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• Ffmpeg mathematical "expression" syntax in filters

  9 novembre 2022, par Jason C

  Multiple ffmpeg filters take a mathematical expression as a parameter, for example setpts and select (examples from docs) :

  


  setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))';
select=select=between(t\,10\,20)


  


  The docs for each filter are generally good about listing available variables for that specific filter, but the actual syntax of this expression appears (?) to be completely undocumented, despite its heavy use. For example, what functions are available (e.g. sin, between) ? Are boolean combinations allowable and if so, what are the operators ? What other mathematical operators are available ?

  


  What is the syntax of these expressions ? Or, at the very least, is some non-ffmpeg library parsing them and if so, what is it ? That way I can at least look up the syntax. Or have I missed some documentation section somewhere...?

  


• Trying to install ffmpeg with brew and I keep getting errors related to "dav1d_bottle_manifest"

  13 décembre 2022, par Jonathan Doe

  I am trying to do some basic DSP in python and in order to play some of my audio files I need to install ffmpeg on my computer.

  


  I am running a 2019 macbook pro.

  


  When I run brew intsall ffmpeg -d

  


  I get this on my terminal output

  


  rm: /usr/local/Homebrew/.git/TMP_FETCH_FAILURES: is a directory
rm: /usr/local/Homebrew/.git/TMP_FETCH_FAILURES: is a directory
Running `brew update --auto-update`...


  


  This auto update just runs forever with no updates of any kind. I'm not sure if it is broken or stuck or what.

  


  I try to manually run :

  


   brew update -d


  


  and the update stalls forever on this section :

  


  + [[ -f /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/.git/FETCH_HEAD ]]
+ touch /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/.git/FETCH_HEAD
+ [[ -z '' ]]
+ [[ 200 == \3\0\4 ]]
+ [[ -n '' ]]
+ local tmp_failure_file=/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/.git/TMP_FETCH_FAILURES
+ rm -f /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/.git/TMP_FETCH_FAILURES
+ [[ -n '' ]]
+ git fetch --tags --force -q origin refs/heads/master:refs/remotes/origin/master


  


  I am having so many problems with brew any help would be appreciated.

  


• Getting just the "loudnorm" summary from ffmpeg

  25 janvier 2024, par Gorillamusha

  I am trying to print just the summary from the loudnorm output in my ffmpeg command.

  


  When using the command :
ffmpeg -hide_banner -y -i input.mp4 -loglevel info -nostats -map 0:a:0 -af loudnorm=I=-23.000000:LRA=7.000000:tp=-3.000000:print_format=json -f null -

  


  I get an output like this :
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'input.mp4': Metadata: major_brand     : isom minor_version   : 512 compatible_brands: isomiso2avc1mp41 encoder         : Lavf60.3.100 Duration: 00:00:30.03, start: 0.000000, bitrate: 20124 kb/s Stream #0:0[0x1](und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x1080 [SAR 1:1 DAR 16:9], 19866 kb/s, 23.98 fps, 23.98 tbr, 19184 tbn (default) Metadata: handler_name    : VideoHandler vendor_id       : [0][0][0][0] encoder         : Lavc60.3.100 h264_nvenc Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 253 kb/s (default) Metadata: handler_name    : SoundHandler vendor_id       : [0][0][0][0] Stream mapping: Stream #0:1 -> #0:0 (aac (native) -> pcm_s16le (native)) Press [q] to stop, [?] for help Output #0, null, to 'pipe:': Metadata: major_brand     : isom minor_version   : 512 compatible_brands: isomiso2avc1mp41 encoder         : Lavf60.3.100 Stream #0:0(und): Audio: pcm_s16le, 192000 Hz, stereo, s16, 6144 kb/s (default) Metadata: handler_name    : SoundHandler vendor_id       : [0][0][0][0] encoder         : Lavc60.3.100 pcm_s16le size=N/A time=00:00:27.20 bitrate=N/A speed=27.2x video:0kB audio:22512kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown [Parsed_loudnorm_0 @ 0x600001ffc000] { "input_i" : "-23.37", "input_tp" : "-7.19", "input_lra" : "4.00", "input_thresh" : "-33.76", "output_i" : "-22.94", "output_tp" : "-6.71", "output_lra" : "3.20", "output_thresh" : "-33.10", "normalization_type" : "dynamic", "target_offset" : "-0.06" }

  


  What I would like to get is just :
{ "input_i" : "-23.37", "input_tp" : "-7.19", "input_lra" : "4.00", "input_thresh" : "-33.76", "output_i" : "-22.94", "output_tp" : "-6.71", "output_lra" : "3.20", "output_thresh" : "-33.10", "normalization_type" : "dynamic", "target_offset" : "-0.06" }

  


  Is there something about my ffmpeg build which prints the stream info by default ?
Is there some way to set this to 'quiet' without stifling the loudnorm output ?
It seems like this is not the way that the command outputs for others, based on the explainations I found online.

  


  I have also tried setting loglevel to quiet, but that mutes the loudnorm output as well.
I have also tried -nostats, but that does not effect the stream output section.