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The ISO/MP4 format demuxer provides support for the ISO Base Media File Format container, commonly used for MP4, M4A, and M4V files.

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Feature Flag

[dependencies]
symphonia = { version = "0.5", features = ["isomp4"] }

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Status

Great - Most media streams play. Inaudible glitches may be present. Most common features are supported.

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Supported Codecs

The ISO/MP4 container can encapsulate various audio codecs:
  • AAC-LC (Advanced Audio Coding)
  • ALAC (Apple Lossless Audio Codec)
  • MP3 (MPEG-1/2 Audio Layer III)
  • FLAC (Free Lossless Audio Codec)
  • Opus

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Gapless Playback

❌ Not supported - The demuxer does not currently support gapless playback.

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Metadata Support

The MP4 format supports iTunes-style metadata tags:
  • Track information (title, artist, album)
  • Album art (cover images)
  • Encoder information
  • Copyright and licensing data
Metadata is automatically parsed when opening MP4 files.

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Usage Example

use symphonia::core::formats::FormatOptions;
use symphonia::core::io::MediaSourceStream;
use symphonia::core::meta::MetadataOptions;
use symphonia::core::probe::Hint;
use std::fs::File;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Open the media file
    let file = Box::new(File::open("audio.m4a")?);
    let mss = MediaSourceStream::new(file, Default::default());

    // Create a hint to help the format registry
    let mut hint = Hint::new();
    hint.with_extension("m4a");

    // Probe the media source
    let format_opts = FormatOptions::default();
    let metadata_opts = MetadataOptions::default();
    
    let probed = symphonia::default::get_probe()
        .format(&hint, mss, &format_opts, &metadata_opts)?;

    let mut format = probed.format;

    // Get the default track
    let track = format.default_track().unwrap();
    
    println!("Codec: {:?}", track.codec_params.codec);
    println!("Sample Rate: {:?}", track.codec_params.sample_rate);
    println!("Channels: {:?}", track.codec_params.channels);

    // Read metadata
    if let Some(metadata) = probed.metadata.get() {
        for tag in metadata.tags() {
            println!("{}: {}", tag.key, tag.value);
        }
    }

    Ok(())
}

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Known Limitations

  • Gapless playback is not supported
  • Some advanced MP4 features may not be fully implemented
  • Fragmented MP4 (fMP4) support is limited
  • DASH and HLS streaming features are not supported

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Crate Information

Crate: symphonia-format-isomp4 Version: 0.5.5 License: MPL-2.0

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