291 lines
12 KiB
Rust
291 lines
12 KiB
Rust
use bytes::Bytes;
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use futures::{Async, Stream};
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use std::{
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io::Cursor,
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mem
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};
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use crate::ebml::EbmlEventSource;
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use crate::error::WebmetroError;
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use crate::webm::*;
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#[derive(Clone, Debug)]
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pub struct ClusterHead {
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pub keyframe: bool,
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pub start: u64,
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pub end: u64,
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/// space for a Cluster tag and a Timecode tag
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/// TODO: consider using a BytesMut here for simplicity
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bytes: [u8;16],
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bytes_used: u8
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}
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impl ClusterHead {
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pub fn new(timecode: u64) -> ClusterHead {
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let mut cluster_head = ClusterHead {
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keyframe: false,
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start: 0,
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end: 0,
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bytes: [0;16],
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bytes_used: 0
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};
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cluster_head.update_timecode(timecode);
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cluster_head
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}
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pub fn update_timecode(&mut self, timecode: u64) {
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let delta = self.end - self.start;
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self.start = timecode;
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self.end = self.start + delta;
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let mut cursor = Cursor::new(self.bytes.as_mut());
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// buffer is sized so these should never fail
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encode_webm_element(WebmElement::Cluster, &mut cursor).unwrap();
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encode_webm_element(WebmElement::Timecode(timecode), &mut cursor).unwrap();
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self.bytes_used = cursor.position() as u8;
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}
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pub fn observe_simpleblock_timecode(&mut self, timecode: i16) {
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let absolute_timecode = self.start + (timecode as u64);
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if absolute_timecode > self.start {
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self.end = absolute_timecode;
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}
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}
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}
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impl AsRef<[u8]> for ClusterHead {
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fn as_ref(&self) -> &[u8] {
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self.bytes[..self.bytes_used as usize].as_ref()
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}
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}
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/// A chunk of WebM data
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#[derive(Clone, Debug)]
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pub enum Chunk {
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Headers {
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bytes: Bytes
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},
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ClusterHead(ClusterHead),
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ClusterBody {
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bytes: Bytes
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}
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}
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impl Chunk {
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/// converts this chunk of data into a Bytes object, perhaps to send over the network
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pub fn into_bytes(self) -> Bytes {
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match self {
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Chunk::Headers {bytes, ..} => bytes,
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Chunk::ClusterHead(cluster_head) => Bytes::from(cluster_head.as_ref()),
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Chunk::ClusterBody {bytes, ..} => bytes
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}
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}
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}
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impl AsRef<[u8]> for Chunk {
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fn as_ref(&self) -> &[u8] {
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match self {
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&Chunk::Headers {ref bytes, ..} => bytes.as_ref(),
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&Chunk::ClusterHead(ref cluster_head) => cluster_head.as_ref(),
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&Chunk::ClusterBody {ref bytes, ..} => bytes.as_ref()
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}
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}
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}
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#[derive(Debug)]
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enum ChunkerState {
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BuildingHeader(Cursor<Vec<u8>>),
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// ClusterHead & body buffer
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BuildingCluster(ClusterHead, Cursor<Vec<u8>>),
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EmittingClusterBody(Vec<u8>),
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EmittingClusterBodyBeforeNewHeader {
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body: Vec<u8>,
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new_header: Cursor<Vec<u8>>
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},
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EmittingFinalClusterBody(Vec<u8>),
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End
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}
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pub struct WebmChunker<S> {
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source: S,
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buffer_size_limit: Option<usize>,
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state: ChunkerState
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}
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impl<S> WebmChunker<S> {
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/// add a "soft" buffer size limit; if a chunk buffer exceeds this size,
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/// error the stream instead of resuming. It's still possible for a buffer
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/// to exceed this size *after* a write, so ensure input sizes are reasonable.
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pub fn with_soft_limit(mut self, limit: usize) -> Self {
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self.buffer_size_limit = Some(limit);
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self
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}
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}
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fn encode(element: WebmElement, buffer: &mut Cursor<Vec<u8>>, limit: Option<usize>) -> Result<(), WebmetroError> {
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if let Some(limit) = limit {
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if limit <= buffer.get_ref().len() {
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return Err(WebmetroError::ResourcesExceeded);
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}
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}
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encode_webm_element(element, buffer).map_err(|err| err.into())
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}
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impl<S: EbmlEventSource> Stream for WebmChunker<S>
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where S::Error: Into<WebmetroError>
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{
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type Item = Chunk;
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type Error = WebmetroError;
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fn poll(&mut self) -> Result<Async<Option<Self::Item>>, WebmetroError> {
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loop {
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let mut return_value = None;
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let mut new_state = None;
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match self.state {
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ChunkerState::BuildingHeader(ref mut buffer) => {
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match self.source.poll_event() {
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Err(passthru) => return Err(passthru.into()),
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Ok(Async::NotReady) => return Ok(Async::NotReady),
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Ok(Async::Ready(None)) => return Ok(Async::Ready(None)),
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Ok(Async::Ready(Some(WebmElement::Cluster))) => {
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let liberated_buffer = mem::replace(buffer, Cursor::new(Vec::new()));
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let header_chunk = Chunk::Headers {bytes: Bytes::from(liberated_buffer.into_inner())};
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return_value = Some(Ok(Async::Ready(Some(header_chunk))));
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new_state = Some(ChunkerState::BuildingCluster(
