[FFmpeg-user] AC3 7.1 audio support

[l***@eyetrap.net]

Hello All,

I cannot find any information about AC3 7.1 audio.
Is that supported for encoding and decoding?

Thanks
Markus

[Moritz Barsnick]

Hi Markus,

Post by l***@eyetrap.net
I cannot find any information about AC3 7.1 audio.
Is that supported for encoding and decoding?

I can't say for the decoder, and have trouble interpreting the source.
But my encoders report that it is not supported (I queried ac3,
ac3_fixed, eac3 here):

***@sunshine:/usr/new/tools/video/ffmpeg/ffmpeg-build-2015-05-19 > for encoder in ac3 ac3_fixed eac3; do echo $encoder:; ffmpeg -hide_banner -help encoder=$encoder | grep 'Supported channel layouts'; done
ac3:
Supported channel layouts: mono stereo 3.0(back) 3.0 quad(side) quad 4.0 5.0(side) 5.0 2 channels (FC+LFE) 2.1 4 channels (FL+FR+LFE+BC) 3.1 5 channels (FL+FR+LFE+SL+SR) 5 channels (FL+FR+LFE+BL+BR) 4.1 5.1(side) 5.1
ac3_fixed:
Supported channel layouts: mono stereo 3.0(back) 3.0 quad(side) quad 4.0 5.0(side) 5.0 2 channels (FC+LFE) 2.1 4 channels (FL+FR+LFE+BC) 3.1 5 channels (FL+FR+LFE+SL+SR) 5 channels (FL+FR+LFE+BL+BR) 4.1 5.1(side) 5.1
eac3:
Supported channel layouts: mono stereo 3.0(back) 3.0 quad(side) quad 4.0 5.0(side) 5.0 2 channels (FC+LFE) 2.1 4 channels (FL+FR+LFE+BC) 3.1 5 channels (FL+FR+LFE+SL+SR) 5 channels (FL+FR+LFE+BL+BR) 4.1 5.1(side) 5.1

Moritz

[Christoph Gerstbauer]

Post by Moritz Barsnick
Hi Markus,

Post by l***@eyetrap.net
I cannot find any information about AC3 7.1 audio.
Is that supported for encoding and decoding?

Hi, as far as I know AC3 standard only supports 6 channels max. -> 5.1

bg
Christoph

[Carl Eugen Hoyos]

Post by l***@eyetrap.net
I cannot find any information about AC3 7.1 audio.

The reason is that AC-3 is only specified for up
to six channels.

Carl Eugen

[Moritz Barsnick]

Post by Carl Eugen Hoyos
The reason is that AC-3 is only specified for up
to six channels.

That would be E-AC3 = Dolby Digital Plus then instead?
http://www.dolby.com/us/en/technologies/dolby-digital-plus.html
Again, I don't _think_ ffmpeg supports 7.1 there.

Moritz

[Carl Eugen Hoyos]

Post by Moritz Barsnick
That would be E-AC3 = Dolby Digital Plus then instead?
http://www.dolby.com/us/en/technologies/dolby-digital-plus.html
Again, I don't _think_ ffmpeg supports 7.1 there.

FFmpeg does support decoding eight-channel E-AC-3.

Carl Eugen

[Andrew Sinclair]

Carl,

Can you point me at where code for the channel maps for 7.1 EAC-3 are?

Post by Carl Eugen Hoyos

Post by Moritz Barsnick
That would be E-AC3 = Dolby Digital Plus then instead?
http://www.dolby.com/us/en/technologies/dolby-digital-plus.html
Again, I don't _think_ ffmpeg supports 7.1 there.

FFmpeg does support decoding eight-channel E-AC-3.
Carl Eugen
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[Carl Eugen Hoyos]

Post by Andrew Sinclair
Can you point me at where code for the channel
maps for 7.1 EAC-3 are?

I was wrong.
It appears that only one sample ever appeared
(the one from the Dolby demo disc) and this
was not enough reason to implement the feature.

I opened ticket #4608 to make sure I won't
misremember again.

Carl Eugen