The MP4 file format is a very popular video format used in motion pictures while the WAV format is the main audio file format for Windows systems that is usually in raw and uncompressed format. There are instances when we need to extract the audio from an MP4 file and save the resulting file in WAV format.

• Meta is exactly what I was looking for: the app is a modern Mac utility that supports all popular audio formats (from standard MP3 and MP4 to FLAC, DSF, and AIFF) and can write metadata formats such as ID3v1, ID3v2, MP4, and APE tags. Unlike other cross-platform or open-source tag editors, Meta’s feature set is focused on one area – editing.
• Mar 12, 2020  The MP4 file format is a very popular video format used in motion pictures while the WAV format is the main audio file format for Windows systems that is usually in raw and uncompressed format. There are instances when we need to extract the audio from an MP4.

Jan 08, 2020  What it does is carry forward the metadata from any format to mp4 i.e. If a mkv file is being encoded by handbrake to mp4 the mp4 will have the metadata that the mkv file had. Most uploaders have all weird names and naming conventions for the metadata, it shows up in plex. Not plex's fault. Just need a way to clean the metadata.

For instance, this can be when you need to obtain a ringtone from an MP4 song, to get audio to use in another video or to separate the audio and video when they are not in proper sync in the MP4 file among other reasons. Saying may seem simple by the actual process to extract audio in the WAV waveform format from an MP4 file is not that direct.

This is because you have to employ online or offline, paid or free versions of software that have been crafted specifically to handle such a task reliably. To get away from the hassle of MP4 to WAV conversion, here is a list of go-to programs that will offer the simplicity of operation and the ultimate convenient converting process. These programs include;

6 Great Apps to Convert MP4 to WAV files in Windows 10 & Mac – Free Download

1. VideoProc

No matter the kind of MP4 file you are dealing with, VideoProc is the ultimate video processing program, free or paid, for both Windows and Mac that will be able to extract the audio for you in WAV file format. You are open to performing MP4 to WAV conversion on single video files and even batch conversion in the instance you need to process multiple files all at once for convenience.

Even after selecting WAV as the output format you can tinker with extra options like the codec to use in the process to change MP4 to WAV. You also get the chance to adjust the output name and the metadata of the same especially if you are dealing with a song. Retrieving the output files after you convert MP4 to WAV can be tedious if at all you are not sure where the software has saved the audio files.

To avoid this, VideoProc lets you specify your own output directory for easier file retrieval later on. At the end of the day, you have the best MP4 to WAV converter app at your disposal.

2. Wondershare MP4 to WAV Converter

Wondershare comes in both an online and offline version so that depending on which is convenient for you, the process to convert MP4 to waveform is just like a walk in the park. Files can be added for conversion via native file browsing method or with the drag-and-drop feature that saves on both time and effort besides facilitating batch MP4 to WAV conversion.

It is worth noting that when comparing this MP4 to WAV converter program with other tools, it has shown to work 30 times faster so you can be sure to have the audio files in just a matter of moments. It does not end at that. Contrary to other tools, this app does not have any limitations whatsoever, especially regarding the number of MP4 files that you can convert.

You will also be able to achieve the popular MP4 to MP3 conversion without any hassle. All that is achieved at high speeds but at the same time not impacting negatively on the quality.

3. Windows Media Player

Windows Media Player has been the default media playback for the Windows platform and being able to convert MP4 to WAV makes it even better. The process is actually very simple and does not involve any complex stuff. Actually, it is just a matter of opening the target MP4 file and then saving it in the WMV file format.

The moment you decide on the directory where you wish the WMV file to be saved, the actual process to change MP4 to WAV commences and happens pretty quick. For those looking to tinker with many options, this will not be the best version of the software for you to use since you are forced to go by the default options.

Windows Media Player makes it here in the list of the best MP4 to WAV converter due to its simplicity, availability, and reliability when you need WAV files without the need to engage in cumbersome software installation processes. Talk of diving right into the task at hand.

