eac3 to ac3...

[Lathe]

Just a quickie... (my usual style)

I'm using UseEac3to to convert eac3 audio files to ac3 so my OPPO player will recognize and play the resulting muxed MKV file.

I was just curious... I'm wondering if it is 'better' or more accurate to convert the eac3 file to lossless Wav first and then convert it back to ac3, or will I lose very much quality simply converting directly from eac3 to ac3 at the same bit rate, say @640?

Thanks!

[Ghitulescu]

All converters go first through a fully decoded state (uncompressed, "lossless" WAV :) )

[tebasuna51]

Like Ghitulescu say you don't need make 2 pass at all, but you can lose quality if convert the eac3 to ac3 at same bitrate because the eac3 compression is more efficient than ac3.

The recommended ac3 bitrate is near the double than the eac3 bitrate, of course 640 Kb/s is the maximum than ac3 support.

[Ghitulescu]

I thought the Oppos can E-AC3... ;)

[Lathe]

I thought the Oppos can E-AC3... ;)

Thanks to both of you! Interesting, I didn't know that the eac3 was actually at a higher 'bit rate' than ac3... Do you think it would be worth converting to, say, DTS @ 1500...?

I have a pretty old OPPO (BDP-83) I think it was the first of it's kind, so I'm sure the newer ones play a LOT more stuff! :)

Thanks again!

[Music Fan]

Are you sure the BDP-83 does not handle eac3 in mkv or ts ?
I also have this player, I believe eac3 is supported but I should verify.

[tebasuna51]

DTS 1509 Kb/s is only a little better than AC3 640 Kb/s, you need golden ears and expensive speakers to difference them.

And a good DTS encoder is more expensive than a new OPPO.

[Lathe]

Are you sure the BDP-83 does not handle eac3 in mkv or ts ?
I also have this player, I believe eac3 is supported but I should verify.

I know for sure that in an MKV file it will not recognize it. That's how I found out the other day after burning 2 MKV movies to disc and then on playback there was no sound recognized. Perhaps it might see it in a BDMV folder, I don't know...

[Lathe]

DTS 1509 Kb/s is only a little better than AC3 640 Kb/s, you need golden ears and expensive speakers to difference them.

And a good DTS encoder is more expensive than a new OPPO.

Heh... 2 1/2 times the bit rate... Are you SURE about that mate? :) I am a pretty avid Audiophile (high end vinyl collection, etc...) but, you could very well be right.

Actually, I already have surecode. Thanks for the input though!

[Music Fan]

I believe the BDP-83 handles eac3 in AVCHD folders (you can make AVCHD with TSmuxer, the video has to be encoded in a standard resolution, not something like 1920*816), but I don't know for TS files.

edit : I verified, it works in AVCHD folders but not in mkv or m2ts (by DLNA because the BDP-83 can't play ts or m2ts on USB key but can by DLNA).

If you make an AVCHD with a big file, don't forget to split by size every 3,99 GiB with TSmuxer because the BDP-83 only handles FAT32. The cuts will be invisible.

[Ghitulescu]

I thought eac3 is not allowed in BD, however it is only not allowed in the core, but the rest of the channels may be eac3 encoded.
Anyway, Oppo 83 definitely can eac3 as it says so in the manual.

BTW, although in theory a lot of formats are allowed by many devices, the implementation of containers are rather poor. I don't think I have a player (or seen one) that can read the text subtitles (SRT) from an MKV, although MKV allows for this. It may be that your Oppo can decode eac3 per spec sheet, but is may not be able to decode it from eg an MKV. Play a bit with combinations of codecs and containers.

[tebasuna51]

Heh... 2 1/2 times the bit rate... Are you SURE about that mate?

Is a old discussion in this forum, brief summary:

The DTS encoder is less efficient (quality/bitrate) than AC3, a AC3 640 is better than DTS 768 but worse than DTS 1536.

