MKV, AAC Or AC3

[jamesj84]

Just a quicky really.
With DVDs I usually convert to MP4 as the files are lower then 4gb. I try to keep the audio intact, if i cant then I use AAC.

With a MKV file, is the best audio codec to use AAC or AC3? if i cant keep the audio lossless from the BD.

[Baldrick]

It depends...

Do you mean if you are converting to MKV? Or from mkv to mp4?
And what do you play with?
And what is the source audio?

[jamesj84]

Sorry i was a bit vague.
I am converting to MKV from my BD rips. I have a media device which plays files from a HDD and it accepts AAC & AC3.

The source audio will be whatever it is on the disc, lossy or lossless(Supposedly). Dependant on the film I will try and keep the audio without encoding it. Just wondered if i do encode which is the best audio codec to use. AC3 or AAC with a MKV file.

[Baldrick]

AC3. Most devices supports it and with 5.1 audio.

[jamesj84]

I thought AAC was a superior format, i maybe wrong. nd does AAC not support 5.1

[Baldrick]

AAC supports 5.1 but maybe not all media players.

[jman98]

I thought AAC was a superior format, i maybe wrong. nd does AAC not support 5.1

AAC is lossy as is AC3. MKV is a container, not an audio format. AAC does support 5.1. Whether it is better than AC3 or not is certainly debatable but given that it is a lossy format converting from AC3 to AAC is going to entail some loss of quality, even if you can't perceive it. I personally find AAC cumbersome to deal with as it is not valid for DVD or BluRay audio. AAC has its supporters, some of whom are Apple fanboys. I can tell you that my personal opinion is that it's a fine codec but I remain skeptical that it is superior to others. If it actually is superior my feeling is that it is so by such a slim margin that most people could never actually tell the difference between it and another good codec in a blind test.

[Atak_Snajpera]

if AAC 2.0 128kbps is transparent so AAC 5.1 320kbps will be transparent as well. (64kbps per channel is enough in AAC-LC)

PS. LFE is ultra easy to compress therefore we don't count it.

[jamesj84]

jamn - I know MKV is a container and aac/ ac3 is the audio compression codec. I was asking if AAC is a superior format. I want my MKVs to be pretty future proof. Looks like as AC3 is more widely known then ill keep with AC3. I know a lot of people on here rate Nero AAC codec thats why i was asking.

[jman98]

I was asking if AAC is a superior format.

Short answer - it's debatable. AAC was really designed to replace MP3 rather than to replace AC3. The fact that AAC supports multiple channels is just a bonus but it really was designed for uses like iTunes rather than as a movie soundtrack.

[tun.tin]

This is what I do to keep:

DVD to MP4 (AAC)
DVD to MKV (AC3)
BD to MKV (DTS)

[Atak_Snajpera]

jamn - I know MKV is a container and aac/ ac3 is the audio compression codec. I was asking if AAC is a superior format. I want my MKVs to be pretty future proof. Looks like as AC3 is more widely known then ill keep with AC3. I know a lot of people on here rate Nero AAC codec thats why i was asking.

Nero AAC Encoder is not the best
http://forum.doom9.org/showthread.php?t=161957

[budwzr]

Another way to compare is by where the file will end up. Web or disc.

[jamesj84]

File is to end up in neither. It will end up on my HDD for playback on my TV.

[ktklein72]

So consider me a noob when it comes to audio & video formats... I've only just begun reading up on the various audio and video formats, codecs, etc. I guess that was as a result of purchasing a Vizio Co-Star GoogleTV STB (Android 3.2). I have a bunch of movies on an external HDD that play fine on my PC, however quite a few of them will not play on my Co-Star (which is attached to a Denon AVR2310CI receiver and Samsung 55in LED LCD TV. I've come to find the Co-Star does not currently support either direct playback of DTS audio nor does it have provisioning for pass-thru. However I have been told since I have a receiver I should consider converting the files' audio to Dolby Digital. Is that AC3? And if DD fails then I can always fall back on AAC. Does anyone have an opinion or comments on this? Before I start converting very large files, I thought I'd float what I was thinking of doing and see if there might be a btter or different way to go about this. Any feedback is most welcome. Thanks.

[fritzi93]

@ktklein72:

Yes, DD is AC3. As already discussed AC3 is more compatible.

I use AC3 5.1 at 640 kb/s (maximum bitrate) for MKVs I play from hard drive on my TV. I do this because my TV can output AC3 5.1 over optical out to receiver. The TV cannot output DTS, downconverting it to PCM stereo.