4. Any Video Converter

This is one of the best MP4 to WAV converter software that not only let’s convert a whole MP4 file but also empowers you with the option to convert just a specific segment of the original file. It is also pretty versatile considering that you are able to convert MP4 to WAV, MP3, AAC, FLAC, M4A among other audio formats that are popular.

You are also opened up to audio personalization in regards to bitrate, sample rate, audio track, audio channel, volume, quality, codec all towards the kind of WAV file that you desire. In the instance you are working on MP4 music files, you will be able to adjust the metadata in tags like the title, artist album, year, genre, track among others besides the option to add lyrics.

With multi-thread processing, conversions are done quickly to complement the batch conversion mode. All in all, it is a simple and multilingual app that is easy to use besides auto powering off your computer when performing unattended MP4 to WAV conversion.

5. Zamzar

Looking to convert MP4 to WAV online and all for free? If yes, Zamzar is here for you to provide a simple process to achieve exactly that. From the moment you add MP4 files to the point where you get the output, the whole process has been very seamless as much as possible to accommodate first-time users. Actually, the process is very straightforward to just involve 3 steps.

In fact, all you need is to add the MP4 files, select WAV as the output file format and finally start the actual conversion process. Especially when you are working on multiple files which can take a bit longer, you need not wait for the audio files to be delivered as you can submit an email address through which you will be notified once the process is complete.

Even as an online app to change MP4 to WAV, it works pretty fast to ensure that you get the output quickly. Your files remain safe too as both the upload and download instances are done via secure connections.

6. iTunes

iTunes is available for download as an offline software for both Mac and Windows to bring in MP4 to WAV conversion capabilities. iTunes is more popular as a playback program but you will be surprised to know that it carries MP4 to WAV or MP4 to MP3 conversion features under its arms.

On Mac, it is preinstalled by default as Apple Music so you just dive right into converting single or multiple MP4 files including whole folders when the need arises without much hassle. Depending on your preferences in iTunes for Windows or Apple Music program, you will get a chance to create audio copies of the MP4 files you are converting from in your library.

During this process, a high level of output quality will be maintained so that you can have crystal clear audio files similar to the one in the original MP4 file. It is a simple process that does not require you to modify lots of options like what other MP4 to WAV converter software do.

As much as the WAV audio format is usually uncompressed and can take up a lot of storage space, there are instances where it is very much needed especially due to its familiarity on the Windows platforms besides being simple in structure to be playable on almost any device.

Luckily, you have been opened up to reliable software that will not only process MP4 files faster but will also see it to it that the final WAV files retain the original quality as much as possible. The ball is now in your court, just download your app of choice and get down to the task at hand. Say goodbye to poor and unreliable MP4 to WAV conversion processes.

This chapter describes how to store metadata in QuickTime Movie files. It also defines keys for some common metadata types as examples of how to employ the metadata capabilities in the QuickTime file format.

Overview

Metadata can be defined as useful information related to media. This section describes a method of associating metadata with media in a QuickTime file that is extensible and allows for language and country tagging. In addition, it provides a means to store the type of the metadata and associate a name with metadata. This method of storing metadata is supported in both QuickTime 7 and QuickTime X.

This metadata format uses a key–value pair for each type of metadata being stored. Standard keys, with specific formats for the values they indicate, have been defined. See QuickTime Metadata Keys for details.

Note: The QuickTime file format also defines user data which, in some limited cases, can be used to store metadata. The method of storing metadata defined in this section provides an extensible and flexible design for handling a wide variety of metadata types.

Data Type

The storage type of metadata items is defined via an enumerated list of data types, defined statically; an example might be “plain Unicode text”. See the Well-Known Types table for details of the standard, defined data types.