To listen differences between AC3 640 and DTS 1536 (also with lossless encoders DTS-MA, TrueHD, Flac...) you need:

- Golden ears. Not old ears (like me), or damaged ears by high volume sounds (headphones, disco, working environment, ...), ...

- Good audio equipment (expensive receiver and speakers).

Then to many people is enough the AC3 640, but each user must do their selection.

If you are a lucky audiophile than can listen the differences feel free to chose your encoder and bitrate.

[microchip8]

I thought eac3 is not allowed in BD, however it is only not allowed in the core, but the rest of the channels may be eac3 encoded.
Anyway, Oppo 83 definitely can eac3 as it says so in the manual.

BTW, although in theory a lot of formats are allowed by many devices, the implementation of containers are rather poor. I don't think I have a player (or seen one) that can read the text subtitles (SRT) from an MKV, although MKV allows for this. It may be that your Oppo can decode eac3 per spec sheet, but is may not be able to decode it from eg an MKV. Play a bit with combinations of codecs and containers.

My somewhat old LG BP620 blu-ray player can decode E-AC-3 and it displays SRT subs in MKV just fine

[tebasuna51]

BTW, although in theory a lot of formats are allowed by many devices, the implementation of containers are rather poor. I don't think I have a player (or seen one) that can read the text subtitles (SRT) from an MKV, although MKV allows for this. It may be that your Oppo can decode eac3 per spec sheet, but is may not be able to decode it from eg an MKV. Play a bit with combinations of codecs and containers.

I don't think was a poor implementation in containers, is a commercial war. Some players don't want support mkv specs.

There are many cheap standalone players than support mkv, DVD/BD ISO's, and others containers.
Of course with support for SRT, ASS, ... subtitles.
And many audio formats than can be passtrough, or decoded to multichannel PCM, to receiver by HDMI.
And many video formats even 4K and HEVC.

[Lathe]

Is a old discussion in this forum, brief summary:

The DTS encoder is less efficient (quality/bitrate) than AC3, a AC3 640 is better than DTS 768 but worse than DTS 1536.

To listen differences between AC3 640 and DTS 1536 (also with lossless encoders DTS-MA, TrueHD, Flac...) you need:

- Golden ears. Not old ears (like me), or damaged ears by high volume sounds (headphones, disco, working environment, ...), ...

- Good audio equipment (expensive receiver and speakers).

Then to many people is enough the AC3 640, but each user must do their selection.

If you are a lucky audiophile than can listen the differences feel free to chose your encoder and bitrate.

That makes total sense mate! 640 is certainly nothing to sneeze at :)

[Lathe]

I believe the BDP-83 handles eac3 in AVCHD folders (you can make AVCHD with TSmuxer, the video has to be encoded in a standard resolution, not something like 1920*816), but I don't know for TS files.

edit : I verified, it works in AVCHD folders but not in mkv or m2ts (by DLNA because the BDP-83 can't play ts or m2ts on USB key but can by DLNA).

If you make an AVCHD with a big file, don't forget to split by size every 3,99 GiB with TSmuxer because the BDP-83 only handles FAT32. The cuts will be invisible.

Heh, I was just coming here now to comment on this very point, but you beat me to it :)

Yeah, I tried putting the eac3 into the BDMV folder, and what's funny is that the OPPO DID indeed recognize it and 'Dolby +' actually came up on the screen (which I've NEVER seen before) BUT... and it is a very big but like Mariah Carey's... I couldn't HEAR anything! Isn't that weird...!

Anyway, that is basically what you just said here, that in the m2ts you cannot use it. But, that IS good to know that it can be used in an AVCHD folder though.

Heh, and another thing to show how HORRIBLY UNobservant I am... As I was just now performing this test on a 5 minute segment, I just NOW noticed that on the eac3 track TSMuxer actually has a bloody checkbox that says 'Downconvert to AC3'! How about that :) The original audio is only @ 224 though, so I don't suppose I will mess with it and just check the box. If I had SEEN that option on TSMuxer, I probably wouldn't have come here and bothered everybody! :D

Thanks all!

