Flac documentation

This page is broken up into the following sections: format - the user-level view of the FLAC format for a more detailed explanation see the format page. Keep in mind that the online version of this document will always apply to the latest release. For older releases, check the documentation included with the release package. However, if you are looking to maximize the compression rate or speed, or want to use the full power of FLAC's metadata system, this section is for you. If not, just skip to the next section.

The first four bytes are to identify the FLAC stream. The metadata that follows contains all the information about the stream except for the audio data itself. After the metadata comes the encoded audio data. FLAC defines several types of metadata blocks see the format page for the complete list.

Metadata blocks can be any length and new ones can be defined. A decoder is allowed to skip any metadata types it does not understand. This block has information like the sample rate, number of channels, etc.

This is useful for checking an entire stream for transmission errors. Other blocks allow for padding, seek tables, tags, cuesheets, and application-specific data. FLAC does not require seek points for seeking but they can speed up seeks, or be used for cueing in editing applications. Audio data and metadata are not interleaved. Like most audio codecs, FLAC splits the unencoded audio data into blocks, and encodes each block separately.

The encoded block is packed into a frame and appended to the stream. The reference encoder uses a single block size for the whole stream but the FLAC format does not require it. The block size is an important parameter to encoding. If it is too small, the frame overhead will lower the compression.

If it is too large, the modeling stage of the compressor will not be able to generate an efficient model.

flac documentation

Understanding FLAC's modeling will help you to improve compression for some kinds of input by varying the block size. In the most general case, using linear prediction on Using the fast fixed predictors, a smaller block size is usually preferable because of the smaller frame header. In the case of stereo input, once the data is blocked it is optionally passed through an inter-channel decorrelation stage.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. Branch: master. Find file. Sign in Sign up. Go back. Launching Xcode If nothing happens, download Xcode and try again.

Latest commit. Closes Latest commit 7a35c52 Apr 7, Xiph in this distribution. You must have libogg 1. Unused parts may be pruned by some simple editing of configure. Also, there are several places in the libFLAC code with comments marked with "OPT:" where a define can be changed to enable code that might be faster on a specific platform.

Experimenting with these can yield faster binaries. Better documentation for these will be forthcoming, but in general, this should work:. Even though it will stop with an explicit message on any failure, it does print out a lot of stuff so you might want to capture the output to a file if you're having a problem.

Also, don't run 'make check' as root because it confuses some of the tests. NOTE: Despite our best efforts it's entirely possible to have problems when using older versions of autoconf, automake, or libtool. If you have the latest versions and still can't get it to work, see the next section on Makefile. May be necessary for building on OS X Intel. If flac crashes when built with this option you will have to go back and configure without --enable-sse.This assumption may be overridden with a command-line option.

It also assumes that files ending in ". Other than this, flac makes no assumptions about file extensions, though the convention is that FLAC files have the extension ". Before going into the full command-line description, a few other things help to sort it out: 1 flac encodes by default, so you must use -d to decode; 2 the options Skip to the tutorial below for examples of some common tasks.

If only one inputfile is specified, it may be "-" for stdin.

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When stdin is used as input, flac will write to stdout. Otherwise flac will perform the desired operation on each input file to similarly named output files meaning for encoding, the extension will be replaced with ". The original file is not deleted unless --delete-input-file is specified. Also, you can force output data to go to stdout using -c. To encode or decode files that start with a dash, use -- to signal the end of options, to keep the filenames themselves from being treated as options: flac -V -- filename.

The format options are used to tell flac the arrangement of samples if the input file or output file when decoding is a raw file. In test mode, flac acts just like in decode mode, except no output file is written. Both decode and test modes detect errors in the stream, but they also detect when the MD5 signature of the decoded audio does not match the stored MD5 signature, even when the bitstream is valid. It will also preserve all the metadata unless you override it with other options e.

Tutorial Some common encoding tasks using flac : flac abc. Why would you want to do this? It allows you to recompress an existing FLAC file with usually higher compression options or a newer version of FLAC and preserve all the metadata like tags too. Some common decoding tasks using flac : flac -d abc.

NOTE: Without -d it means re-encode abc. General Options -v--version Show the flac version number. Running flac without arguments shows the short help screen by default. Otherwise the exit code will be 0. The exit codes are the same as in decode mode. This option is mainly for developers; the output will be a text file that has data about each frame and subframe. The exit code will be the only way to determine successful completion. This is useful for scripts, and setting tags in situations where the locale is wrong.

This option must appear before any tag options! By default, flac warns that the output file already exists and continues to the next file.

May only be used when encoding a single file. May not be used in conjunction with --output-prefix. If there was an error including a verify error the input file is left intact.

flac documentation

Use --no-preserve-modtime to make output files have the current time and default permissions. If decoding, restore any saved non-audio chunks from FLAC metadata when writing the decoded file. Foreign metadata cannot be transcoded, e.To request a quote, fill out our Contact Form and we'll call you or Call Us now at.