Meaning or Purpose

The meaning of a metadata item identifies what it represents: a copyright notice, the performer’s name, and so on. It uses an extensible namespace allowing for meanings or keys to be added, and then referenced, from metadata items. These keys may be four-character codes, names in reverse-address format (such as “com.apple.quicktime.windowlocation”) or any other key format including native formats from external metadata standards. A key is tagged with its namespace allowing for extension in the future. It is recommended that reverse-address format be used in the general case: this provides an extensible syntax for vendor data or for other organizations or standards bodies.

Data Location

Metadata is stored immediately in the corresponding atom structures, by value.

Localization

A metadata item can be identified as specific to a country or set of countries, to a language or set of languages, or to some combination of languages and countries. This identification allows for a default value (suitable for any language or country not explicitly called out), a single value, or a list of values.

Storage Location in a QuickTime File

Within a QuickTime file, metadata can be stored within a movie atom (‘moov’), a track atom (‘trak’) or a media atom (‘mdia’). Only one metadata atom is allowed for each location. If there is user data and metadata stored in the same location, and both declare the same information, for example, declare a copyright notice, the metadata takes precedence.

Metadata Structure

The container for metadata is an atom of type ‘meta’. The metadata atom must contain the following subatoms: metadata handler atom (‘hdlr’), metadata item keys atom (‘keys’), and metadata item list atom (‘ilst’). Other optional atoms that may be contained in a metadata atom include the country list atom (‘ctry’), language list atom (‘lang’) and free space atom (‘free’). The country list and language list atoms can be used to store localized data in an efficient manner. The free space atom may be used to reserve space in a metadata atom for later additions to it, or to zero out bytes within a metadata atom after editing and removing elements from it. The free space atom may not occur within any other subatom contained in the metadata atom.

Metadata Atom

The metadata atom is the container for carrying metadata.

Figure 3-1 shows a sample layout for this atom.

Metadata Handler Atom

The metadata handler atom is a full atom with an atom type of ‘hdlr’. It defines the structure used for all types of metadata stored within the metadata atom.

The layout of the metadata handler atom is defined:

A 32-bit unsigned integer that indicates the size in bytes of the atom structure

A 32-bit unsigned integer value set to 'hdlr'

One byte that is set to 0

Three bytes that are set to 0

A 32-bit integer that is set to 0

A 32-bit integer that indicates the structure used in the metadata atom, set to ‘mdta’

An array of 3 const unsigned 32-bit integers set to 0

The name is a NULL-terminated string in UTF-8 characters which gives a human-readable name for a metadata type, for debugging and inspection purposes. The string may be empty or a single byte containing 0.

Note: A reader parsing a metadata atom should confirm the handler type in the metadata handler atom is ‘mdta’ before interpreting any other structures in the metadata atom according to the specification presented here. If the handler type is not ‘mdta’, the interpretation is defined by another specification.

Metadata Header Atom

The metadata format optionally assigns unique identifiers to metadata items for such purposes as defining stable identifiers for external references into the set of metadata items. This is accomplished by including an item information atom in added metadata item atoms contained by the metadata item list atom. Such unique identifiers must be guaranteed to be unique.

To make the assignment of unique item identifiers more efficient, the metadata atom may contain a metadata header atom holding the integer value for the next unique item identifier to assign stored in the nextItemID field. In general it holds a value one greater than the largest identifier used so far.

Important: The metadata header atom must exist if there are metadata item atoms containing an item information atom indicating the item’s unique ID.

Upon assigning the identifier to a metadata item, if the value of the nextItemID field is less than 0xFFFFFFFF, it should be incremented to the next unused value. If the value of nextItemID is equal to 0xFFFFFFFF, it should not be changed: in that case, a search for an unused item identifier value in the range from 0 to 0xFFFFFFFF is needed for all additions.

The metadata header atom is a full atom with an atom type of ‘mhdr’. It contains the following fields:

A 32-bit unsigned integer that indicates the size in bytes of the atom structure

A 32-bit unsigned integer value set to 'mdhr'

One byte that is set to 0.

Three bytes that are set to 0.

