Visual Circuits ReelTime 2, ReelTime 4, ReelTime Series User Manual

ReelTime Series
Board Encoding
Parameters

User Manual

Visual Circuits Corporation

Trademarks

The Visual Circuits logo is a registered trademark in the United States
and other countries. All other products, services or compan y names
mentioned herein are claimed as trademarks and trade names by their
respective companies.

c Visual Circuits, 1999-2000. All rights reserved.
No porti on of this manual may be cop ied by any means without the prior
consent of Visual Circuits.

Visual Circuits
5155 East River Road, Suite 401
Minneapolis, MN 55421

http://www.visualcircuits.com

Visual Circuits Publication Number: 813-0015a

All specifications are subject to change without notice.

CONTENTS

Encoding Parameters . . . . . . . . . . . . . . . . . . . . . 1

Required Encoding Parameters. . . . . . . . . . . . . . . . . . .1

Encoding Recommendations. . . . . . . . . . . . . . . . . . . . .2

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . 5

Stuttering files during Playback . . . . . . . . . . . . . . .5

"Latent Images" or "Flashing" during playback . . .6
SMPTE time codes are not recognized properly. . .7

On Screen (GIF) Overlay Information. . . . . . . . . . 9

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

i

Contents

ii

ENCODING PARAMETERS

Required Encoding Parameters

1. Files must be program stream MPEG2 files of audio/video,
video only or audio only. Visual Circuits 4ReelTime Pro,
4ReelTime RGB and MPEG Plus products do not currently
support transport stream MPEG files decoding.

2. Use 4:2:0, not 4:2:2 encoding.

3. In MPEG-2, both fields should be encoded. Thi s i s t he nor ma l
default.

4. The audio track must be MPEG Layer 2. Files with audio and

video tracks cannot be mixed with video only or audio only
files on the same channel during playback. It is recommended
to encode a “blank” au dio track, if there is no audio is present
on the original source tape. This will standardize all MPEG

files and provide easy future management of video content.

5. POPVideo Player – Standard (IDE Hard Drive):
Recommended bit r ates for standa rd POPVideo Players a re 4-6
mbps per channel. The total bit rate of a POPVideo Player
must not exceed 24 mbps across four channels (i.e. averaging 6
mbps per channel) . Channels may be encoded at different bit
rates as long as 24 mbps is not exceeded across a single hard
drive, 4-channel Player.

6. POPVideo Player – Upgrade (SCSI Hard Drive): POPvideo
Players upgraded with SCSI hard drives will play up to 8
channels at 6 mbps per channel. The total bit rate of a SCSI
POPvideo Play er must not exceed 4 8 mbps.

7. Recommended DVP Server (SCSI): Re commended bit rates
for standard DVP servers are 6-10 mbps per channel. DVP
Servers can support up to 15 mbps per channel and 40 mbps
across one 4-channel Visual Circuits MPEG-2 decoder board.
Larger, custom servers of 20-24 channels can sustain a
maximum bit rate of 6 mbps per channel, regardless of hard
disk drive configuration.

1

Encoding Parameters

Encoding Recommendations

1. Resolution: 720 X 480 or 704 X 480 in NTSC; 704 X 576 in
PAL.

2. Closed GOP (Group of Pictures) with an “I-frame” every 15

frames is recommended.

3. The recommended audio bit rate is 384kbps and a sampling
rate of 48khz. The audio output voltage of the 4ReelTime Pro/
Plus has a maximum level (without clipping) of 3.75v, or

11.5dBV (refere nce d t o 1v). The noise floor is -67db with files
stopped. The noise floor changes to -44db when a file is
playing. In our testing, we have found that some MPEG2
encoders ha ve s ome audio los s when encodin g. For e xample, a
Vibrint encoder has a 3db audio loss. Some encoders may not
have any loss. It is recommended to play back test files using
the original source tapes to confirm audi o levels prior to
encoding an entire project. This will allow for calibration of
the encoding system to obtain the desired audio level.

4. The recommended bit rates are as follows: good quality or for
scenes without much motion-- minimum 4 mega bits per
second (mbps); for good quality with most content—6 mbps;
for good quality with high-motion scenes—8 mbps; for
demanding content—10 mbps; and for the highest possible
quality with demanding material—15 mbps.

5. When encoding files annotate and store notes on the audio
lev els of bot h the sourc e tape a nd input set tings of t he encoder.
It then will be possible to verify audio levels of subsequently
encoded files. It's desirable to maintain a baseline audio level
across all files of a presentation whether at a sing le or multip le
locations. If no encoding notes or data is available from
previously encoded files, compar e the files. When possible
measure audio levels of the source tapes and of the encoded

2