Grass Valley Imagestore 750 v.3.0.1 - Manual (Page 133)

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Imagestore 750
User Manual
• Dolby Digital 32 bit.
• Dolby Digital 16 bit channel 1.
• Dolby Digital 16 bit channel 2.
The encoder supports these automatic data rate modes:
• Auto 384
• Auto 448
The data rate is adapted to the channel coding (1/0, 2/0, . . . , 3/2) where 384 kbps and 448 kbps
are the maximum rates. This is the recommended mode.
 Note: The standard data rate for ATSC transmission in the USA is 384 kbps.
The Dolby Digital (AC-3) encoder’s data rate may be set to any one of the following:
56 kbps 64 kbps 80 kbps 96 kbps 112 kbps 128 kbps
160 kbps 192 kbps 224 kbps 256 kbps 320 kbps 384 kbps
448 kbps 512 kbps 576 kbps 640 kbps
The channel modes (stereo, 5.1, etc.) determine the best data rate. This table summarizes the
modes:
Dolby Processing Times
The Imagestore 750 takes one or more video frames to perform Dolby decoding and encoding:
Note: The Imagestore 750 has built-in video delays that allow you to compensate for these
delays. (See
Video Frame Delays on page 43 and Audio Delays on page 146.)
Table 6-2: Channel Mode Data Rates
Channel Mode Data Rate
1/0 C From 56 kbps , usually 96 kbps (mono)
2/0 L,R From 112 kbps , usually 192 kbps (stereo)
3/0 L,C,R From 256 kbps
2/1 L,R,S From 256 kbps
3/1 L,C,R,S From 320 kbps
2/2 L,R,Ls,Rs From 320 kbps
3/2 L,C,R,Ls,Lr From 384 kbps , often 448 kbps
Table 6-3: Dolby Processing Times
Type Direction Video Frames
Dolby E Decode 1
Dolby Digital Decode 1
Dolby E Encode 1
Dolby Digital Encode 6