---------- Forwarded message --------- От: Terry Corbet <[email protected]> Date: вс, 1 янв. 2023 г., 09:10 Subject: [Libav-user] Creating Panned MP3 Clips To: <[email protected]> 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. 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 [email protected] https://ffmpeg.org/mailman/listinfo/libav-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".