On Sun, Jan 1, 2023 at 12:57 PM Paul B Mahol <one...@gmail.com> wrote:
> > > On Sun, Jan 1, 2023 at 7:36 AM Andrew Randrianasulu < > randrianas...@gmail.com> wrote: > >> >> >> вс, 1 янв. 2023 г., 09:10 Terry Corbet <tcor...@ix.netcom.com>: >> >>> I have recently discovered how to use the Audacity Envelope Tool to turn >>> a standard stereo MP3 file into a modified one in which throughout the >>> entire duration of the clip the apparent source of the sounds will >>> traverse from left to right. >> >> >> may be pan filter can do something by altering volumes of individual >> channels but as far as I can see you can't change its parameters at runtime? >> >> >> https://ffmpeg.org/ffmpeg-filters.html#Changing-options-at-runtime-with-a-command >> >> ==== >> Filter pan >> Remix channels with coefficients (panning). >> Inputs: >> #0: default (audio) >> Outputs: >> #0: default (audio) >> pan AVOptions: >> args <string> ..F.A...... >> === >> >> no T , as you can see (ffmpeg 5.1) >> >> I wonder if our software (cinelerra-gg, video editor, so a bit >> heavyweight) can do this via built-in keyframing .. I'll ask on our >> maillist. >> >> > Nope, your software can't do it. > > Use ffmpeg's stereotools filter with asendcmd. Supports runtime changing > of parameters. > Thanks for suggestion! Yes, fully automatic panning on variable length clips probably not easy to automate in CinGG (even in bath mode). But I opened said filter (stereotools) and apparently I can set cingg plugin keyframes for its internal parameters .. I do not think we have timeline support for ff filters, but does this system offer any advantage in our case? > > >> >> >> While I could use that workflow to >>> manually perform the same transformation on multiple files, for my own >>> use as well as to help other family members [who generally have limited >>> computer skills] I want to automate that workflow. >>> >>> Over the past four days I have played as much catch-up on the many >>> topics and toolkits which appear might permit me to engineer a software >>> solution to this requirement. As a newbie, I probably will not >>> correctly summarize what I believe to be the possible tools and >>> approaches, so please forgive any misuse to the correct terminology. I >>> hope/believe that I might be able to state my concepts/questions in a >>> manner which will be most considerate of the time of those who >>> participate in this mailing list and most quickly help me move closer to >>> a good approach to the challenge. >>> >>> 01. I have managed to download the libraries which are used for the >>> maintenance of the ffmpeg, ffprobe and ffplay triumvirate of tools. >>> >>> 02. I have managed to successfully build some sample C programs [taken >>> from the doc\examples sub-directory and other miscellaneous snippets >>> found by following the wonderful links from your Wiki] using the >>> CodeBlocks IDE framework. >>> >>> 03. I have squirreled my way through the parts of the Doxygen >>> documentation which seem like they would be most apropos. >>> >>> What I did not discover was any functions or examples of what I assumed >>> I would be needing to do, which essential would be to process the audio >>> frames of the FrontLeft [FL] and FrontRight [FR] channels of coming out >>> of a stream of packets. That caused me to think that perhaps I would >>> find examples of that processing by searching the Audacity sources to >>> learn when and how they use the ffmpeg libraries. And somewhere between >>> the Audacity and FFmpeg sites I stumbled upon some sources and some >>> documentation concerning what I suppose are two reasonable libraries >>> devoted to "resampling" -- soxr and swr. >>> >>> It was about at that point that I concluded that my modification of the >>> sampled frames probably does not fall within the ambit of what is meant >>> by resampling at all and that led to an investigation of what Nyquist >>> was all about. Wow, what a guy Mr. Dannenberg must be. The 2007 >>> Nyquist Reference Manual is a jaw-dropping read. >>> >>> I think that is enough background/context. Here's were I would >>> appreciate any suggestions: >>> >>> A. Would it be possible to accomplish the steps necessary to achieve >>> the desired result just using ffmpeg.exe? I imagine that, using the >>> command line tool and an appropriate shell scripting language, it might >>> be necessary to make multiple passes of the original .mp3 file and/or >>> the two separate channels. I am not concerned about that loss of >>> throughput; it will always be far faster than any manual procedure. >>> >>> B. Nonetheless, there are some advantages that would accrue from >>> accomplishing the work entirely in an application .exe with a little GUI >>> glitter to help the user be able to attempt some trial-and-error >>> [preview] with slight changes in some of the parameters of the task >>> depending upon the nature of the audio content and the manner in which >>> the user will eventually play the output on different devices in >>> different environments. Since I will not have the capabilities for >>> building an Envelope in the manner that Nyquist [Lisp] accomplishes >>> that, can anyone point me to any sample code doing that in C with the >>> eight ffmpeg .dll libraries? >>> >>> C. Or -- and I appreciate that it is not fair to ask this of this mail >>> group -- but I would appreciate any experience/advice as to whether the >>> solution really ought to be accomplished by some scripting and/or macro >>> facilities wrapped around Audacity? >>> >>> Thank you so much for the fantastic capabilities you have provided with >>> the entire FFmpeg effort and for your patience in reading through my >>> questions as the bell is about to strike on the New Year. >>> >>> _______________________________________________ >>> Libav-user mailing list >>> Libav-user@ffmpeg.org >>> https://ffmpeg.org/mailman/listinfo/libav-user >>> >>> To unsubscribe, visit link above, or email >>> libav-user-requ...@ffmpeg.org with subject "unsubscribe". >>> >> _______________________________________________ >> Libav-user mailing list >> Libav-user@ffmpeg.org >> https://ffmpeg.org/mailman/listinfo/libav-user >> >> To unsubscribe, visit link above, or email >> libav-user-requ...@ffmpeg.org with subject "unsubscribe". >> > _______________________________________________ > Libav-user mailing list > Libav-user@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/libav-user > > To unsubscribe, visit link above, or email > libav-user-requ...@ffmpeg.org with subject "unsubscribe". >
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