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ClusterHead::new(0),
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Cursor::new(Vec::new())
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));
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},
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Ok(Async::Ready(Some(WebmElement::Info))) => {},
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Ok(Async::Ready(Some(WebmElement::Void))) => {},
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Ok(Async::Ready(Some(WebmElement::Unknown(_)))) => {},
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Ok(Async::Ready(Some(element))) => {
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encode(element, buffer, self.buffer_size_limit).unwrap_or_else(|err| {
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return_value = Some(Err(err));
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new_state = Some(ChunkerState::End);
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});
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}
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}
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},
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ChunkerState::BuildingCluster(ref mut cluster_head, ref mut buffer) => {
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match self.source.poll_event() {
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Err(passthru) => return Err(passthru.into()),
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Ok(Async::NotReady) => return Ok(Async::NotReady),
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Ok(Async::Ready(Some(element @ WebmElement::EbmlHead)))
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| Ok(Async::Ready(Some(element @ WebmElement::Segment))) => {
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let liberated_cluster_head = mem::replace(cluster_head, ClusterHead::new(0));
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let liberated_buffer = mem::replace(buffer, Cursor::new(Vec::new()));
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let mut new_header_cursor = Cursor::new(Vec::new());
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match encode(element, &mut new_header_cursor, self.buffer_size_limit) {
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Ok(_) => {
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return_value = Some(Ok(Async::Ready(Some(Chunk::ClusterHead(liberated_cluster_head)))));
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new_state = Some(ChunkerState::EmittingClusterBodyBeforeNewHeader{
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body: liberated_buffer.into_inner(),
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new_header: new_header_cursor
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});
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},
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Err(err) => {
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return_value = Some(Err(err));
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new_state = Some(ChunkerState::End);
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}
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}
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}
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Ok(Async::Ready(Some(WebmElement::Cluster))) => {
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let liberated_cluster_head = mem::replace(cluster_head, ClusterHead::new(0));
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let liberated_buffer = mem::replace(buffer, Cursor::new(Vec::new()));
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return_value = Some(Ok(Async::Ready(Some(Chunk::ClusterHead(liberated_cluster_head)))));
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new_state = Some(ChunkerState::EmittingClusterBody(liberated_buffer.into_inner()));
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},
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Ok(Async::Ready(Some(WebmElement::Timecode(timecode)))) => {
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cluster_head.update_timecode(timecode);
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},
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Ok(Async::Ready(Some(WebmElement::SimpleBlock(ref block)))) => {
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if (block.flags & 0b10000000) != 0 {
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// TODO: this is incorrect, condition needs to also affirm we're the first video block of the cluster
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cluster_head.keyframe = true;
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}
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cluster_head.observe_simpleblock_timecode(block.timecode);
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encode(WebmElement::SimpleBlock(*block), buffer, self.buffer_size_limit).unwrap_or_else(|err| {
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return_value = Some(Err(err));
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new_state = Some(ChunkerState::End);
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});
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},
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Ok(Async::Ready(Some(WebmElement::Info))) => {},
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Ok(Async::Ready(Some(WebmElement::Void))) => {},
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Ok(Async::Ready(Some(WebmElement::Unknown(_)))) => {},
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Ok(Async::Ready(Some(element))) => {
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encode(element, buffer, self.buffer_size_limit).unwrap_or_else(|err| {
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return_value = Some(Err(err));
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new_state = Some(ChunkerState::End);
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});
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},
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Ok(Async::Ready(None)) => {
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// flush final Cluster on end of stream
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let liberated_cluster_head = mem::replace(cluster_head, ClusterHead::new(0));
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let liberated_buffer = mem::replace(buffer, Cursor::new(Vec::new()));
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return_value = Some(Ok(Async::Ready(Some(Chunk::ClusterHead(liberated_cluster_head)))));
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new_state = Some(ChunkerState::EmittingFinalClusterBody(liberated_buffer.into_inner()));
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}
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}
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},
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ChunkerState::EmittingClusterBody(ref mut buffer) => {
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let liberated_buffer = mem::replace(buffer, Vec::new());
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return_value = Some(Ok(Async::Ready(Some(Chunk::ClusterBody {bytes: Bytes::from(liberated_buffer)}))));
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new_state = Some(ChunkerState::BuildingCluster(
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ClusterHead::new(0),
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Cursor::new(Vec::new())
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));
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},
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ChunkerState::EmittingClusterBodyBeforeNewHeader { ref mut body, ref mut new_header } => {
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let liberated_body = mem::replace(body, Vec::new());
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let liberated_header_cursor = mem::replace(new_header, Cursor::new(Vec::new()));
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return_value = Some(Ok(Async::Ready(Some(Chunk::ClusterBody {bytes: Bytes::from(liberated_body)}))));
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new_state = Some(ChunkerState::BuildingHeader(liberated_header_cursor));
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},
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ChunkerState::EmittingFinalClusterBody(ref mut buffer) => {
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// flush final Cluster on end of stream
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let liberated_buffer = mem::replace(buffer, Vec::new());
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return_value = Some(Ok(Async::Ready(Some(Chunk::ClusterBody {bytes: Bytes::from(liberated_buffer)}))));
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new_state = Some(ChunkerState::End);
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},
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ChunkerState::End => return Ok(Async::Ready(None))
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};
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if let Some(new_state) = new_state {
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self.state = new_state;
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}
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if let Some(return_value) = return_value {
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return return_value;
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}
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}
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}
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}
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pub trait WebmStream where Self: Sized + EbmlEventSource {
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fn chunk_webm(self) -> WebmChunker<Self> {
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WebmChunker {
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source: self,
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buffer_size_limit: None,
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state: ChunkerState::BuildingHeader(Cursor::new(Vec::new()))
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}
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}
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}
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impl<T: EbmlEventSource> WebmStream for T {}
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#[cfg(test)]
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mod tests {
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use crate::chunk::*;
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#[test]
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fn enough_space_for_header() {
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ClusterHead::new(u64::max_value());
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}
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}
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