Every week hundreds of mp3 audiofiles are loaded into the Zara playlist of KDX Worldround Radio. Of these a disappointing number contain distortion.
Audio distortion is unpleasant to the ear, causes quick listener fatique, and is generally a turn-off.
There are many ways to generate audio distortion, but a common and observable problem is the over-driven digital audiofile, packed to the hilt and overflowing with clipping distortion. This can be seen on the graph in an audio editor.
For radio stations knowing good audio technique is as important as understanding transmission technology.
A fraction of faulty programs are repaired by re-processing, but it's better to do it right in the first place. Not all kinds of distortion can be corrected.
Operating an audio school is beyond the capacity of this website or the ALPB, but if contributors provide links to textual or video tutorials it might be helpful to anyone seeking to improve their recording know-how.
If you keep your Mp3's at 320K at 44.1Khz sampling rate it should sound good as ling as you keep the DB around 89. Mp3Gain is good or use NextKast to automatically normalize the Mp3's. Its why I love that program so much. Winston has gone a long way to make the Audio sound good Online and Part 15 transmitters. Winamp rips Mp3's very nicely. I think CDEX use to be a nice FREE program that did a nice job too. Media Monkey is a good choice as well. Some of the FREE CD Rippers are not as good.
It is clear from your post, TheLegacy, that you know what's going on with mp3 audio.
In fact, TheLegacy's post offers a quick check to examine your own mp3 knowledge... if you know what The Legacy just said and what he meant by it, you're probably in pretty good shape.
If you aren't sure what he's talking about, it's time for continuing education.
Many years ago a family member was tasked with singing a hymn for her mother's funeral. She was a professional singer having performed with such groups as Fred Waring's Pennsylvanians and also as a vocalist in many stage productions. Though she was very much a professional she was afraid that emotions would overtake her at the funeral so she decided to make a recording of her performance and play that rather than trying to sing.
Someone in the family operated the tape recorder and apparently didn't bother or know how to set and check levels. It was many years later that I was given the original tape to see if I could "clean it up a bit". The most obvious and difficult problem was that toward the end of the hymn at the crescendo the waveform was terribly clipped. (I assume that the recordist set the level at the soft beginning and didn't allow for the crescendo at the end.) Removal of background thumps and bumps was easy but it took quite a lot of effort and time to deal with the clipping. Realizing that one cannot restore what is not there the best I could do was apply filtering to tame the distortion. The result was acceptable but not perfect and most listeners would not notice the problem.
I played my fixed cut for an old friend who is an avid audiophile and I did not tell him about the fix. His comment was essentially that the recording was good but it was distorted at the end. He was surprised that I was able to fix it as well as I had.
If not for the special meaning of this recording I would not spend the time and effort for such a repair.
I learned a long time ago when I made recordings of live performances in high school and college to get it right the first time rather than try to fix it later.
Yes, Neil is correct. Try to make a bad recording sound great is nearly impossible. The link below is to fellow Part 15 Broadcaster Jay in Antioch, Il. He has done a wonderful job cleaning up and re-processing Old Time Radio shows. Give him a listen. I rebroadcast with his permission much of his work. The neighbors love it. he also has a "FREE" re-broadcaster for MAC and Windows that will reconnect if the stream drops and allows you to enter an eight second sound file that identifies YOUR station that is fired by a low frequency tone he generates. It has the acpability to re-sync the time so it is within a few seconds of real-time. Enjoy: http://radio.macinmind.com/
Just wonedering if my rants are distorted.
Atrain you are wondering if I'm speaking about your Rant mp3 programs since I once wrote to you about hum and over-recording.
If it were about you alone I wouldn't post a public comment, but since you've asked, I will comment about your recordings. Keep reading.
First, my complaint about sound has to do with many many programs... I probably carry as many as 100 different shows from many producers.
Common problems include muffled voice quality. A possible cause of this might be the hi/mid/lo equalizer controls on the mic channels of many audio boards. Many people screw those up by cutting highs and boosting lows. I wish those controls weren't right out in the open where people can mess them up. Atrain's mic is excellent, a clear professional quality mic.
Another frequent problem is clip-distortion caused by over-driving a mic-preamp input, very often because condenser mics have far higher output than dynamic (magnetic) microphones, and the condensers need special padding/attenuation/compensation to enter the preamp without distortion. Atrain Radio does not have mic pre-amp distortion.
Phase distortion is heard as smeared highs when two mics are mixed from different distances causing "time-distortion", caused either by poor stereo setup or mics being too close together in a multi-mic setup. Atrain Radio does not have phase distortion.
Hums and buzzes. Not as common as the other problems, but it does happen. Atrain's first couple of Rants had a noticible AC hum, but I talked to him about it and he got it solved.
Mics too far away from talkers. Too common and I hate it. Podcasters go to an event to record a speech with mics 10, 20 or more feet away from the talker. Horrible and unprofessional result very annoying to listeners. Atrain has never had this problem on his recordings.
