DTS-HD in Audacity

[onlysleeping23]

When importing a DTS-HD file in Audacity, is it using the lossless or lossy core audio?

Is it best to transcode DTS-HD (or True-HD, for that matter,) to PCM before editing?

Thanks for any help!

[stwd4nder2]

I believe internally it's just using ffmpeg to convert it to PCM, so it should be lossless

[onlysleeping23]

Thank you!

[mlnl]

adding to this
audacity just uses ffmpeg, so when you import DTS-HD or truehd it gets decoded to pcm. ffmpeg will use the lossless stream, not the lossy core, assuming it’s supported.

pre-transcoding to PCM doesn’t really give you anything quality-wise. editing is pcm either way. just watch your final export, that’s where quality actually matters.

[velocity]

Transcoding beforehand only makes sense for AC-3/E-AC-3, you must use:

Code:

ffmpeg -drc_scale 0 -i file.ac3 file.flac

This will disable dynamic range compression applied on decoding. If you want to use WAV instead of FLAC, specify:

Code:

ffmpeg -drc_scale 0 -i file.ac3 -c:a pcm_s24le file.awv

Otherwise it will get cut to 16-bit - you should instead dither it back down at the end of your processing.

I'm not 100% certain that it doesn't affect TrueHD as well. For DTS/DTS-HD there is no such thing. In any case, doesn't hurt to have -drc_scale 0 in all of your processing, for other codecs it just gets ignored.

[symphoniefantastique]

Transcoding beforehand only makes sense for AC-3/E-AC-3, you must use:

Code:

ffmpeg -drc_scale 0 -i file.ac3 file.flac

This will disable dynamic range compression applied on decoding. If you want to use WAV instead of FLAC, specify:

Code:

ffmpeg -drc_scale 0 -i file.ac3 -c:a pcm_s24le file.awv

Otherwise it will get cut to 16-bit - you should instead dither it back down at the end of your processing.

I'm not 100% certain that it doesn't affect TrueHD as well. For DTS/DTS-HD there is no such thing. In any case, doesn't hurt to have -drc_scale 0 in all of your processing, for other codecs it just gets ignored.

Unless I'm misunderstanding, isn't an ac3 source going to be 16 bit anyway? Just curious if the 24 designation is really needed when converting to wav, but I know I could be missing something.

I remember learning about this need to disable DRC before importing into Audacity and realizing I had to go back and redo some of my previous work lol but thankfully not an insane amount. So this is definitely helpful info.