A 32-bit unsigned integer indicating the value to use for the item ID of the next item created or assigned an item ID. If the value is all ones, it indicates that future additions will require a search for an unused item ID.

Note: If the last metadata item with an item information atom is removed and value of nextItemID is 0xFFFFFFFF, an implementation may reset the metadata header atom’s nextItemID value to 0 so that new assignments are again efficient (that is, they do not require a search for unused identifiers).

Extensibility

In order to allow metadata to be rewritten easily and without the need to rewrite the entire QuickTime movie file, free space atoms may occur anywhere in the definition of the metadata atom between the positions of other atoms contained by the metadata atom. Free space atoms may not be inserted between items in the metadata item list atom or within atoms in the metadata item list atom. This restriction on free space atom definition avoids the risk of confusing a free space atom with a meaning of a ‘free’ identifier or a value atom of type ‘free’ defined in the context of the metadata atom structure.

Similarly, UUID atoms for specific extensions may be placed in any position where a succession of atoms is permitted. Note that UUID atoms should not be created for atoms already defined using four-character codes.

Unrecognized atoms (that is, those atoms whose types not defined in the context of the metadata atom structure and are contained within the metadata item list atom) are ignored.

Localization List Sets

When metadata items have individual values associated with more than one country or more than one language, a country list atom and/or language list atom are required. Alternatively, if all values are associated with zero or one country, no country list atom is required, and if all values are associated with zero or one language, no language list atom is required.

Country List Atom

When one or more items must be identified as being suitable for more than one country, each list of countries is stored in this otherwise optional atom. The country list atom is a full atom with an atom type of ‘ctry’.

Each list starts with a two-byte count of the number of items in the list, and then each ISO 3166 code representing countries in the list.

The atom consists of a count of the number of lists, expressed as a 32-bit integer, and then these lists, appended end-to-end. The country list atom contains the following fields:

A 32-bit unsigned integer that indicates the size in bytes of the atom structure

A 32-bit unsigned integer value set to 'ctry'

One byte that is set to 0.

Three bytes that are set to 0.

A 32-bit integer indicating the number of Country arrays to follow in this atom.

A 16-bit integer indicating the number of Countries in the array.

An array of 16-bit integers, defined according to the ISO 3166 definition of country codes.

Note that:

• Indexes into the country list atom are 1-based.

• Zero (0) is reserved and never used as an index.

• Currently, there is a limit of 255 countries that may be recorded in a country list atom.

An example country list atom consisting of two country lists with two and three countries, respectively, is shown in Table 3-1.

Language List Atom

When one or more items must be identified as being suitable for more than one language, each list of languages is stored in this otherwise optional atom. The language list atom is a full atom with an atom type of ‘lang’.

Each list starts with a 2-byte count of the number of items in the list, and then each ISO 639-2/T code, packed into two bytes, according to the ISO Language Code definition in the MP4 specification.

The atom consists of a count of the number of lists, expressed as a 32-bit integer, and then these lists, appended end-to-end. The language list atom contains the following fields:

A 32-bit unsigned integer that indicates the size in bytes of the atom structure

A 32-bit unsigned integer value set to 'lang'

One byte that is set to 0.

Three bytes that are set to 0.

A 32-bit integer indicating the number of language arrays to follow in this atom.

A 16-bit integer indicating the number of languages in the array.

An array of 16-bit integers, defined according to the ISO 639-2/T definition of language codes.

Note that:

• Indexes into the Language List atom are 1-based.

• Zero (0) is reserved and never used as an index.

• Currently, there is a limit of 255 languages that may be recorded in a Language List atom.

Table 3-2 shows an example Language List atom consisting of two language lists with three and two languages, respectively.

Metadata Item Keys Atom

The metadata item keys atom holds a list of the metadata keys that may be present in the metadata atom. This list is indexed starting with 1; 0 is a reserved index value. The metadata item keys atom is a full atom with an atom type of ‘keys’.

