Playback of MP4 file

[ChrisBensch]

I have a HighDef movie encoded using megui-x264 and belight for 5.1 ac3 to 5.1 aac using one if it's presets. I use megui to mux the resulting files into a single MP4. I opened it with VLC and it recognizes the video but the audio shows as 2 channels. WHen the video starts, VLC errors out with an error from lib_faad. Any ideas as to why the audio isn't being recognized/played back? Is there a "preferred" method of AVC playback? I've installed the latest ffmpeg from x264.nl with no luck.

[ChrisBensch]

I extracted the aac track and played it back with VLC and it fully recognizes all 6 channels and sounds great. I even tried to remux the aac track and the video track with YAMB and it still errors out, recognizes the audio as 2 channel instead of 6.

[Kurtnoise]

why not testing the playback with MPC (Media player Classic) ? Don't forget to uncheck the downmix for AAC in MPC settings...

[ChrisBensch]

I've tried that as well. One thing I tried that *DID* work is using MeGUI and the "autoencode" option on a small test file. It played back just fine using a 5.1 aac file. Only issue was that VLC still only detected a 2 channel file. MPC plays the file, it doesn't show how many channels, but show it as a "GPAC etc etc etc". So, this leads me to believe that there is a flaw in my process

[ChrisBensch]

OK, this is weird...i encoded the test clip with MeGUI using "Auto Encode" and also Nero Recode using essentially the same settings (particularly the Audio). The files both played in VLC, the MeGUI file only showed 2 channels of audio, the Recode file showed 6 channels of audio...I don't understand it? Is there something in the muxing process that flags the number of audio channels?

[bond]

in mp4 there are two switches:
1 tells that the audio stream is mono
2 tells that the audio stream is multichannel (which includes stereo)

some player get this wrong and think that "2" means two channels
no idea why nero shows 6 channels (maybe they place "6" where only 1 and 2 are allowed?)

why vlc borks on the file? no idea. try another libfaad decoder/player, like coreaac or mpc or mplayer

edit: moved to where it belongs

[ChrisBensch]

@bond: thanks for correcting the proper category

I've got fully working files now, muxing with YAMB 1.4, when mp4box analyzes the file it shows what I expect

Track # 1 Info - TrackID 1 - TimeScale 2997 - Duration 00:01:41.768
Media Info: Language "und" - Type "vide" - Sub Type "avc1" - 2440 samples
MPEG-4 Config: Visual Stream - ObjectTypeIndication 0x21
AVC/H264 Video - Visual Size 1280 x 608
Self-synchronized

Track # 2 Info - TrackID 2 - TimeScale 48000 - Duration 00:01:41.269
Media Info: Language "und" - Type "soun" - Sub Type "mp4a" - 4747 samples
MPEG-4 Config: Audio Stream - ObjectTypeIndication 0x67
MPEG-2 Audio AAC LC - 6 Channel(s) - SampleRate 48000
Synchronized on stream 1

But when VLC and MPC play the file, they both recognize as "Stereo" or "2 channels"

My biggest concern comes because I plan on playing these files through my Home Theater PC and wish to maintain my surround sound.

[bond]

i already gave you the answer why they show "stereo"

[SeeMoreDigital]

My biggest concern comes because I plan on playing these files through my Home Theater PC and wish to maintain my surround sound.Hi Chris,

Yes, this is a known issue with both VLC player and Media Player Classic: -

http://img423.imageshack.us/img423/247/mpc8kn.png

But don't panic because although Media Player Classic's own MP4 parser states the AAC stream only contains 2 channels, it does in-fact puke out all 6 channels.

EDIT: I've tested 6Ch AAC files thru' my DSS amp by using FFdshows AAC-to-AC3 transcoder.... And also tested them in hardware players, with no issues at all :)


Cheers

[ChrisBensch]

@bond: thanks again

I took the same files and muxed them with megui into MKV container and both players (vlc and mpc) show the correct audio channels. I'm guessing with this info, and what bond has said, that it is a problem with how the players are reading the data in the mp4 container.

[ChrisBensch]

@SeeMoreDigital: Thanks! When I use that properties dialog, it shows the following info:

Video: MPEG4 Video (AVC) 1280x608 [GPAC ISO Video Handler]
Audio: AAC 48000Hz stereo 546Kbps [GPAC ISO Audio Handler]

So I'm not sure what filters I have that are giving that instead of what you have, but it was hidden from me ;)

[bond]

the "gpac video handler" and "6ch aac-lc" thingie are tracknames, which you can set as you want via mp4box/yamb

[SeeMoreDigital]

Yes... to confirm what Bond mentioned, I "manually" entered the information highlighted in yellow. You can do this yourself in YAMB ;)

If you use Haali's MP4 splitter/parser instead of MPC's built in splitter/parser, you will see this: -

http://img524.imageshack.us/img524/7046/haali2rz.png


Cheers

[rdk]

Hallo,
my standalone player support NERO DIGITAL, but when i mux video and audio streams with mp4box using Yamb, resulted mp4 file
plays smooth on my player about 5...10min and than strong stuttering on video and sound (on PC is OK). When i mux with 3ivx muxer it works
fine, where is the problem with mp4box? My player is with MT1389DE chip, i also have used ARM and DSP parts from other
NERO DIGITAL compatible MTK firmwares with the same result. I mux XviD(25fs without packed bitstream) with HE-AAC5.1
or aacPLUS v2 5.1.
Sorry for bad English!

[SeeMoreDigital]

What is the make and model number of your stand-alone player please?

I'm not aware of any MediaTek chip-set based players that are NeroDigital (MPEG-4 SP/ASP) capable..... Yours sounds like one of the first ;)


Cheers

[rdk]

Elite PV399X
here is firmware upgrade:
http://www.elite.bg/Update/PV_399x_update.htm
Peekton 6006 also works with NERO DIGITAL, and Scott DMX-10 too.

[SeeMoreDigital]

So it's: -

The Elite PV-399
http://www.elite.bg/asp/view_prod.asp?article_id=PV-399X&Lang=BG

The Peekton PK6006: -
http://www.peekton.com/article.php4?sid=31


Cheers