Audio Processing: Exploring Dynamic Range Compression
Tools and Updates
Progress Report #2
Project Updates
So Far...
Our project has been moving along nicely so far - we are in the process of implementing six different audio compressors utilizing both feed-back and feed-forward arrangements and three different side chain topologies. We have altered our initial focus slightly as we decided to move towards teaching compression in a broader sense (in both technical and laymans terms) instead of focusing specifically on the attack and release parameters of one compressor. We believe this will allow our work to foster an understanding of audio compression for a wider audience.
Figure 1: Encoded name for each of our six compressors - the values in this table are used as inputs to our driver function in MATLAB
Moving Forward
Our plan for the last week before we present is to put our six compressor implementations through a variety of tests using different input parameters to evaluate their musical characteristics. We will fully develop our analysis based on these tests and present our results. We also hope to incorporate our original idea of highlight attack and release time for at least one of our compressor designs. We have also talked about including a 'distortion' or 'warmth' componant in one or more of our designs to more accurately emulate the sonic characteristics of analog designs.
Our Tools
All of our processing thus far has been in MATLAB using many of the functions we have discussed in class (audioread, for example). We have also directly implemented one of the 'simple systems' we saw in our course work, namely the Leaky Integrator, as a part of our peak detector module in our compressors. We plan to implement our compressors, or at least a subset of them, as VST plug-ins as well (VST is the most commonly used format for plug-ins to Digtal Audio Workstations). In order to develop these plug-ins we will make use of both C++ coding and another intermediate plug-in format called RackAFX.
The most exciting part of our project so far was to hear our compressor working on audio that was recorded by one of our members. All three of our members are also audio engineers so it was very rewarding to create a tool like those we use every time we are in the studio.