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Bug 3929 - Mix_Init always returns 0 - no supported music interfaces found
Summary: Mix_Init always returns 0 - no supported music interfaces found
Status: RESOLVED FIXED
Alias: None
Product: SDL_mixer
Classification: Unclassified
Component: misc (show other bugs)
Version: 2.0.2
Hardware: x86 Linux
: P2 blocker
Assignee: Ryan C. Gordon
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2017-10-31 09:57 UTC by Steffen Pankratz
Modified: 2018-03-01 15:59 UTC (History)
2 users (show)

See Also:

Attachments
Patch for has_music function (618 bytes, patch)
2017-10-31 09:57 UTC, Steffen Pankratz 		Details | Diff
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Description Steffen Pankratz 2017-10-31 09:57:50 UTC 
Created attachment 3049 [details]
Patch for has_music function

Previously working code broke after the upgrade to version 2.0.2.

The call 'Mix_Init(MIX_INIT_OGG)' always returned 0.
I made sure that SDL_mixer was built with support for Ogg Vorbis.

After I little bit of debugging, it looks to me like the implementation in the 'has_music' function might be wrong.

'Mix_Init' calls 'load_music' which sets 'loaded' to 'SDL_TRUE' for all supported music interfaces.

'Mix_Init' then calls 'has_music' for the requested music interface.
'has_music' checks that the requested music interface was 'opened'.

Which is not that case at that time, so I think 'opened' should be replace by 'loaded'.

For me the attached patch fixed the problem.
Comment 1 Martin Stumpf 2018-02-28 10:38:42 UTC 
Hey!

I had the exact same problem, and the exact same idea.
Replacing 'opened' with 'loaded' in 'has_music' won't work though, as the 'opened' check is intentional later, in 'open_music', to see if the ogg music did actually open. What needs to be changed is the way the error flag in Mix_Init gets generated ...

@devs this should be a simple fix and I'd do it myself if I had the commit rights. Hope it gets fixed soon :)
Comment 2 Martin Stumpf 2018-02-28 10:43:24 UTC 
This problem, however, only concerns the return flag of Mix_Init, it does not break any functionality. Just ignoring the return flag (which is still not good, however) is an acceptable workaround until this gets fixed.
Comment 3 Sam Lantinga 2018-02-28 18:19:03 UTC 
This should be fixed in this commit, can you verify?
https://hg.libsdl.org/SDL_mixer/rev/7fa15b556953
Comment 4 Martin Stumpf 2018-03-01 11:17:33 UTC 
Seems like it :)
Didn't test extensively, but the return code of Mix_Init seems correct.

Greetings and thanks,
Martin
Comment 5 Sam Lantinga 2018-03-01 15:59:58 UTC 
Great, thanks!