In your case, I'd suggest you go with AC3. There are various ways to do it depending on what your source files are.

Good luck and welcome to the forum.

[hello_hello]

I use the Nero AAC encoder and the default Q0.50 quality setting.
In my opinion it's not worth re-encoding AC3 as AAC simply because it doesn't reduce the file size enough at that quality (unless you downmix multichannel to stereo in the process). DTS audio is a different story though. The file size reduction can be quiet significant.

Generally I keep the original AC3 audio if possible. If not, I convert DTS to AAC. The only downside to AAC is there's no "passthrough" option with most devices as there is for AC3 or DTS, but aside from that AAC is fine and probably more widely supported by media players than DTS.
Personally I don't care about passthrough options as I just downmix multichannel to stereo for playback anyway, given multichannel audio is just a silly gimmick . But each to their own.

I've yet to read an AAC encoder comparison which doesn't concentrate solely on low bitrate encoding which for me makes them irrelevant. At higher bitrates each encoder is probably about the same. If someone knows of an AAC encoder comparison using higher bitrates I'd be interested to see it.

[ktklein72]

@ktklein72:

Yes, DD is AC3. As already discussed AC3 is more compatible.

I use AC3 5.1 at 640 kb/s (maximum bitrate) for MKVs I play from hard drive on my TV. I do this because my TV can output AC3 5.1 over optical out to receiver. The TV cannot output DTS, downconverting it to PCM stereo.

In your case, I'd suggest you go with AC3. There are various ways to do it depending on what your source files are.

Good luck and welcome to the forum.

Thanks for the suggestion, I'll definitely try it that way.

Sent from my Eclipsed DROID X2 using Tapatalk 2.4.10

[jman98]

ktklein72 - don't dig up old threads (this is called "grave robbing") and add to them. Your situation is different enough from the original thread that you should have just made a new thread. Also you arguably have hijacked this thread too because you're not exactly in the same situation as the original poster. As a general rule, if the thread is more than about 6 months old and you do not have critical information to add that does something like answer an unanswered question in the thread, just make a new thread.

[ktklein72]

Thank you for your input and while I agree this is an aged thread, like the OP I have MKV files stored on a HDD. While I am not ripping from DVD at this very moment, I felt the audio aspects of this thread also applied to my situation. I'm sorry you feel I hijacked a thread that's been dormant for 10 months. If you like, remove my comments or move them to a separate thread as you see fit. Too many forums are way too up tight and I understand why so many people are apprehensive to ask questions. Gotta tell ya, not feeling very welcome here after reading your post.

Sent from my Eclipsed DROID X2 using Tapatalk 2.4.10

[hello_hello]

Now you've been scolded for posting in an old thread for no logical reason, you mentioned converting very large files..... I assume you realise you probably only need to convert the audio while you can simply copy the video?

There's many ways to do it, but if I was converting the audio in lots of MKVs I'd probably use this method because it allows you to convert more then one at a time, and it's easy to start the conversion process and walk away while letting the conversion program do it's thing.
For the conversion part I'd use foobar2000. It's an audio player but also a good converter. It's been a while since I've installed it but I'm pretty sure for dts and ac3 you'll need to install the relevant decoder plugins, which can be found on the foobar2000 site. For encoding you'll have to download the relevant encoders if you don't already have them and tell foobar2000 where to find them the first time you want to use them. It's LAME for MP3, NeroAAC for AAC, AFTEN for AC3.... and a few others, but they're the main ones you're likely to use.

Once it's set up it's just a matter of opening all the MKVs for which you want to convert the audio with foobar2000. It'll play/convert the audio in MKV/MP4/AVI files without the need to extract it first. With them all loaded into a playlist, highlight them all, right click and select convert, then select "..." which takes you to the encoder setup. Fom there you can choose the encoder and options such as bitrate and output file naming etc and save it as a preset. Once you're done, start converting, and foobar2000 will convert as many simultaneously as you have CPU cores until it's finished.

When it's done, open an original MKV with MKVMergeGUI and add the converted audio. Highlight the original audio track and under the "format specific options" tab make note of any audio delay. If there is one, apply the same delay to the converted audio. De-select the original audio track and start muxing to create a new MKV containing the converted audio. If you want to keep both audio streams, try moving the converted audio up in the order until it's above the original audio. Hopefully that'll get your player to use the first audio stream it finds in the MKV while still allowing you to keep the original. You can only try it..... but there's no reason not to have multiple audio streams in an MKV.

