TLDR: Make sure to export MP3s to be played on iphone/ipad/ios in Constant Bitrate (CBR). There is a setting in the export edit screen to change from Variable Bitrate (VBR) to CBR. You want CBR if you want to avoid the skipping mentioned in this post. CBR at 192 kbs did the trick for me, as suggested by the experts in this thread.
Further, I would like to note that this is not an error or defect in Ardour. No, ardour’s default MP3 export is set to VBR, and the users need to know what settings they need for the hardware they are using. There is tons of information about VBR and CBR and from what I can tell from researching after this experience, any benefits of VBR are outweighed in the fact that many hardware and software systems choke up on VBR for all kinds of reasons. This is why the file would only choke on ios. It was a VBR export. Once I changed it to a CBR at 192, no skips, no problems. Thanks for helping me solve this frustrating problem. Finally, I would like to note that I repeated the solution in audiacity. Indeed, the default export setting in audacity was also VBR. When I took the same .wav file from ardour and exported from audacity at same CBR 192, it was perfect and produced a file the exact same size as ardours file, which makes sense because they both use FFMPEG as the converter. Thus, it is not a problem with ardour, but with a conflict between ios playblack and use of VBR .mp3s. To avoid, use CBR.
Hello. This is a strange one.
I record a session in ardour. If I export to a .wav, it plays on all hardware no problem. So for instance, it plays through my mac, on my linux box, on my iphone, etc., without any skips.
Now, when I export the session to any .mp3 format through ardour, it still plays beautifully on all the hardware-- EXCEPT for the iphone. So each time the .mp3 starts on the iphone, there is a skip of a several seconds, and it happens a few times. Only in the begining of the track, like the first 10 seconds. So, if I play the .mp3 on my mac, through itunes or quicktime, it works fine. on my linux box through any media player fine. on my iphone, skips.
OK, here is the very weird part: so i figured i would try to outsmart the system. i took the .wav export of the session, opened it in audacity, and then, in audactiy, saved the .wav to a .mp3. because i presumed there was a problem somehow with how ardour is making the .mp3. well, same exact problem with this .mp3 file. this happens on any .mp3 file that is created either from an ardour session or a .wav of an an ardour session, ONLY on iphone playback. the only way i can get an .mp3 that does not skip is to import the .wav (which is the mastered session file) into garageband, and then export to .mp3. if i do that, it does not skip on iphone.
here is the problem with this issue: its bad for sending files to others who use iphones. you never know if your .mp3 will skip. it may be a problem with apple, but somehow, ardour is triggering it. it only happens with sessions created on ardour. does not happen if i create my mix on garageband and export to mp3 or if i import my ardour .wav to garage band and export to .mp3.
the skip is similar to the old days of CD players when you woudl accidentally shake the player and it would skip. also, important, the .mp3 plays just fine on any other hardware. this only happens on the iphone playback.
i have also just reported this issue on the bug tracker. issue # 0008571.
any help or ideas?
thanks so much,
a dedicated ardour fan
edit: iphone Xs Max, software version 14.3; new - able to repeat also on an ipad