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....
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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.
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" )
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
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.
Paste the string and <enter>
Much appreciated. Thank you.
Out of interested is there another line to convert AC3 to AAC?
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
Thank you for the info. I will do some research and have a play.
What a great idea. Thank you,