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2. Creating audio files suitable for podcasts: The Three Cs.


• Less is ALWAYS more.

• OK, very nearly always. Well, much more frequently than most people seem to realise.

• Edit, edit, re-edit. Cut out the flim-flam. Keep it lean.

• Sound editors (e.g. Audacity) are much more than just tools for putting sounds in order. They are your gateway to audio creativity, so use them to their full potential.

• Not all podcasts should sound the same. Create an audio style that suits your content. Or perhaps the style is the content …


• A podcast is the contemporary equivalent of a radio with a tape-recorder sitting next to it. That was always illegal - for the majority of broadcast music that anyone would want to listen to anyway - and podcasting suffers from the same problem.

• Therefore, you can’t podcast everything legally. You must have the copyright-holder’s permission to do so IN ALL CASES. Some (very few, and mostly independent) labels / artists explicitly issue their music with a ‘podsafe’ license, but this has not caught on in the mainstream for obvious reasons (i.e. loss of revenue, as labels and artists make money from airplay / download licences). Even the biggest broadcasters – who can afford to pay - haven’t got blanket podcasting licences for their output yet. In fact, it’s all a bit of a stushie in legal-land right now.

• In the meantime, play stuff that you can get permission for, i.e. your own music, or music made by people you know who can explicitly give you permission (if they’ve got a label, you’ll need to clear it with them first). Or do speech podcasts! Podcasting is the niche-audience medium par excellence, so do what it’s best at. Check one of the podcast directories to see exactly how niche it can get …


• DO NOT, DO not, do NOT, Do NOT – just don’t, I’m telling you – attempt to put an uncompressed (e.g. CD) audio file up on the internet UNDER ANY CIRCUMSTANCES. There is no point whatsoever until approx. 10 years time when data transfer rates over the net for domestic users are approaching CD transfer speeds. A CD audio file is approximately 10MB in size for every minute of audio. Even on a fast – very, very fast – broadband connection it will take you AT LEAST 5 MINUTES to download 1 MINUTE of audio and that is just a WASTE of EVERYONE’S TIME and bandwidth – including yours. On a dial-up modem, 1 minute of CD audio will take approx. 4 million years to download. That’s not even faintly amusing.

• So, lose the (semi-) redundant musical information inherent in a CD file and compress the finished product (e.g. using the MP3 export function in Audacity, or using iTunes’ integrated compressor) before uploading it. Most media players support MP3, so use MP3 as your compression codec. There are plenty of other ‘codecs’ (file types) around – AAC (which the iTunes music store uses), Real Player, the wondrously-monikered Ogg Vorbis, etc etc. Just use MP3 unless you want to intentionally limit your listenership and piss people off.

• You should be able to choose your compression ‘bit-rate’ when you export your file. If you get the chance, select ‘Variable Bit Rate’ for the best results. Very good results are obtained at an MP3 compression bit-rate (i.e. number of bits / sec) of 192Kb/s. This is for detailed stuff. The iTunes music store works at 128 Kb/s (from memory) and it can be a bit ropey. At less than approx. 56 Kb/s funny wee noticeable sonic ‘artifacts’ get introduced – known as Nyquist frequencies – that go bleep bleep bloop all over your music. They’re kinda cool in their own way, but maybe not what you want. They can be EQ’d out, but only at the receiver’s end, and the music can end up losing a lot of its brightness. Speech is less susceptible to these problems due to its limited frequency range, so you can compress more heavily more successfully – often to 20 Kb/s.

• The higher the bit-rate, the larger the file size and the longer the download. If you want a cat’s chance in hell of people with a dial-up modem sitting at a computer long enough to download your podcast, you’ll need to operate at a maximum speed of approx. 50 Kb/s. At this rate, it’ll take around twice as long to download as to listen to. Faster connection = faster download. Simple.

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howto/podcasting/contentcopyrightcompression.txt · Last modified: 2014/05/23 10:55 (external edit)