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• Compiling ffmpeg and using gas-preprocessor on Tiger ?

  19 avril 2016, par Tom

  Beginner trying to compile ffmpeg on a PowerMac G4, Mac OS X 10.4.11, Xcode 2.5 for use on this Mac (not iOS).

  I started out with Stephen Jungels tutorial (link), although it doesn’t cover Mac OS X 10.4 per se. I install LAME, FAAC/FAAD and x264 without errors. All goes well until I use ./configure for ffmpeg :

  ./configure --enable-shared --enable-libmp3lame --enable-libfaac --enable-libx264 --enable-gpl --enable-nonfree

  After some crunching, I get "Creating config.mak and config.h..." and an error "WARNING : GNU assembler not found, install gas-preprocessor". So I look for it online (https://github.com/yuvi/gas-preprocessor), move "gas-preprocessor.pl" to /usr/local/bin as instructed. Apparently it isn’t doing anything, as repeated configure gives the same error. Having gas-preprocessor.pl in the ffmpeg dir doesn’t seem to help either.

  Am I missing something that I should be doing with gas-preprocessor.pl ?

• Unable to find replacement for -vol [closed]

  21 février 2024, par Michael Benton

  I'm referring to this thread posted years ago.

  


  While I was testing Downmixing without discarding the LFE channel (Dave_750's answer) on ffmpeg, which included the formula

  


  ffmpeg -i "sourcetrack.dts" -c dca -vol 425 -af "pan=stereo|c0=0.5*c2+0.707*c0+0.707*c4+0.5*c3|c1=0.5*c2+0.707*c1+0.707*c5+0.5*c3" "outputstereo.dts"


  


  the cmd raised the following error :

  


  Unrecognized option 'vol'. Error splitting the argument list: Option not found


  


  The formula I put in cmd wasn't the same as the one in the thread at the beginning, because I replaced in it the attributes of my ac3 track.

  


  ffmpeg -i "inputsurround.ac3" -vol 425 -af "pan=stereo|c0=0.5*c2+0.707*c0+0.707*c4+0.5*c3|c1=0.5*c2+0.707*c1+0.707*c5+0.5*c3" -c:a ac3 -b:a 320k -ar 48000 "outputstereo.ac3"


  


  Through this thread, I discovered that the -vol function was deprecated years ago.

  


  I found another thread where the syntax used was

  


  -af volume=N


  


  (where N stands for a percentage or, if N is followed by "dB", a dB value).

  


  I'm not sure if -af volume behaves exactly like -vol while downmixing to stereo the ac3.

  


  I went back editing the formula :

  


  ffmpeg -i "inputsurround.ac3" -af "volume=425" -af "pan=stereo|c0=0.5*c2+0.707*c0+0.707*c4+0.5*c3|c1=0.5*c2+0.707*c1+0.707*c5+0.5*c3" -c:a ac3 -b:a 320k -ar 48000 "outputstereo.ac3"


  


  It raised the following warning (which didn't stop the file generation) :

  


  Multiple -filter/-af/-vf options specified for stream 0, only the last option '-filter:a pan=stereo|c0=0.5*c2+0.707*c0+0.707*c4+0.5*c3|c1=0.5*c2+0.707*c1+0.707*c5+0.5*c3' will be used


  


  As I already suspected, I couldn't use two "-af" in the same command. The generated file is useless, because ffmpeg only applied one of the two commands. I also tried with N defined in dB, with no success.

  


  I continued my search and, from another thread, I learned that I could use

  


  -filter_complex "[1] formula1;[0] formula2"


  


  to resolve my issue.

  


  My formula then became :

  


  ffmpeg -i "inputsurround.ac3" -filter_complex "[1]volume=425;[0]pan=stereo|c0=0.5*c2+0.707*c0+0.707*c4+0.5*c3|c1=0.5*c2+0.707*c1+0.707*c5+0.5*c3" -c:a ac3 -b:a 320k -ar 48000 "outputstereo.ac3"


  


  And it still raised an error :

  


  Invalid file index 1 in filtergraph description [1]volume=425;[0]pan=stereo|c0=0.5*c2+0.707*c0+0.707*c4+0.5*c3|c1=0.5*c2+0.707*c1+0.707*c5+0.5*c3.
Error initializing complex filters: Invalid argument


  


  To simplify the formula, I went back using -af with the properties of -filter_complex. And I got :

  


  ffmpeg -i "inputsurround.ac3" -af "[1]volume=425;[0]pan=stereo|c0=0.5*c2+0.707*c0+0.707*c4+0.5*c3|c1=0.5*c2+0.707*c1+0.707*c5+0.5*c3" -c:a ac3 -b:a 320k -ar 48000 "outputstereo.ac3"


  


  Again, another error :

  


  Simple filtergraph '[1]volume=425;[0]pan=stereo|c0=0.5*c2+0.707*c0+0.707*c4+0.5*c3|c1=0.5*c2+0.707*c1+0.707*c5+0.5*c3' was expected to have exactly 1 input and 1 output. However, it had 2 input(s) and 2 output(s). Please adjust, or use a complex filtergraph (-filter_complex) instead.
[aost#0:0/ac3 @ 000001d83b4c4200] Error initializing a simple filtergraph
Error opening output file outputstereo.ac3.
Error opening output files: Invalid argument


  


  whether I used a semicolon or comma as a separator.

  


  I'm completely lost at this point as I don't have deep knowledge of the topic.

  


  


  • has -vol been deprecated or I've searched badly/it's a syntax typo ?

    


  


  • if -vol has been deprecated, is there a way to rewrite the formula such that it outputs the result intended by the original user ?

    


  


  • if I replace c0, c1, c2, c3, c4, c5 to FL, FR, FC, LF, BL, BR in the formula, would I get a different channel layout ? (my file is : L, R, C, LFE, Ls, Rs)

    


  


  


  I'll try to clear every doubt. Any help is highly appreciated !

  


• ffmpegthumbnailer not generating thumbnails of size 600

  24 juillet 2015, par Shamith c

  I got an issue with ffmpegthumbnailer, used following command to generate thumbnails from new.mp4.

  ffmpegthumbnailer -i new.mp4 -o tmpfile1.jpg -c jpg -q 10 -s 600

  Got following error and failed to generate thumbnail.

  Not a native file, thumbnailing will likely fail
  
  Segmentation fault (core dumped)

  I tried to create another version using same command except size attribute( -s 640 instead of -s 600).

  ffmpegthumbnailer -i new.mp4 -o tmpfile1.jpg -c jpg -q 10 -s 640

  thumbnail successfully generated.

  I don’t know why thumbnail of version-600 not getting generated.