[FFmpeg-user] 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 <Nomis101 at web.de>:
>>>> (-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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