AC3 to AAC Troubles - Need Help

[stilllogicz]

So I've been using MeGui to convert ac3 to aac in the past with no issues but today I keep running into a problem that I can't seem to solve on my own.

The converter detects that there is clipping and that a 2nd pass will be needed. After it is done, the audio length is triple (1hr becomes 3hr, etc) and the audio plays back super slow.

I've never ran into a clipping issue before with any other files so what do you think I should do to fix this problem?

Here is the log:

[a02] Encoding AAC <0.50> with NeroAacEnc...
[a02] Clipping detected, a 2nd pass will be necessary. <WARNING>
[a02] Starting 2nd pass...
[a02] Extracting audio track number 2...
[a02] Removing AC3 dialog normalization...
[a02] Decoding with libav/ffmpeg...
[a02] Reducing depth from 64 to 32 bits...
[a02] Encoding AAC <0.50> with NeroAacEnc...
[a02] Applying -0.59dB gain...

[jman98]

Is there a compelling reason (ie. Apple forces you to do this) that you are converting in the first place? Generally speaking AC3 is far better supported than AAC and on top of that, AAC is a lossy codec so there's absolutely nothing to be gained except MAYBE some minuscule space savings by doing this type of conversion.

[jman98]

P.S. Some people mistakenly believe that if they convert their video to MP4 containers that they HAVE to use AAC audio. This was changed several years ago, but still a lot of people are not aware of the change. AC3 is now fully supported in MP4 containers.

[El Heggunte]

Make sure your copy of MeGUI uses the latest version of eac3to.

Or even better, drop MeGUI and learn how to use eac3to directly in the command-line interface.

[hello_hello]

Or even better, drop MeGUI and learn how to use eac3to directly in the command-line interface.

And by doing so it'll fix stilllogicz's problem how??

[hello_hello]

I'd agree that if you're using the default AAC quality setting (which you are) then unless you're mixing multichannel audio down to stereo there's little to be gained by converting AC3 to AAC. I generally only convert DTS audio to AAC, while I keep the original audio if it's AC3.

I'm fairly sure the clipping issue is due to eac3to removing the dialogue normalization (which is used to adjust the AC3 volume so dialogue between AC3 soundtracks should be roughly the same) and this is increasing the volume enough for very slight (0.59db) clipping to occur, very possibly only in one section of the audio. Or the original AC3 might have included a little clipping without the dialogue normalisation being removed, but either way, a second pass was therefore run to reduce the volume by an appropriate amount while encoding to prevent clipping. That's all fairly normal and nothing to worry about.

As for the speed issue, and I'm kind of guessing here..... I think it's caused by the AC3 audio being decoded using the wrong bitrate, but if that's why the encoded video is so much slower I'm not sure why it happens, and as I said, I'm guessing. Do you have another program on your PC which will convert the audio? If not, maybe try converting it to Flac first (because it's lossless) or try a different "preferred decoder" to see if you get the same result.

[unclescoob]

AC3 is now fully supported in MP4 containers.

I just toyed with MP4Muxer to mux my ac3 with my MP4(H264-created with Handbrake).

Windows Media Player would just play the MP4 elementary stream with no problem, before I muxed that stream with the ac3 audio file.

Once both were joined, it wouldn't play it anymore, ALTHOUGH, VLC would.

This worries me in terms of compatibility. Is that a red flag, the fact that now Windows Media Player won't play it, but VLC will?

Where did I go wrong?

[El Heggunte]

^ (Wild Guess) On Windows 7, Windows Media Player *by default* will use the media splitters provided by Micro$oft, and probably that MP4 splitter doesn't support AC3 in an MP4 file. OTOH both MPC-HC and LAV Splitter support AC3 in MP4 (and in fact LAV Splitter supports even VC-1 and DTS in MP4 )

[unclescoob]

so if I were to ever attempt to burn this for blu-ray, I generally shouldn't have a problem, correct?

[jman98]

AC3 is now fully supported in MP4 containers.

I just toyed with MP4Muxer to mux my ac3 with my MP4(H264-created with Handbrake).

Windows Media Player would just play the MP4 elementary stream with no problem, before I muxed that stream with the ac3 audio file.

Once both were joined, it wouldn't play it anymore, ALTHOUGH, VLC would.

This worries me in terms of compatibility. Is that a red flag, the fact that now Windows Media Player won't play it, but VLC will?

Where did I go wrong?

