From App Builders development team
We want your feedback!
In SAB 8.5, we added support for audio encoded with the Ogg Opus codec stored in WebM container format. Ogg Opus has better quality at lower bitrates than MP3. The audio files distributed by Faith Comes By Hearing are 64 kbps MP3s. You can encode that audio with Ogg Opus at 16 kbps at 1/3 to 1/4 of the size and it will sound similar in quality.
Ogg Opus in webm container format is supported by Android 5.0 (API 21).
Ogg Opus in caf container format is supported by iOS 11. [We made the iOS app support webm and do the minor conversion in the app so you can use the same audio files with both Android and iOS.]
We are working with Faith Comes By Hearing to support their next version of Digital Bible Platform. They are interested in supporting Ogg Opus at 16 kbps some time in the future. So webm files should be able to be downloaded from “FCBH Digital Bible Platform” source in Scripture App Builder.
To convert MP3 to Ogg Opus, you can use FFmpeg. This gets installed with Aeneas.
With SAB 8.5, if FFmpeg is installed and can be found, you can do the conversion from the Audio page.
- go to the Audio Files tab
- select the chapters you would like to convert
- right-click and select “Convert Audio Files…”
- select File Format = webm, Bit rate = 16 kbps and click Next
- click Create Files (the default location is App Builder/Scripture Apps/Audio)
- click on the “Add Audio Files…” button in the Audio Files tab and browse to the location of the new files and add them to your project.
If you want to do it on your own from the command-line, here are the parameters that are used:
ffmpeg -y -i input.mp3 -map_metadata 0 -write_xing 0 -b:a 16k -map 0:a -vbr off -application voip output.webm
Please contact me by replying here or by email (chris underscore hubbard at sil dot org) with your feedback on the quality of the audio in 16 kbps Ogg Opus.
For His Great Name,
Lead Mobile Software Developer
SIL Language Technology Development