Eac3 Atmos To Ac3

[abkjr]

Hello,

Currently i have an audio receiver that can decode only ac3 and DTS files. Newer files having eac3 content which has atmos data when converted to ac3 via ffpmeg do give out muddy audio. I recently installed cavernize atmos decoder. However it outputs the files as PCM. Is there any way we can get proper ac3 or DTS audio from eac3 atmos source

[tebasuna51]

Welcome to the Doom9 forum.
Maybe this question can be for the Audio sub-forum

...converted to ac3 via ffpmeg do give out muddy audio...

How do you make that conversion?
Work fine here, see below.

With CavernizeGUI you must select 5.1 side output and:

"ffmpeg.exe" -drc_scale 0 -i "any_audio_file" -acodec ac3 -center_mixlev 0.707 -ab 640k "output.ac3"

[abkjr]

Conversion done using :
ffmpeg -i inputfile -codec copy -acodec ac3 outputfile.

Is there any recommendation for setting the content processing value.(PCM integer or PCM float). The input audio stream is a 768KBps atmos file.

[tebasuna51]

You can't copy the eac3 (7.1) to the ac3 (max 5.1).
See my sintax, don't forget "-drc_scale 0" to avoid low volume.

If you want a better downmix 7.1 -> 5.1 than ffmpeg default read the 7.1 downmix function? (https://forum.doom9.org/showthread.php?t=181726) thread

"ffmpeg.exe" -drc_scale 0 -i "Atmos71.eac3" -filter_complex "asplit [f][s]; [f] pan=3.1|c0=c0|c1=c1|c2=c2|c3=c3 [r]; [s] pan=stereo|c0=0.5*c4+0.5*c6|c1=0.5*c5+0.5*c7, compand=attacks=0:decays=0:points=-90/-84|-10/-4|-6/-2|-0/-0.3, aformat=channel_layouts=stereo [d]; [r][d] amerge [a]" -map "[a]" -acodec ac3 -center_mixlev 0.707 -dsurex_mode 2 -ab 640k "ac351.ac3"

The CavernizeGUI output always 16 bits int (by the moment) the 32 float don't work but select it, maybe work in the future.

[SeeMoreDigital]

Hello,
Newer files having eac3 content which has atmos data when converted to ac3 via ffpmeg do give out muddy audio...Out of interest... Which newer files have eac3 audio?

[tebasuna51]

I see many TV captures for instance.

[FranceBB]

Out of interest... Which newer files have eac3 audio?

Lots of broadcast .ts feeds too, like, any important Champions League football game.