DTS:X and Atmos.

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DTS:X and Atmos.

Nomis101 🐝
I know, FFmpeg does not officialy support DTS:X and Atmos. But, inspired from a HandBrake question on github[1], I just want to clarify something.
If a DTS:X or Dolby Atmos stream is copied into another container (-acodec copy), will the DTS:X / Atmos related information be fully/partly
stripped away or will it be preserved?

Thanks

[1]https://github.com/HandBrake/HandBrake/issues/2831
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Re: DTS:X and Atmos.

Carl Eugen Hoyos-2
Am Mo., 1. Juni 2020 um 20:19 Uhr schrieb Nomis101 <[hidden email]>:
>
> I know, FFmpeg does not officialy support DTS:X and Atmos. But, inspired
> from a HandBrake question on github[1], I just want to clarify something.
> If a DTS:X or Dolby Atmos stream is copied into another container
> (-acodec copy), will the DTS:X / Atmos related information be fully/partly
> stripped away or will it be preserved?

You forgot to point to your DTS:X sample.

Note that there is nothing relevant hidden in a E-AC3 stream,
this is just marketing speech.

Carl Eugen
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Re: DTS:X and Atmos.

Nomis101 🐝
Am 01.06.20 um 21:27 schrieb Carl Eugen Hoyos:
> Am Mo., 1. Juni 2020 um 20:19 Uhr schrieb Nomis101 <[hidden email]>:
>>
>> I know, FFmpeg does not officialy support DTS:X and Atmos. But, inspired
>> from a HandBrake question on github[1], I just want to clarify something.
>> If a DTS:X or Dolby Atmos stream is copied into another container
>> (-acodec copy), will the DTS:X / Atmos related information be fully/partly
>> stripped away or will it be preserved?
>
> You forgot to point to your DTS:X sample.

Oh, you are right. I've corrected that. It actually is from https://thedigitaltheater.com/dts-trailers/

>
> Note that there is nothing relevant hidden in a E-AC3 stream,
> this is just marketing speech.

Good to now. I was just confused by this comment:
https://github.com/FFmpeg/FFmpeg/blob/adea33f46513821c111c602a0692b78315688c1b/libavcodec/mlpdec.c#L367
I thought, maybe the Atmos stuff is in a substream, that is stripped away. So, thanks for that information.

>
> Carl Eugen
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Re: DTS:X and Atmos.

Moritz Barsnick
On Mon, Jun 01, 2020 at 23:06:41 +0200, Nomis101 wrote:
> Am 01.06.20 um 21:27 schrieb Carl Eugen Hoyos:
> > Am Mo., 1. Juni 2020 um 20:19 Uhr schrieb Nomis101 <[hidden email]>:
> >> (-acodec copy), will the DTS:X / Atmos related information be fully/partly
> >> stripped away or will it be preserved?

Did you try? ;-)

> > Note that there is nothing relevant hidden in a E-AC3 stream,
> > this is just marketing speech.
>
> Good to now. I was just confused by this comment:
> https://github.com/FFmpeg/FFmpeg/blob/adea33f46513821c111c602a0692b78315688c1b/libavcodec/mlpdec.c#L367
> I thought, maybe the Atmos stuff is in a substream, that is stripped away. So, thanks for that information.

That's the decoder you're looking at, which isn't used if you use the
copy codec.

Cheers,
Moritz
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Re: DTS:X and Atmos.

Nomis101 🐝
Am 02.06.20 um 13:18 schrieb Moritz Barsnick:
> On Mon, Jun 01, 2020 at 23:06:41 +0200, Nomis101 wrote:
>> Am 01.06.20 um 21:27 schrieb Carl Eugen Hoyos:
>>> Am Mo., 1. Juni 2020 um 20:19 Uhr schrieb Nomis101 <[hidden email]>:
>>>> (-acodec copy), will the DTS:X / Atmos related information be fully/partly
>>>> stripped away or will it be preserved?
>
> Did you try? ;-)

Yes I did. I posted the result in the mentioned HandBrake bug on github. I compared the MediaInfo output of the original and the file after -c copy.
There are differences, but I am not sure if this differences are relevant or not. For example:

- For Atmos in TrueHD, the original has a Format of "AC-3 MLP FBA 16-ch", after the copy it is just "MLP FBA 16-ch".

- For Atmos in TrueHD, the original has a Format/Info of "Audio Coding 3 + Meridian Lossless Packing FBA with 16-channel presentation", after copy it is just "Meridian Lossless Packing FBA with
16-channel presentation".

- For Atmos in TrueHD, the original has a muxing modus "Stream extension", after copy, it does not show any muxing modus anymore.

- For Atmos in TrueHD, the original has a Compression mode of "Lossy", after the copy, it is "Lossless".

- For Atmos in E-AC3, also after copy, there is no "Muxing modus" anymore.

- For DTS:X, the original has an Codec-ID "A_DTS", after the copy it is "mp4a-A9".

- For DTS:X, the original has a Bit depth of 24 bit, after copy it does not show any Bit depth anymore.

>
>>> Note that there is nothing relevant hidden in a E-AC3 stream,
>>> this is just marketing speech.
>>
>> Good to now. I was just confused by this comment:
>> https://github.com/FFmpeg/FFmpeg/blob/adea33f46513821c111c602a0692b78315688c1b/libavcodec/mlpdec.c#L367
>> I thought, maybe the Atmos stuff is in a substream, that is stripped away. So, thanks for that information.
>
> That's the decoder you're looking at, which isn't used if you use the
> copy codec.

Thanks!

>
> Cheers,
> Moritz
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