Are these symptoms of insufficient CPU for decoding opus on Sansa Clip+

[Gene]

I've switched my music files on my Sansa Clip+ over to 96kbps opus after using mp3 and then vorbis for years but with opus I've noticed a few problems on my Rockboxed Sansa Clip+:

Occasionally some songs will start playing at the 0:03-0:05 region instead of at 0:00 as expected. I am able to seek back to 0:00 when this happens but it will only start playing at 0:00 sometimes; other times it instantly skips forward to about 0:03-0:05 again and starts playing there. This never happened with mp3 or vorbis, is this due to buffering/increased CPU requirements for decoding opus? It seems to be repeatable with some tracks but intermittent with others. I've tried reencoding to opus at various bitrates, internal memory vs sd card, etc and it keeps happening.

Also I've had 2 hard freezes in the middle of playing opus files that I've also never experienced with mp3 or vorbis.

Are these symptoms that I could reasonably expect to be due to insufficient CPU for realtime decoding of opus, or is there something else I should check? Sorry I'm not incredibly knowledgeable about what other information I should provide, but if there's crash logs or something somewhere that would be helpful I'd be glad to post them.

[saratoga]

No, lack of CPU power just causes playback to pause for a bit until it catches up with the decoder.  You'll never skip audio, just play it more slowly.  Those problems sound like a glitch in the decoder or a problem with the files.  You didn't mention what version you're on, but updating to something in the last year would be a good idea if you haven't since a lot of work was done on the Opus decoder. 

[Gene]

No, lack of CPU power just causes playback to pause for a bit until it catches up with the decoder.  You'll never skip audio, just play it more slowly.  Those problems sound like a glitch in the decoder or a problem with the files.  You didn't mention what version you're on, but updating to something in the last year would be a good idea if you haven't since a lot of work was done on the Opus decoder.

I'm running c3c2c91-150421

The opus files play back fine in several players on PC, and decode to WAV fine as well. Any other suggestions?

EDIT: I just manually updated to 47d0537-150518 and still have the same issues.

EDIT 2: And I just used Rockbox Utility and did a full uninstall of Rockbox, then used it to reinstall 47d0537-150518 and still have the same issues.

EDIT 3: After a bunch of tinkering, it seems like the problem is either with how dbpoweramp is converting to opus, or how Rockbox is decoding/playing dbpoweramp encoded opus files.

I generally use dbpoweramp 14.4 (Opus Release 2.2 Opus (1.1)) to encode FLAC to opus and these are the files that sometimes skip the first ~4-5 seconds of a song when played on rockbox.

When I convert the same source FLAC files to opus using foobar 1.3.8 's free encoder pack (Opus v0.1.9 libopus v1.1) the files do not skip on rockbox.

Both the opus files created by dbpoweramp and foobar have no issue playing on foobar 1.3.8 and VLC 2.2.1, and they both decode to wav without apparent issue. I don't know much about opus files/headers/etc technically speaking to see what's going wrong with how Rockbox is handling the dbpoweramp created ones, but I'll gladly help with samples or something if anyone's interested.

[saratoga]

If you post a link to one of those files i can at least try it on my device.

[Gene]

I have determined that the issue is Rockbox's mishandling of many .opus files with Traktor4 tags. These are metadata tags in the file itself created by the DJ program Traktor.

My source FLACs had Traktor4 tags which dbpoweramp was copying to the .opus file, where foobar was stripping them.

VLC, foobar, and other players seem to play opus files with these tags just fine, but Rockbox skips the first ~5 seconds of the song on playback for many of these files.

[saratoga]

The file you sent me fails to decode at all in the sim with a codec header error.  Post a bug report with a link to an example file. 

[Gene]

The file you sent me fails to decode at all in the sim with a codec header error.  Post a bug report with a link to an example file.

I get the same error for any opus file I've tried in the sim, from various sources, even ones that work fine on the sansa clip+ hardware, so I think the sim has a problem, but that's another issue entirely.

Can you try the file on real hardware?