[Flac-dev] In which release did FLAC support 192kHz sample rate?
lechameleon at gmail.com
Sat Dec 22 20:10:43 PST 2007
In reviewing the changelogs its unclear in which release FLAC began
supporting a sample rate of 192kHz.
The reason for my question is that there are many forums and university
studies that state that FLAC does not support a sample rate of 192kHz
however the current documentation (assumed 1.2.1b) under FORMAT under
FRAME_HEADER does note that it is supported.
If it was not supported from the beginning then I would assume there would
be a record of this in the changelogs. If it was supported from the
beginning then Im baffled why so many posts note that it does not.
Thank you in advance for any clarification youre able to provide on this
Some references (there are many others):
1. Helios Labs Technology Ltd.
FLAC is an open source lossless compression format for audio files. Unlike
MP3, WMA, MPEG4 and other audio formats, FLAC retains every bit of the
original audio, ensuring no loss of sound quality when uncompressed again,
exactly like how Zip files retain every bit of information of the source
files. The advantage with FLAC over Wave is its ability to reduce the size
of audio down to around 60% of its original size on average.
In this test, we have compressed our wave test files into the FLAC format
and tested the files that successfully compressed. Unfortunately, the FLAC
encoder did not support our 192kHz wave samples.
The test results are as follows:
Fail - Noise
Fail - Noise
Fail - Noise
Fail - Crash
Unlike our wave tests, the player only supported a handful of our FLAC test
files. While it is nice to see it supporting up to 96kHz, unfortunately it
was unable to handle any of the 24-bit FLAC files. For example, the 24-bit
44kHz file causes the player to crash, while the 24-bit 96kHz file simply
refuses to play. Hopefully a future firmware update will add support for
24-bit FLAC files.
Note: This article referenced that FLAC 1.1.3 was used.
2. Lossless and Perceptual Coding of Digital Audio
Peter Noll, Tilman Liebchen
Technische Universität Berlin, Fachgebiet Nachrichtenübertragung (formerly
noll at nue.tu-berlin.de, liebchen at nue.tu-berlin.de
The following, the compression ratio is defined as
C = Original File Size / Compressed File Size
Table 2 compares the compression ratios of the popular open source codec
FLAC and the MPEG-4 ALS codec from TU Berlin . Higher values mean better
compression. Almost 1 GB of stereo waveform data was used to measure the
average compression ratios for different
48 kHz / 16-bit
48 kHz / 24-bit
96 kHz / 24-bit
192 kHz / 24-bit
Table 2: Compression ratios for different audio formats
(192 kHz material is not supported by FLAC).
The compression ratio typically decreases with higher amplitude resolutions,
but improves with higher sampling rates. The results also show that ALS
outperforms FLAC for all formats, particularly for high-definition material
(96 kHz / 24-bit).
Note: This article does not note which version of FLAC was used.
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