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Remove experimental block-size beam-search algorithm.
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@yotarok
yotarok committed Oct 3, 2023
1 parent a594b2a commit 37891dd
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Showing 6 changed files with 4 additions and 243 deletions.
8 changes: 2 additions & 6 deletions flacenc-bin/src/main.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -140,12 +140,8 @@ fn run_encoder(
encoder_config: &config::Encoder,
source: source::PreloadedSignal,
) -> Result<Stream, SourceError> {
if encoder_config.block_sizes.len() == 1 {
let block_size = encoder_config.block_sizes[0];
coding::encode_with_fixed_block_size(encoder_config, source, block_size)
} else {
coding::encode_with_multiple_block_sizes(encoder_config, source)
}
let block_size = encoder_config.block_sizes[0];
coding::encode_with_fixed_block_size(encoder_config, source, block_size)
}

fn main_body(args: Args) -> Result<(), i32> {
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4 changes: 0 additions & 4 deletions report/bsbs.config.toml
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This file was deleted.

218 changes: 0 additions & 218 deletions src/coding.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,10 +15,6 @@
//! Controller connecting coding algorithms.

use std::cell::RefCell;
#[cfg(feature = "experimental")]
use std::collections::BTreeSet;
#[cfg(feature = "experimental")]
use std::sync::Arc;

#[cfg(feature = "par")]
use rayon::iter::IntoParallelIterator;
Expand All @@ -37,15 +33,12 @@ use super::component::StreamInfo;
use super::component::SubFrame;
use super::component::Verbatim;
use super::config;
#[cfg(feature = "experimental")]
use super::constant::BSBS_DEFAULT_BEAM_WIDTH_MULTIPLIER;
use super::constant::MAX_LPC_ORDER;
use super::error::SourceError;
use super::lpc;
use super::rice;
use super::source::Context;
use super::source::FrameBuf;
use super::source::Seekable;
use super::source::Source;

#[cfg(feature = "fakesimd")]
Expand Down Expand Up @@ -544,217 +537,6 @@ pub fn encode_with_fixed_block_size<T: Source>(
Ok(stream)
}

/// A hypothesis for block-size beam search.
#[cfg(feature = "experimental")]
struct Hyp {
frame: Frame,
offset: usize,
block_size: usize,
samples: usize,
bits: usize,
back_pointer: Option<Arc<Hyp>>,
is_last: bool,
context: Context,
}

#[cfg(feature = "experimental")]
impl Hyp {
/// Creates a new beam-search node connecting to the given `back_pointer`.
///
/// # Error
///
/// Returns `SourceError` when it failed to read from `src`.
pub fn new<T: Seekable>(
src: &mut T,
block_size: usize,
config: &config::Encoder,
stream_info: &StreamInfo,
back_pointer: Option<Arc<Self>>,
) -> Result<Arc<Self>, SourceError> {
// OPTIMIZE ME: Heap allocation done for each hyp.
let mut framebuf = FrameBuf::with_size(stream_info.channels(), block_size);
let offset = back_pointer.as_ref().map_or(0, |h| h.next_offset());
let mut ctx = back_pointer.as_ref().map_or_else(
|| Context::new(stream_info.bits_per_sample(), stream_info.channels()),
|hyp| hyp.context.clone(),
);
src.read_samples_from(offset, &mut framebuf, &mut ctx)?;
let frame_samples = std::cmp::min(src.len() - offset, block_size);
let frame = encode_frame(config, &framebuf, offset, stream_info);
let bits = frame.count_bits();
let prev_samples = back_pointer.as_ref().map_or(0, |h| h.samples);
let prev_bits = back_pointer.as_ref().map_or(0, |h| h.bits);
Ok(Arc::new(Self {
frame,
offset,
block_size,
samples: prev_samples + frame_samples,
bits: prev_bits + bits,
back_pointer,
is_last: frame_samples != block_size,
context: ctx,
}))
}

pub const fn next_offset(&self) -> usize {
self.offset + self.block_size
}

pub fn bits_per_sample(&self) -> f64 {
self.bits as f64 / self.samples as f64
}
}

#[cfg(feature = "experimental")]
struct BeamSearch<'a, T: Seekable> {
config: &'a config::Encoder,
stream_info: &'a StreamInfo,
src: &'a mut T,
beam_width: usize,
best_hyp: Option<Arc<Hyp>>,
current_hyps: Vec<Arc<Hyp>>,
next_hyps: Vec<Arc<Hyp>>,
prune_markers: BTreeSet<usize>,
}

#[cfg(feature = "experimental")]
impl<'a, T: Seekable> BeamSearch<'a, T> {
pub fn new(
config: &'a config::Encoder,
stream_info: &'a StreamInfo,
src: &'a mut T,
) -> Result<Self, SourceError> {
let beam_width = config
.block_size_search_beam_width
.unwrap_or(config.block_sizes.len() * BSBS_DEFAULT_BEAM_WIDTH_MULTIPLIER);
let mut ret = Self {
config,
stream_info,
src,
beam_width,
best_hyp: None,
current_hyps: vec![],
next_hyps: vec![],
prune_markers: BTreeSet::new(),
};
ret.extend_one(&None)?;
ret.prune_and_update();
Ok(ret)
}

pub fn extend_all(&mut self) -> Result<(), SourceError> {
self.next_hyps.clear();
let current_hyps = self.current_hyps.clone();
for hyp in &current_hyps {
self.extend_one(&Some(Arc::clone(hyp)))?;
}
self.prune_and_update();
Ok(())
}