You're not a newbie. What it's a "red flag" for is that WMP is a piece of #$%^. Seriously. Jagabo has posted before that if you're willing to do a large amount of tweaking filters that you can get it to play just about anything, but out of the box it's a piece of crap as you are finding out. My advice would be do NOT use WMP for ANY serious "compatibility testing". I'm also not really sold on MP4 containers. Unless you have Apple stuff that demands it, there's no reason EVER to not use MKV. If you wrapped your files in an MKV container even craptacular WMP could probably play that correctly with AC3 audio.

You need to take away from this that WMP is junk and relying on it is a bad idea.

[unclescoob]

I'm also not really sold on MP4 containers. Unless you have Apple stuff that demands it, there's no reason EVER to not use MKV.

Well, I'm using Handbrake (x264) to transcode my vob to H.264, which results in an MP4 file. My goal is to author for blu-ray destination.

[poisondeathray]

handbrake doesn't make blu-ray compliant files , nor is AAC blu-ray compliant

If you want real blu-ray, you should leave it as an lementary stream before authoring (should not be put into a container)

But many newer blu-ray players have support for mkv and can play other file types (non authored), and non compliant files

[unclescoob]

handbrake doesn't make blu-ray compliant files

handbrake makes H.264 MP4 files at High Level. Is this not the appropriate standard for blu-ray, or am I missing something?

If you want real blu-ray, you should leave it as an elementary stream...

This contradicts your statement regarding handbrake not making blu-ray appropriate files. So you're stating that the elementary video file is blu-ray compatible?

...before authoring (should not be put into a container)

Meaning?

[El Heggunte]

handbrake doesn't make blu-ray compliant files

handbrake makes H.264 MP4 files at High Level. Is this not the appropriate standard for blu-ray, or am I missing something?

Yes, you are missing *many* things

http://forum.doom9.org/showthread.php?p=1399419#post1399419

[poisondeathray]

handbrake doesn't make blu-ray compliant files

handbrake makes H.264 MP4 files at High Level. Is this not the appropriate standard for blu-ray, or am I missing something?

see El Heggunte's link above

also
https://sites.google.com/site/x264bluray/home

If you want real blu-ray, you should leave it as an elementary stream...

This contradicts your statement regarding handbrake not making blu-ray appropriate files. So you're stating that the elementary video file is blu-ray compatible?

An elementary stream with blu-ray compatible encoding settings

...before authoring (should not be put into a container)

Meaning?

Raw AVC . Video only (no audio, no container - ie. no mp4, no mkv)

[unclescoob]

Yes, you are missing *many* things

OOooOOOOO, Spooky Spooky!!!

Fine. I'll check out the link this weekend and compare.

[unclescoob]

Wait, hold on...one more thing...Handbrake uses x264. So what you're saying is that it may use it, but it does not utilize x264's blu-ray compatible options?

[poisondeathray]

Wait, hold on...one more thing...Handbrake uses x264. So what you're saying is that it may use it, but it does not utilize x264's blu-ray compatible options?

bingo! it doesn't use blu-ray compatible settings

you need a bunch of things (look in those links above) in order to make it compatible with blu-ray (there are many restrictions)

It's analgous to MPEG2 for DVD, there are many rules & restrictions as well . These standards are to ensure that discs actually play in every blu-ray player or dvd player

This is one of many reasons why optical media sucks - get a media player instead (this was discussed in one of your other threads)

[unclescoob]

[QUOTE=poisondeathray;2175168get a media player instead (this was discussed in one of your other threads)[/QUOTE]

Yeah I know. I did a little homework on those media players and they semi-suck. Why semi? They do what they say they do, but they don't actually have a hard drive, where I can store my movies in. A Playstation3, on the other hand, does. And it plays MP4 files.

[poisondeathray]

Yeah I know. I did a little homework on those media players and they semi-suck. Why semi? They do what they say they do, but they don't actually have a hard drive, where I can store my movies in. A Playstation3, on the other hand, does. And it plays MP4 files.

Media players play all sorts of files, MP4 container support as well. PS3 is quite limited, it won't play many types of files or containers

That's a plus - you usually want to store things on HDD separately . That is your medium. They are portable, fairly compact, cheap, no clutter, easy to store, re-usable, high utility

Cost / GB is much lower than optical media even with today's elevated prices (and think of the added storage costs and CLUTTER of cd cases or binders)

The cost of some of these media players is ~ $60 (e.g. asus oplay mini) , 2TB HDD is about $100 (preflood they were about $80 )

[unclescoob]

Yes, but they require some router to stream my movie to my TV. I don't like the idea of relying on signals for something like this. I want something with a tangeable hard drive that's actually storing my movies in it and connects to my TV. I don't care for equipment that requires a crutch in order to function. PS3 plays MP4 containers (handbrake). I know this for a fact.

