Batch Convert 6 channel AAC to AC3?

[massarosareloud]

Hello everyone,
This is my first post! Unfortunately I am stuck ):

I have a couple hundred .mp4 files, converted using handbrake from DVDs, and they are all 6 channel AAC audio. My HT receiver cannot decode AAC but it can decode AC3, unfortunately I did not know this until now. I was hoping that a batch convert option was available somewhere, I don't want to change the video track, just the audio.

I know I could demux the streams, convert the AAC to AC3, then remux back. But for a couple hundred files that would get old very fast.

Anybody have any ideas?

[pcspeak]

http://www.any-video-converter.com/products/for_video_free/
This will allow you to load all your files and then batch convert.
Experiment with 1-3 clips first to get the parameters correct.

[massarosareloud]

I know of that program and have used it before, but can I convert only the audio track using that program and just leave the video untouched?

[Baldrick]

You could try xmedia recode, open all mp4s, under format choose mp4, under audio choose ac3, under the video tab choose copy. But you wont get 5.1 ac3.

If you want to convert to ac3 with 5.1 I think you have to use eac3to. I don't know any guis that batch convert.

[jman98]

The insane but cheap solution as long as your time means nothing to you-
Use anything to convert those hundreds of files to AC3 audio.

The sane but non-free solution-
Just buy a Western Digital or similar media player and play the files as is. The WD supports AAC audio.

[smitbret]

Unfortunately, I don't see a way to do what you wanna do.

You could do it in three batches with MeGUI, though. You can queue up multiple files to demux, click "Start" and walk away for awhile (3-4 minutes per?). When they've all been demuxed, set up the conversions. You can set up one AC3 profile and just load all of the .aac files with that profile and queue 'em up. Click "Start" and walk away. Upon completion of that, Remux using the same formula.

Sucks, but I don't know of anything that will do it otherwise.

[pcspeak]

AVC is, among many other things, a sort of GUI for Mencoder.
A look at the AVC vdoconv.log gives some parameters.

Install MPlayer.
Save the following line as a .cmd file (e.g. test.cmd) changing the path to mencoder.exe to reflect its location on your computer.

for %%a in ("*.mp4") do c:\Path To\mencoder.exe -mc 0 -ffourcc DIVX -ovc copy -channels 6 -oac lavc -lavcopts acodec=ac3:abitrate=384 -o "%%~na_NEW.mp4" "%%a"

Run test.cmd from the same folder as one of the MP4 clips.

May we have the 'Mediainfo' results from one of your clips.

[massarosareloud]

When I do what you suggested pcspeak the command module window opens and closes very quickly. Too quickly for me to see what is written. I did change the path to mencoder.exe. Any ideas? And where should I expect the output file?

General
Complete name : E:\My Documents\My TV\The Office\Season 2\E01 The Dundies.m4v
Format : MPEG-4
Format profile : Base Media / Version 2
Codec ID : mp42
File size : 458 MiB
Duration : 20mn 53s
Overall bit rate : 3 062 Kbps
Encoded date : UTC 2011-09-23 10:15:07
Tagged date : UTC 2011-09-23 10:19:36
Writing application : HandBrake 0.9.5 2011010300

Video
ID : 1
Format : MPEG-4 Visual
Format profile : Simple@L1
Format settings, BVOP : No
Format settings, QPel : No
Format settings, GMC : No warppoints
Format settings, Matrix : Default (H.263)
Codec ID : 20
Duration : 20mn 53s
Bit rate mode : Variable
Bit rate : 2 608 Kbps
Maximum bit rate : 3 901 Mbps
Width : 720 pixels
Height : 478 pixels
Display aspect ratio : 16:9
Frame rate mode : Variable
Frame rate : 23.976 fps
Minimum frame rate : 15.986 fps
Maximum frame rate : 29.970 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Compression mode : Lossy
Bits/(Pixel*Frame) : 0.316
Stream size : 390 MiB (85%)
Writing library : Lavc52.94.3
Encoded date : UTC 2011-09-23 10:15:07
Tagged date : UTC 2011-09-23 10:19:36

Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 20mn 53s
Bit rate mode : Variable
Bit rate : 442 Kbps
Maximum bit rate : 722 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Compression mode : Lossy
Stream size : 66.1 MiB (14%)
Language : English
Encoded date : UTC 2011-09-23 10:15:07
Tagged date : UTC 2011-09-23 10:19:36

Text #1
ID : 3
Format : mp4s
Codec ID : E0
Duration : 20mn 4s
Bit rate mode : Variable
Bit rate : 8 147 bps
Maximum bit rate : 4 290 Mbps
Stream size : 1.17 MiB (0%)
Language : English
Encoded date : UTC 2011-09-23 10:15:07
Tagged date : UTC 2011-09-23 10:19:25

Text #2
ID : 4
Format : Apple text
Codec ID : text
Duration : 20mn 53s
Bit rate mode : Constant
Bit rate : 1 bps
Stream size : 92.0 Bytes (0%)
Encoded date : UTC 2011-09-23 10:15:07
Tagged date : UTC 2011-09-23 10:19:36

[pcspeak]

Aha! Not MP4 but M4V with a bitrate of 442
Changed the bitrate and added a pause.

for %%a in ("*.m4v") do c:\Path To\mencoder.exe -mc 0 -ffourcc DIVX -ovc copy -channels 6 -oac lavc -lavcopts acodec=ac3:abitrate=442 -o "%%~na_NEW.m4v" "%%a"
pause

I don't think it will work, yet.
Is it possible to upload a small sample clip?
I can't seem to find an m4v with 6 channel AAC. Plenty of 2 channel.

Cheers!

[massarosareloud]

It did not work unfortunately, but I am very thankful for all the work you are doing! Here is a screenshot of the command window, which now stays open but still doesn't work. http://imageshack.us/photo/my-images/11/unledwtv.jpg/

I can upload a small sample clip, but not right now. Later today I should be able to.

[massarosareloud]

Actually, would I lose any video quality by just running all those videos files through handbrake again and keeping the video settings the same but changing the audio to AC3? That would be exactly what I needed, assuming that doesn't lower the video quality.

[pcspeak]

Because of the spaces in the path string you must have double quotation marks around it.

"c:\Program Files (x86)\AnvSoft\Any Video Converter\gnu\avc\mencoder.exe" -mc 0 .................

Edited because I missed the last post:-

I agree. Using handbrake, which I have never used, is probably the way to go.
If there is an option to do a direct stream copy of the video and only convert the audio then go for it.

Luck.