Ogg FLAC

Lossless FLAC audio wrapped in Ogg — useful when you need a richer transport layer.

Pro Audio Converter can convert audio files to and from Ogg FLAC (.oga).

You can think of an audio codec as having two layers. The inside layer is the raw compressed data, and the outside layer is the "container" or "transport layer" that splits and arranges the compressed data into pieces so it can be seeked through, edited, and so on.

"Native" FLAC is the compressed FLAC data stored in a very minimalist container, designed to be very efficient at storing single audio streams.

Ogg FLAC is the compressed FLAC data stored in an Ogg container. Ogg is a much more powerful transport layer that enables mixing several kinds of different streams (audio, data, metadata, etc). The overhead is slightly higher than with native FLAC.

If all you are doing is compressing audio to be played back later, native FLAC will do everything you need, is more widely supported, and will yield smaller files. If you plan to edit the compressed audio, or want to multiplex the audio with video later in an Ogg container, Ogg FLAC is the better choice.

Encoding Options

Compression Level — Higher compression levels result in smaller file sizes but longer encode times. Lower compression levels produce larger files that encode faster. The compression level does not affect the sound quality of the file.

Sample Rate — The number of samples of audio carried per second, measured in Hz or kHz (1000 Hz). 44.1 kHz is the sampling rate of audio CDs and 48.0 kHz is common for professional video. Higher sample rates result in higher quality audio with larger file sizes. Setting this to Auto creates an output file with the same sample rate as the input file.

Bit Depth — The number of bits used to represent each sample. Increasing bit depth reduces quantization noise and improves the signal-to-noise ratio by about 6 dB per bit. 24-bit digital audio has a theoretical maximum S/N of 144 dB, compared to 96 dB for 16-bit. Audio CDs use 16 bits; 24-bit is common in professional audio and video.

Verify Encoding — With this option, a decoder is run in parallel to the encoder and its output is compared against the original input. If a difference is found, FLAC will stop with an error.