Chicagoland Public Access Television operated by

Getting Ready for Broadcast: Digital Files


File Format

Must be in MPEG-2 format. No other video formats will be accepted. (note that MPEG-2 is an entirely different format than MPEG-4)



Resolution must be 720x480. Note that this is in standard definition, not HD. Depending on which editing software you use, your export preset will probably be labelled something like "NTSC DV". Do not select "720P" as your export setting, as that will create an HD file and is not compatible with our system.


Frame Rate

Frame rate must be 29.97 fps



The file can have a constant or variable bitrate. A higher bitrate will result in higher video quality, but will also increase the file size. The maximum bitrate supported is 9 Mb/s, so keep it at or below 9.


Aspect Ratio

Our access channels broadcast in standard definition, so a 4x3 aspect ratio is recommended:

Files submitted in a 16x9 aspect ratio will play, but will automatically be squeezed to fit 4x3, distorting the picture:

If your source material is 16X9, then you can avoid distorted playback by exporting it as a 4x3, either cropping it, or letterboxing the top or bottom:


Sampling Rate

4:2:0 sampling rate is required on all files. If your video editing software has a "Profile" option in the export settings, set it to "Main". This will give you the proper 4:2:0 sampling rate.



Your audio export setting should be set to MPEG audio. DO NOT choose Dolby Digital or AC3, as this audio will not playback correctly over our servers. Also, it is suggested to encode audio at 44.1 KHz for optimal performance.



It is now unnecessary to include Comcast's 30-second disclaimer. These disclaimers will now be automatically inserted at the beginning of each program when it airs. It is also unnecessary to include any bars and tone, countdown or black at the beginning or end of the program. Your program content is all you need included in the file.



For a 30-minute timeslot, the maximum length of your program should be 29:30. For a 60-minute timeslot, the maximum length of your program should be 59:30. If your program runs long, it will be automatically cut off when airing.


File Naming

Files should be named with the name of your program and either the episode number, or the date of the first airing. Our video servers do not like spaces in the names, so please use underscores or dashes in place of spaces. Example: "Community_Forum_7-21-16" or "Community_Forum_ep156"


File Delivery

Video files are too large to email, so you will have to make use of a file sharing service to send it to your playback facility. Some popular options include DropBox, Google Drive or WeTransfer. Once your file is uploaded, you will need to email the link to your playback facility. Note that if you are airing the same show in multiple areas, then you will need to send the link to all the playback facilities in which you air.

Alternatively, you can drop off files on a USB thumb drive at your local playback facility.