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OGG/Opus: Fix property reading

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Serial 2022-12-04 12:35:51 -05:00 committed by Alex
parent 365b5c1ce3
commit 2cc96f618b
1 changed files with 29 additions and 18 deletions
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47
src/ogg/opus/properties.rs
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@ -103,27 +103,38 @@ where
decode_err!(@BAIL Opus, "Invalid channel count for mapping family");
}
// Get the last pages' absolute granule position
let last_page = find_last_page(data)?;
let last_page_abgp = last_page.header().abgp;
// Get the stream length
// Also safe to unwrap, metadata is checked prior
let metadata_packet = packets.get(1).unwrap();
let header_size = identification_packet.len() + metadata_packet.len();
let last_page = find_last_page(data);
let file_length = data.seek(SeekFrom::End(0))?;
let stream_len = file_length - header_size as u64;
if let Some(frame_count) = last_page_abgp.checked_sub(first_page_abgp + u64::from(pre_skip)) {
let length = (frame_count as f64) * 1000.0 / 48000.0_f64 + 0.5;
properties.duration = Duration::from_millis(length as u64);
if let Ok(last_page) = last_page {
let first_page_abgp = first_page_header.abgp;
let last_page_abgp = last_page.header().abgp;
properties.overall_bitrate = ((file_length as f64) * 8.0 / length) as u32;
properties.audio_bitrate = ((stream_len as f64) * 8.0 / length) as u32;
let total_samples = last_page_abgp
.saturating_sub(first_page_abgp)
// https://datatracker.ietf.org/doc/html/draft-terriberry-oggopus-01#section-4.1:
//
// A 'pre-skip' field in the ID header (see Section 5.1) signals the
// number of samples which should be skipped (decoded but discarded)
.saturating_sub(u64::from(pre_skip));
if total_samples > 0 {
// Best case scenario
let length = total_samples as f64 * 1000.0 / 48000.0;
// Get the stream length by subtracting the length of the header packets
// Safe to unwrap, metadata is checked prior
let metadata_packet = packets.get(1).unwrap();
let header_size = identification_packet.len() + metadata_packet.len();
let stream_len = file_length - header_size as u64;
properties.duration = Duration::from_millis(length as u64);
properties.overall_bitrate = ((file_length as f64) * 8.0 / length) as u32;
properties.audio_bitrate = ((stream_len as f64) * 8.0 / length) as u32;
} else {
log::debug!("Opus: The file contains invalid PCM values, unable to calculate length");
}
}
Ok(properties)