I have a question that has been on my mind lately.
Due to a unique situation, I needed to transcode a couple DTS-MA 5.1 tracks that weren’t playing correctly. I didn’t want to do a lossy encode to AAC, so I left the video intact and transcoded the audio to FLAC 5.1.
My receiver gets audio tracks over ARC. So of course, as per ARC spec, DTS and DD+ are fine, but DTS-MA and TrueHD get transcoded. Same for FLAC.
But the receiver itself handles all the formats fine. I have a Shield directly attached to the receiver., and it direct-plays DTS-MA and TrueHD as expected. However, it also direct-plays FLAC 5.1 just fine, treating it as PCM. As a bonus, the FLAC 5.1 track has significant file size savings over both TrueHD and DTS-MA and should be lossless.
So there’s my question: If FLAC is lossless and more efficient than DTS-MA or TrueHD, is there any specific advantages to leaving the formats intact? Does DTS or Dolby add anything special to those tracks that make it worth leaving them alone?
(This is ignoring Dolby Atmos. Any Atmos tracks are always left intact)
I don’t think that flac is that much (or any) more efficient than truehd/dts-ma, so if you are getting significant file size differences, then something is else is going on.
As far as I can remember, most lossless HD audio is native 7.1, so if you are converting to flac 5.1, then perhaps you are most likely losing 2 full channels of audio data.
or maybe you are flac encoding the (lossy) dolby digital stream.
The answer is, in theory “No”. You can transport the full fidelity of a DTSHD-MA track in a flac file too. Up to 7.1 channels, AFAIK.
The advantage of the DTS format is, that you have always a ‘core’ DTS stream embedded. This core stream is "lossy"ly compressed.
Which means that even if a device doesn’t have support for DTS HD-MA, it might still have support for the basic DTS core track.
So it can at least play audio (although with reduced audio quality) without the need to convert the file first.
Were it not for the market penetration of DTS, we could be happily streaming Flac audio tracks to all of our devices. But DTS was here first, before we had high-resolution flac files.
It could also have to do with the fact that flac is open source and is freely available. Which means you can also freely copy and convert the data stream. Certain groups of people don’t like that idea very much.
When it comes to Dolby Atmos, then the DTS format does have an advantage. I am not aware that you can store the additional Atmos metadata in a flac file.