Over-driven mp3 audiofiles. A biggie and very common problem. I think the engineer is trying to cram maximum level to use up every digit of headroom but overshoots into clipping and the ugly distortion. This is similar to overmodulating a radio transmitter, but it's the audiofile that's being over-modulated. It is good practice to leave some unused space above the peaks on the level graph, the signal-to-noise of digital sound is sufficient to leave a safety margin above the peaks. Atrains Radios files have noticable over-shoot and clipping of the audio files, but he is not alone as many many programs have the same problem. With Atrain's Rants I am able to lower the recording level and de-clip using Audacity.
Not a stab. It's a mission to perfect the sound of online and part 15 audio.
Atrain you are wondering if I'm speaking about your Rant mp3 programs since I once wrote to you about hum and over-recording.
If it were about you alone I wouldn't post a public comment, but since you've asked, I will comment about your recordings. Keep reading.
First, my complaint about sound has to do with many many programs... I probably carry as many as 100 different shows from many producers.
Common problems include muffled voice quality. A possible cause of this might be the hi/mid/lo equalizer controls on the mic channels of many audio boards. Many people screw those up by cutting highs and boosting lows. I wish those controls weren't right out in the open where people can mess them up. Atrain's mic is excellent, a clear professional quality mic.
Another frequent problem is clip-distortion caused by over-driving a mic-preamp input, very often because condenser mics have far higher output than dynamic (magnetic) microphones, and the condensers need special padding/attenuation/compensation to enter the preamp without distortion. Atrain Radio does not have mic pre-amp distortion.
Phase distortion is heard as smeared highs when two mics are mixed from different distances causing "time-distortion", caused either by poor stereo setup or mics being too close together in a multi-mic setup. Atrain Radio does not have phase distortion.
Hums and buzzes. Not as common as the other problems, but it does happen. Atrain's first couple of Rants had a noticible AC hum, but I talked to him about it and he got it solved.
Mics too far away from talkers. Too common and I hate it. Podcasters go to an event to record a speech with mics 10, 20 or more feet away from the talker. Horrible and unprofessional result very annoying to listeners. Atrain has never had this problem on his recordings.
Over-driven mp3 audiofiles. A biggie and very common problem. I think the engineer is trying to cram maximum level to use up every digit of headroom but overshoots into clipping and the ugly distortion. This is similar to overmodulating a radio transmitter, but it's the audiofile that's being over-modulated. It is good practice to leave some unused space above the peaks on the level graph, the signal-to-noise of digital sound is sufficient to leave a safety margin above the peaks. Atrains Radios files have noticable over-shoot and clipping of the audio files, but he is not alone as many many programs have the same problem. With Atrain's Rants I am able to lower the recording level and de-clip using Audacity.
Not a stab. It's a mission to perfect the sound of online and Part 15 audio.
"Program Relations" is the title given to the staff member who keeps contact with program producers, and for a Part 15 station it is one of the jobs for the sole station owner.
Some of the issues the "program Relations" person must face include obtaining permission to carry a program, dealing with objectionable content, hoping for good audio quality from good programs, and try to keep the job itself manageable so it doesn't take up too much time.
At the front of every relationship is asking for permission. I usually want this by e-mail so I have proof, but recently I severed ties with a program that had given me verbal permission and then complained, "I don't remember giving you permission."
I've had about five shows with excessive and needless use of the F-bomb so I simply marked their links as VULGAR and stopped carrying those shows.
As explained in Post # 1 there are audio problems, and if producers don't know how to handle audio I usually try to stay out of it because I've found that many individuals will keep doing it the way they do it and become annoyed by criticism.
Case in point was a weekly half-hour news magazine show that ran very loud music behind their narratives often making it impossible to understand the words being spoken. I wrote them an e-mail about it, saying that the content was great but was often unhearable. They shot back a bunch of excuses and continued doing the show the same way, so I dropped it.
Carl Said: "Atrain's first couple of Rants had a noticible AC hum, but I talked to him about it and he got it solved."
I asked: Did you offer him a warm meal?
Well that puts me at ease, and I shall try to leave more space on the file to lessen the over-modualation.
Druid Hills John WDCX asked if we offered Atrain a warm meal for fixing audio hum.
As of this time the KDX Worldround Restaurant is not open but we will be opening the "Stopped Truck Diner" featuring Line Dancing with Pets On Leash. Probably serve cold snacks.
KDX Worldwide now in Japan: https://www.pinterest.com/pin/126593439497205503/
The Japan KDX franchise goes to show that Part 15 stations have worldwide influence that they aren't even aware of.
I would like to visit our Japan establishment, but I'd never get the Gas Meter Radio through airport security.
Add this one to my list of things that go wrong with mp3 audiofiles that are posted as podcasts or programs...
Audio tracks that otherwise sound fine but occasionally have drop-outs.
And no, you do not have this problem with your audio programs Atrain!
I'll tell you one example of the problem...
The Reverend Billy and his Church of Stop Shopping does a weekly show on WBAI New York, which appears as a video-file from which I extract an mp3 track. The production and mixing is complex and well done, the audio quality excellent, but every so many minutes or seconds the audio disappears and then comes back.
http://www.revbilly.com/the_rev_billy_show
What causes that problem?