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. > > > 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". >
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