On Sun, Jan 1, 2023 at 5:21 PM Andrew Randrianasulu <randrianas...@gmail.com> wrote:
> > > 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? > Timeline and runtime changeable parameters are different things, they are not same. Timeline just disables/bypass processing in certain time frames. While runtime parameters can be changed at any time frame. But parameters can also be slowly interpolated so that no artifacts appear upon changes. > >> >>> >>> >>> 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". >> > _______________________________________________ > 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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