fix(player): correct reverse playback frame positioning
- Read frames from reverse_end_ms instead of reverse_start_ms - Reverse buffer now displays correct video content (130s instead of 139s) - Maintain forward playback compatibility
This commit is contained in:
accusys
@@ -1,6 +1,7 @@
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//! FFmpeg wrapper
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use anyhow::{Context, Result};
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use std::collections::VecDeque;
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use std::io::{BufReader, Read};
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use std::path::Path;
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use std::process::{Child, ChildStdout, Command, Stdio};
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@@ -20,6 +21,14 @@ pub struct FFmpegDecoder {
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process: Option<Child>,
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stdout: Option<BufReader<ChildStdout>>,
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info: VideoInfo,
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frame_buffer: VecDeque<Vec<u8>>,
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frame_times: VecDeque<u64>,
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buffer_loaded: bool,
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current_read_ms: u64,
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display_time_ms: u64,
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reverse_start_ms: u64,
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reverse_end_ms: u64,
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in_reverse_mode: bool,
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}
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impl FFmpegDecoder {
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@@ -32,6 +41,14 @@ impl FFmpegDecoder {
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process: None,
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stdout: None,
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info,
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frame_buffer: VecDeque::new(),
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frame_times: VecDeque::new(),
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buffer_loaded: false,
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current_read_ms: 0,
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display_time_ms: 0,
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reverse_start_ms: 0,
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reverse_end_ms: 0,
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in_reverse_mode: false,
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})
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}
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@@ -124,12 +141,39 @@ impl FFmpegDecoder {
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self.process = Some(child);
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self.stdout = Some(BufReader::new(stdout));
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self.current_read_ms = start_ms;
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Ok(())
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}
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pub fn seek(&mut self, timestamp_ms: u64) -> Result<()> {
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self.start_decoding(timestamp_ms)
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self.in_reverse_mode = false;
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self.frame_buffer.clear();
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self.current_read_ms = timestamp_ms;
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self.start_decoding(timestamp_ms)?;
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let frame_size = (self.info.width * self.info.height * 3) as usize;
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for _ in 0..5 {
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let mut dummy = vec![0u8; frame_size];
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if let Some(ref mut reader) = self.stdout {
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if reader.read_exact(&mut dummy).is_err() {
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break;
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}
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}
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}
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Ok(())
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}
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pub fn enable_reverse(&mut self, start_ms: u64, end_ms: u64) {
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self.stop();
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self.frame_buffer.clear();
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self.frame_times.clear();
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self.buffer_loaded = false;
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self.reverse_start_ms = start_ms;
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self.reverse_end_ms = end_ms;
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self.current_read_ms = end_ms;
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self.display_time_ms = start_ms;
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self.in_reverse_mode = true;
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self.start_decoding(end_ms).ok();
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}
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pub fn stop(&mut self) {
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@@ -142,11 +186,33 @@ impl FFmpegDecoder {
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pub fn read_frame(&mut self) -> Result<Option<Vec<u8>>> {
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let frame_size = (self.info.width * self.info.height * 3) as usize;
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if let Some(frame) = self.frame_buffer.pop_front() {
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if self.in_reverse_mode && self.frame_buffer.len() < 300 {
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let _ = self.refill_reverse_buffer(600);
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}
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return Ok(Some(frame));
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}
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if self.in_reverse_mode {
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if self.current_read_ms <= self.reverse_end_ms {
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return Ok(None);
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}
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let _ = self.refill_reverse_buffer(30);
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if let Some(frame) = self.frame_buffer.pop_front() {
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return Ok(Some(frame));
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}
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return Ok(None);
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}
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let mut buffer = vec![0u8; frame_size];
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if let Some(ref mut reader) = self.stdout {
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match reader.read_exact(&mut buffer) {
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Ok(_) => Ok(Some(buffer)),
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Ok(_) => {
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self.current_read_ms += 16;
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Ok(Some(buffer))
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}
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Err(e) if e.kind() == std::io::ErrorKind::UnexpectedEof => Ok(None),
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Err(e) => Err(e.into()),
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}
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@@ -154,6 +220,133 @@ impl FFmpegDecoder {
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Ok(None)
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}
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}
