Tag Archives: compression

Red Hot Radio

As it turns out, just like in audio engineering, in 2-way radio you can’t just look at the power meter and assume your signal is great. It might actually be unintelligible.

Back in my early days (6 months ago), I noticed that my RF power meter seldom hit 100W on voice. I know that the duty cycle of voice on sideband is significantly less than 100%, but even the peaks weren’t hitting it. Frustrated with apparently not getting my signal out of the region, I turned on the built-in audio compressor, tweaked the compression amount, and got that average power a bit higher to somewhere that looked right.

As I learned recently on the regional AARC 10-Meter Net (Sundays 3pm CT on 28.410MHz USB), my fellow net participants complained that there must be some RF feedback into my mic or something because my vocal peaks were seriously hot and distorted. They had been complaining for a few weeks, and I assumed it was some insufficient grounding in my car. While discussing it during a net, I mentioned that I had compression turned on; they asked me to turn it off, and the distortion went away.


So, uh, remember that owner’s manual thing, and the part in it that tells the owner how to configure mic gain and compression? Yeah, so if I follow that, and look at the ALC (audio level control) meter instead of the RF power meter, and if I adjust things so the average and peaks stay within a specified range, then my signal should sound better.

I hooked up my dummy load, went to 10m sideband, spoke gibberish into the mic and tweaked the mic gain and compression amount to a range that makes sense (at least visually). I’ll try an A/B test on the next 10m net to see if it worked.

It’s not the output power that wins friends and gains contacts; it’s the signal quality. You can reach across the country on 10W if your antenna is good, the sky is right, and your signal is clean. Otherwise, you’re splattering your distorted RF energy across the band, you’re burning battery power, and you’re wasting someone else’s time.

Catching FLAC

Last weekend, I began the slow, arduous process of re-ripping my entire CD collection into files easily playable on my computer. This time, instead of ripping into 192kbit MP3 with the LAME codec (like I did last time), I’m ripping them into FLAC. This has important implications.

First and foremost is that FLAC is lossless, meaning no data is thrown away between the transition from CD to the final sound file. MP3 is a lossy codec, and uses tons of statistical mojo to analyze the sound data of the CD and throw away the bits that your ears can’t hear, crunching the file size tremendously. The problem with this method is that you’re losing the quieter nuances of your music. FLAC’s strength is that it’s able to take the input waveforms and chop them up into similar, easy-to-compress chunks, making the file smaller than the original uncompressed form but on playback the audio is a perfect, exact copy of its original form.

Secondly, since FLAC doesn’t compress the file sizes as well as MP3 (with the obvious quality tradeoffs), the overall space needed to store my music collection has grown tremendously. Instead of storing an entire album in roughly 80 megabytes of space, it now takes an average of 350 megabytes. That’s a large bite to swallow, but with the falling prices of high-capacity hard drives, it’s nothing nowadays. Considering the audio CD format stores around 700 megabytes, that’s not so bad.

I’ve been meaning to do this, because even with my bad ears I can still sometimes hear the strange audio artifacts of the MP3 compression — called “sizzle” in the industry — when I’m listening to my stuff. After I ripped my first disc and gave a listen, I was shocked at the quality difference. There were little pieces of the sound, stuff from the studio, or the audience, or quiet stuff put into the mix, that I never knew was there after listening to the MP3-encoded form for years. The sound came out of my speakers; FLAC saves the exact same stereo phasing that’s mixed into the CD in the final file, and no amount of MP3 bitrate is going to capture that level of nuance. I’m shocked.

So last weekend, I bought a 1 Terabyte hard disk (that’s roughly 1,000,000 Megabytes), installed it, and started ripping the CDs on my shelf. Within two days, I had the shelf of CDs I’ve acquired since 2007; about 60 discs total. And then I cracked open the 120-pound crate of CDs that I’ve collected since my first disc in 1991. These were packed up at my last place, and I’ve just now gotten around to digging them out. I’m about 1/8th of the way through my entire collection, so I expect this to take a while.

When it’s all said and done, my hope is that I will never have to break out a CD again to get quality audio. The end FLAC files can be used as perfect copies to produce any sort of MP3, OGG, or next-generation compressed audio file for ease of portability. Any other use (like for listening at home), I can rely on the FLAC.

MIDI In the Window

My song is done. I did it. I finished a project. I won.

It’s called “Stars In the Window”, and you can’t hear it until Wires 6 comes out. It’s in the electronica phylum, naturally, just like all the rest of my music. But this song is an evolution from the rest. The methods are different. The tools are different. I have a drum machine. I’m using softsynths. I’m using MIDI. With enough outboard gear, I could record the entire song, all instruments and parts, in one take, if I wanted to. That’s the beauty of MIDI. Once you record audio data, the content (patch, notes, and arrangement) is mostly fixed; once you record MIDI, you can edit and rearrange with no loss of sound quality. It’s just note data, and it’s up to the synths to figure it out on playback. It’s beautiful.

