12.06.2007 03:48 PM
Originally featured on BroadcastEngineering.com
Crystal Vision SYNNER-E embeds Dolby E, AES audio streams together
Crystal Vision has released SYNNER-E, a video synchronizer for broadcasters working with a mixture of AES and Dolby E audio streams. SYNNER-E is a combined synchronizer, audio delay tracker and embedder, with a complete input stage for asynchronous SDI and analog, digital or Dolby E audio into an embedded audio system.
With a circuit board form factor that fits standard Crystal Vision frames, the SYNNER-E allows a mixture of Dolby E and standard AES within a single audio group, ideal for surround-sound or multilingual applications. Surround-sound programs have their 5.1 channels encoded in a single AES stream of Dolby E, with a second AES feed containing a standard stereo pair for end users without a surround-sound decoder. This also makes it easier for the broadcaster to monitor the audio.
Most current broadcast infrastructures only accept a single audio group. Because Dolby E data is processed differently from standard audio, embedding these two types together makes synchronizing them difficult. SYNNER-E separates the Dolby E and standard audio, synchronizing both types as appropriate, then recreates the audio with the delay matching the video, correctly coping with any video frame drops or repeats and causing no disturbance to either audio stream.
SYNNER-E will automatically synchronize sources between zero and two fields, dealing with any incorrect frame rates plus any delays by taking its timing from the external analog reference. Delay mode is ideal for when the frame rate is correct but the source has been passed through equipment and therefore been delayed for a few lines, with timing derived from the SDI input. SYNNER-E has a short minimum delay of 3.8μs, while in 625-line applications picture disturbances on untimed input cuts are avoided by waiting until line 23 to relock. Automatic freeze is available when input fails through signal loss. In addition, a manual freeze allows SYNNER-E to be used as a simple still store.
The audio routing of the stereo pairs is performed with three switching matrixes. Standard AES is routed from the de-embedder and piggyback (if fitted) by the main routing matrix, while Dolby E is transported to the output embedder by two stereo switches. One embedder is used for standard AES only, with the other capable of handling AES, Dolby E or both. SYNNER-E can detect the presence of Dolby E encoded audio in either channel of a selected audio group. This can be used to trigger a GPI, allowing the engineer to recall a user defined preset to automatically select how the incoming embedded and external audio is processed.
Crystal Vision's SYNAD-E was the original synchronizer to allow Dolby E and AES within a single audio group. The new SYNNER-E extends this technology by adding the option of fitting a piggyback to the motherboard, allowing the embedding of external analog or digital audio into the SDI.
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