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pub fn fill_reverse_buffer(&mut self, num_frames: usize) -> Result<()> {
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let frame_size = (self.info.width * self.info.height * 3) as usize;
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self.frame_buffer.clear();
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self.frame_times.clear();
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let frame_duration_ms = (1000.0 / self.info.fps) as u64;
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let total_range = self.reverse_start_ms.saturating_sub(self.reverse_end_ms);
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let max_frames = (total_range / frame_duration_ms).max(1) as usize;
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let frames_to_read = max_frames.min(num_frames);
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let mut temp_frames: Vec<Vec<u8>> = Vec::new();
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let mut temp_times: Vec<u64> = Vec::new();
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for _ in 0..frames_to_read {
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let mut buffer = vec![0u8; frame_size];
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if let Some(ref mut reader) = self.stdout {
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match reader.read_exact(&mut buffer) {
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Ok(_) => {
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temp_frames.push(buffer);
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temp_times.push(self.current_read_ms);
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self.current_read_ms += frame_duration_ms;
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}
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Err(_) => break,
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}
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} else {
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break;
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}
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}
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for i in (0..temp_frames.len()).rev() {
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self.frame_buffer.push_back(temp_frames.remove(i));
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self.frame_times.push_back(temp_times.remove(i));
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}
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Ok(())
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}
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pub fn refill_reverse_buffer(&mut self, _num_frames: usize) -> Result<()> {
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if !self.in_reverse_mode {
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return Ok(());
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}
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self.frame_buffer.clear();
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self.frame_times.clear();
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self.current_read_ms = self.reverse_end_ms;
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self.display_time_ms = self.reverse_start_ms;
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let frame_duration_ms = (1000.0 / self.info.fps) as u64;
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let frames_to_read =
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((self.reverse_start_ms - self.reverse_end_ms) / frame_duration_ms).max(1) as usize;
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self.stop();
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self.start_decoding(self.reverse_end_ms)?;
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let frame_size = (self.info.width * self.info.height * 3) as usize;
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let mut temp_frames: Vec<Vec<u8>> = Vec::new();
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let mut temp_times: Vec<u64> = Vec::new();
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for _ in 0..frames_to_read {
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let mut buffer = vec![0u8; frame_size];
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if let Some(ref mut reader) = self.stdout {
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match reader.read_exact(&mut buffer) {
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Ok(_) => {
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temp_frames.push(buffer);
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temp_times.push(self.current_read_ms);
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self.current_read_ms += frame_duration_ms;
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}
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Err(_) => break,
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}
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} else {
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break;
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}
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}
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for i in (0..temp_frames.len()).rev() {
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self.frame_buffer.push_back(temp_frames.remove(i));
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self.frame_times.push_back(temp_times.remove(i));
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}
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Ok(())
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}
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pub fn has_frames_in_buffer(&self) -> bool {
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!self.frame_buffer.is_empty()
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}
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pub fn buffer_size(&self) -> usize {
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self.frame_buffer.len()
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}
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pub fn get_buffer_front(&mut self) -> Option<Vec<u8>> {
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self.frame_buffer.pop_front()
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}
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pub fn get_frame_time(&mut self) -> Option<u64> {
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if self.in_reverse_mode {
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let time = self.display_time_ms;
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self.display_time_ms = self
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.display_time_ms
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.saturating_sub((1000.0 / self.info.fps) as u64);
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Some(time)
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} else {
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self.frame_times.pop_front()
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}
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}
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pub fn needs_loading(&self) -> bool {
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self.in_reverse_mode && self.frame_buffer.len() < 300
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}
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pub fn get_current_time_ms(&self) -> u64 {
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self.current_read_ms
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}
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pub fn set_current_time_ms(&mut self, ms: u64) {
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self.current_read_ms = ms;
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}
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pub fn get_reverse_end_ms(&self) -> u64 {
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self.reverse_end_ms
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}
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pub fn is_at_boundary(&self) -> bool {
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self.in_reverse_mode && self.current_read_ms <= self.reverse_end_ms
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}
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}
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impl Drop for FFmpegDecoder {
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