The quality of your audio is critical to the way your program will sound when stations air it. Click on the tabs below for information on the basic standards and specifications for programs submitted to the ContentDepot®.
- Program Formats
- Recording Levels
- Encoding Files
As the program distributor, you will determine the appropriate format for your program and how it is sent to ContentDepot as well as how it is delivered to stations. Live streams, in addition to being delivered to the ContentDepot in real time over ISDN or other circuits, can also originate as playbacks of pre-recorded media or computer files that you send to the Network Operations Center (NOC) for playout. Live programs are delivered to stations as streams that stations can send directly to air in real time or record for later playback as permitted by your broadcast rights.
File deliveries of pre-recorded content to stations originate from the ContentDepot as files that you upload via the ContentDepot portal in MP2 audio format.
Regardless of the methods chosen for delivery to the stations or to the ContentDepot, it is important that producers adhere to the standards below when producing their content. Failure to observe these standards may result in poor audio quality when the content is played on-air at a station.
The PRSS will not be responsible for providing any additional transmissions of programs that do not meet the standards.
Pre-recorded, file-based programs can be automated by stations for broadcast and require the least manual intervention. Therefore, program distributors are encouraged to use the features of the file delivery system whenever possible if this format is appropriate to your program content. Obviously, programming that must be aired in real time (e.g., news and live music events) must continue to be delivered through the system as live streams.
The following are general guidelines for ContentDepot recording levels that must be observed when constructing your program master.
In referencing recording levels, dBfs (decibels or dB relative to full scale) is the scale most often used. This indicates the maximum peak record level as indicated by a metering device such as a digital audio workstation, DAT or CD recorder, or a plug-in metering device. Generally speaking, 0 dBfs is the maximum level. Levels are expressed as negative numbers relative to full scale (fs)-for example, -15 dBfs.
Please note that decibel values have no absolute relationship to the electrical power output of an audio device.
The desired maximum dynamic range between peak and average levels for the ContentDepot is 12 dB. Recommended levels are:
- 0vu at -15 dBfs
- No peaks higher than -3 dBfs
The remaining 3 dB should be left as headroom to allow leeway for future processing and for the inexactness of signal chains.
If you are adding automation cue tones to your program, they should be recorded 5 dB below the selected reference tone level.
- When the reference tone is -15 dBfs, then the cue tone level is -20 dBfs.
Managing program levels is an ongoing discussion of tools and best practices; detailed recommendations are well beyond the scope of this overview. In general, you should produce programs for file delivery with smooth and consistent average levels. Merely keeping peak levels within ContentDepot-recommended limits does not guarantee smooth integration with other programs.
Once you have created your master sound file, you need to encode the file into the standard ContentDepot format. To get the best audio quality, be sure to create each encoded file from the master sound file. If you are using a batch encoder, multiple conversions can be made in one session using the master sound file. You may use the tools of your choice to encode your files, but you must set the encoding parameters correctly for each ContentDepot file.
The following list gives the appropriate encoding parameters for a broadcast-quality sound file. Specific encoding parameters are not required for audition samples (MP3) submitted to the ContentDepot.
File purpose: Broadcast-Quality Sound File
File format: .mp2 (MPEG 1, Layer II)
Mode: stereo or mono
Bit Rate: 128 kbps mono or 256 kbps for stereo
Sampling Rate: 44.1 KHz
Bit Depth: 16 bit
Frame Padding: Must be turned off
ID3(Audio) Tags: Must be turned off
Do I still need to include silence at the beginning and end of each file?
A half second of audio silence at the beginning and end of each segment is required to prevent up and downcutting. Remember to calculate this silence into your total episode length. The ContentDepot will provide a total episode length when all segments have been uploaded that you can use to confirm the proper length.
The following encoding tools have been tested with the ContentDepot and can make ContentDepot-compliant files. This information does not constitute an endorsement of any of the organizations or products listed, and all content is subject to change.
|Adobe Audition CS6 and CC||Mac and Windows||Compliant|
|Audacity 2.0.6||Windows||Compliant, but may require an additional FFmpeg Import/Export Library download|
|Awave v11.0||Windows||Compliant, but requires a DLL version of the toolame encoder to make MP2's. Mac version under evaluation.|
|Hindenburg Journalist||Mac and Windows||Compliant|
|PRX Encoder||Mac and Windows||Compliant, but latest version does not encode mono files on Mac|
|Smart Audio Converter||Windows||Compliant|
Last updated April 2, 2015