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use std::borrow::Cow; use std::fmt; use derive_builder::Builder; use shorthand::ShortHand; use crate::tags::{ ExtInf, ExtXByteRange, ExtXDateRange, ExtXDiscontinuity, ExtXKey, ExtXMap, ExtXProgramDateTime, }; use crate::types::{DecryptionKey, ProtocolVersion}; use crate::{Decryptable, RequiredVersion}; /// A video is split into smaller chunks called [`MediaSegment`]s, which are /// specified by a uri and optionally a byte range. /// /// Each `MediaSegment` must carry the continuation of the encoded bitstream /// from the end of the segment with the previous [`MediaSegment::number`], /// where values in a series such as timestamps and continuity counters must /// continue uninterrupted. The only exceptions are the first [`MediaSegment`] /// ever to appear in a [`MediaPlaylist`] and [`MediaSegment`]s that are /// explicitly signaled as discontinuities. /// Unmarked media discontinuities can trigger playback errors. /// /// Any `MediaSegment` that contains video should include enough information /// to initialize a video decoder and decode a continuous set of frames that /// includes the final frame in the segment; network efficiency is optimized if /// there is enough information in the segment to decode all frames in the /// segment. /// /// For example, any `MediaSegment` containing H.264 video should /// contain an Instantaneous Decoding Refresh (IDR); frames prior to the first /// IDR will be downloaded but possibly discarded. /// /// [`MediaPlaylist`]: crate::MediaPlaylist #[derive(ShortHand, Debug, Clone, Builder, PartialEq, Eq, PartialOrd, Ord, Hash)] #[builder(setter(strip_option))] #[shorthand(enable(must_use, skip))] pub struct MediaSegment<'a> { /// Each [`MediaSegment`] has a number, which allows synchronization between /// different variants. /// /// ## Note /// /// This number must not be specified, because it will be assigned /// automatically by [`MediaPlaylistBuilder::segments`]. The first /// [`MediaSegment::number`] in a [`MediaPlaylist`] will either be 0 or the /// number returned by the [`ExtXDiscontinuitySequence`] if one is /// provided. /// The following segments will be the previous segment number + 1. /// /// [`MediaPlaylistBuilder::segments`]: /// crate::builder::MediaPlaylistBuilder::segments /// [`MediaPlaylist`]: crate::MediaPlaylist /// [`ExtXMediaSequence`]: crate::tags::ExtXMediaSequence /// [`ExtXDiscontinuitySequence`]: crate::tags::ExtXDiscontinuitySequence #[builder(default, setter(custom))] #[shorthand(disable(set, skip))] pub(crate) number: usize, #[builder(default, setter(custom))] pub(crate) explicit_number: bool, /// This field specifies how to decrypt a [`MediaSegment`], which can only /// be encrypted with one [`EncryptionMethod`], using one [`DecryptionKey`] /// and [`DecryptionKey::iv`]. /// /// However, a server may offer multiple ways to retrieve that key by /// providing multiple keys with different [`DecryptionKey::format`]s. /// /// Any unencrypted segment that is preceded by an encrypted segment must /// have an [`ExtXKey::empty`]. Otherwise, the client will misinterpret /// those segments as encrypted. /// /// The server may set the HTTP Expires header in the key response to /// indicate the duration for which the key can be cached. /// /// ## Note /// /// This field is optional and a missing value or an [`ExtXKey::empty()`] /// indicates an unencrypted media segment. /// /// [`ExtXMap`]: crate::tags::ExtXMap /// [`KeyFormat`]: crate::types::KeyFormat /// [`EncryptionMethod`]: crate::types::EncryptionMethod #[builder(default, setter(into))] pub keys: Vec<ExtXKey<'a>>, /// This field specifies how to obtain the Media Initialization Section /// required to parse the applicable `MediaSegment`s. /// /// ## Note /// /// This field is optional, but should be specified for media segments in /// playlists with an [`ExtXIFramesOnly`] tag when the first `MediaSegment` /// in the playlist (or the first segment following a segment marked with /// [`MediaSegment::has_discontinuity`]) does not immediately follow the /// Media Initialization Section at the beginning of its resource. /// /// [`ExtXIFramesOnly`]: crate::tags::ExtXIFramesOnly #[builder(default)] pub map: Option<ExtXMap<'a>>, /// This field indicates that a `MediaSegment` is a sub-range of the /// resource identified by its URI. /// /// ## Note /// /// This field is optional. #[builder(default, setter(into))] pub byte_range: Option<ExtXByteRange>, /// This field associates a date-range (i.e., a range of time defined by a /// starting and ending date) with a set of attribute/value pairs. /// /// ## Note /// /// This field is