Crate nom_exif

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Expand description

nom-exif is an Exif/metadata parsing library written in pure Rust with nom.

§Supported File Types

  • Image
    • *.heic, *.heif, etc.
    • *.jpg, *.jpeg
    • *.tiff, *.tif
  • Video/Audio
    • ISO base media file format (ISOBMFF): *.mp4, *.mov, *.3gp, etc.
    • Matroska based file format: *.webm, *.mkv, *.mka, etc.

§Key Features

  • Ergonomic Design

    • Unified Workflow for Various File Types

      Now, multimedia files of different types and formats (including images, videos, and audio) can be processed using a unified method. This consistent API interface simplifies user experience and reduces cognitive load.

      The usage is demonstrated in the following examples. examples/rexiftool is also a good example.

    • Two style APIs for Exif

      iterator style (ExifIter) and get style (Exif). The former is parse-on-demand, and therefore, more detailed error information can be captured; the latter is simpler and easier to use.

  • Performance

    • Zero-copy when appropriate: Use borrowing and slicing instead of copying whenever possible.

    • Minimize I/O operations: When metadata is stored at the end/middle of a large file (such as a QuickTime file does), Seek rather than Read to quickly locate the location of the metadata (if the reader supports Seek).

    • Share I/O and parsing buffer between multiple parse calls: This can improve performance and avoid the overhead and memory fragmentation caused by frequent memory allocation. This feature is very useful when you need to perform batch parsing.

    • Pay as you go: When working with ExifIter, all entries are lazy-parsed. That is, only when you iterate over ExifIter will the IFD entries be parsed one by one.

  • Robustness and stability

    Through long-term Fuzz testing, and tons of crash issues discovered during testing have been fixed. Thanks to @sigaloid for pointing this out!

  • Supports both sync and async APIs

§Unified Workflow for Various File Types

By using MediaSource & MediaParser, multimedia files of different types and formats (including images, videos, and audio) can be processed using a unified method.

Here’s an example:

use nom_exif::*;

fn main() -> Result<()> {
    let mut parser = MediaParser::new();

    let files = [
        "./testdata/exif.heic",
        "./testdata/exif.jpg",
        "./testdata/tif.tif",
        "./testdata/meta.mov",
        "./testdata/meta.mp4",
        "./testdata/webm_480.webm",
        "./testdata/mkv_640x360.mkv",
        "./testdata/mka.mka",
        "./testdata/3gp_640x360.3gp"
    ];

    for f in files {
        let ms = MediaSource::file_path("./testdata/exif.heic")?;

        if ms.has_exif() {
            // Parse the file as an Exif-compatible file
            let mut iter: ExifIter = parser.parse(ms)?;
            // ...
        } else if ms.has_track() {
            // Parse the file as a track
            let info: TrackInfo = parser.parse(ms)?;
            // ...
        }
    }

    Ok(())
}

§Sync API: MediaSource + MediaParser

MediaSource is an abstraction of multimedia data sources, which can be created from any object that implements the Read trait, and can be parsed by MediaParser.

Example:

use nom_exif::*;

fn main() -> Result<()> {
    let mut parser = MediaParser::new();
     
    let ms = MediaSource::file_path("./testdata/exif.heic")?;
    assert!(ms.has_exif());
     
    let mut iter: ExifIter = parser.parse(ms)?;
    let exif: Exif = iter.into();
    assert_eq!(exif.get(ExifTag::Make).unwrap().as_str().unwrap(), "Apple");

    let ms = MediaSource::file_path("./testdata/meta.mov")?;
    assert!(ms.has_track());
     
    let info: TrackInfo = parser.parse(ms)?;
    assert_eq!(info.get(TrackInfoTag::Make), Some(&"Apple".into()));
    assert_eq!(info.get(TrackInfoTag::Model), Some(&"iPhone X".into()));
    assert_eq!(info.get(TrackInfoTag::GpsIso6709), Some(&"+27.1281+100.2508+000.000/".into()));
    assert_eq!(info.get_gps_info().unwrap().latitude_ref, 'N');
    assert_eq!(
        info.get_gps_info().unwrap().latitude,
        [(27, 1), (7, 1), (68, 100)].into(),
    );

    // `MediaSource` can also be created from a `TcpStream`:
    // let ms = MediaSource::tcp_stream(stream)?;

    // Or from any `Read + Seek`:
    // let ms = MediaSource::seekable(stream)?;
     
    // From any `Read`:
    // let ms = MediaSource::unseekable(stream)?;
     
    Ok(())
}

See MediaSource & MediaParser for more information.

§Async API: AsyncMediaSource + AsyncMediaParser

Likewise, AsyncMediaParser is an abstraction for asynchronous multimedia data sources, which can be created from any object that implements the AsyncRead trait, and can be parsed by AsyncMediaParser.

