Re: [Flac-dev] Support for CAF in flac command-line?
On Mon, Mar 7, 2011 at 11:25 AM, Brian Willoughby bri...@sounds.wa.com wrote: All professional tools use conversion factors such as 0x8000 for float-to-int and int-to-float because it has a single significant bit, and thus this factor does not increase the bit depth of the samples passing through. i'm not sure what all means, but i don't think its remotely as clear cut as you insist: http://blog.bjornroche.com/2009/12/int-float-int-its-jungle-out-there.html moreover, its critically important to note that this issue arises primarily for float=16 bit int conversions, where generally dithering should be done anyway. the noise introduced by dithering will be at least on the same order of magnitude as the 0.005% error caused by different choices in the conversion factor. conversions to other bit depths don't face (precisely) the same issue. its great that you're absolutely convinced that your view of this is right. i generally have a lot of respect for your opinions. the problem is that there are 4 other people whose opinions i respect equally, and when i've discussed it with them, my only conclusion in aggregate has to be it depends. --p ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
On Mar 7, 2011, at 08:46, Paul Davis wrote: On Mon, Mar 7, 2011 at 11:25 AM, Brian Willoughby bri...@sounds.wa.com wrote: All professional tools use conversion factors such as 0x8000 for float-to-int and int-to-float because it has a single significant bit, and thus this factor does not increase the bit depth of the samples passing through. i'm not sure what all means, but i don't think its remotely as clear cut as you insist: http://blog.bjornroche.com/2009/12/int-float-int-its-jungle-out- there.html moreover, its critically important to note that this issue arises primarily for float=16 bit int conversions, where generally dithering should be done anyway. the noise introduced by dithering will be at least on the same order of magnitude as the 0.005% error caused by different choices in the conversion factor. conversions to other bit depths don't face (precisely) the same issue. its great that you're absolutely convinced that your view of this is right. i generally have a lot of respect for your opinions. the problem is that there are 4 other people whose opinions i respect equally, and when i've discussed it with them, my only conclusion in aggregate has to be it depends. Thanks. I should qualify my statements by explaining that I'm talking about real music that comes from an A/D, with the understanding that 24-bit integers in twos-complement format are the standard. I should also point out that my goal is to preserve the original bits unless an operation other than format conversion is specifically enabled. In the context of FLAC - a lossless audio codec - this is entirely compatible. My statements would not be appropriate for synthesized waveforms that did not originate in the real world by way of A/D converters. In that world, there is freedom to deviate from the specific limitations of A/D converters, and thus there might be some hesitance to apply a default conversion that might clip certain synthesized waveforms that were created without concern for the realities of analog conversion. In that case, I would suggest that those who create such entirely synthetic waveforms should take the extra steps necessary to condition their signals for actual D/A converters, and then a transparent float-to-int conversion would not cause any additional problems. It's only when the synthetic algorithms rely on side effects of a lossy conversion that things get hairy. Brian ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
Brian Willoughby wrote: On Mar 6, 2011, at 01:22, Erik de Castro Lopo wrote: Brian Willoughby wrote: Hopefully, libsndfile no longer uses the incorrect 0x7FFF (32767) factor for float to 16-bit integer conversions, because that would make it unacceptable for lossless file conversions. That is a statement of opinion rather than fact but I won't go into that here. It is a statement of mathematical fact, not opinion. There are at least three different suboptimal solutions to this problem. The FAQ here: http://www.mega-nerd.com/libsndfile/FAQ.html#Q010 explains my choice of sub-optimal solutin. That FAQ question also provides two ways of using libsndfile that avoid all suboptimal solutions. Erik -- -- Erik de Castro Lopo http://www.mega-nerd.com/ ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
Brian Willoughby wrote: Hopefully, libsndfile no longer uses the incorrect 0x7FFF (32767) factor for float to 16-bit integer conversions, because that would make it unacceptable for lossless file conversions. That is a statement of opinion rather than fact but I won't go into that here. However, there is a way avoid that feature of libsndfile by avoiding the use of floats during the conversion. For instance, when convering from one format to another, sndfile-convert does this: if ((outfileminor == SF_FORMAT_DOUBLE) || (outfileminor == SF_FORMAT_FLOAT) || (infileminor == SF_FORMAT_DOUBLE) || (infileminor == SF_FORMAT_FLOAT) || (infileminor == SF_FORMAT_VORBIS) || (outfileminor == SF_FORMAT_VORBIS)) sfe_copy_data_fp (outfile, infile, sfinfo.channels) ; else sfe_copy_data_int (outfile, infile, sfinfo.channels) ; That is the second path (sfe_copy_data_int) would be used for FLAC - CAF and CAF - FLAC conversions. Erik -- -- Erik de Castro Lopo http://www.mega-nerd.com/ ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