[Lathe]

Ah GEEZ... Another wrinkle...

So, I checked the bloody box to downconvert to AC3 and the resulting BDMV folder has NO audio! Grrrr...! Okay, so I'm looking at the TSMuxer log and it shows that the eac track to have a 'core' @ '0' bit rate... The origin is an MKV file. So, I'm thinking that maybe it is like a TrueHD stream where in an MKV file the core has been 'ripped out' and then the resulting audio is not recognized UNLESS you use something like UseEac3to to put the core back in, and THEN TSMuxer will recognize it and you can hear it. I don't know...

I guess I'll just hafta go back to extracting the eac3 track, drop it into UsEac3to and convert it to AC3...

Oh well...

[Lathe]

Sooooo, just in closing...

If I am converting from eac3 to ac3, and you guys are saying that eac3 is of higher quality, should I then use a higher bit rate when I convert to ac3? In other words, if the original track is eac3 @ 224, should I convert to ac3 @ 320 or even 448?

Thanks!

[Ghitulescu]

You should rerip the disc, it may be that something is wrong with the resulted MKV (bad options, wrong settings)...

[Music Fan]

Yes because I guarantee that the BDP-83 can play eac3 in AVCHD folders, you should hear something and you don't have to check 'Downconvert to AC3' in TSMuxer.

[tebasuna51]

if the original track is eac3 @ 224, should I convert to ac3 @ 320 or even 448?

If source is 5.1, 320 for AC3 is too poor, at least 384 or better 448.

If source is 2.0 I think is enough 320 or even 256.

[hello_hello]

It's getting a bit long in the tooth (2007) but no doubt still perfectly valid when it comes to DTS v AC3. I'm not sure I've come across a more thorough listening test comparison.

EBU Evaluations of Multichannel Audio Codecs (https://tech.ebu.ch/docs/tech/tech3324.pdf ‎) (PDF)

If I remember correctly, even back then AAC was holding it's own against DTS and AC3 at far lower bitrates than either, except for an inability to encode applause well. I can't say it's something I've noticed since I switched to AAC myself, although I'm happy to encode at a reasonable bitrate, or maybe that's no longer a problem.

Having said all that, we mere mortals generally don't encode AC3 and/or DTS with their official encoders. I'm not saying the alternatives are bad, but encoding with a Dolby hardware encoder would probably be a different proposition to encoding with eac3to/Aften, quality wise. At least in theory.

I'm sure I've read a few of DTS vs AC3 conspiracy theories. DTS can sound better because it tends to be a little louder and the human brain often interprets that as better. Multichannel DTS is sometimes mixed differently to AC3. I think that one comes from older movies being remastered, remixed and re-released, and when the remastered audio is DTS instead of AC3 the codec gets too much credit. I'm sure the LFE channel is involved in that one too, but I can't remember how exactly.
If none of the above, the one I'm terribly inclined to believe is DTS obtains it's slightly higher perceived quality through a high bitrate placebo effect. Not that I've compared them myself. My speakers aren't horrible, but not of codec comparison quality either.

Admittedly a bit of a tangent, but it's comedy gold.
Listening tests reveal significant sound quality differences between various digital music storage technologies. (http://www.enjoythemusic.com/hificritic/vol5_no3/listening_to_storage.htm)
If nothing else, scroll down to "Different Drives, Same NAS" and read that section.

[Lathe]

Thanks TB51 & Hello#2!

That's what I was guessing. Hello#2 is likely correct (I always appreciate your interesting and insightful input, as usual :) ) but, to tickle my 'placebo' I'm currently, as we 'speak', using Surecode to convert an audio file from eac3 @ 640 to DTS @ 1536, just to cover my 'perceived' bases...

Thanks guys!

[Music Fan]

I don't understand why you absolutley want to re-encode your file. Try to re-rip the movie or to extract audio from your mkv with eac3to or ffmpeg, there's maybe a header problem which makes it unplayable by the Oppo (which recognizes it though).

