Encoding Requirements and Recommendations

Before using the Web Application to build a database of content that can be played, you have to upload the content to the Digital Broadcaster via your network or capture content to the Digital Broadcaster via the optional onboard MPEG Encoder. The encoding requirements, as well as encoding recommendations, listed below provide a minimum set of criteria to create compatible MPEG content. The applicability of the recommendations depends on the encoder and the editing software your installation uses.

TelVue^® strongly recommends you review these encoding requirements and recommendations, as well as the requirements for your encoder and editing software, to determine what encoding criteria will work best for your installation.  Sample settings for several popular encoding packages are provided on the USB key and the TelVue support portal. Encode and test a few files before committing resources to a large effort.

Encoding Requirements

The Digital Broadcaster supports standard MPEG program and transport streams. In order to ensure optimum video playout quality on the Digital Broadcaster, MPEG video and audio content must be encoded to certain specifications.

B-series ASI and IPTV servers support MPEG-2 Transport streams with Constant Rate Transport only.

Video files for playout must be encoded into a multiplexed MPEG-2 program or transport stream or MPEG-1 system stream format. Video can be encoded at rates up to 10 Mbps.

The video and audio timestamps in a file must be continuous and increasing, with no haphazard edits that might affect the timestamps. The time between the first and last timestamps in a file should reflect the actual duration of the file.

Encoding Recommendations

TelVue recommends you follow these criteria when encoding.  However, the criteria you need to encode MPEG files for use at your installation will vary, depending on the encoder in use, whether you edit files or just play them end-to-end, and the software used to edit files.  Refer to the encoder and editing software documentation for their requirements.

• MPEG profile and level: main profile, main level (requirement)
• Analog servers play only content encoded with the 4:2:0 profile.
• Digital servers play both 4:2:0 and 4:2:2.
• Resolution: 720 X 480 for NTSC, 720 x 576 for PAL
• Frame rate: 29.97 frames/second for NTSC, 25 frames/second for PAL
• Aspect ratio: 4:3
• Chroma format: 4:2:0

Structure: Closed GOP (Group of Pictures) with one I-frame and four P-frames every 15 frames, using the pattern IBBPBBPBBPBBPBB

• Pack size of 2048 bytes
• Field Encoding Order: bottom field first (BFF)
• Interlaced video (whereas deinterlaced video is typically used for web media)
• Audio bit rate of 192 kbps, 224 kbps, 256 kbps, or 384 kbps
• Audio sampling rate of 48 kHz or 44.1 kHz
• Audio sampling rate of 1152
• Audio mode: stereo
• Audio codec: MPEG-1 Layer II, Stereo AC-3, AC-3 5.1, or Linear PCM (LPCM) depending on your server output type.  See the chart on page 5.

Program stream files should terminate with an end code (00 00 01 b9).

Maximum program mux rate of 10.08 Mbps for standard-definition interlaced video. The mux rate is the sum of the video bitrate, the audio bitrate, and the overhead required by your encoder.  You can use the formula M = V + A + O(V + A).

For example, if your encoder requires 10% overhead, you could encode at the maximum audio bitrate of 384 kbps and be able to encode at a video bitrate up to 8.779 Mbps. (10.08 Mbps = V + 384 kbps + .10[V + 384 kbps] Solve for V to get 8.7796363 Mbps.)

If your encoder requires 25% overhead and you encode at the maximum audio bitrate of 384 kbps, you would be able to encode at a video bitrate up to 7.68 Mbps. (10.08 Mbps = V + 384 kbps + .25[V + 384 kbps] Solve for V to get 7.68 Mbps.)

Recommended bit rates for various types of video content are as follows:

• 4 Mbps for good quality video with low motion
• 6 Mbps for good quality with average motion
• 8 Mbps for good quality with high motion and
• 9 Mbps for high quality with high motion content.

Video sequence header before every GOP to facilitate random access (stop & start anywhere in file) needed for virtual trims and continuity resume. Files from a DVD will have the video sequence header.

Transport streams should include Random Access Indicators for random access support.

B-Series SDI, HD-SDI, and ASI supported multiplexed bit rates for various types of video content are as follows:

• SDI: up to 50 Mbps 4:2:0 & 4:2:2
• HD-SDI: up to 45Mbps 4:2:2
• MPEG2 Transport Stream (TS): up to 70Mbps – Simultaneous Capture and Playout