How to embed audio in an Impress presentation

[DavidL1]

I’ve created an Impress presentation which has to be exported as PowerPoint so a third-party can run it. The video component of the slides works well whether shown on a Linux (OpenSuSE) / Impress system or saved as a .ppt file and run on a Windows / PowerPoint system.

Two MP3 audio files provide background music for the whole presentation. The first one runs from slide-2 to slide 14, and the second from slide 15 to the end. This works fine on Linux / Impress if all three files are in the same path. (Using the slide-transition menu isn’t a problem - I know about the “Apply Transition To All Slides” catch!)

However it doesn’t work on the third-party’s Windows / PowerPoint system. It might if the location of the audio files were redefined in PowerPoint, but for practical reasons the whole presentation needs to be contained in one PowerPoinf file by embedding the audio.

I can embed the two audio files so they start at the appropiate two slides (#2 and #14) but they run only for the duration of those slides. How can I fix this? I understand PowerPoint has a “Presentation” window where these variables can be set.

[DavidL1]

It seems nobody has a ready answer, and I suspect this is a limitation of Impress which I’ve seen hinted elsewhere. However it significantly reduces Impress’ usefulness IMO. In this case the presentation was a tribute to a deceased family member, and the people involved needed a PowerPoint file which just works, not software-setup instructions.

But for the benefit of anyone with a similar issue, here are some tips & suggestions relating to OpenSuSE 15.5 in particular, but most Linux distributions would include these packages.

The best workaround seems to be converting the Impress presentation to an MP4 video which can be run simply by left-clicking the file, and in this case it was also about half the size of the Impress .odp file. I installed ‘simplescreenrecorder’ configured with an H.264 video codec and two MP3 audio in an MP4 envelope, and it did a great job (thank you Maarten Baert!!). This package supports all output formats supported by ‘libavformat’. But note:

• All multimedia packages must be switched to those in packman-essentials in order to download the H.264 codec.

• ‘simplescreenrecorder’ needs to be able to elevate thread priority in order to maintain proper synchronisation, which can be done by editing /etc/security/limits.conf or by using the ‘nice’ shell command and ‘top’ to check. Each slide was displayed for 18 seconds, with a 1-sec fade to the next one.

Another issue was that the two MP3 audio files had quite different recording levels, but I discovered ‘mp3gain’. To quote from the package description:

mp3gain - MP3 Volume Normalizer based on Replay Gain

MP3Gain analyzes and adjusts mp3 files so that they have the same volume. It does not just do peak normalization, as many normalizers do. Instead, it does some statistical analysis to determine how loud the file actually sounds to the human ear. Also, the changes MP3Gain makes are completely lossless. There is no quality lost in the change because the program adjusts the mp3 file directly, without decoding and re-encoding.

I understand “Replay Gain” is a standard of some sort, and the mp3gain’ package only rewrites the MP3 metadata, not the audio data.