pub fn done(&self) -> bool {
self.current_hyps.is_empty()
}

pub fn results(&self) -> impl Iterator<Item = Arc<Hyp>> {
let mut ret = vec![];
if let Some(best) = self.best_hyp.as_ref() {
let mut cur = Arc::clone(best);
loop {
ret.push(Arc::clone(&cur));
if let Some(prev) = cur.back_pointer.as_ref() {
cur = Arc::clone(prev);
} else {
break;
}
}
}
ret.into_iter().rev()
}

fn update_best_hyp(&mut self, hyp: Arc<Hyp>) {
let best_bps = self
.best_hyp
.as_ref()
.map_or(f64::MAX, |h| h.bits_per_sample());
if hyp.bits_per_sample() < best_bps {
self.best_hyp = Some(hyp);
}
}

fn extend_one(&mut self, back_pointer: &Option<Arc<Hyp>>) -> Result<(), SourceError> {
for &bs in &self.config.block_sizes {
let hyp = Hyp::new(
self.src,
bs,
self.config,
self.stream_info,
back_pointer.clone(),
)?;
if hyp.is_last {
self.update_best_hyp(Arc::clone(&hyp));
} else {
self.next_hyps.push(hyp);
}
}
Ok(())
}

fn prune_and_update(&mut self) {
self.next_hyps.sort_by(|x, y| {
x.bits_per_sample()
.partial_cmp(&y.bits_per_sample())
.unwrap()
});
self.prune_markers.clear();
self.current_hyps.clear();
for hyp in &self.next_hyps {
if self.prune_markers.contains(&hyp.next_offset()) {
continue;
}
self.prune_markers.insert(hyp.next_offset());
self.current_hyps.push(Arc::clone(hyp));
}
self.current_hyps.truncate(self.beam_width);
}
}

/// Searches combination of block sizes and encodes `src` in variable length format.
///
/// # Errors
///
/// This function returns `SourceError` when it failed to read samples from `src`.
#[cfg(feature = "experimental")]
#[allow(clippy::missing_panics_doc)]
pub fn encode_with_multiple_block_sizes<T: Seekable>(
config: &config::Encoder,
mut src: T,
) -> Result<Stream, SourceError> {
let mut stream = Stream::new(src.sample_rate(), src.channels(), src.bits_per_sample());
let stream_info = stream.stream_info();
let mut beam_search = BeamSearch::new(config, stream_info, &mut src)?;

// TODO: MD5 checksums are not supported in BSBS mode.
while !beam_search.done() {
beam_search.extend_all()?;
}
for hyp in beam_search.results() {
stream.add_frame(hyp.frame.clone());
}
stream.stream_info_mut().set_total_samples(src.len());

Ok(stream)
}

#[cfg(not(feature = "experimental"))]
#[allow(unused_mut, clippy::missing_errors_doc)]
pub fn encode_with_multiple_block_sizes<T: Seekable>(
_config: &config::Encoder,
mut _src: T,
) -> Result<Stream, SourceError> {
unimplemented!("Multiple block-size is only supported when flacenc is built with \"experimental\" feature enabled.")
}

#[cfg(test)]
mod tests {
use super::*;
Expand Down
13 changes: 2 additions & 11 deletions src/config.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -34,8 +34,6 @@ use super::lpc::Window;
pub struct Encoder {
/// The possible block sizes encoder can use.
pub block_sizes: Vec<usize>,
/// Beam width for block-size search.
pub block_size_search_beam_width: Option<usize>,
/// Whether encoder runs on multi-thread mode.
pub multithread: bool,
/// Configuration for stereo-coding module.
Expand All @@ -51,7 +49,6 @@ impl Default for Encoder {
stereo_coding: StereoCoding::default(),
subframe_coding: SubFrameCoding::default(),
block_sizes: vec![4096usize],
block_size_search_beam_width: None,
multithread: cfg!(feature = "par"),
}
}
Expand All @@ -65,16 +62,10 @@ impl Verify for Encoder {
"Must specify at least one block size.",
));
}
if !cfg!(feature = "experimental") && self.block_sizes.len() > 1 {
if self.block_sizes.len() > 1 {
return Err(VerifyError::new(
"block_sizes",
"Multiple blocksize mode is only allowed when \"experimental\" feature is enabled.",
));
}
if self.block_size_search_beam_width == Some(0) {
return Err(VerifyError::new(
"block_size_search_beam_width",
"Must be more than 1.",
"Multiple blocksize mode is not supported currently.",
));
}
for (i, &bs) in self.block_sizes.iter().enumerate() {
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3 changes: 0 additions & 3 deletions src/constant.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -21,9 +21,6 @@ pub enum ExitCode {
InvalidConfig = -1,
}

/// Default block-size beam-search width in factor of #choices.
pub const BSBS_DEFAULT_BEAM_WIDTH_MULTIPLIER: usize = 2;

/// Maximum length of a block.
pub const MIN_BLOCKSIZE_SUPPORTED: usize = 32;

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1 change: 0 additions & 1 deletion testtool/reporter.py
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Original file line number Diff line number Diff line change
Expand Up @@ -37,7 +37,6 @@
"default": [],
"st": ["-c", "report/st.config.toml"],
"dmse": ["-c", "report/dmse.config.toml"],
"bsbs": ["-c", "report/bsbs.config.toml"],
"mae": ["-c", "report/mae.config.toml"],
}
REFERENCE_BINPATH = "flac-1.3.4/src/flac/flac"
Expand Down

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