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Last edited by WAusJackBauer; 17th Jun 2021 at 05:37.
I'm willing to pay someone $50 if they can resolve this.
Last edited by WAusJackBauer; 21st Jun 2021 at 20:02.
Raising this to $100
Davexnet has already given you a solution in post #28. You might want to play with the coefficients to get the mix you want.
Attached is your 5.1 audio from post #8 downmixed to stereo using his coefficients. Try uploading it to youtube and see how it sounds.
Last edited by WAusJackBauer; 2nd Jul 2021 at 02:26.
Download ffmpeg. Put a copy of ffmpeg.exe in C:\Windows\System32\.
Start Notepad. Copy/Paste this text into it (slight changes from davexnet's post).
ffmpeg -i %1 -vol 420 -af "pan=stereo|FL=0.5*FC+0.707*FL+0.707*BL+0.5*LFE|FR=0.5*FC+0.707*FR+0.707*BR+0.5*LFE" -c:v copy -b:a 224K "stereomix.mp4"
In Explorer drag/drop your video onto the batch file. In a while (depending on the length of your file) you'll have a file called stereomix.mp4.
In the ffmpeg command the "vol=420" means multiply the volume by a factor of 420/256, about 1.64.
The "pan=stereo" arguments specify how the channels should be mixed.
FC is the front center channel
FL is the front left channel
FR is the front right channel
BL is the back left channel
BR ir the back right channel
LFE is the sub channel (Low Frequency Effects)
so "FL=0.5*FC+0.707*FL+0.707*BL+0.5*LFE" means the front left channel should be a mix of:
0.5 times the front center channel
plus 0.707 times the front left channel
plus 0.707 times the back left channel
plus 0.5 * the sub channel
"FR=0.5*FC+0.707*FR+0.707*BR+0.5*LFE" does the same for the front right channel except right channels are used instead of the left.
An audio codec wasn't specified bus since ffmpeg was told to create an mp4 file it will default to aac. "-b:a 224K" tell it to use an audio bitrate of 224 Kbps.
The standard ATSC downmix is:
ffmpeg -i %1 -af "pan=stereo|FL < 1.0*FL + 0.707*FC + 0.707*BL|FR < 1.0*FR + 0.707*FC + 0.707*BR" -c:v copy -b:a 224K "stereomix.mp4"
ffmpeg -i %1 -c:v copy -ac 2 -b:a 224K "stereomix.mp4"
Some other useful information: https://superuser.com/questions/852400/properly-downmix-5-1-to-stereo-using-ffmpeg
Last edited by jagabo; 2nd Jul 2021 at 09:04.