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Topic: HQ AC3 decoding with FFMPEG (or not ?) (Read 573 times) previous topic - next topic
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HQ AC3 decoding with FFMPEG (or not ?)

I need to squeeze out the maximum possible audio quality out of cameras' (256Kb/48kHz) AC3 audio recordings.

Here's the commandline I wanna use:
Code: [Select]
ffmpeg -drc_scale 0 -i <filename.ac3> -c:a pcm_f32le <filename.wav>

...any suggestion (for example about dithering) ?
...do you think is better to choose foobar instead of ffmpeg ?

Thanks in advance !
F.O.R.A.R.T. npo

Re: HQ AC3 decoding with FFMPEG (or not ?)

Reply #1
for long-term archival, better to keep the original.
who knows, what kind of technology gets invented in the future.
plus it's way more compact that way.

if you have to re-encode (e.g. nontrivial editing other than a coarse trimming), then yes, this makes sense.
any subsequent steps would not be specific to the original format, at that point it's just (floating point) audio. all the general best practices apply.
a fan of AutoEq + Meier Crossfeed

 

Re: HQ AC3 decoding with FFMPEG (or not ?)

Reply #2
Quote
...any suggestion (for example about dithering) ?
Don't dither floating point.    (AC3, like all lossy compression, doesn't store individual samples and there is no actual bit depth.)

You're supposed to dither when you reduce the bit depth

Dither is added noise that's supposed to sound better than quantization noise.    You shouldn't add noise unnecessarily, and you shouldn't dither more than once.      

Under normal conditions you can't hear dither or quantization noise at 16-bits or better, so it's the last thing I worry about.   But it's "good practice" when you downsample.   It's probably a good idea at 8-bits where you CAN hear quantization noise.