new tracker item here: https://sourceforge.net/tracker2/?func=detailaid=2491177group_id=13478atid=363478 ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
--- Martin Leese [EMAIL PROTECTED] wrote: Brian Willoughby [EMAIL PROTECTED] wrote: Hello all, Is anyone here potentially up to the task of adding support for CAF (the CoreAudio Format) into the flac command-line? ... I've already made some recordings that are so long that they cannot be uncompressed from FLAC to WAV or AIFF because they would exceed 4 GB - the maximum file size for those formats. CAF does not have the same 4 GB limitations. Erik de Castro Lopo [EMAIL PROTECTED] wrote: ... Whats more, the sndfile-convert program can also convert from FLAC to the following file formats that support 63 bit file offsets: Au, Caf, rf64, w64 I am glad somebody mentioned RF64. Supporting RF64 instead of CAF would solve Brian's problem equally well, and would be the natural extension to supporting WAVE. BTW current flac in CVS supports RF64 and wave64; they will be in the next release. I'll have to look into CAF. ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
On Sat, Nov 29, 2008 at 2:20 PM, Josh Coalson [EMAIL PROTECTED] wrote: --- Martin Leese [EMAIL PROTECTED] wrote: Erik de Castro Lopo [EMAIL PROTECTED] wrote: ... Whats more, the sndfile-convert program can also convert from FLAC to the following file formats that support 63 bit file offsets: Au, Caf, rf64, w64 I am glad somebody mentioned RF64. Supporting RF64 instead of CAF would solve Brian's problem equally well, and would be the natural extension to supporting WAVE. BTW current flac in CVS supports RF64 and wave64; they will be in the next release. I'll have to look into CAF. Core Audio Format (CAF) is from Apple, visit: http://developer.apple.com/documentation/MusicAudio/CoreAudio-date.html I have never tried to code CAF, but my guess is that it will be a lot more work than the successors to WAVE. Regards, Martin -- Martin J Leese E-mail: martin.leese stanfordalumni.org Web: http://members.tripod.com/martin_leese/ ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
Martin Leese wrote: Core Audio Format (CAF) is from Apple, visit: http://developer.apple.com/documentation/MusicAudio/CoreAudio-date.html I have never tried to code CAF, but my guess is that it will be a lot more work than the successors to WAVE. I have coded CAF (as part of libsndfile) and IMO, CAf is no harder than WAV. Erik -- - Erik de Castro Lopo - Safety versus Expressiveness is a false dichotomy -- you can have both. Compare ObjectiveCaml with CeePlusPlus: OCaml obtains expressiveness without compromising safety, while C++ obtains it by throwing away safety. The latter is just bad design. -- David Hopwood ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
Brian Willoughby wrote: RF64 support sure would be nice, but it wouldn't really help to do this instead of CAF. This pre-release of libsndfile supports both: http://www.mega-nerd.com/tmp/libsndfile-1.0.18pre24e.tar.gz Erik -- - Erik de Castro Lopo - If trees could scream, would we be so cavalier about cutting them down? We might, if they screamed all the time, for no good reason. -- Jack Handey ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
On Sun, 2008-10-12 at 19:26 -0700, Brian Willoughby wrote: Hello all, Is anyone here potentially up to the task of adding support for CAF (the CoreAudio Format) into the flac command-line? This would present minimal difficulty under OSX, due to the presence of the CoreAudio API, but the real challenge would be to support CAF on Unix and Windows - everywhere that flac is now available. Although the format is rather unknown, there are some very specific advantages to adding CAF support. I am a little suprised that you don't know that CAF is already supported by libsndfile, on every platform where libsndfile works (which includes just about every unix and windows platforms i know of). ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
I will quote from the CAF spec: This document is intended for anyone who needs to understand the structure of CAF files. You can use the information in this document, for example, to write a CAF parser or to extend the types of data stored in CAF files. Because CAF files offer many advantages over other audio file formats, anyone writing an application for Mac OS X that reads or writes audio files should read at least the overview chapter to gain an understanding of the features of CAF files. In addition, you need the information in this document if you want to use CAF files on other platforms. End users of professional audio software may be interested in this document in order to learn more about the capabilities of software that supports CAF. IANAL, but I sure hope Apple wouldn't sue someone who write[s] a CAF parser or want[s] to use CAF files on other platforms. Hopefully, the existence of libsndfile support for CAF shows that the format is open. Brian Willoughby Sound Consulting On Oct 12, 2008, at 22:27, Michael Crawford wrote: My hunch is that Apple does not want to encumber the format, but I'll let their public documents speak for them. In any event, it's a very good issue to be aware of from the start. I'm afraid AAC (MPEG-4 audio) has many, many patents. Unlike MP3, one cannot even distribute the binary of an Open Source player. AAC stands for Apple Audio Codec - it's their lossy codec. ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