The one thing which might interrupt the above process is MKVs which use chapters. foobar2000 opens each chapter in an MKV as if it's an individual file. There's a few ways around it but using MKVCleaver to extract the audio from those MKV's and converting the extracted audio instead might be the easiest. MKVCleaver will open a bunch of MKVs and batch extract the audio from them to make it easier.

[ktklein72]

Thanks for the detailed suggestion hello_hello. Yes, I did realize only the audio needed to be converted but apparently didn't clearly convey in my original post what I was thinking in my head. LOL. I'll have to find some time this weekend to play around. I just purchased a brand new laptop, so besides foobar2000, I definitely will need to also install the relevant decoders and encoders. If I have any questions I'll be sure to PM you.

And... Now that my initial scolding is behind me, hopefully my future posts and subsequent replies will be less chaotic at the on start.

Thanks again for jumping in and providing some clear direction for me. Now if only the Vizio Co-Star either properly licensed DTS or allowed pass-thru none of this would even be necessary. Some are holding out hope that the GoogleTV 3 update will add this functionality but I'm not holding my breath. Thanks again!

[hello_hello]

I neglected to mention MKVMergeGUI has a job queue, so when replacing the audio streams there's no need to sit there waiting for it to remux the new MKV each time. Add/replace the audio as above and use the "add to job queue" button, then open the next MKV and add/replace the audio, add it to the queue..... then you can walk away while MKVMergeGUI does it's thing.

The main reason I suggested the above method is because you said you have many to convert and foobar2000 will convert a bunch of files in a "batch".... plus I use it as my audio player/converter so I'm familiar with it.

If you have any problems setting up an encoder, it'll probably be the AFTEN AC3 encoder as I'm not sure foobar2000 has a default preset for it (I can't remember). If not, use the method above to get to the encoder configuration and set it up this way when the encoder configuration opens.

Click on "Output Format".
If AFTEN/AC3 isn't there as a preset, click on "add new" and in the top encoder drop down box, choose "custom".
In the "Encoder File" section, point foobar2000 to wherever you've saved aften.exe.
Extension: ac3
Parameters: -readtoeof 1 -v 0 -b 448 - %d
Format: Lossy:
Highest BPS mode: 32
Display: put whatever you like there.

Select okay and use the back button.

Under Destination, I use "%filename%" (without the quotes) for the Output Style/Format which gives you the same output file name as each input file name.

Use the back button again and save the converter setup as a preset which will then appear under the right click convert menu. Hit the Convert button and you're off.

The AFTEN "-b 448" parameter is the bitrate, and you can change it to whatever you like. I'm not sure what the maximum is, but that's what I generally use for multi-channel AC3 (although I hardly ever encode using AC3). If you don't specify a bitrate, apparently AFTEN picks one according to the number of input channels. More info here: http://aften.sourceforge.net/longhelp.html
I've got two converter presets for Aften, the other's the same as above except the bitrate is 192Kbps for stereo audio, but you can do it however you like.
Hopefully that'll help as the foobar2000 encoder setup mightn't be overly intuitive.

I thought someone else may have offered some ideas by now, but I'm sure there'd be a program or three dedicated to converting the audio in MKV/MP4 files which let you open one or several, tell it the desired audio format and it'll spit out new MKVs/MP4s without re-encoding the video. I just don't know of any off the top of my head... maybe a bit of a Google on something like "MKV audio converter" might turn something up if you feel like looking.

MeGUI will let you load video files into it's audio encoding section. It'll only run one at a time but you can add multiple encoding jobs to the queue and then run it, but you'd still need to replace the audio manually using MKVMergeGUI. I'm pretty sure it comes with all the encoders you'll need though.

I probably won't be around much over the weekend.... I've actually got to work, but if you PM me I'll get back to you when I get a chance.

[PowerFalcon]

Some sites will only accept AAC-LC audio codec, is there a equal, better, alternative ?

[hogger129]

Some sites will only accept AAC-LC audio codec, is there a equal, better, alternative ?

What do you mean by "sites?"

[kshively]

The most important reason to use AAC-LC is for playback on iOS devices. iOS devices will not play other audio formats.

[Mephesto]

Oh good lord.

You didn't clarify "superior codec" but I'll assume you're talking about quality.

1. AC3 sucks balls, MP3 is far superior to AC3 and AAC is superior to MP3. Do the math.

2. Nero AAC is the best AAC codec out there. Stay away from Hydrogenaudio listening tests. The idiots for some reason now don't control the target bitrate yet advertise a target bitrate. For their 64 kb/s test they allowed bitrates as high as 128 for some codecs on a few samples. If you compare Nero with a low bitrate to a notoriously crappy codec like QuickTime with a high bitrate, what the **** do you expect to happen?

