On Thu, Jun 23, 2022 at 6:45 PM Jeremy F <[email protected]> wrote:
> Hi I'm probably using ffmpeg in an edge-case way, but I simply want to take > 2 channels/stereo, and end up with 6 channels of audio, where I can > apply/modify/filter each channel as I please. And I figured out the ffmpeg > magic to do this, but along my dive into this it appears that no matter the > method used to upmix (of which there are many such as "-ac 6", "asplit", > "pan", "channelsplit") it appears no matter what, I'm forced to use the > upmixing scheme that always sets channel 4 to a lowpass filter of 128hz, > rendering it useless for my case. > > There doesn't appear to be a way to disable this that I can find, and it > seems like there should be > > My current command I'm using, which works great except for channel 4 > (labeled r2 in here). No matter what filter I apply, it always ends up > being a lowpass of 128. > > -err_detect ignore_err -filter_complex > > [0:a]channelsplit[left][right];[left]asplit=3[l1][l2][l3];[l1]aecho=1.0:0.7:25|60:0.5|0.3[l1];[l2]lowpass=f=550[l2];[l3]adelay=1,aecho=1.0:0.7:25|60:0.5|0.3[l3];[right]asplit=3[r1][r2][r3];[r1]aecho=1.0:0.7:25|60:0.5|0.3[r1];[r2]lowpass=f=550[r2];[r3]adelay=1,aecho=1.0:0.7:25|60:0.5|0.3[r3];[l1][r1][l2][r2][l3][r3]amerge=inputs=6[a] > -map 0:v -map [a] -acodec aac -c:v copy > > > The code, at a glance, seems to corroborate this, but it's a bit beyond my > depth to do anything further (and I don't want to compile / make a custom > version of ffmpeg) > > https://github.com/FFmpeg/FFmpeg/blob/9aa20d28cdda0dcaa4daa2848670a6530c6ba26a/libavfilter/af_surround.c > > So, if possible, how can I disabled the upmixing scheme? > The surround filter have nothing to do with that filtergraph above. And I really failed to understand what you are trying to do. > Thanks! > -- > Sincerely, > > Jeremy > _______________________________________________ > ffmpeg-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". > _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
