Convert 5.1AAc in 2channel stereo in .mp4

[Aasshhuu]

First of all This is my first day here so forgive me if make any mistakes...
I'm tired of searching for methods n tools n experimenting on mp4 to convert its 5.1 in 2 channel so that it can be played via USB On my SONY LED 3D.. There r many tools(mkv all in one) which work flawlessly in converting mkv to mp4+convert 5.1 to 2+add subs... but isnt there even one tool which can convert 5.1 to 2 channel without re-encoding video...? if there is then plz help or if u know any methods doing so plz share.. extracting with yamb then reencoding audio n joining again dont work for me....
Thanks..

[jman98]

I don't know of any tool that can accept MP4 input, convert the audio, and produce a new MP4 with the new audio. I think you will have to extract the audio and make a new MP4.

Supposedly the program called BeHappy can convert from 5.1 AAC to 2.0 AAC, but as I avoid AAC audio like the plague I have never personally tried this.

[bat999]

Hi

Try with FFmpeg from here ---> http://ffmpeg.zeranoe.com/builds/

ffmpeg -i filename.mp4 -c:v copy -c:a aac -strict experimental -b:a 128k -ac 2 -scodec copy new_filename.mp4

[poisondeathray]

another option is avidemux

video=>copy
audio=>aac
audio=> filters => mixer stereo
format=> mp4

Ctrl+S to save and enter extension e.g. "myfile.mp4"

[robertcollier4]

Update: slightly updated.
Here is a batch file to downmix the audio from all mkv's in current directory to 2.0 stereo via eac3to Dolby Pro Logic II conversion. Then it will recompress the downmixed audio via Quicktime AAC TrueVBR. Then it will remux the source video and the 2.0 AAC audio to a new MKV file.

You will need to specify the paths to eac3to, mkvmerge (from MKVToolNix), and qaac.exe. All 3 of these tools are available for free from the Internet.

@echo off
set PATH_EAC3TO=D:\VideoProcessing\eac3to327
set PATH_MKVMERGE=D:\VideoProcessing\mkvtoolnix-unicode-5.9.0
set PATH_QAAC=D:\VideoProcessing\qaac

for /f %%a IN ('dir /b *.mkv') do (
echo ---------------------- BATCH STARTING %%~na%%~xa

%PATH_EAC3TO%\eac3to.exe "%%~na%%~xa" -log="%%~na.eac3to.log" 2: stdout.wav -downDpl | %PATH_QAAC%\qaac.exe --tvbr 90 --quality 2 --rate keep --no-delay - -o "%%~na.m4a"

%PATH_MKVMERGE%\mkvmerge.exe -o "%%~na-stereoremux.mkv" --compression -1:none -A -S "%%~na%%~xa" --language 0:eng --compression 0:none -a 0 "%%~na.m4a" -D -A -M -B -T --no-chapters --no-global-tags "%%~na%%~xa"

)

[Greg2041]

Hi

Try with FFmpeg from here ---> http://ffmpeg.zeranoe.com/builds/

ffmpeg -i filename.mp4 -c:v copy -c:a aac -strict experimental -b:a 128k -ac 2 -scodec copy new_filename.mp4

In very, very simple layman terms, if I download ffmeg, how do I convert a 5.1 file to stereo?

Learning slowly....

Greg

[sambat]

Assuming it's an mp4 as above.
Create a folder in the C drive called ffmpeg
Copy ffmpeg.exe to the folder.
Copy the source mp4 file to the folder.
Change the name of the mp4 file to filename.mp4
Highlight and copy the following string:

ffmpeg -i filename.mp4 -c:v copy -c:a aac -strict experimental -b:a 128k -ac 2 -scodec copy new_filename.mp4

Browse to and highlight the ffmpeg folder.
Hold down the shift key and right click on the folder.
Select 'Open command window here'.
Paste the string and <enter>


Or, click Start, type run <enter>, type cmd and click 'OK'.
The command screen pops up.
Type:
cd c:\ffmpeg

Paste the string and <enter>

[Greg2041]

Much appreciated. Thank you.

Out of interested is there another line to convert AC3 to AAC?

Thanks again

Greg

[sambat]

Google for the particular conversion you want.
This is an mpeg file converted to mp4 with aac stereo.

ffmpeg -i source.mpg -b:v 8000k -ab 128 -ac 2 clip.MP4

These values replace the default that ffmpeg uses - (I'm not sure what the default values are).
-b:v 8000k = video bitrate 8mb/sec
-ab 128 = audio bitrate 128 kilobits/sec
-ac 2 = audio to have 2 channels

This example, ffmpeg sees the output is to be mp4 and assigns AVC + AAC streams to the output.
ffmpeg -i clip.avi clip.mp4

[Greg2041]

Thank you for the info. I will do some research and have a play.



Greg

[transporterfan]

If you need batch processing you could try XMedia Recode.
Set Video to Copy and Audio to convert. You can set your own bitrates, channels etc.

[Greg2041]

What a great idea. Thank you,

Greg