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Bug 5187

Summary: [PATCH] ogg playback not working on big-endian devices when using Tremor instead of Vorbis
Product: SDL_mixer Reporter: sergiou87 <sergio.padrino+libsdl>
Component: miscAssignee: Ryan C. Gordon <icculus>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: critical    
Priority: P2    
Version: 2.0.4   
Hardware: PowerPC   
OS: Other   
Attachments: Fix for ogg playback on big-endian hosts

Description sergiou87 2020-06-14 10:15:05 UTC 
Created attachment 4382 [details]
Fix for ogg playback on big-endian hosts

The root of the problem is that SDL_mixer *always* provides an audio stream in little-endian byte order (AUDIO_S16). This has two consequences:

- Since Tremor doesn't swap bytes for big-endian devices, it means ov_read from Tremor will provide data in big-endian instead of little-endian as required by the AUDIO_S16 mentioned above, so audio will be unplayable.

- When using Vorbis, bytes will be swapped twice in big-endian devices: first by ov_read to little-endian when reading the file data, and then to big-endian by SDL_Convert_Byteswap before sending the data to the audio device.

Applying this patch fixes Tremor support on big-endian devices and improves
performance/efficiency of Vorbis on big-endian devices.

You can see the changes here: https://github.com/sergiou87/SDL_mixer/commit/a2ceebacdd005791c04b60e5a88c254c619bdffc

Also attached a patch in case it's easier to handle. Happy to submit it to the commit mailing list also if makes things easier.
Comment 1 Sam Lantinga 2020-06-15 17:08:47 UTC 
Patch added, thanks!
https://hg.libsdl.org/SDL_mixer/rev/e6f2d0a83df5