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Brokers Offer your clients better benefit options with Aflac supplemental insurance policies. Request a Quote. Products Products. Resources Customer Resources. Provide your information so an Aflac agent can reach you.In addition each codec may support so-called private options, which are specific for a given codec.

Sometimes, a global option may only affect a specific kind of codec, and may be nonsensical or ignored by another, so you need to be aware of the meaning of the specified options. Also some options are meant only for decoding or encoding. In 1-pass mode, bitrate tolerance specifies how far ratecontrol is willing to deviate from the target average bitrate value.

Lowering tolerance too much has an adverse effect on quality. Only write platform- build- and time-independent data. This ensures that file and data checksums are reproducible and match between platforms. Its primary use is for regression testing. It is the fundamental unit of time in seconds in terms of which frame timestamps are represented. Set cutoff bandwidth.

Supported only by selected encoders, see their respective documentation sections.

flac documentation

It is set by some decoders to indicate constant frame size. Set video quantizer scale compression VBR. It is used as a constant in the ratecontrol equation. Must be an integer between -1 and If a value of -1 is used, it will choose an automatic value depending on the encoder. Set single coefficient elimination threshold for luminance negative values also consider DC coefficient. Set single coefficient elimination threshold for chrominance negative values also consider dc coefficient. Note: experimental decoders can pose a security risk, do not use this for decoding untrusted input.

This is useful if you want to analyze the content of a video and thus want everything to be decoded no matter what. This option will not result in a video that is pleasing to watch in case of errors. Set rate control equation.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.

Skip to content. Permalink Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. Branch: master. Find file Copy path. Cannot retrieve contributors at this time. Raw Blame History. The metadata that follows contains all the information about the stream except for the audio data itself.

After the metadata comes the encoded audio data. Metadata blocks can be any length and new ones can be defined. A decoder is allowed to skip any metadata types it does not understand.

This block has information like the sample rate, number of channels, etc. This is useful for checking an entire stream for transmission errors. FLAC does not require seek points for seeking but they can speed up seeks, or be used for cueing in editing applications. The resulting stream will be FLAC compatible; decoders that are aware of your metadata can use it and the rest will safely ignore it.

Audio data and metadata are not interleaved. Like most audio codecs, FLAC splits the unencoded audio data into blocks, and encodes each block separately. The encoded block is packed into a frame and appended to the stream. The reference encoder uses a single block size for the whole stream but the FLAC format does not require it.

FLAC Documentation

If it is too small, the frame overhead will lower the compression. If it is too large, the modeling stage of the compressor will not be able to generate an efficient model. Understanding FLAC's modeling will help you to improve compression for some kinds of input by varying the block size.

In the most general case, using linear prediction on Using the fast fixed predictors, a smaller block size is usually preferable because of the smaller frame header. This is a lossless process, unlike joint stereo. For normal CD audio this can result in significant extra compression.

The function's parameters also have to be transmitted so they should not be so complex as to eat up the savings. FLAC has two methods of forming approximations: 1 fitting a simple polynomial to the signal; and 2 general linear predictive coding LPC.

I will not go into the details here, only some generalities that involve the encoding options. The higher the maximum LPC order, the slower, but more accurate, the model will be.Matches ID3v1 tags.

Matches ID3v2 tags. Constructs a FLAC file from file. If readProperties is true the file's audio properties will also be read. Constructs an FLAC file from file. If this file contains and ID3v2 tag the frames will be created using frameFactory. Constructs a FLAC file from stream. Destroys this instance of the File.

Reimplemented from TagLib::File. Add a new picture to the file. The file takes ownership of the picture and will handle freeing its memory. If no audio properties were read then this will return a null pointer. Implements TagLib::File. Returns whether or not the file on disk actually has an ID3v1 tag.

Returns whether or not the file on disk actually has an ID3v2 tag. Returns a pointer to the ID3v1 tag of the file. If create is false the default this returns a null pointer if there is no valid APE tag.

If create is true it will create an APE tag if one does not exist and returns a valid pointer. Returns a pointer to the ID3v2 tag of the file. If create is false the default this returns a null pointer if there is no valid ID3v2 tag.

If create is true it will create an ID3v2 tag if one does not exist and returns a valid pointer. Returns a list of pictures attached to the FLAC file. Implements the unified property interface — export function. If the file contains more than one tag e. Removes an attached picture. If del is true the picture's memory will be freed; if it is false, it must be deleted by the user. Save the file. This will primarily save the XiphComment, but will also keep any old ID3-tags up to date.

If the file has no XiphComment, one will be constructed from the ID3-tags. Set the ID3vFrameFactory to something other than the default. This can be used to specify the way that ID3v2 frames will be interpreted when. Implements the unified property interface — import function. This always creates a Xiph comment, if none exists. The return value relates to the Xiph comment only. This will remove the tags that match the OR-ed together TagTypes from the file. By default it removes all tags.

Returns the Tag for this file. If create is false the default this returns a null pointer if there is no valid XiphComment.

flac documentation

If create is true it will create a XiphComment if one does not exist and returns a valid pointer.


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