The blog is being migrated and merged with multiple Imphenzia blogs so the format and content will be inconsistent for a while.

Powerboat passing by to game-loop audio

This year I went to the Nynäs Offshore Race which takes place only a 30 minute walk from my home in Nynäshamn. I brought my new "field recording kit" that may not be the most portable setup in the world, but it gives me the best option for recording directional spot mono audio using a Rode NTG3 shotgun microhpone and environmental ambiences and stereo effects with a pair of Sennheiser MKH 8040 micorphones. The mics are housed in wind-protecting Rode and Rycote blimps with dead kittens (those huge furry things to block most of the wind.) I record the 3 channels of audio into a Sound Devices 633 field mixer at 192 kHz 24 bit audio.

I recorded quite a few powerboats as the passed by - but getting usable game audio is quite tricky. I'll tell you why:

First of all, there is a PA system with an announcer that feels obligated to speak non-stop which is great for the audience but terrible for someone who wants to capture the boats and nothing else. I had to find a spot close enough to the boats, but far away enough from the diesel-powered speakers pushing out a distorted commentator voic.

Then there is the audience, they tend to chat and cheer a lot so I had to find a spot far enough away from most of them - luckily the powerboats are loud so the gain is not set too high which reduces the chance of spectator voices.

Another challenge is that you don't really get that close to the boats, they have to drive where it's deep and safe enough which isn't always that close to land.

The splashing water is another parameter to consider, but again, not loud enough to be too great of a problem.

The biggest problem, however, is that the boats pass by producing a sound that fades in and out and shifts in pitch due to the doppler effect. By default they will be great if you want to have the sound of a passing powerboat - but you could never apply that sound to a boat in a game since it simply doesn't loop well.

Turning the passing powerboat sound into looping game audio

I put together a video where a single powerboat passing by is turned into a short loop of game audio that could be used on a powerboat. If you need to do something similar, or if you are just curious what work goes into converting the sound, have a look:

I ended up using the audio from the Rode NTG3 shotgun mic this time since I didn't need it to be stereo and it produced the longest sustainable sound as I aimed the microphone at the boat as it passed by. It also contained the least polluted sound since the design of the shotgun mic blocks off-axis sounds fairly well.

This sound loop, among many others, will be included in the next update of the Universal Sound FX library.

Create seamless loops for game music

Making seamless loops is an essential part in creating music suitable for games. Loops will keep the distribution size of games to a minimum and it also makes the audio cheaper to license which is crucial for smaller indie game developers.

Although I've been making music as the trance artist "Imphenzia" for 14 years, which is starting to sound like a very long time also making me sound old, I've only been releasing music for games during the past 3-4 years as "Imphenzia Soundtrack." I mention this for no apparent reason at all, so lets move on.

I've created a video tutorial of how I go about when creating a seamless loop. In this case it's an orchestral movie-style piece of music that will be added to my library of non-exclusive music. I use Steinberg Cubase 5.5 and Sony Sound Forge 10 to create the loop but you will probably be able to replicate the steps in your sequencer and audio editor of choice.

Time for the tutorial - have a look at it and don't forget to watch it in 720p so you can read the options better.

I hope the tutorial helps you to create perfect seamless loops of your music. Some of the important things to stress are:

  • Repeat the music you want to loop three times in your sequencer, exactly 3 times down to the measure. Why? It's because you want to ensure a good loop including any trailing audio at the end of the music piece, it could be decay, reverb trails, and echo.

  • Export the audio to a Wav file (or a format of choice) and load it into a good sound editor.

  • Crop out the center third of the music, use sample precision to do this.

  • Remove any clicks by ensuring that the audio file starts and stops on 0 dB exactly (or infinitely low as Sound Forge describes it.) This is performed by fading in the start and fading out the end by only a few samples, 20-100 samples is usually suitable.

In the video tutorial I also mention a Javascript that I've created for Sound Forge that will perform the selection of the center third, cropping, and fading the ends to ensure a good loop point. This particular Javascript will be the topic of my next blog post so do come back soon.