A customer had a video for a website. But it was in high definition and with a large pixel footprint.
The video needed to be made smaller, of a size appropriate to the web page, making its bandwidth usage optimal.
I chose to use ffmpeg to make my conversions. I could also use it to get the video’s info: width, height etc
I had previously installed ffmpeg using
apt-get install ffmpeg
File Info
During the conversion I would need to know the existing width and height.
Using ffmpeg I can get this info. Either by using ffprobe or ffmpeg, as given below:
ffprobe inputVideo.mov
or
ffmpeg -i inputVideo.mov
Which gives the following output:
ffprobe version 3.3.2 Copyright (c) 2007-2017 the FFmpeg developers built with gcc 6.3.0 (Debian 6.3.0-21) 20170628 configuration: --disable-decoder=amrnb --disable-decoder=libopenjpeg --disable-mips32r2 --disable-mips32r6 --disable-mips64r6 --disable-mipsdsp --disable-mipsdspr2 --disable-mipsfpu --disable-msa --disable-libopencv --disable-podpages --disable-stripping --enable-avfilter --enable-avresample --enable-gcrypt --enable-gnutls --enable-gpl --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libfdk-aac --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libilbc --enable-libkvazaar --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtesseract --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx265 --enable-libxvid --enable-libzvbi --enable-nonfree --enable-opengl --enable-openssl --enable-postproc --enable-pthreads --enable-shared --enable-version3 --incdir=/usr/include/x86_64-linux-gnu --libdir=/usr/lib/x86_64-linux-gnu --prefix=/usr --toolchain=hardened --enable-frei0r --enable-chromaprint --enable-libx264 --enable-libiec61883 --enable-libdc1394 --enable-vaapi --disable-opencl --enable-libmfx --disable-altivec --shlibdir=/usr/lib/x86_64-linux-gnu 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 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'theVideo.mov': Metadata: major_brand : qt minor_version : 537199360 compatible_brands: qt creation_time : 2017-07-10T19:59:39.000000Z Duration: 00:03:59.11, start: 0.000000, bitrate: 7402 kb/s Stream #0:0(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, stereo, s16, 1536 kb/s (default) Metadata: creation_time : 2017-07-10T19:59:39.000000Z handler_name : Apple Alias Data Handler Stream #0:1(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080, 5863 kb/s, 23.98 fps, 23.98 tbr, 2997 tbn, 5994 tbc (default) Metadata: creation_time : 2017-07-10T19:59:39.000000Z handler_name : Apple Alias Data Handler encoder : H.264
The relevant details can be copied
And then to resize..
Scaling the Image Size
Using the scale parameter the size of the image can be changed.
ffmpeg -i inputVideo.avi -vf scale=320:240 outputVideo.avi
I began with this, basing my sizes on calculating the width and height of the original information.
ffmpeg -i inputVideo.avi -vf scale=320:240 outputVideo.avi
This will keep the aspect ratio, setting the horizontal size.
ffmpeg -i inputVideo.avi -vf scale=320:-1 outputVideo_320.avi
This makes it easier, only the one calculation and the other looks after itself.
For a simple multiplier scaling
ffmpeg -i input.avi -vf scale=iw/2:ih outputVideo_half_width.avi
Changing the Video Encoding
And best of all as you can see from the above I’ve simply set the output file name and ffmpeg has worked out the required encoding.
If you wish to also create other variations on the original video, for example mp4, mkv and ogv then substitute the extension on the outputVideo,
Flags and Faststart
Using the combination of what is movflags amd faststart the metadata fro the video can be added to the start.
ffmpeg -i inputVideo.avi -movflags faststart -vf scale=320:240 outputVideo.avi
This will make the processing of the video. when viewed. With potentially less chance of buffering issues.
However, it will take longer in processing and creating the scaled resultant video.
Further Thoughts
I used ffmpeg on Linux. It’s also available on Windows and macOS.