This atom has the following structure:

A 32-bit unsigned integer that indicates the size in bytes of the atom structure

A 32-bit unsigned integer value set to 'keys'

One byte that is set to 0

Three bytes that are set to 0

A 32-bit integer indicating the number of key arrays to follow in this atom

A 32-bit integer indicating the size of the entire structure containing a key definition. Therefore the key_size = sizeof(key_size) + sizeof(key_namespace) + sizeof(key_value). Since key_size and key_namespace are both 32 bit integers, together they have a size of 8 bytes. Hence, the key_value structure will be equal to key_size - 8.

A 32-bit integer defining a naming scheme used for metadata keys. Location metadata keys, for example, use the ‘mdta’ key namespace.

An array of 8-bit integers, each containing the actual name of the metadata key. Keys with the ‘mdta’ namespace use a reverse DNS naming convention. For example, the location metadata coordinates use a metadata key_value of ‘com.apple.quicktime.location.ISO6709’.

Note that:

• Indexes into the metadata item keys atom are 1-based (1…entry_count).

• Zero (0) is reserved and never used as an index.

• The structure of key_value depends upon the key namespace.

Figure 3-2 shows a sample layout for this atom.

Figure 3-3 shows an example of a metadata item keys atom consisting of three keys: two from one key namespace and a third from another key namespace.

Metadata Item List Atom

The metadata item list atom holds a list of actual metadata values that are present in the metadata atom. The metadata items are formatted as a list of items. The metadata item list atom is of type ‘ilst’ and contains a number of metadata items, each of which is an atom.

Figure 3-4 shows the connection between keys.

Metadata Item Atom

Each item in the metadata item list atom is identified by its key. The atom type for each metadata item atom should be set equal to the index of the key for the metadata within the item atom, taking this index from the metadata item keys atom. In addition, each metadata item atom contains a Value Atom, to hold the value of the metadata item.

The metadata item atom has the following structure:

An optional item information atom, see Item Information Atom (ID and flags)

An optional name atom, defined below.

An array of value atoms, defined below.

Value Atom

The value of the metadata item is expressed as immediate data in a value atom. The value atom starts with two fields: a type indicator, and a locale indicator. Both the type and locale indicators are four bytes long. There may be multiple ‘value’ entries, using different type, country or language codes (see the Data Ordering section below for the required ordering).

The Value atom structure contains the following fields:

A type indicator, defined in Type Indicator.

A locale indicator, defined in Locale Indicator.

Type Indicator

The type indicator is formed of four bytes split between two fields. The first byte indicates the set of types from which the type is drawn. The second through fourth byte forms the second field and its interpretation depends upon the value in the first field.

The indicator byte must have a value of 0, meaning the type is drawn from the well-known set of types. All other values are reserved.

If the type indicator byte is 0, the following 24 bits hold the well-known type. Please refer to the list of Well-Known Types, in the Well-Known Types section below.

Locale Indicator

The locale indicator is formatted as a four-byte value. It is formed from two two-byte values: a country indicator, and a language indicator. In each case, the two-byte field has the possible values shown in Table 3-3.

Note that both ISO 3166 and ISO 639-2/T codes have a nonzero value in their top byte, and so will have a value > 255.

Software applications that read metadata may be customized for a specific set of countries or languages. If a metadata writer does not want to limit a metadata item to a specific set of countries, it should use the reserved value ZZ from ISO 3166 as its country code. Similarly if the metadata writer does not want to limit the user’s language (this is not recommended) it uses the value ‘und’ (undetermined) from the ISO 639-2/T specification.

A software application matches a country code if either (a) the value to be matched to is 0 (default) or (b) the codes are equal. A software application matches to a list of codes if its value is a member of that list. A software application matches to a locale if both country and language match.

Table 3-4 shows some example metadata tags.

