Hi i have ac3 5.1 audio track
I wanna convert to streo
How can I do it with ffmpeg?
By the how many channels in 5.1 audio track
And a streo track
I don't know much about audio
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Even i also did research but guides which am seeing is confusing lil bit that why I posted here
In guides i readed something about channels but
what is channel idk
May be mono have one channel and streo have 2 channels but not sure...
And may be 5.1 has 5 channels
And may be channels affects file size also
Like more channels means more file size
Still am not sure about anything ,that's why I need a clear explanation on this topic
If you're happy with the default mapping and levels:
ffmpeg -i input.ac3 -ac 2 output.ext
So -ac specifies channels?
What if I put only 1 channel
Then sound will only play in one side of my headphone or both side?
More channels will make file size bigger?..
A 2.0 (aka stereo) file has 2 channels for 2 speakers, like headphones and most TVs.
Downmixing is the process of reducing 6 channels into usually 2 for stereo playback.
This is more technical, but for playback on stereo equipment such as headphones and TVs I would actually advice not to use a ProLogic compatible downmix (proper term is Lt/Rt), which is often the default. Reason is it mixes the two surround channels equally into both, left and right, therefore removing the ability to discern left and right sounds of the original surround channels. They would just appear to be in the middle then. For stereo playback a Lo/Ro downmix (often labeled "Stereo") yields better results.
For smartphones/mobile phones how many channels are used widely?
Why don't you try it and find out?
Whenever i try ,i find something new errors
Whatever I'll try it in this evening and give error reports
Last edited by kirito; 2nd Jan 2022 at 02:50.
when i tried to encode my ac3 5.1 audio to opus 32k with this code
ffmpeg -i input.ac3 -c:a libopus -b:a 32k output.opus
[Attachment 62681 - Click to enlarge]
then i did some research on this error
on this site it says i have to add -af "channelmap=channel_layout=5.1" to my code
then i tried encoding this this code
ffmpeg -i input.ac3 -c:a libopus -b:a 32k -af "channelmap=channel_layout=5.1" output.opus
[Attachment 62682 - Click to enlarge]
it worked but output sound quality was to much badd
then i looked at this guide
[Attachment 62683 - Click to enlarge]
it says with -ac 2 this code we can also do it
so i tried encoding with this code
ffmpeg -i input.ac3 -c:a libopus -b:a 32k -ac 2 output.opus
[Attachment 62684 - Click to enlarge]
now my question is with
-af "channelmap=channel_layout=5.1" this code why sound qaulity bad and with,
-ac 2 this code sound qaulity good
i checked both output files codecs information in vlc player
output.opus codec information
[Attachment 62685 - Click to enlarge]
-ac 2 output codec information
[Attachment 62686 - Click to enlarge]
-af "channelmap=channel_layout=5.1" this code do? and
-ac 2 this code
Last edited by ProWo; 3rd Jan 2022 at 04:23.
For audio video conversion encoding i like cli better then gui because -
Cli = can do everything
Gui = can do limited things
When you do the mix down to 2 channel stereo, be sure to also include Dynamic Range Compression otherwise the audio from the satellite speakers will drown out the main central speaker. This happens alot on youtube where people directly upload their dvdrips and just leave it to be auto processed by the youtube software - the result is that the background music drowns out segments of narration and where people speak to each other.
A lot of people like to boost the center channel (as suggested by sageone) for more prominent dialog.
For the purposes described here, downmixing a 5.1 source with the given ffmpeg command, 2 channels = stereo. Unless of course the 5.1 source is mono.
Last edited by jagabo; 12th Jan 2022 at 22:46.
I did say IF a source was mono...
My source audio 5.1 has 6 channels and all channel has different signals.....
So if i downmix to 2 channel then I'll get left and right channel with same signals or both will have different signals??
Or you could just try it and find out for yourself.
Axel Slingerland should never have brought this up. All it's doing is confusing you.
Last edited by jagabo; 13th Jan 2022 at 09:31.
I was just making friendly conversation. But your response isn't. So never mind.