optional. #[builder(default)] pub date_range: Option<ExtXDateRange<'a>>, /// This field indicates a discontinuity between the `MediaSegment` that /// follows it and the one that preceded it. /// /// ## Note /// /// This field is required if any of the following characteristics change: /// - file format /// - number, type, and identifiers of tracks /// - timestamp, sequence /// /// This field should be present if any of the following characteristics /// change: /// - encoding parameters /// - encoding sequence #[builder(default)] pub has_discontinuity: bool, /// This field associates the first sample of a media segment with an /// absolute date and/or time. /// /// ## Note /// /// This field is optional. #[builder(default)] pub program_date_time: Option<ExtXProgramDateTime<'a>>, /// This field indicates the duration of a media segment. /// /// ## Note /// /// This field is required. #[builder(setter(into))] pub duration: ExtInf<'a>, /// The URI of a media segment. /// /// ## Note /// /// This field is required. #[builder(setter(into))] #[shorthand(enable(into), disable(skip))] uri: Cow<'a, str>, } impl<'a> MediaSegment<'a> { /// Returns a builder for a [`MediaSegment`]. /// /// # Example /// /// ``` /// # use hls_m3u8::MediaSegment; /// use hls_m3u8::tags::ExtXMap; /// use std::time::Duration; /// /// let segment = MediaSegment::builder() /// .map(ExtXMap::new("https://www.example.com/")) /// .byte_range(5..25) /// .has_discontinuity(true) /// .duration(Duration::from_secs(4)) /// .uri("http://www.uri.com/") /// .build()?; /// # Ok::<(), String>(()) /// ``` #[must_use] #[inline] pub fn builder() -> MediaSegmentBuilder<'static> { MediaSegmentBuilder::default() } /// Makes the struct independent of its lifetime, by taking ownership of all /// internal [`Cow`]s. /// /// # Note /// /// This is a relatively expensive operation. #[must_use] #[allow(clippy::redundant_closure_for_method_calls)] pub fn into_owned(self) -> MediaSegment<'static> { MediaSegment { number: self.number, explicit_number: self.explicit_number, keys: self.keys.into_iter().map(|k| k.into_owned()).collect(), map: self.map.map(|v| v.into_owned()), byte_range: self.byte_range, date_range: self.date_range.map(|v| v.into_owned()), has_discontinuity: self.has_discontinuity, program_date_time: self.program_date_time.map(|v| v.into_owned()), duration: self.duration.into_owned(), uri: Cow::Owned(self.uri.into_owned()), } } } impl<'a> MediaSegmentBuilder<'a> { /// Pushes an [`ExtXKey`] tag. pub fn push_key<VALUE: Into<ExtXKey<'a>>>(&mut self, value: VALUE) -> &mut Self { if let Some(keys) = &mut self.keys { keys.push(value.into()); } else { self.keys = Some(vec![value.into()]); } self } /// The number of a [`MediaSegment`]. Normally this should not be set /// explicitly, because the [`MediaPlaylist::builder`] will automatically /// apply the correct number. /// /// [`MediaPlaylist::builder`]: crate::MediaPlaylist::builder pub fn number(&mut self, value: Option<usize>) -> &mut Self { self.number = value; self.explicit_number = Some(value.is_some()); self } } impl<'a> fmt::Display for MediaSegment<'a> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { // NOTE: self.keys will be printed by the `MediaPlaylist` to prevent redundance. if let Some(value) = &self.map { writeln!(f, "{}", value)?; } if let Some(value) = &self.byte_range { writeln!(f, "{}", value)?; } if let Some(value) = &self.date_range { writeln!(f, "{}", value)?; } if self.has_discontinuity { writeln!(f, "{}", ExtXDiscontinuity)?; } if let Some(value) = &self.program_date_time { writeln!(f, "{}", value)?; } writeln!(f, "{}", self.duration)?; writeln!(f, "{}", self.uri)?; Ok(()) } } impl<'a> RequiredVersion for MediaSegment<'a> { fn required_version(&self) -> ProtocolVersion { required_version![ self.keys, self.map, self.byte_range, self.date_range, { if self.has_discontinuity { Some(ExtXDiscontinuity) } else { None } }, self.program_date_time, self.duration ] } } impl<'a> Decryptable<'a> for MediaSegment<'a> { fn keys(&self) -> Vec<&DecryptionKey<'a>> { // self.keys.iter().filter_map(ExtXKey::as_ref).collect() } } #[cfg(test)] mod tests { use super::*; use pretty_assertions::assert_eq; use std::time::Duration; #[test] fn test_display() { assert_eq!( MediaSegment::builder() .map(ExtXMap::new("https://www.example.com/")) .byte_range(ExtXByteRange::from(5..25)) .has_discontinuity(true) .duration(ExtInf::new(Duration::from_secs(4))) .uri("http://www.uri.com/") .build() .unwrap() .to_string(), concat!( "#EXT-X-MAP:URI=\"https://www.example.com/\"\n", "#EXT-X-BYTERANGE:20@5\n", "#EXT-X-DISCONTINUITY\n", "#EXTINF:4,\n", "http://www.uri.com/\n" ) .to_string() ); } }