does MP4 contain 5.1 ch audio?

[neo76]

Hi all,

I recently started collecting MP4 videos and when I have been watching them I seem to have a basic doubt. Does an MP4 video file contain 5.1 ch audio? I mean would the audio quality in a MP4 file be better than its XviD or DivX counterpart?

The MP4s are all BRRips and supposedly seems to have been converted from a BR source. I like the video quality but I'm not sure I'm hearing 5.1 audio when I view the videos so I wanted to know from anyone who has experienced this.

If MP4 is just 2 channel stereo then I rather stick to the DivX/XviD versions of bdrips or brrips. Though I find most brrips are mp4 encoded.

Any comments would be most appreciated.

Thanks.

[poisondeathray]

MP4 is a container. It can contain 5.1AC3 or 5.1AAC or stereo or mp3 or other audio. But if it's 5.1 AC3, you need a splitter that can handle it in order to "hear" it . Use mediainfo if you don't know what is inside

[minerva.thegift]

For what it's worth, I've used Handbrake to make a .mp4 file with 5.1 AC3 audio and VLC can play it (on my computer) but when I put the file on an external hard drive and hook it up to my Xbox 360 it cannot play it. You can read about my Xbox 360 tests here.

I recently started collecting MP4 videos and when I have been watching them I seem to have a basic doubt. Does an MP4 video file contain 5.1 ch audio? I mean would the audio quality in a MP4 file be better than its XviD or DivX counterpart?

The short answer is "yes," if you mean what I think you mean.

I think there might be a bit of confusion as to what a XviD or DivX file is - I'm guessing you're referring to a video compressed with the XviD or DivX codec and placed in the .avi container. That .mp4 file that I made - the one with 5.1 AC3 audio - also had XviD video (because that's one of the main codecs supported by the Xbox 360 and I was working on testing with it.) The .avi container was (and still is, I suppose) a common container for XviD encoded video, but it is not the only option. Such .avi files were (and sometimes still are) generally made using Stereo audio only (not full surround sound) and so yes, 5.1 channel AC3 audio would generally sound "better" (and certainly be nicer in a full home theater) than Stereo sound common in Xvid (.avi) files.

To further complicate things just a bit, though, the .avi container can now support AC3 audio - that's one of the tests I ran in that Xbox 360 forum thread. I don't think it used to be able to, but it can now. In other words, the exact same video (XviD) and audio (5.1 AC3) could be put into either a .mp4 file or a .avi file (or, for that matter, a .mkv file or one of several other containers) and in theory they'd all sound/look the same since they would have the same audio/video inside them.

Read around here on the forums about codecs and containers if this seems a bit fuzzy (or just reply in this thread and I'm sure someone could help you out )

[neo76]

Thanks for the response.

poisondeathray - how can I use the splitter to hear the 5.1 ch audio? on my home theatre system? i have a yamaha receiver. And I'm connecting my WD HD Media player to this receiver. Basically is the mp4 that am playing an inferior quality and hence am not able to hear the surround sound? 'Cos very often when I try with xvid or divx videos the sound is excellent but its only with mp4 files that I've been facing this issue.

And I've tried to use media info and some of the mo4 files do have 6 ch audio. So am not able to figure out why the sound quality is not the way it sounds using the same title in xvid format?

[minerva.thegift]

As I understand it, only some hardware will support 5.1 ch audio in the .mp4 container. When you look at it with mediainfo and it tells you that it does have 6 ch audio, then you know that the problem is not the file but the hardware. In other words, the surround sound is there in the file but your speakers don't know how to play it.

[Reelman472]

Neo76

Just a couple of questions. Doesn't your reciever indicate on the front panel what channels are being used? Also, how do you have the wdtv hooked up? Composite or hdmi? Actually thats 3 questions.

Reelman472

[neo76]

hi reelman, actually my receiver shows 5 ch stereo but am still not able to get the same 5.1 channel with the mp4 file, though i can get that with a Xvid equivalent of the same movie file. The basic difference I can find is, I need to crank up the volume on my receiver whenever I use mp4 files.

Secondly, am using digital optical output for sound. I tried using hdmi but for some reason I dont get any output using the hdmi cable.

[frlev120]

Your audio in MP4 must be AAC LC not AC3.

I know the thread is dead, but just in case...

[jagabo]

MP4 has officially supported AC3 audio for a few years now. The issue is whether or not the player can handle it since many have not been updated.

[leviny]

My BD player (non DLNA sony bdp-s380) plays files from my windows 7 media player library over a network. it'll play MP4 files, but not the AC3 passthru (done in handbrake) only 2 ch mixdown. it will also play mpeg2 files from my library, with 5.1 audio. two questions

Does a newer player play 5.1 mp4 files? is DLNA required/relevant at all?

How can I convert an mp4 file with 5.1 to mpeg2 with 5.1? is it possible to maintain the HD resolution in this mpeg2 file?

[Herve]

MP4 has officially supported AC3 audio

NO !!!
No ISO specification allowed it
But Apple implemented it in its own proprietary format ".m4v"

ISO still says (3 years after your post):
audio = MPEG-1 Layer III, MPEG-1 Layer II, MPEG-1 Layer I, AAC, AAC+, eAAC+, SBR
…and no other audio format.

PS: there is some non-standard audio formats ammowed by third parties: but they are only handeled by the proprietary software which "allow this non-specf feature" (or by VLC which allows everything).

(…and if I mistook, please gimme a link to a specification/audio book, to validate your assertion )
PS: I know this is an old thread, but while googling for something else, I -once again- reach it…
bye

[Sergio29]

and if I mistook, please gimme a link to a specification/audio book, to validate your assertion )

http://www.mp4ra.org/codecs.html

[jagabo]

MP4 has officially supported AC3 audio

NO !!!
No ISO specification allowed it
But Apple implemented it in its own proprietary format ".m4v"

Which is nothing more than an MP4 container with a different extension.

[El Heggunte]

Not-So-Off-Topic...

— MP4Box still doesn't support ALAC, ALS, DTS

— L-Smash still doesn't support MLP/TrueHD