Paul Davis wrote: I am a little suprised that you don't know that CAF is already supported by libsndfile, on every platform where libsndfile works (which includes just about every unix and windows platforms i know of). Thanks Paul. Yep, Caf support was added in July 2005. Whats more, the sndfile-convert program can also convert from FLAC to the following file formats that support 63 bit file offsets: Au, Caf, rf64, w64 Cheers, Erik -- - Erik de Castro Lopo - It has been discovered that C++ provides a remarkable facility for concealing the trival details of a program -- such as where its bugs are. -- David Keppel ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
Michael Crawford wrote: Unlike MP3, one cannot even distribute the binary of an Open Source player. Even distributing an MP3 software player requires the payment of license fees: http://www.mp3licensing.com/royalty/software.html Erik -- - Erik de Castro Lopo - If I were on life-support, I'd rather have it run by a Gameboy than a Windows box. -- Cliff Wells in comp.lang.python ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
On Sun, Oct 12, 2008 at 11:56 PM, Erik de Castro Lopo [EMAIL PROTECTED] wrote: Even distributing an MP3 software player requires the payment of license fees: http://www.mp3licensing.com/royalty/software.html Thanks for pointing that out - you might have just saved me a world of hurt. However, there are many Open Source players - is there a license exception for them, just for decoding? Or can they only be distributed from countries that don't recognize software patents? That's the case with VLC, for example, it's from France. Ogg Frog is GPL. Mike -- Michael David Crawford mdcrawford at gmail dot com Enjoy my art, photography, music and writing at http://www.geometricvisions.com/ --- Free Compact Disc --- ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
Michael Crawford wrote: However, there are many Open Source players Yep, I believe that the distributors of those MP3 players owe the MP3 patent holders money. - is there a license exception for them, just for decoding? Not that I know of. Or can they only be distributed from countries that don't recognize software patents? I believe that these players are on shaky legal ground in the US and in many other contries. Erik -- - Erik de Castro Lopo - We respect the right of everyone to believe whatever they like. But there are two important limits to religious tolerance. First, I have no right to legal protection against your scepticism, criticism or ridicule. Religion is too powerful a force, and is too often a cause of injustice or evil, for it to be immune from discussion and debate. -- David Pannick QC http://www.timesonline.co.uk/tol/life_and_style/career_and_jobs/legal/article729808.ece ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
RF64 support sure would be nice, but it wouldn't really help to do this instead of CAF. For one thing, Logic Studio Pro does not seem to support RF64, because the manual states that WAVE and BWF are limited to 4 GB. CAF may be a format which lacks universal support, but RF64 is also very limited in usefulness. Treating either one as a substitute for the other is not going to help. Personally, I'd welcome support for either or both. With an open- source project like this, I'm not going to complain about any added features, so long as we all understand that there is no substitute for CAF. Brian Willoughby Sound Consulting On Oct 13, 2008, at 08:59, Martin Leese wrote: Brian Willoughby [EMAIL PROTECTED] wrote: Hello all, Is anyone here potentially up to the task of adding support for CAF (the CoreAudio Format) into the flac command-line? ... I've already made some recordings that are so long that they cannot be uncompressed from FLAC to WAV or AIFF because they would exceed 4 GB - the maximum file size for those formats. CAF does not have the same 4 GB limitations. Erik de Castro Lopo [EMAIL PROTECTED] wrote: ... Whats more, the sndfile-convert program can also convert from FLAC to the following file formats that support 63 bit file offsets: Au, Caf, rf64, w64 I am glad somebody mentioned RF64. Supporting RF64 instead of CAF would solve Brian's problem equally well, and would be the natural extension to supporting WAVE. Regards, Martin ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
