benilla-octo/crates/benilla-app/examples/stream_probe.rs

//! `cargo run -p benilla-app --example stream_probe -- [<file-in-chain>…]` — does a streamed track
//! decode as many frames as it declares?
//!
//! The question behind the zone-music dropouts. A streaming sound's transport runs to the frame
//! count the container *declares* (`codec_params.n_frames`), while the audio it can actually play
//! is whatever the decoder yields. When the declaration overstates the content, the stream spends
//! the difference audible with nothing to play: `third_party/kira`'s decode scheduler asks
//! `frame_at_index` for a frame past the real end, which decodes chunk after chunk looking for an
//! index that will never arrive. The renderer's frame ring drains, the position stops advancing,
//! and — because no error was raised and the transport never reached its end — the sound stays
//! `Playing`, so benilla's reap-and-schedule-the-next-track pass never fires
//! (`sound/zone.rs`'s music transport). That is a silent music slot that only a zone change clears.
//!
//! Reads every copy through the chain, so it answers for the bytes the client actually plays
//! ([`benilla_formats::Chain`]), not a copy on disk. With no argument it probes the tracks named
//! on stdin, one chain path per line.
//!
//! Prints, per track: the declared frame count, the frames actually decoded, and the number of
//! chunks that came back empty on the way. `declared > decoded` is the defect; the empty-chunk
//! tally says whether the decoder stalls before it reports EOF.

use std::io::BufRead;

use symphonia::core::codecs::Decoder;
use symphonia::core::formats::FormatReader;
use symphonia::core::io::MediaSourceStream;
use symphonia::core::probe::Hint;

/// The decoder's own frame count for one buffer, matching kira's `load_frames_from_buffer_ref`.
fn frames_in(buf: &symphonia::core::audio::AudioBufferRef) -> usize {
    use symphonia::core::audio::Signal;
    match buf {
        symphonia::core::audio::AudioBufferRef::U8(b) => b.frames(),
        symphonia::core::audio::AudioBufferRef::U16(b) => b.frames(),
        symphonia::core::audio::AudioBufferRef::U24(b) => b.frames(),
        symphonia::core::audio::AudioBufferRef::U32(b) => b.frames(),
        symphonia::core::audio::AudioBufferRef::S8(b) => b.frames(),
        symphonia::core::audio::AudioBufferRef::S16(b) => b.frames(),
        symphonia::core::audio::AudioBufferRef::S24(b) => b.frames(),
        symphonia::core::audio::AudioBufferRef::S32(b) => b.frames(),
        symphonia::core::audio::AudioBufferRef::F32(b) => b.frames(),
        symphonia::core::audio::AudioBufferRef::F64(b) => b.frames(),
    }
}

fn main() {
    let Some(data) = benilla_formats::wow_data() else {
        eprintln!("no install");
        std::process::exit(1);
    };
    let chain = benilla_formats::Chain::open(&data).expect("chain opens");

    let args: Vec<String> = std::env::args().skip(1).collect();
    let names: Vec<String> = if args.is_empty() {
        std::io::stdin()
            .lock()
            .lines()
            .map_while(Result::ok)
            .map(|l| l.trim().to_string())
            .filter(|l| !l.is_empty())
            .collect()
    } else {
        args
    };

    println!(
        "{:<58} {:>10} {:>10} {:>9} {:>6}  verdict",
        "track", "declared", "decoded", "short by", "empty"
    );
    let mut bad = 0usize;
    for name in &names {
        let path = name.replace('/', "\\");
        let Ok(bytes) = chain.read(&path) else {
            println!("{:<58} not in the chain", short(&path));
            continue;
        };
        match probe(bytes) {
            Err(e) => println!("{:<58} {e}", short(&path)),
            Ok((declared, decoded, empty)) => {
                let verdict = if declared > decoded {
                    bad += 1;
                    "DECLARES MORE THAN IT HAS"
                } else {
                    "ok"
                };
                println!(
                    "{:<58} {declared:>10} {decoded:>10} {:>9} {empty:>6}  {verdict}",
                    short(&path),
                    declared.saturating_sub(decoded),
                );
            }
        }
    }
    println!(
        "\n{bad} of {} track(s) declare more frames than they decode",
        names.len()
    );
}

fn short(p: &str) -> String {
    p.rsplit('\\').next().unwrap_or(p).to_string()
}

/// `(declared, decoded, empty_chunks)` for one track, decoded exactly as kira's decoder does.
fn probe(bytes: Vec<u8>) -> Result<(usize, usize, usize), String> {
    let source = std::io::Cursor::new(bytes);
    let mss = MediaSourceStream::new(Box::new(source), Default::default());
    let probed = symphonia::default::get_probe()
        .format(
            &Hint::default(),
            mss,
            &Default::default(),
            &Default::default(),
        )
        .map_err(|e| format!("probe: {e}"))?;
    let mut format_reader: Box<dyn FormatReader> = probed.format;
    let track = format_reader.default_track().ok_or("no default track")?;
    let declared: usize = track
        .codec_params
        .n_frames
        .ok_or("no declared frame count")?
        .try_into()
        .map_err(|_| "frame count does not fit usize")?;
    let track_id = track.id;
    let mut decoder: Box<dyn Decoder> = symphonia::default::get_codecs()
        .make(&track.codec_params, &Default::default())
        .map_err(|e| format!("codec: {e}"))?;

    let mut decoded = 0usize;
    let mut empty = 0usize;
    // The read ends where kira's decoder would report an error, which is what stops the sound.
    while let Ok(packet) = format_reader.next_packet() {
        if packet.track_id() != track_id {
            continue;
        }
        match decoder.decode(&packet) {
            Ok(buf) => {
                let n = frames_in(&buf);
                if n == 0 {
                    empty += 1;
                }
                decoded += n;
            }
            Err(_) => empty += 1,
        }
    }
    Ok((declared, decoded, empty))
}