VA Mastering Session
Given that the focus of this project’s creative application lands on mixing in the post-production stage of audio production, mastering tracks with incorporation of VA encoding is something that would be beneficial to enquire into as it falls within the same production stage. Mastering full tracks with VA may present some different applications and also investigate whether existing stereo image phase relationships can be taken further into exocentric space.
Starting the iterations in the following room model with default material settings, and a surround 6-channel arrangement of sources with LR split mono signals on each respective side. Iteration 1 led to some heavy distortion of mid-bass frequency resonances, subsequently iteration 2 followed with reduced signal volume from sources. The result was a VA render which contained more dynamic range, however distortion continued to alter the mid-bass undesirably.
It 1 - VA Rec#01.wav https://drive.google.com/file/d/1vbW7sPkpAOdzeUjx0siLUyTjVwmfo-YK/view?usp=share_link
It 2 - VA Rec#02.wav https://drive.google.com/file/d/1hYCUPhkjHQ0bg5-BSPcUMPzRvoasxvFH/view?usp=share_link
In these there was also a heavy buildup of reflection cues incoming from the front which resulted in an internalised stereo image opposed to an exocentric image, this would be addressed in the next iteration. Following iteration 2, a geometry tagged gameobject was placed several feet directly in front of the HRTFs receiver perspective to deflect front reflections and act as a baffle board for these unwanted cues. The requirement here to implement into a master requires a subtle approach to the application of VA encoding, as this stage of post-production works with small adjustments to the overall final mixdown. The baffle board here worked with this in mind, as it pushed the VA stereo image wider and although reducing the overall level the board also maintained a clear centre space for the unprocessed track layer.
It 3 - VA Rec#04.wav https://drive.google.com/file/d/1o5spJWe0aEKcLHLSORUiDH3JDbE6I9Qv/view?usp=sharing
On iteration 4, I rearranged the source positions around the listener. This was done to increase the exocentric aspect of the render, as previous iterations used a round arrangement of sources circling the HRTF receiver which led to smaller differences in ITD / ILD between each. Aiming to increase these by reconstructing the original stems within the VAS at large differences meant that the original stereo image would be altered further, splaying the 6 LR sources into more of a funnel with sequentially taller height positioning and increased width the more forward LR sources are. EQ was also applied to the stems to reduce the bass which was leading to high-amplitude resonances and distortion.
It 4 - VA Rec#05.wav https://drive.google.com/file/d/1b1JCUeh0M7yi76m8ql3SgiM8aa-R5sp6/view?usp=sharing
Following iteration 4, it was clear the reduction in bass had led to high-mid output which when layered with the original track in Logic Pro resulted in a tinny and metallic mix, possibly due to phase issues from the high-mid focused VA. Along with this, the lacking bass energy sapped a distinction of liveness from the final layered VA / Original track, for this reason the EQ was removed and the original stems would be utilised going forward. To further the difference of ILD / ITD I also made subtle sequential increases of source level from back to front perspectives so that the far front sources output at the highest level, and moved the baffle slightly nearer to the receiver to compensate.
It 5 - VA Rec#07.wav https://drive.google.com/file/d/1dOO00zG7C8PrpC23Mpf8sfmknNUAuH53/view?usp=share_link
As iteration 5 had gleaned positive results with a now more spatial render lacking the EQ, iteration 6 focused on gain staging to properly match levels of reflections to the original track levels whilst still maintaining no clipping. During this there were many cycles of alteration, monitoring playback / recording, assessing and then reiterating to reach a point where levels were balanced in a full stereo image without distortion. Once this was met a final render was done for the next iteration, there was however the issue of this iteration having a point where timing slipped in the playbacks internal clock, leading to a discrepancy around 30 seconds in where all timing differences were shifted. This was likely due to the reimported audio not being set to PCM in it’s engine compression properties, being set instead to Vorbis, so this was adjusted to PCM. There is still at this point the issue of occasional artefacts crackling into the renders, this is seemingly due to performance drops and lag on the engines end where processing takes place, as they are both audible in the monitoring and in the recording, demonstrating they’re occurring at least before the recording stage / internal audio routing software.
It 6 - VA Rec#08.wav https://drive.google.com/file/d/1bJ4Vv8CqpXwZOSbFexj210wbaPnflSl4/view?usp=sharing
Following iteration 6, there was some final adjustment of source placement further in the directions set earlier in iteration 4. This was to increasingly emphasise the spatial aspect and reflection cues of the render, as when layed back in with the original track these were still masked somewhat by the unprocessed layer. Along with this alteration, the mixer levels within the engine itself were adjusted to allow for more dynamics as by this point there was a squash to the final encoded recordings due to high-amplitude levels peaking and being walled off. The adjustment of mixer in the engine meant that on render of cues the levels would still maintain their dynamics, as source adjustments are not realised until render these wouldn’t have the same effect if reduced, with overall virtual acoustic reflections and cues only being minimised rather than overall final recorded level. Finally before the next iteration, I adjusted some of the room material properties to the wood model provided by Steam Audio, with the aim of adjusting resonants slightly to a more high-mid focus.
It 7 - VA Rec#10.wav https://drive.google.com/file/d/1OFZKpjhAhCzxZnTBKWPqknu3GfytQwhv/view?usp=sharing
For the next iteration of this mastering session for the track, source levels were adjusted based off what was previously stated with the aim being to increase dynamics between each relatively to create a more visceral timbre which emphasised the live sound I was aiming for. Along with this, I bounced the stems for sources without the bass & kick along with some percussive elements to focus the VA encoding on more naturally long-tailed reverberant sounds as well as away from the low end where mud and boom had accumulated. The result of this iteration then when layered gave the results aimed for, with a subtle enhancement of stereo width imparting reverberant and resonant room timbre with a live feel and increased level of depth.
It 8 - VA Rec#14.wav https://drive.google.com/file/d/1zKzMqMXo7Z4ITThn9Cyr_C60MbDSh9Gi/view?usp=share_link
Before the final iteration render was completed, the room material was switched to the glass model to get something with more mid-high focus over the previous mid range resonances, noticeable especially on the snare. Into the mastering session now, the final iteration recording has been imported alongside the original track, these two then doubletrack to make the final master. For processing, linear EQ had to be used to maintain any phase relationships by avoiding any coloration and ensuring the original phase is maintained, the inverse with a standard EQ unit being what led to the tinny metallic timbre earlier. As VA signal contains much less direct sound over reflections, the two are bussed together similarly to how an aux sends to reverb units then returns to the channel. Below are versions of the combined final VA master, along with the bounces of both the clean / VA tracks individually.
Dry - DRY ONLY - Sapphire Remix - Mike Blue - Sociodelic - VA Master 44.1kHz.wav https://drive.google.com/file/d/1FoNcGN5T3weDPr8uXiy0YgikikispNgZ/view?usp=share_link
VA - VA ONLY - Sapphire Remix - Mike Blue - Sociodelic - VA Master 44.1kHz.wav https://drive.google.com/file/d/1s3eiNMmd7DQQclJivTjnP8w3xEsGg714/view?usp=share_link
Final VA Master - Sapphire Remix - Mike Blue - Sociodelic - VA Master 3 44.1kHz.wav https://drive.google.com/file/d/1KbXwPT2sxunXwqlX8nNFBnbRabrfWII4/view?usp=share_link
Following the mastering implementation documented here, the same process was applied to Track 5 / 6.