3. I was banned from Hydrogenaudio when I inquired about this. That should tell you the credibility of those faggots.

The listening tests they did in the past was far more useful and Nero triumphed in all of them for a decade. Now that they are outdated, even those have ceased to be useful.

[hogger129]

1. AC3 sucks balls, MP3 is far superior to AC3 and AAC is superior to MP3. Do the math.

Dolby Digital and AAC/MP3 were designed for different things. I can tell you right now that MP3 does not support multichannel audio like 5.1, where Dolby Digital and AAC both do. The reason to use Dolby Digital is compatibility. AAC is supported on many things these days, but rarely in 5.1.

2. Nero AAC is the best AAC codec out there. Stay away from Hydrogenaudio listening tests. The idiots for some reason now don't control the target bitrate yet advertise a target bitrate. For their 64 kb/s test they allowed bitrates as high as 128 for some codecs on a few samples. If you compare Nero with a low bitrate to a notoriously crappy codec like QuickTime with a high bitrate, what the **** do you expect to happen?

Okay. I still think those people over on Hydrogenaudio are more credible than you are though.

3. I was banned from Hydrogenaudio when I inquired about this. That should tell you the credibility of those faggots.

Is that really why you were banned, or was it because of these types of rants?

The listening tests they did in the past was far more useful and Nero triumphed in all of them for a decade. Now that they are outdated, even those have ceased to be useful.

Again, AAC is a great codec, but there isn't a lot that supports it in 5.1. Dolby Digital 5.1 IS supported on everything I've seen, every receiver I have seen can decode it (can't say the same for AAC 5.1), so I don't know what good reason there is not to use Dolby Digital 5.1. Even at a lower bitrate like 384kbps it still sounds good.

[Mephesto]

Dolby Digital and AAC/MP3 were designed for different things. I can tell you right now that MP3 does not support multichannel audio like 5.1, where Dolby Digital and AAC both do. The reason to use Dolby Digital is compatibility. AAC is supported on many things these days, but rarely in 5.1.

1. You're wrong, MP3 in MPEG-2 mode does support 5.1.
2. We're talking about quality, not compatibility. OP didn't clarify what he meant by "superior" codec.

Okay. I still think those people over on Hydrogenaudio are more credible than you are though.

Take my advice or don't, Mr. Hogger. I don't give a shit. Most don't which is why most prefer aXXo and YIFY torrents to rips that DON'T look like garbage.

Is that really why you were banned, or was it because of these types of rants?

Yeah, how dare some ******* nobody that's not part of my boy club actually see through my bullshit and rant about my rigged listening tests that I intentionally bias and pretend that they're credible because developers are members of my site?

*SILENCED!*

[hogger129]

Dolby Digital and AAC/MP3 were designed for different things. I can tell you right now that MP3 does not support multichannel audio like 5.1, where Dolby Digital and AAC both do. The reason to use Dolby Digital is compatibility. AAC is supported on many things these days, but rarely in 5.1.

1. You're wrong, MP3 in MPEG-2 mode does support 5.1.
2. We're talking about quality, not compatibility. OP didn't clarify what he meant by "superior" codec.

Okay. I still think those people over on Hydrogenaudio are more credible than you are though.

Take my advice or don't, Mr. Hogger. I don't give a shit. Most don't which is why most prefer aXXo and YIFY torrents to rips that DON'T look like garbage.

Is that really why you were banned, or was it because of these types of rants?

Yeah, how dare some ******* nobody that's not part of my boy club actually see through my bullshit and rant about my rigged listening tests that I intentionally bias and pretend that they're credible because developers are members of my site?

*SILENCED!*

***********Just a quicky really.
With DVDs I usually convert to MP4 as the files are lower then 4gb. I try to keep the audio intact, if i cant then I use AAC.

With a MKV file, is the best audio codec to use AAC or AC3? if i cant keep the audio lossless from the BD. ************


The original poster is asking us which codec he should use inside .mkv. Why would you not consider compatibility?

I say unless he wants 5.1 surround sound, use AAC. If he wants 5.1 surround sound, use Dolby Digital 5.1. DD 5.1 also has better compression than .mp2, which matters since the original poster talked about space.

By the way, torrenting is illegal. Stop stealing and just buy the stuff. I would imagine that a BD shoved down inside 1GB doesn't look very good.