On Sun, Oct 12, 2008 at 7:26 PM, Brian Willoughby [EMAIL PROTECTED] wrote: Is anyone here potentially up to the task of adding support for CAF (the CoreAudio Format) into the flac command-line? This would present minimal difficulty under OSX, due to the presence of the CoreAudio API, but the real challenge would be to support CAF on Unix and Windows - everywhere that flac is now available. I expect I could do it as part of my work on Ogg Frog: http://www.oggfrog.com/free-music-software In the short term, I would do it by accessing the QuickTime APIs - which *are* available on Windows, if you install either iTunes or QuickTime for Windows. (The iTunes install includes QuickTime.) In the long term, I could write a codec for it that would be straightforward to integrate into the flac command-line tool. That would allow its use on UNIX. HOWEVER! Is the CoreAudio file format or its associated algorithms patented? QuickTime in general has many patents. A patent wouldn't stop me from writing the source code, but a binary couldn't be provided by anyone in a country that recognizes software patents. Mike -- Michael David Crawford mdcrawford at gmail dot com Enjoy my art, photography, music and writing at http://www.geometricvisions.com/ --- Free Compact Disc --- ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
Thanks for the interest, Michael. I don't use Ogg, so I'm a little wary that standard FLAC would be left out of any Ogg Frog implementation. But I say that mostly out of ignorance. I have noticed that there seem to be two worlds for FLAC, inside Ogg and outside. It's important to be aware of the fact that many hardware devices support the FLAC format directly, without the Ogg container/wrapper. I would want the ability to convert FLAC to CAF directly, hopefully without an intermediate Ogg file (since I'm talking about file sizes where each is over 4 GB). QuickTime is a very good suggestion, and gets two platforms supported rather than one, as the AudioFile API in CoreAudio would do. However, QuickTime tends to be rather limited, and when developers run into those limitations, Apple engineers tend to recommend that folks turn to CoreAudio for full support. Also, I really would like to support Unix, assuming that there are as many Unix folks using FLAC as there are Windows users taking advantage of this underground format. As for the patent question, it's a very smart question, but I think as soon as any interested developer looks at the CAF specification from Apple, it should be readily apparent what the legal ramifications are. My hunch is that Apple does not want to encumber the format, but I'll let their public documents speak for them. In any event, it's a very good issue to be aware of from the start. Thanks again for the comments, and be sure to keep us informed if you do anything. Brian Willoughby Sound Consulting On Oct 12, 2008, at 21:25, Michael Crawford wrote: On Sun, Oct 12, 2008 at 7:26 PM, Brian Willoughby [EMAIL PROTECTED] wrote: Is anyone here potentially up to the task of adding support for CAF (the CoreAudio Format) into the flac command-line? This would present minimal difficulty under OSX, due to the presence of the CoreAudio API, but the real challenge would be to support CAF on Unix and Windows - everywhere that flac is now available. I expect I could do it as part of my work on Ogg Frog: http://www.oggfrog.com/free-music-software In the short term, I would do it by accessing the QuickTime APIs - which *are* available on Windows, if you install either iTunes or QuickTime for Windows. (The iTunes install includes QuickTime.) In the long term, I could write a codec for it that would be straightforward to integrate into the flac command-line tool. That would allow its use on UNIX. HOWEVER! Is the CoreAudio file format or its associated algorithms patented? QuickTime in general has many patents. A patent wouldn't stop me from writing the source code, but a binary couldn't be provided by anyone in a country that recognizes software patents. Mike ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
Re: [Flac-dev] Support for CAF in flac command-line?
Thanks for the interest, Michael. I hope I really can be of help. I don't use Ogg, so I'm a little wary that standard FLAC would be left out of any Ogg Frog implementation. Ogg Frog already supports native FLAC as a player. Version 1.0 will only support playing and decoding, but version 1.1 will support encoding, and I'll be sure to support FLAC with and without Ogg. I must hasten to point out that I don't offer any downloads yet - the UI is in a very primitive state. My hunch is that Apple does not want to encumber the format, but I'll let their public documents speak for them. In any event, it's a very good issue to be aware of from the start. I'm afraid AAC (MPEG-4 audio) has many, many patents. Unlike MP3, one cannot even distribute the binary of an Open Source player. AAC stands for Apple Audio Codec - it's their lossy codec. Thanks again for the comments, and be sure to keep us informed if you do anything. Of course. Mike -- Michael David Crawford mdcrawford at gmail dot com Enjoy my art, photography, music and writing at http://www.geometricvisions.com/ --- Free Compact Disc --- ___ Flac-dev mailing list Flac-dev@xiph.org http://lists.xiph.org/mailman/listinfo/flac-dev
