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Comment by saagarjha | Hacker News Reader

Related, but I was looking for an audio format that could embed these loop points inside of it so the file would be small but play infinitely. Is there anything "standard" that does this? I looked into WAV and AIFF, which seem to have "cue" points, but they don't seem to quite do what I want…

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The "standard" is unfortunately (as far as I can determine) not open source, but it is an "open" standard. The REX2 file format from Propellerhead is documented somewhere at https://www.reasonstudios.com/developers but you will need to sign up for a developer account. I'm pretty sure it's free to use, and it's supported by most serious DAWs.

>"REX2 is a proprietary type of audio sample loop file format developed by Propellerhead, a Swedish music software company.

It is one of the most popular and widely supported loop file formats for sequencer and digital audio workstation software. It is supported by PreSonus Studio One, Propellerhead Reason, Steinberg Cubase, Steinberg Nuendo, Cockos REAPER, Apple Logic, Digidesign Pro Tools, Ableton Live, Cakewalk Project5, Cakewalk Sonar, Image-Line FL Studio, MOTU Digital Performer, MOTU Mach 5 (software sampler), and Synapse Audio Orion Platinum, among others."

https://en.wikipedia.org/wiki/REX2

Ideally I'd be able to play this on an iPod :(

That's up to the media player (with standard WAV / AIFF etc). If it buffers the file and respects cue points, you should be able to have seamless playback, but very few media players get this 100% correct. See https://en.wikipedia.org/wiki/Gapless_playback for mroe details.

What are we meant to look for on that Wikipedia article page, and how does it relate to looping? The article says nothing about cue points as far as I can see.

Just because you have loop points defined doesn't automatically mean that every player will be able to process them in a seamless way.

I responded to a sibling comment here with some more details about what I was wondering about: https://news.ycombinator.com/item?id=21384082

Basically, what I was wondering about was rather, even though that article tells us which players support gapless playback, it doesn't say which players support loop points.

Looping (with normal WAV files etc) is gapless playback. You can get almost perfect looping if you use buffering.

The wikipedia article is basically just illustrating that, to do looping on an iPod (as requested) you would just require sample accurate wav files, and a media player that supported gapless playback.

My apologies but what I was wondering about was rather, even though that article tells us which players support gapless playback, it doesn't say which players support loop points.

In order to know which player to use we would need to know which players support both gapless playback and loop points. Preferably the list of such software would also state whether the player was also able to do gapless playback of loop points, since conceivably a player might be able to gapless playback when transitioning between songs but might not do it properly in the case of loop points.

Did something change about their licensing? At least up until recently I remember that Propellerheads applied proprietary licensing terms and requiring every developer to be associated with a company for any of their third-party stuff including REX and ReWire.

I think you're probably correct. They had a press release in 2004 talking about "opening" the format. It's a bit of a let down to tell the truth.

"In the past, major Developers such as Steinberg and Emagic applied for and obtained a license to support REX playback in their applications. Now as an open format, any manufacturer, large or small, can support REX playback in their applications.

Third-party manufacturers are encouraged to download REX2 developer documentation. Implementing the Propellerheads REX2 file format in other applications or hardware is free of charge. Further information about the REX2 file format is available at http://www.propellerheads.se/developer"

https://www.reasonstudios.com/press/21-propellerhead-softwar...

A bit more info at https://www.reasonstudios.com/developer/index.cfm?fuseaction...

EDIT: Speeling

WAV has also the info you need, in the "smpl" (Sampler information) chunk. You can also embed this into FLAC files as foreign metadata of type "riff".

Reference: http://www-mmsp.ece.mcgill.ca/Documents/AudioFormats/WAVE/Do...

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