[poisondeathray]

Yes, but they require some router to stream my movie to my TV. I don't like relying on signals. I want something with a tangeable hard drive that's actually storing my movies in it. PS3 plays MP4 containers (handbrake). I know this for a fact.

Yes PS3 plays MP4 (with certain settings), but the exact same video in a MKV is unsupported. The point was, that media players play dozen's of other types of video that the PS3 doesn't (higher compatibilty). (It sounded to me your point about MP4 was insinuating that media players didn't play MP4)

You can connect media players directly to your TV (hard line) as well, you don' t need to stream it. Some less expensive media players don't even have streaming capability

Since you already have a PS3, just use that with MP4

For someone looking to buy new, a media player has much more utility, less expensive, supports many more formats, more capacity, more utility (but of course doesn't play games)

[unclescoob]

Do media players actually have hard drives? And I ask this because taking a look at the box in the store, it does not specify this. Went to Best Buy the other day, and the salesman said it does not. It just streams. Now, this was a Wetern Digital player (most popular). Went to a Radio Shack the other day and was given the same information: Media Players only stream. I took a look at the product box and that's pretty much what it says. Does not even specify if it has a hard-drive. So which ones are you referring to?

[unclescoob]

BTW, my files are MP4, not MKV

[poisondeathray]

Do media players actually have hard drives? And I ask this because taking a look at the box in the store, it does not specify this. Went to Best Buy the other day, and the salesman said it does not. It just streams. Now, this was a Wetern Digital player (most popular). Went to a Radio Shack the other day and was given the same information: Media Players only stream. I took a look at the product box and that's pretty much what it says. Does not even specify if it has a hard-drive. So which ones are you referring to?

They are usually don't come with HDD

You plug in a USB key, or USB connected storage device (that's the beauty of it)

[poisondeathray]

BTW, my files are MP4, not MKV

Yes , I know, I'm just explaining the utility of being able to play other files, support for other formats .

Or are you only using this for these files, never going to use it for anything else ?

[unclescoob]

I'm pretty much converting all of my AVS files to MP4 with Handbrake. They look terrific, and I'd like to do this with the rest of my VOB collection. And again, I don't like having to connect a storage device to a media player and then connect that to the TV. They should have their own hard drives that can store files, and not rely on what I have. That's like having a tow truck take your car around town, and you sitting behind the wheel telling people that you're driving.

[poisondeathray]

I'm pretty much converting all of my AVS files to MP4 with Handbrake. They look terrific, and I'd like to do this with the rest of my VOB collection. And again, I don't like having to connect a storage device to a media player and then connect that to the TV. They should have their own hard drives that can store files, and not rely on what I have. That's like having a tow truck take your car around town, and you sitting behind the wheel telling people that you're driving.

Sure, you can weigh the pros/cons. Do whatever meets your needs. I only see positives here

The modularity and expandabilty aspect of HDD is what is appealing to me. Whether it comes with a HDD or not is irrelevant to me . You either buy it separately or pay more for it included.

When you start to build a library of movies, home videos, etc, you will easily have 100's of TB. How do you plan to store that ? Do you think a single HDD will hold all that? A movie from blu-ray can be 25-50GB. Are you looking for a device that comes with a HDD that isn't upgradable or doesn't allow for expansion ?

You can store home video's on a HDD + enclosure. e.g. You can store movies on another HDD. Maybe a vacation on another HDD. You can organize it however you want.

[unclescoob]

Well, well well. Seems to me that my old friend Avidemux converts to H. 264/MPEG-4/AVC. The blu-ray Standard. And it uses x264.

So if i wish to make a compatible disc, Avidemux is the way to go. Handbrake can't do this.

[hello_hello]

Handbrake uses the x264 encoder, so why can't it?

I'm not sure I understand the logic behind not using a playback device which can play media from an external drive, even if it has an internal drive which you prefer to use. I have all my media stored on external USB drives. Probably around 6TBs in total. It doesn't matter whether I'm using the PC for playback, the Bluray player, or the media player built into the TV. I just plug an external drive in and I'm away. I can lend a hard drive to someone else in the house or copy stuff to a thumb drive for them to use in the same way and not lose my media player.
Using a device which only plays media it stores internally... well you've immediately restricted your options and to use your analogy..... it's a bit like driving a tow truck that won't actually tow anything...