12G-AM Mini-Converter v1.0 20 www.aja.com
SRC
This setting determines whether AES audio inputs are passed through the sample
rate converter before embedding. Turn this setting Off for compatibility with
non-PCM bitstreams such as Dolby-E or Dolby-B.
Choose Auto, On, or Off for each of the indicated input channel pairs: (Ch 1/2, Ch
3/4, Ch 5/6, Ch 7/8).
• Auto - Automatically selects whether incoming AES audio is sample rate
converted. If channel status bits are detected that indicate the audio is PCM
(normal digital audio), the audio will be passed through the sample rate
converter. If compressed audio (such as Dolby) bits are detected, the sample
rate converter is bypassed (it would corrupt the compressed data).
• On - Pass all input AES audio through the sample rate converter before
embedding (for example, for use with PCM audio). AES inputs are sample rate
converted to a 48KHz rate synchronous to the video input.
• Off - Do not pass any input AES audio through the sample rate converter
before embedding (for example, for use with Dolby® Digital from a
synchronous source).
NOTE: For proper operation with SRC Off, the AES input timing must be externally
synchronized to the input SDI.
About SRC Settings
48KHz synchronous ancillary packets are disembedded and passed unaltered
to the AES outputs regardless of the SRC setting. With the SRC setting Off, data
packets are passed from the AES inputs to embedded ancillary packets un-
altered, according to SMPTE 337M. All AES3-2003 defined channel status bits are
passed through unaltered in both the embed and dis-embed directions—except
for the sample rate field, which is always set to 48KHz. The channel status CRC is
re-calculated and inserted into the bitstream. This ability, along with a very small
audio embed/disembed latency, ensures 100 percent compatibility with Dolby®
bitstreams.
