le Chameleon
2007-Dec-31 15:15 UTC
[Flac-dev] In which release did FLAC support 192kHz sample rate?
Greetings, In reviewing the changelogs it?s 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 I?m baffled why so many posts note that it does not. Thank you in advance for any clarification you?re able to provide on this subject. Leonard Chameleon Some references (there are many others): 1. Helios Labs Technology Ltd. FLAC Audio 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: Sample Rate Bit Depth Channels Result 22kHz 16bit Stereo Pass 44kHz 8bit Mono Fail - Noise 44kHz 8bit Stereo Fail - Noise 44kHz 16bit Mono Pass 44kHz 16bit Stereo Pass 44kHz 24bit Mono Fail - Noise 44kHz 24bit Stereo Fail - Crash 48kHz 16bit Stereo Pass 96kHz 16bit Stereo Pass 96kHz 24bit Stereo Fail 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 Universit?t Berlin, Fachgebiet Nachrichten?bertragung (formerly Fernmeldetechnik) noll@nue.tu-berlin.de, liebchen@nue.tu-berlin.de Compression Results 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 [3]. Higher values mean better compression. Almost 1 GB of stereo waveform data was used to measure the average compression ratios for different audio formats. Audio Format FLAC (open source) MPEG-4 ALS (TU Berlin) 48 kHz / 16-bit 2.06 2.24 48 kHz / 24-bit 1.46 1.59 96 kHz / 24-bit 1.76 2.16 192 kHz / 24-bit - 2.66 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. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.xiph.org/pipermail/flac-dev/attachments/20071222/9117bae5/attachment-0001.html
Josh Coalson
2008-Jan-17 11:09 UTC
[Flac-dev] In which release did FLAC support 192kHz sample rate?
--- le Chameleon <lechameleon@gmail.com> wrote:> Greetings, > > In reviewing the changelogs it?s unclear in which release FLAC began > supporting a sample rate of 192kHz.flac has always supported 192kHz. it was not in the subset until 1.2.0; before that you had to use the --lax option to encode 192kHz, which was explained in the error message since flac 1.1.1 ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping