(&self) -> AvifResult<RepetitionCount> {
        if !self.elst_seen {
            return Ok(RepetitionCount::Unknown);
        }
        if self.is_repeating {
            if self.track_duration == u64::MAX {
                // If isRepeating is true and the track duration is unknown/indefinite, then set the
                // repetition count to infinite(Section 9.6.1 of ISO/IEC 23008-12 Part 12).
                return Ok(RepetitionCount::Infinite);
            } else {
                // Section 9.6.1. of ISO/IEC 23008-12 Part 12: 1, the entire edit list is repeated a
                // sufficient number of times to equal the track duration.
                //
                // Since libavif uses repetitionCount (which is 0-based), we subtract the value by 1
                // to derive the number of repetitions.
                assert!(self.segment_duration != 0);
                // We specifically check for trackDuration == 0 here and not when it is actually
                // read in order to accept files which inadvertently has a trackDuration of 0
                // without any edit lists.
                if self.track_duration == 0 {
                    return Err(AvifError::BmffParseFailed(
                        "invalid track duration 0".into(),
                    ));
                }
                let repetition_count: u64 = self.track_duration.div_ceil(self.segment_duration) - 1;
                return match i32::try_from(repetition_count) {
                    Ok(value) => Ok(RepetitionCount::Finite(value)),
                    Err(_) => Ok(RepetitionCount::Infinite),
                };
            }
        }
        Ok(RepetitionCount::Finite(0))
    }

    pub(crate) fn image_timing(&self, image_index: u32) -> AvifResult<ImageTiming> {
        let sample_table = self.sample_table.unwrap_ref();
        let mut image_timing = ImageTiming {
            timescale: self.media_timescale as u64,
            pts_in_timescales: 0,
            ..ImageTiming::default()
        };
        for i in 0..image_index as usize {
            checked_incr!(
                image_timing.pts_in_timescales,
                sample_table.image_delta(i)? as u64
            );
        }
        image_timing.duration_in_timescales =
            sample_table.image_delta(image_index as usize)? as u64;
        if image_timing.timescale > 0 {
            image_timing.pts =
                image_timing.pts_in_timescales as f64 / image_timing.timescale as f64;
            image_timing.duration =
                image_timing.duration_in_timescales as f64 / image_timing.timescale as f64;
        } else {
            image_timing.pts = 0.0;
            image_timing.duration = 0.0;
        }
        Ok(image_timing)
    }
}

#[derive(Debug)]
pub struct TimeToSample {
    pub sample_count: u32,
    pub sample_delta: u32,
}

// Section 8.7.4.3 of ISO/IEC 14496-12.
#[derive(Debug)]
pub struct SampleToChunk {
    pub first_chunk: u32, // 1-based
    pub samples_per_chunk: u32,
    pub sample_description_index: u32, // 1-based
}

#[derive(Debug, Default)]
pub struct SampleDescription {
    pub format: String,
    pub properties: Vec<ItemProperty>,
}

impl SampleDescription {
    pub(crate) fn is_supported_format(&self) -> bool {
        [
            "av01",
            #[cfg(feature = "heic")]
            "hvc1",
        ]
        .contains(&self.format.as_str())
    }
}

#[derive(Debug)]
pub enum SampleSize {
    FixedSize(u32),
    Sizes(Vec<u32>),
}

impl Default for SampleSize {
    fn default() -> Self {
        Self::FixedSize(0)
    }
}

#[derive(Debug, Default)]
pub struct SampleTable {
    pub chunk_offsets: Vec<u64>,
    pub sample_to_chunk: Vec<SampleToChunk>,
    pub sample_size: SampleSize,
    pub sync_samples: Vec<u32>,
    pub time_to_sample: Vec<TimeToSample>,
    pub sample_descriptions: Vec<SampleDescription>,
}

impl SampleTable {
    pub(crate) fn has_av1_sample(&self) -> bool {
        self.sample_descriptions
            .iter()
            .any(|x| x.is_supported_format())
    }

    // returns the number of samples in the chunk.
    pub(crate) fn get_sample_count_of_chunk(&self, chunk_index: u32) -> u32 {
        for entry in self.sample_to_chunk.iter().rev() {
            if entry.first_chunk <= chunk_index + 1 {
                return entry.samples_per_chunk;
            }
        }
        0
    }

    pub(crate) fn get_properties(&self) -> Option<&Vec<ItemProperty>> {
        Some(
            &self
                .sample_descriptions
                .iter()
                .find(|x| x.is_supported_format())?
                .properties,
        )
    }

    pub(crate) fn sample_size(&self, index: usize) -> AvifResult<usize> {
        usize_from_u32(match &self.sample_size {
            SampleSize::FixedSize(size) => *size,
            SampleSize::Sizes(sizes) => {
                if index >= sizes.len() {
                    return Err(AvifError::BmffParseFailed(
                        "not enough sampel sizes in the table".into(),
                    ));
                }
                sizes[index]
            }
        })
    }

    pub(crate) fn image_delta(&self, index: usize) -> AvifResult<u32> {
        let mut max_index: u32 = 0;
        for (i, time_to_sample) in self.time_to_sample.iter().enumerate() {
            checked_incr!(max_index, time_to_sample.sample_count);
            if index < max_index as usize || i == self.time_to_sample.len() - 1 {
                return Ok(time_to_sample.sample_delta);
            }
        }
        Ok(1)
    }
}

/// cbindgen:rename-all=CamelCase
#[repr(C)]
#[derive(Clone, Copy, Debug, Default)]
pub struct ImageTiming {
    pub timescale: u64,
    pub pts: f64,
    pub pts_in_timescales: u64,
    pub duration: f64,
    pub duration_in_timescales: u64,
}