To reiterate, if the country_indicator value is in the range 1 to 255, it is interpreted as the 1-based index for a country list in the Country Language atom in the Metadata atom. If the language_indicator value is in the range 1 to 255, it is interpreted as the 1-based index for a language list in the Language List atom in the Metadata atom. Otherwise, the country_indicator or language_indicator is unspecified (0) or holds the immediate value for a single country or language.

Item Information Atom (ID and flags)

The optional item information atom contains information about the item: item-specific flags and item optional identifier. This ID must be unique within the metadata atom. To simplify assignment of item identifiers, the metadata header atom’s nextItemInfo field can be used as described in Metadata Header Atom.

The item information atom must be present if the item has an assigned ID or has nonzero flags.

No flags are currently defined; they should be set to 0 in this version of the specification.

The item information atom is a full atom with an atom type of ‘itif’. This atom has the following structure:

A 32-bit unsigned integer that indicates the size in bytes of the atom structure

A 32-bit unsigned integer value set to 'itif'

One byte that is set to 0.

Three bytes that are set to 0.

An unsigned 32-bit integer, unique within the container.

Name

The Name atom is a full atom with an atom type of ‘name’. This atom contains a metadata name formatted as a string of UTF-8 characters, to fill the atom. It is optional. If it is not present, the item is unnamed, and cannot be referred to by name. Names are not user visible; they provide a way to refer to metadata items. The maximum length of a name may be limited in specific environments.

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No two metadata items may have the same name.

This atom has the following structure:

One byte that is set to 0.

Three bytes that are set to 0.

An array of bytes, constituting a UTF-8 string, containing the name.

Data Atom Structure

The Data atom has an atom type of ‘data’, and contains four bytes each of type and locale indicators, as specified in Type Indicator and Locale Indicator, and then the actual value of the metadata, formatted as required by the type.

This atom has the following structure:

The type indicator, as defined in Type Indicator.

Edit Metadata Mp4 Mac

The locale indicator, as defined in Locale Indicator.

An array of bytes containing the value of the metadata.

Data Ordering

Multiple values for the same tag represent multiple representations of the same information, differing either by language or storage type or by the size or nature of the data. For example, an artist name may be supplied in three ways:

• as a large JPEG of their signature

• as a smaller ‘thumbnail’ JPEG of their signature

• as text

An application may then choose the variation of the the artist name to display based on the size it needs.

Data must be ordered in each item from the most-specific data to the most general. An application may, if it wishes, stop ‘searching’ for a value once it finds a value that it can display (it has an acceptable locale and type).

Well-Known Types

The basic cellspacing='0' cellpadding='5'>Table 3-5 Well-known data types

Code

Type

Comment

0

reserved

Reserved for use where no type needs to be indicated

1

UTF-8

Without any count or NULL terminator

2

UTF-16

Also known as UTF-16BE

Mac App Change Metadata Mp4 Download

3

S/JIS

Deprecated unless it is needed for special Japanese characters

4

UTF-8 sort

Variant storage of a string for sorting only

5

UTF-16 sort

Variant storage of a string for sorting only

13

JPEG

In a JFIF wrapper

14

PNG

In a PNG wrapper

21

BE Signed Integer

A big-endian signed integer in 1,2,3 or 4 bytes

Note: This data type is not supported in Timed Metadata Media. Use one of the fixed-size signed integer data types (that is, type codes 65, 66, or 67) instead.

22

BE Unsigned Integer

A big-endian unsigned integer in 1,2,3 or 4 bytes; size of value determines integer size

Note: This data type is not supported in Timed Metadata Media. Use one of the fixed-size unsigned integer data types (that is, type codes 75, 76, or 77) instead.

