If this helps anyone, I made a discovery regarding amix with atempo and trim. Chronicled below.
Here's my FFMPEG install on Mac OSX: ffmpeg version 3.3.4 Copyright (c) 2000-2017 the FFmpeg developers built with Apple LLVM version 6.1.0 (clang-602.0.53) (based on LLVM 3.6.0svn) configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3.4 --enable-shared --enable-pthreads --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-gpl --enable-libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma --enable-nonfree --enable-vda libavutil 55. 58.100 / 55. 58.100 libavcodec 57. 89.100 / 57. 89.100 libavformat 57. 71.100 / 57. 71.100 libavdevice 57. 6.100 / 57. 6.100 libavfilter 6. 82.100 / 6. 82.100 libavresample 3. 5. 0 / 3. 5. 0 libswscale 4. 6.100 / 4. 6.100 libswresample 2. 7.100 / 2. 7.100 libpostproc 54. 5.100 / 54. 5.100 I was trying to mix audio from 3 different mp4's. This didn't work... When trying to run the above I got the dreaded hung terminal. No error, just got to this line and hung... Started examining the differences in scaling, trim times, etc for each video (these are being set in an app I'm building so they are variable) and here's what I saw... I tried all kinds of things until I discovered that the issue was with the 2nd video. I could change the atrim from 0:21.35 to 0:21 and it would work. So, trying to figure out what was different, I notivced that scaling was 1.x rather than 0.x for that video. Btw, the only reason I had broken up the commands in the complex filter as it was the only way I could get any of it to work earlier in testing. Here's what ended up working for all I've tested so far. The magic deal is this... Whenever the audio is scaled up in time, iow, slowed down, you have to first apply any trimming and then pass the scaling factor. Conversely, if it's sped up, you have to first apply scaling (atempo), then calculate the /relative/ trim values (based on the scaling factor) and apply the resulting trim values to the scaled audio (in the chain). Another thing I discovered is, if there's any time-scaling applied to any video's audio at all, even if there's no time trim, you /have/ to include the trim command but use the full length as the values. Eg, if it's a 5 second video, trim=0:5. -- Sent from: http://www.ffmpeg-archive.org/ _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
