Tech Specs

[ezahp]

Here's the tech spec sheet for BBC radio - the British state broadcaster. Interesting reading............



FILE FORMAT
Audio files should be submitted in the RIFF/WAV format with metadata either contained in a separate XML file or embedded in one of the header chunks. This will allow automation of file transfer.
If the audio file is programme material delivered for broadcast, then the audio format for the file will be : Linear PCM, 44.1 KHz, 16 Bit (or greater, by prior agreement) except for programmes for BBC Scotland and BBC Northern Ireland, which should be at 48kHz. See: Linear Audio.
AUDIO PROPERTIES
Audio Quality:
Audio quality remains the producer's overall responsibility. The importance of consistent levels and overall quality cannot be over-stressed. Distortion, noise, induced hum etc. should not be audible. During the production process, audio should not be subjected to bit rate reduction (eg recording on Minidisc) see: Data Compression. Multiple transfers involving bit rate reduction should be avoided, otherwise coding artefacts are likely to be audible. See: Cascade.
The recording should contain, where appropriate, the full transmittable audio bandwidth (20Hz to 20kHz). Exceptions may be made; examples include archive material or material gathered necessarily under adverse conditions. Please see the guidance for outside source working.
Any such deviations from the normal standards or anything which could be interpreted as a fault or error must be noted on the recording report.
For details on Balance Control, refer to the relevant commissioning Network.
Stereo:
Stereo programmes must always be supplied as a single wav file with the two channels (see: Channel) recorded as A and B (ie. left and right) not as M and S (ie. sum and difference).
Stereo programmes must be recorded so as to be compatible for listeners in mono. In general signals should be in phase between channels. The S (difference) signal should rarely exceed the M (sum) signal (otherwise cancellation can result when the signal is heard in mono). Avoid extremes of stereo imagery or “out of phase” effects as these present problems with mono compatibility.
Mono:
Even if the programme content is entirely mono it should still be recorded as two identical channels (A and B) with zero phase difference between them.
PROGRAMME & RECORDING LEVELS
Maximum level of programme audio:

For those using a correctly calibrated PPM the programme audio should peak up to PPM6 on A, B and/or M. See: LEVELS.

If you are using a digital bar-graph meter (see: Meters) regular readings of -10dBFS (10dB below absolute Full Scale or Maximum Coding) are desirable. Occasional transient readings above this are acceptable.
The BBC will accept files whose programme level equates to peaks up to PPM 6. See: Peak Programme Level.
Normalisation should not be relied on to control programme levels.
For a wav file demonstrating network specific audio balance and control requirements, contact the commissioning Network.
TONE. See: Reference Tone.
Not every Network requires tone. Check the delivery requirements with the commissioning network or click here.
Reference tone, where used, should be at -18dBFS or PPM 4 on A, B and/or M.
If submitting material with reference tone, tone and programme material must be have been monitored and measured through the same technical chain. The level of the tone must be equivalent to 0dBu and no less than 8dB below peak audio level for the programme material.
THE LEVEL OF TONE MUST HAVE A KNOWN RELATIONSHIP WITH THE LEVEL OF THE PROGRAMME MATERIAL AND THIS MUST BE STATED; for example: “Tone at 8dB below peak programme level”.

[ezahp]

ok, well i thought it was funny/peculiar.........how often have you been tempted to deliver a stereo mix in M/S? How often do you check that the material you're handing over has a frequency range from 20 Hz to 20 kHz? - and "no distortion...should be audible" - well that takes out about 98% of popular music as well as every film soundtrack I've ever worked on........very odd indeed IMHO

[minister]

The BBC used M/S for years as a standard, so it is not all that strange. For Non-Brits, it might appear odd.

Also, in the days of yore, a lot of material was not 20-20.