23

BE Float32

A big-endian 32-bit floating point value (IEEE754)

24

BE Float64

A big-endian 64-bit floating point value (IEEE754)

27

BMP

Windows bitmap format graphics

28

QuickTime Metadata atom

A block of data having the structure of the Metadata atom defined in this specification

65

8-bit Signed Integer

An 8-bit signed integer

66

BE 16-bit Signed Integer

A big-endian 16-bit signed integer

67

BE 32-bit Signed Integer

A big-endian 32-bit signed integer

70

BE PointF32

A block of data representing a two dimensional (2D) point with 32-bit big-endian floating point x and y coordinates. It has the structure:

struct { BEFloat32 x; BEFloat32 y; }

71

BE DimensionsF32

A block of data representing 2D dimensions with 32-bit big-endian floating point width and height. It has the structure:

struct { BEFloat32 width; BEFloat32 height; }

72

BE RectF32

A block of data representing a 2D rectangle with 32-bit big-endian floating point x and y coordinates and a 32-bit big-endian floating point width and height size. It has the structure:

struct { BEFloat32 x; BEFloat32 y; BEFloat32 width; BEFloat32 height;}

or the equivalent structure:

struct { PointF32 origin; DimensionsF32 size; }

74

BE 64-bit Signed Integer

A big-endian 64-bit signed integer

75

8-bit Unsigned Integer

An 8-bit unsigned integer

76

BE 16-bit Unsigned Integer

A big-endian 16-bit unsigned integer

77

BE 32-bit Unsigned Integer

A big-endian 32-bit unsigned integer

78

BE 64-bit Unsigned Integer

A big-endian 64-bit unsigned integer

79

AffineTransformF64

A block of data representing a 3x3 transformation matrix. It has the structure:

struct { BEFloat64 matrix[3][3]; }

The sorting variant of text is used for languages in which sorting is not evident from the written form (for example, some forms of Asian languages). In these cases, the sorting can only be performed by a human who can identify the actual words by understanding the context. For these languages, an alternative form of the same information can be stored using a different representation of the same text which can be machine sorted. This alternative representation is still sorted according to the sort rules of the language in question, as defined for the text system in use (for example, Unicode). In general, a simple lexical sorting which compares the values of the characters alone is not sufficient.

Location Metadata

Many systems have the ability to detect or establish their position in a coordinate reference system. The specification “ISO 6709:2008 Standard representation of geographic point location by coordinates” describes one way of storing such information. One of the common systems is the Global Positioning System (GPS) developed by the US Department of Defense. Other systems include the ability of some cellular telephone systems to triangulate the position of cell-phones, and the possibility that IEEE 802.11 Wireless Base Stations are tagged with their position (whereupon mobile units that can ‘see’ their signal can establish that they are probably ‘near’ that location).

This support is increasingly common in still and movie cameras, or composite devices (such as camera-phones) that can function as cameras.

Apple has defined a key for storing the location coordinates as metadata, as well as several auxiliary pieces of information about a location. For all the location metadata keys defined in this specification, the Metadata atom handler-type should be ‘mdta’. See the com.apple.quicktime.location.ISO6709 entry in the following table for a description of the main location metadata key, and the additional table describing auxiliary location metadata keys.

QuickTime Metadata Keys

QuickTime has defined the keys shown in Table 3-6 for holding data in a Metadata atom:

In addition, QuickTime recommends the auxiliary keys shown in Table 3-7 for holding additional metadata to be associated with a location.

Direction Definition

For the metadata keys which define a direction, com.apple.quicktime.direction.facing and com.apple.quicktime.direction.motion, directions are specified as a string consisting of one or two angles, separated by a slash if two occur. The first is a compass direction, expressed in degrees and decimal degrees, optionally preceded by the characters “+” or “-”, and optionally followed by the character “M”. The direction is determined as accurately as possible; the nominal due north (zero degrees) is defined as facing along a line of longitude of the location system, unless the angle is followed by the “M” character indicating a magnetic heading. The second is an elevation direction, expressed in degrees and decimal degrees between +90.0 and -90.0, with 0 being horizontal (level), +90.0 being straight up, and -90.0 being straight down (and for these two cases, the compass direction is irrelevant).

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