On 9/12/18, Paul B Mahol <one...@gmail.com> wrote: > On 9/12/18, Michael Koch <astroelectro...@t-online.de> wrote: >> Am 12.09.2018 um 09:55 schrieb Paul B Mahol: >>> Hi, >>> >>> On 9/12/18, Michael Koch <astroelectro...@t-online.de> wrote: >>>> Is it possible to multiply audio samples from two sources? >>>> I'd like to downconvert the 15kHz to 25kHz range to the 0 to 10kHz >>>> range. First apply a strong 15kHz highpass filter, then multiply the >>>> signal with a 15kHz sine wave (which produces sum and difference >>>> signals), then apply a 10kHz lowpass filter. >>> There is no yet amultiply audio filter, but I could write it. >>> >>> Am I correct that for it you need two audio streams as input and one >>> audio stream as output? >> >> yes, two inputs and one output. I think it would be best if it works >> independant of bit depth. First normalize the input signals to -1...+1 >> range, then multiply them so that the result is also in the -1...+1 >> range, then normalize back to 16bit or 24bit range. > > It will internally work with floating-point numbers only (32bits or > 64bits). > Normalization is done with other filters. > > Meanwhile you can use sox multiply effect. > > Note that sox internally operates with 32bit integers. >
You can find filter in master branch of FFmpeg repository. _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
