Preparing releases from internet-based broadcasts

Internet Radios: Common rules, frequent mistakes and all about superior quality.

Basic Radio Selection Considerations

• For TheMixingBowl of interest are only the stations offering DJ sets that you can't buy anywhere as that it is what TheMixingBowl is all about. Only radio stations meeting this requirement are listed here.
• Not all radio stations broadcasting DJ sets are suitable for TheMixingBowl.org as they do not meet the minimum quality requirements to allow their sets being uploaded to TheMixingBowl. This applies mainly to Internet-based radio stations as most of them are broadcasting nuked sets of low quality (sets that would be available elsewhere in much higher quality). A whitelist for high-quality internet-based stations broadcasting original DJ-sets can be found Catego.
• Special care needs to be taken for radio stations broadcasting digital signals as the bitrate might be very low. Minimum acceptable bitrates for digital broadcasts need to be taken into account.

Radio Quality Assessment

Many radio stations are broadcasting in different formats and not only in one. We assume that all radio stations are broadcasting in stereo in the following.

• Analogue radio broadcasts (FM frequencies, cable, satellite) [RAW - format]
• Digital radio broadcasts (DAB, Freeview, DVB-S, DVB-T, DVB-C) [ MP2 -format]
• Digital internet broadcasts (stream, podcast) [ MP3, AAC+, WMA, RA, OGG -formats]

One can now safely deduce a quality order among all the different formats. Topmost given is the format with the highest quality, the entry at the bottom of the listing is a strict No-No if you have a choice.

• Digital broadcasts with complete transparency (exceptionally high bitrates).
• Analogue broadcasts without noise and digital broadcasts with near-transparency.
• Noisy analogue broadcasts and digital broadcasts at medium bitrates.
• Digital broadcasts at low bitrates.

Okay, we do not need to discuss the quality of analogue broadcasts as everyone can easily distinguish a noisy broadcast from an excellent quality broadcast but when is a digital broadcast transparent or near-tranparent? One has to know, that all digital formats used to broadcast music are lossy and do not contain all the original audio information. Lossless digital broadcasts do not exist up to now. The quality of a digital broadcast is determined by two values both together, the bitrate and the frequency. Transparency means that the human ear cannot distinguish the broadcasted signal from the original high quality music set.

• Frequency (almost independent from the format):
  • >40 kHz: transparent (such as the "CD-quality" of 44.1 kHz).
  • 32-40 kHz: near-transparent.
  • <32 kHz: one can hear the lower frequencies only, the high frequencies are cut off.

• Bitrate (for the formats MP2, MP3, WMA, RA valid as a rule of thumb):
  • >192kbps: transparent
  • 160-192kbps: near-transparent
  • 112-160kbps: medium bitrates, one can easily hear differences to the original
  • <112kbps: low bitrates, usually with lots of "crispy" distortions at higher frequencies

• Bitrate (for the more advanced formats AAC+ and OGG):
  • >160kbps: transparent
  • 96-160kbps: near-transparent
  • 64-96kbps: medium bitrates, higher frequencies are removed, sounds "smooth".
  • <64kbps: low bitrates, suitable for speech or mono transmissions only.

By looking at all available radio stations one will easily find out that a broadcast of transparent audio data does not exist. Most are not even near-transparent. It is therefore recommended to listen to analogue broadcasts, where possible, especially when transmitted by cable or satellite. The same applies for recordings of audio broadcasts that are going to be uploaded to TheMixingBowl

This page is a stub. You can help us expand it by logging in with your TMB username/password and editing it.