[tebasuna51]

About:
Listening tests reveal significant sound quality differences between various digital music storage technologies. (http://www.enjoythemusic.com/hificritic/vol5_no3/listening_to_storage.htm).

You are right

- When a standalone player or PC do the DAC conversion and send the analogic audio to an audio amplifier there are many things than can limit the quality: speed of CD/HDD storage, drivers, quality of DAC, thermal noise added, quality of analog cables, ...

- But when the standalone player or PC send digital audio to a receiver many of that questions are irrelevant. Now the quality depend of your receiver (DAC, allowed decoders, digital conexión, ...)

Standard cheap/old receivers have DTS/AC3 decoders only, than can be received by a SPDIF conexion, by SPDIF you can send only stereo PCM (decoded by the player)

With modern receivers and a HDMI conexión we have more decoders (at last DTS-MA and TrueHD) but even if the receiver don't have the decoder (AAC, E-AC3, FLAC, ...) the player can decode the stream and send PCM multichannel by HDMI.


About:
EBU Evaluations of Multichannel Audio Codecs (https://tech.ebu.ch/docs/tech/tech3324.pdf ‎) (PDF)

The test was made over HDTV audio streams, without check typical streams in movies DVD/BD like DTS 768 or AC3 640, but is interesting.

I join the most relevant codecs/bitrate from Phase 1 and 2 in the attached image.
See the big red regtangle in HE-AAC than means than not all samples are qualified like Excellent

[Lathe]

I don't understand why you absolutley want to re-encode your file. Try to re-rip the movie or to extract audio from your mkv with eac3to or ffmpeg, there's maybe a header problem which makes it unplayable by the Oppo (which recognizes it though).

Beeeeeeeecause, it's not play'n mate... Sure, if I was more technically proficient I would LOVE to narrow it down and figure out WHY the hell the eac3 doesn't play in an MKV file or a BDMV file. BUT... dude, it's just bleed'n EASIER to extract and re-encode the file resulting in something that I DO know and DOES work and sticking it back in (so to speak...)

Thanks everyone for your very excellent input and most informative comments. Even though in THIS particular case I'm happy to do the simple fix and move on, NORMALLY I am very much interested and curious to understand the inner workings of A/V and why it does (or doesn't) do what it does.

One thing that I feel really did help me in your comments is that I sure didn't know that eac3 was somehow better quality (compression) than ac3, thus the bit rates of both formats NOT being equal. I had no idea... Also too, that I don't hafta bother with doing 2 conversions and 2 passes. So, now I know that if I want to re-encode an eac3 file, that according to your recommendations, I go with a much higher ac3 bit rate, just in case (not, again, that the resulting audio is necessarily THAT earthshakingly better, but at least to know that I am at least trying to keep to my Audiophile aspirations)

Cheers!

[Music Fan]

Beeeeeeeecause, it's not play'n mate... Sure, if I was more technically proficient I would LOVE to narrow it down and figure out WHY the hell the eac3 doesn't play in an MKV file or a BDMV file. BUT... dude, it's just bleed'n EASIER to extract and re-encode the file resulting in something that I DO know and DOES work and sticking it back in (so to speak...)
As I said earlier, you can try to simply extract it without re-encoding, it re-writes the header and sometimes helps to make it playable.
Try with a short extract of your mkv if it's too big.
If you need quality, that's something to try.

[Lathe]

As I said earlier, you can try to simply extract it without re-encoding, it re-writes the header and sometimes helps to make it playable.
Try with a short extract of your mkv if it's too big.
If you need quality, that's something to try.

Excellent suggestion! I forgot about what you said ab out the header being re-written. I'll give it a go!

[Lathe]

Just a quickie...

When I DO use Surecode to convert to DTS, does anyone know why it only uses 25% CPU utilization, even if I go to TM and raise the Priority? I can't seem to get it to use more...