View Issue Details

IDProjectCategoryView StatusLast Update
0000766OpenMPTFile Format Supportpublic2019-03-01 20:50
Reportermanx Assigned Tomanx  
Status resolvedResolutionfixed 
Target VersionOpenMPT / libopenmpt 0.4.0 (upgrade first)Fixed in VersionOpenMPT / libopenmpt 0.4.0 (upgrade first) 
Summary0000766: 64bit WAVE-like file format

Stream export with 192kHz/4/float format in Wave files will overflow the data chunk size after 23 minutes.
FLAC is only an option for integer formats and not floating point.
Possible formats with 64bit file size and floating point support:
1) RIFF WAVE : Chain multiple data chunks in (hack-ish but somewhat not uncommon practice)
2) EBU RF64 :
3) Sony Wave64 :
4) Apple CAF :
5) OggPCM :
6) AU/.snd Sun Audio :

Additional Information

Discussion of different 64bit file formats can be found at

TagsNo tags attached.
Has the bug occurred in previous versions?
Tested code revision (in case you know it)


related to 0001209 closed Write lossless audio files which ignore silent regions 




2017-10-02 19:28

administrator   ~0003282

Last edited: 2017-10-04 16:58

AU would be the simplest, and we already can read the format as samples.
W64 is probably the most useful and probably second easiest to implement (both for writing and loading as sample).
OggPCM is easy to write, however loading OggPCM requires a considerable amount of work in order to parse the channel mapping headers correctly and handle the downmixing. Also, it is not used anywhere in practice.
RF64 quite honestly looks like an utter mess of hacks.
WAV with multiple chunks is just way too dirty to consider.
CAF is not considered any more because it is kind of Apple-specific, however it is extensively and clearly specified.



2017-10-04 17:02

administrator   ~0003292

Last edited: 2017-10-05 20:21

W64: The Cue64/Marker chunk is ambiguously specified with respect to whether it implements chunk-external padding (like all other chunks) or chunk-internal padding. Implementations differ on behaviour in the wild: ScalaAudioFile writes chunk-external padding, Reaper writes chunk-internal padding.
W64: The Cue64/marker chunk uses UTF16 encoding, however all other string metadata inherits the problem of unspecified 8bit enconding from RIFF WAVE. Gloriously inconsistent.



2017-10-08 15:51

administrator   ~0003299

AU export implemented in r9067. Given that none of the considered formats is perfect and without quirks, AU was chosen because of its simplicity.

Issue History

Date Modified Username Field Change
2016-04-20 17:08 manx New Issue
2016-05-04 08:08 manx Product Version OpenMPT 1.26.00.* (old testing) =>
2017-09-22 12:15 manx Assigned To => manx
2017-09-22 12:15 manx Status new => assigned
2017-09-22 12:15 manx Target Version OpenMPT 1.?? (long term goals) => OpenMPT / libopenmpt 0.4.0 (upgrade first)
2017-09-29 17:25 manx Description Updated
2017-10-02 19:28 manx Note Added: 0003282
2017-10-02 19:30 manx Description Updated
2017-10-02 19:32 manx Description Updated
2017-10-04 16:58 manx Note Edited: 0003282
2017-10-04 16:59 manx Description Updated
2017-10-04 17:02 manx Note Added: 0003292
2017-10-05 20:21 manx Note Edited: 0003292
2017-10-08 15:51 manx Status assigned => resolved
2017-10-08 15:51 manx Resolution open => fixed
2017-10-08 15:51 manx Fixed in Version => OpenMPT / libopenmpt 0.4.0 (upgrade first)
2017-10-08 15:51 manx Note Added: 0003299
2019-03-01 20:50 manx Relationship added related to 0001209