12/31/2022 0 Comments Dolby dts sound for fm radio![]() No doubt receiver manufacturers are working hard to incorporate these into their products. But now that transcoding solutions are becoming available the UK is no different from all other European standards. Earlier versions of the UK D Book were only able to recommend the presence of transcoding. So the answer does lie in the need for the receiver to either transcode to a suitable format such as Dolby AC-3 or DTS or to output multi-channel linear PCM. Experience shows that some receivers can also have issues detecting suchĬhanges unless the user tunes away and then reselects the service. It therefore needs very comprehensive monitoring to ensure the operation is reliable. Even if there are some decoders that can run different audio decoders concurrently it would not be possible to mandate the use of these specific solutions.Ĭhanging the characteristics of the broadcast stream at programme junctions can be very difficult to achieve reliably in a broadcast head-end as many different systems need to be synchronised. This disruption is acceptable when tuning between different services but not acceptable at programme junctions. This is because the receiver needs to detect the use of a different audio codec, load into its DSP the firmware for decoding that audio codec and then start decoding the audio. Unfortunately the restriction I've just described around the ability only to have a single audio codec working at any one time means that changing audio codecs at programme junctions results in disruption to the decoded audio. I've also been asked why we don't switch to using Dolby during the programmes which do not carry audio descriptions. ![]() In order to help manufacturers with their product development example streams with AAC-LC/HE-AAC audio description have been freely available to manufacturers since October 2009. The current bitrates used for the AAC-LC audio are entirely commensurate with those that could have been used for a Dolby AC3 (Dolby Digital) solution. So, the main audio and the audio description must use the same encoding family in order for them to be successfully combined together at the receiver. There is a very common restriction in the silicon devices (which underpin all receivers) that only a single type of audio decoder can be working at any one time. The main audio is coded as AAC-LC and only the audio description is encoded as HE-AAC. In order to achieve this we have to use the HE-AAC/AAC audio codec present in Freeview HD receivers. There are two to three programmes everyday which are audio described. The BBC is required to provide an audio description service on BBC HD. As always there's a quite complex reason behind this decision so I thought it would be a good idea to do a post on it. Some people have asked why we don't currently use Dolby as the sound solution for Freeview HD.
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