So, like I’ve said before, I sat up at a coffeeshop, started the sequencer with a clicktrack, and used MIDI-Ox to turn my computer keyboard into a MIDI controller which I played like a piano. I just played ad lib, and let the song flow where it went. When I felt like I was done, I stopped recording, saved the MIDI data, and played back what I had just done. Spent the next week or two in the editing phase, playing it back a thousand times until I figured out the best note spacing, song arrangement, note volumes. When I was satisfied, I wrote a bass track to counterpoint the melody. Polished that.

And then during that process, figured out a basic drum rhythm with kick and snare. The idea that stuck with me the most was a shuffling rhythm with a sound halfway between a jazz brush and a soft-rock snap. It’s not your usual 4/4 kick snare electronic combo, and I’m happy with that. This gave me ample opportunity to learn my drum machine, learn the basic rules on programming a rhythm phrase, how to make different phrases and string them together into a song which I could play back in realtime along with the rest of the song’s audio. MIDI timecode is a beautiful thing.

Then, the cymbals. I wanted the cymbals to be more lively, more, I dunno, freeform than could be afforded with the limitations of the 16-beat rhythm phrases I had built. So I went to the aide of my MIDI-controller, used that to hammer out the basic cymbals track, with the drum machine as the sound module. Got that data down and spent the better part of a weekend fine-tuning it, editing cymbal events, working on velocities. Nearly made myself deaf from the high-frequency snaps while editing because I had my headphones on and the sound was too loud while doing so…for hours on end. Ears fatigued, I had to take a few days’ break; they’re still not 100% back to their 70% capacity, but I’m fairing well. The cymbals got done. They moved iteratively. The whole process was iterative. They were accidental in how they appear to be not formulaic and how they sound like the work of an improvisationalist drummer. That surprised me.

The writing phase was over. Time to render everything into seperate sound files and deal with the mix and effects. The basic mix was good; my first time listening to everything put together, my first chance to hear all the work of my hands put together and as one solid piece, it gave me an eargasm. I wept.

Spent about a week working on the mix, trying to get it louder. It sounded great on its own, but it needed to stand up volume-wise to other music of the genre. This is when I learned about audio compression and what has been dubbed The Loudness War. It is good to be loud enough, but not too loud. I noticed that the louder I got it, the more distorted and “tinny” it got, the more it lost its gorgeous dynamic range. The distance between soft parts and loud parts is very, very important, and it’s a thing overlooked by today’s music, which is a travesty.

Compression is a cold, uncaring bitch. I’ve learned that. She gives you great and swelling promises of volume and clarity, and then destroys your dreams by breathing on you. Pumping. Distorting. Clipping. I learned that hard-knee limiting is a dangerous thing, and only to be used as a last resort. It crunches the tips of your waveform until they’re flat, and each flat spot spews clipped overtones all over your clear sound. I tried various compressor recipes and found that putting mild compression on your melody tracks, punchy compression on your bass tracks, and using a series of 3:1 -6dB compression followed by hard-knee ∞:1 -3dB compression on the master was the best mix. The best decay time is short; this prevents breathing. Overall, this gives the effect of singling out each track for their unique properties into something that meshes into a master mix which is then itself put through a soft-knee compressor. I’m so happy with the mix.

Having good sources was most important. This time around, I’m using real synths, not canned loops like the rest of my music (even if I made those loops). This is the real thing. If you start with something that’s full and rich, you end up with something that’s full and rich. Matter of fact, until the end of the writing, before I added the sounds of crickets and frogs on the ends of the track, nothing was a canned loop. Yeah, like woah. A vast departure from my traditional tools and methods. About time, too.

All in all, the sound of the track is as if Bill Laswell had a love-child with Enya Ryan who then gave it up to Toby Marks of Banco de Gaia for adoption, who raised it in the tradition of techno (all major chords). The love-child then looked in the past and tried to track down its ancestors and instead found something more rewarding: itself.

Once I played back the initial melody I had pecked out on the keyboard, with the patch I had recorded with, the image I drew in my mind was that of staring out the window of a dark van or car, like I had done so many times in my youth, looking out at the stars flying over us as we flew down the southeast Arkansas highways. Quite often, those stars were my solace; they were my sign that there is something out there, that I was not alone, that we are not alone. Those same stars I gazed at in my college years. Those same stars I see on my drives out of town. Those same stars are over us now. Bigger than I, more numerous than we, more permanent than everything. There. They are there. In the window.