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Newest AC-3 encoding software, Which free Dolby Digital encoder is being maintained?
euphemism_treadm...
post Apr 15 2014, 20:18
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After some deliberation, I think I've decided to go with ATSC A/52 to put a bunch of CDDA on a DVD. It would be nice to not have to resample everything to 48 kHz but I was disappointed to realize what a closed standard DVD-Audio is - MLP isn't really an accessible compression scheme for non-commercial home users (is it?) - DTS isn't for 2-channel signals and MPEG Audio Layer II is less of a sure bet on NTSC players (are there any other viable compression schemes for DVD playback I'm missing?)

For maximum compatibility I guess that leaves AC-3. (How does that compare with MP2 for music at higher/est bitrates?) I'd read older threads that said that aften was a better than the ac3 encoder in ffmpeg. Great. But then I looked at a page from aften's lead developer and since then he's incorporated that into libav with improvements. OK, I'll use that. But then I read a thread saying libav has (had?) some problems with AC-3 decoding that ffmpeg did not. But has ffmpeg incorporated any of libav's improvements to aften?

It turns out libav's fork from ffmpeg was fairly acrimonious and I'm not really interested in getting into that whole drama here, but is there an ac3 encoder for Linux that the community tends to recommend?

I've learned that "best" can be a fraught question on these hyperempirical boards (hear, hear!) so let me see if I can reword it a bit more neutrally - which A/52 encoder has been most recently maintained and builds on the bugfixes and perceptual improvements from previous ones?

Alternately, is there any sort of unanimity whether commercial software is an improvement over libre encoders?

This post has been edited by euphemism_treadmill: Apr 15 2014, 20:21
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DVDdoug
post Apr 15 2014, 22:17
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I'd say try 'em both. If you don't hear a difference use whatever is more convenient.

I'm running Windows, and I've used WAVtoac3encoder (Aften) and whatever (unknown) encoders that came with my video software (Corel Video Studio and Womble). They all sound just fine to me and I've never had any decoding problems playing the DVDs. I may have "played around" with Audacity (FFmpeg) but I'm pretty sure I've never made a DVD from the file.

I've always used at least 256kbps. I never bothered trying anything lower because the space of compressed audio on an audio/video DVD is not significant.

I've never done any careful listening tests... A great-sounding recording sounds great on my home-theater system (especially if it's 5.1 surround).

QUOTE
(How does that compare with MP2 for music at higher/est bitrates?)
I don't know. If you are not going to use MP2, does it matter? As a very general rule, at higher bitrates all lossy compression tends to be transparent. The lower you go, the more data you are "throwing away", and it becomes more important to have a "good" or "smart" compression algorithm.

I had a capure card that captured analog audio/video and it used MP2 audio (and MPEG-2 video). It's hard to say since the original was analog, but I didn't notice any degradation when transcoding to AC3. If I was going to be picky I'd use LPCM, but I don't remember if I ever used LPCM on a VHS-to-DVD transfer.

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...but I was disappointed to realize what a closed standard DVD-Audio is.
Well... At least it's a standard and if you make a DVD anybody with a DVD player can play it. There is only one way to make an audio CD. Blu-Ray has the opposite problem with 6 or 8 different audio formats.

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Octocontrabass
post Apr 16 2014, 01:44
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Given that you're going to be putting audio on the disc with no video, just go for the highest bitrate you can (448 kbps, if Wikipedia is correct). You'll have a hard time noticing any difference at such a high rate, regardless of the encoder you're using.

(Or just use uncompressed PCM, if you can live with only five or six hours of audio per disc layer.)

This post has been edited by Octocontrabass: Apr 16 2014, 01:45
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euphemism_treadm...
post Apr 17 2014, 19:41
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QUOTE (DVDdoug) *
QUOTE
(How does that compare with MP2 for music at higher/est bitrates?)
I don't know. If you are not going to use MP2, does it matter?

If MP2 was generally thought to be appreciably better for musical sources, I would strongly consider it despite the lesser compatibility.

QUOTE
As a very general rule, at higher bitrates all lossy compression tends to be transparent.

I'd seen multiple sources saying that AC-3 was good enough for movies where you're not paying full attention to the sound but for music it fared poorly. I wasn't sure if this was even for the maximum bitrate on stereo signals or just the standard rates used for video divided by 6 channels.

QUOTE (Octocontrabass) *
Given that you're going to be putting audio on the disc with no video, just go for the highest bitrate you can (448 kbps, if Wikipedia is correct). You'll have a hard time noticing any difference at such a high rate, regardless of the encoder you're using.

Yes, that was my plan, but I'd read a commenter saying that, even at higher bitrates, with more difficult passages (i.e. castanets) AC-3 handled the attacks and other such transients poorly.
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krabapple
post Apr 18 2014, 16:28
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QUOTE (euphemism_treadmill @ Apr 17 2014, 14:41) *
I'd seen multiple sources saying that AC-3 was good enough for movies where you're not paying full attention to the sound but for music it fared poorly. I wasn't sure if this was even for the maximum bitrate on stereo signals or just the standard rates used for video divided by 6 channels.



I've seen multiple sources dismiss AC3 and DTS as simply terrible for music and instantly recognizable as being inferior to lossless.

I don't pay attention to those multiple sources. It's just the usual audiophile prejudice with no bias-controlled data to offer and absolutely zero understanding of what 'lossy perceptual encoding' entails.

This post has been edited by krabapple: Apr 18 2014, 16:35
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LithosZA
post Apr 18 2014, 17:52
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I vote for high bitrate AC-3 or LPCM, but I am not sure if there is any quality differences between ffmpeg's AC3 and aften.
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