Enable async feature flag for nom-exif in your Cargo.toml:

[dependencies]
nom-exif = { version = "1", features = ["async"] }

See [AsyncMediaSource] & [AsyncMediaParser] for more information.

§GPS Info

ExifIter provides a convenience method for parsing gps information. (Exif & TrackInfo also provide a get_gps_info mthod).

use nom_exif::*;

fn main() -> Result<()> {
    let mut parser = MediaParser::new();
     
    let ms = MediaSource::file_path("./testdata/exif.heic")?;
    let iter: ExifIter = parser.parse(ms)?;

    let gps_info = iter.parse_gps_info()?.unwrap();
    assert_eq!(gps_info.format_iso6709(), "+43.29013+084.22713+1595.950CRSWGS_84/");
    assert_eq!(gps_info.latitude_ref, 'N');
    assert_eq!(gps_info.longitude_ref, 'E');
    assert_eq!(
        gps_info.latitude,
        [(43, 1), (17, 1), (2446, 100)].into(),
    );
    Ok(())
}

For more usage details, please refer to the API documentation.

§CLI Tool rexiftool

§Human Readable Output

cargo run --example rexiftool testdata/meta.mov:

Make                            => Apple
Model                           => iPhone X
Software                        => 12.1.2
CreateDate                      => 2024-02-02T08:09:57+00:00
Duration                        => 500
ImageWidth                      => 720
ImageHeight                     => 1280
GpsIso6709                      => +27.1281+100.2508+000.000/

§Json Dump

cargo run --example rexiftool testdata/meta.mov -j:

{
  "ImageWidth": "720",
  "Software": "12.1.2",
  "ImageHeight": "1280",
  "Make": "Apple",
  "GpsIso6709": "+27.1281+100.2508+000.000/",
  "CreateDate": "2024-02-02T08:09:57+00:00",
  "Model": "iPhone X",
  "Duration": "500"
}

§Parsing Files in Directory

rexiftool also supports batch parsing of all files in a folder (non-recursive).

cargo run --example rexiftool testdata/:

File: "testdata/embedded-in-heic.mov"
------------------------------------------------
Make                            => Apple
Model                           => iPhone 15 Pro
Software                        => 17.1
CreateDate                      => 2023-11-02T12:01:02+00:00
Duration                        => 2795
ImageWidth                      => 1920
ImageHeight                     => 1440
GpsIso6709                      => +22.5797+113.9380+028.396/

File: "testdata/compatible-brands-fail.heic"
------------------------------------------------
Unrecognized file format, consider filing a bug @ https://github.com/mindeng/nom-exif.

File: "testdata/webm_480.webm"
------------------------------------------------
CreateDate                      => 2009-09-09T09:09:09+00:00
Duration                        => 30543
ImageWidth                      => 480
ImageHeight                     => 270

File: "testdata/mka.mka"
------------------------------------------------
Duration                        => 3422
ImageWidth                      => 0
ImageHeight                     => 0

File: "testdata/exif-one-entry.heic"
------------------------------------------------
Orientation                     => 1

File: "testdata/no-exif.jpg"
------------------------------------------------
Error: parse failed: Exif not found

File: "testdata/exif.jpg"
------------------------------------------------
ImageWidth                      => 3072
Model                           => vivo X90 Pro+
ImageHeight                     => 4096
ModifyDate                      => 2023-07-09T20:36:33+08:00
YCbCrPositioning                => 1
ExifOffset                      => 201
MakerNote                       => Undefined[0x30]
RecommendedExposureIndex        => 454
SensitivityType                 => 2
ISOSpeedRatings                 => 454
ExposureProgram                 => 2
FNumber                         => 175/100 (1.7500)
ExposureTime                    => 9997/1000000 (0.0100)
SensingMethod                   => 2
SubSecTimeDigitized             => 616
OffsetTimeOriginal              => +08:00
SubSecTimeOriginal              => 616
OffsetTime                      => +08:00
SubSecTime                      => 616
FocalLength                     => 8670/1000 (8.6700)
Flash                           => 16
LightSource                     => 21
MeteringMode                    => 1
SceneCaptureType                => 0
UserComment                     => filter: 0; fileterIntensity: 0.0; filterMask: 0; algolist: 0;
...

Structs§

Enums§

  • EntryValue
    Represent a parsed entry value.
  • Error
  • ExifTag
    Defines recognized Exif tags. All tags can be parsed, no matter if it is defined here. This enum definition is just for ease of use.
  • FileFormatDeprecated
    Deprecated: Please use [MediaSource] instead.
  • TrackInfoTag
    Try to keep the tag name consistent with crate::ExifTag, and add some unique to video/audio, such as DurationMs.

Functions§

Type Aliases§