Notes on video conversion with mencoder

Input from: DVD | video file | rtmp stream | Flash audio | edits | audio file | FM | language merge | desktop | pictures
Output to: Android, iPhone or Mac | Nokia S60, S40 etc | Windows 10 | Zoom Cloud Meetings | Old Windows or Windows Mobile | MP3 audio | DVD, VCD or SVCD

Input options

DVD

• Track 1, default language, subtitles off:
  dvd://1 -dvd-device PATH -sid 31 (where PATH is the path to the DVD image)
• To select language and subtitles: pass numbers to -aid and -sid (see what's printed by mplayer); goes after the input it applies to
• If the disc was not "finalised" by the DVD recorder, mplayer may be able to read the device node directly (on GNU/Linux /dev/sdc or similar; /dev/rdisk1 on a Mac)
• If mencoder doesn't work well on a particular DVD, you could also try ffmpeg:
  cd $DVD_DIR/VIDEO_TS && ffmpeg -i "concat:$(echo *.VOB|tr ' ' '|')" -map 0:1 -map 0:3
  or cat $DVD_DIR/VIDEO_TS/*.VOB | ffmpeg -i - -map 0:1 -map 0:3
  where for a multi-title DVD you'll need to figure out the correct set of VOB files, and -map 0:1 and -map 0:3 might need to be refined according to ffmpeg's output of the language list; you'll also need to add some ffmpeg output options, e.g. -vcodec mpeg4 -b:v 600k -strict -2 -g 50 -vf yadif -c:a aac -b:a 160k output.mp4
  These commands do not handle subtitles.
  Some discs work better with mencoder, while other discs work better with ffmpeg, so both commands are useful to keep.

.flv and other video files

• Just specify the filename
• Can trim with -ss start-second and/or -endpos length
• Can save a clip to a separate file using -o clip.avi -oac lavc -ovc lavc and then combine multiple clips by specifying all their filenames on an mencoder command (when doing this it might be necessary to list the scaling and output options before the inputs)
• If the sound is not synchronized, try setting the framerate explicitly with -fps 24 (or 27 or whatever) after each input file, maybe even adding -mc 0 in older versions

rtmp streams embedded in complex Javascript etc

• As root, do:
  iptables -t nat -A OUTPUT -p tcp --dport 1935 -m owner \! --uid-owner root -j REDIRECT
  rtmpsuck
• Leave it running while playing the video in a Flash-enabled browser like Google Chrome (which must be run as a non-root user for this to work)
• Check rtmpsuck output for captured files, then proceed as above
• If you get issues due to reconnection near the start of the stream, you may have to edit out a small section of the video. For example if the problem occurs around 64 seconds in, try -mc 0 -noskip -edl <(echo 63 65 0)

Flash audio

Edit decision lists

Audio file (static or blank picture)

• Output file might not concatenate well with other tracks, but the dvdauthor command (below) can take multiple mpg inputs

FM radio

Two language versions

• Fast command to keep just the sound from videoS and the picture and subtitles VideoP (useful if the speaker of VideoP's language wants only subtitles):
  ffmpeg -i videoS.mp4 -i videoP.mp4 -map 0:a:0 -map 1:v:0 -map 1:s:0 -c copy -c:s mov_text output.mp4
  this might require subtitles to be switched on in the player
  • To specify that the subtitles are Chinese, add -metadata:s:s:0 language=zho (this only affects player menus)

To play the two videos on separate devices but time-synchronised over a local network:

• on the first device,
  mplayer -udp-$'m\!x61s\x74\x65r' -udp-ip (second device's IP) video1.mp4
• and on the second device,
  mplayer -udp-$'\x73\x6c\x61\x76e' -udp-seek-threshold 0.1 -udp-ip (second device's IP) video2.mp4

To play the two videos on the same machine, one with sound only and sent to HDMI, the other with full-screen picture, and sound sent to Bluetooth, set the system to use PulseAudio (not PipeWire: Raspberry Pi OS 12 needs sudo raspi-config / Advanced / Audio to set it back to PulseAudio) and do:
mplayer -noconsolecontrols -vo null -udp-$'\x73\x6c\x61\x76e' -udp-seek-threshold 0.1 -ao pulse::alsa_output.platform-(value from pacmd list-sinks).hdmi.hdmi-stereo video2.mp4 & mplayer -fs -nosub -udp-$'m\!x61s\x74\x65r' -ao pulse::bluez_sink.(MAC address).a2dp_sink video1.mp4
(also works with URLs instead of saved video files, in which case I suggest adding -cache-min 1 -cache 1048576 to each command if you have 4GB+ of RAM)

To have the two languages in two stereo channels on the same player, first create a WAV file:

• For older versions of ffmpeg:
  ffmpeg -i input1.mp4 -i input2.mp4 -filter_complex '[0:a]aconvert=s16:mono[l]; [1:a]aconvert=s16:mono[r]; [l][r]amerge[snd]' -map '[snd]' audio.wav
• For newer versions of ffmpeg (e.g. 3.1.3):
  ffmpeg -i input1.mp4 -i input2.mp4 -filter_complex '[0:a]aformat=sample_fmts=s16:channel_layouts=mono[l]; [1:a]aformat=sample_fmts=s16:channel_layouts=mono[r]; [l][r]amerge[snd]' -map '[snd]' audio.wav

Then, to keep the picture from the first file, do:
ffmpeg -i input1.mp4 -i audio.wav -map 0:v -map 1:a -vcodec copy output.mkv
and proceed with output.mkv (if it lacks sound, it's probably an ffmpeg version issue: try -b:v 10000k output.mp4 instead of -vcodec copy output.mkv).

Or if the pictures differ as well (for example on-screen text has been translated) then you might wish to show both pictures at once. The following command will do that, positioning them diagonally to reduce peripheral-motion annoyance when trying to watch only one; it works only if both videos are the same size.

ffmpeg -i input1.mp4 -i input2.mp4 -i audio.wav -filter_complex '[0:v]pad=iw*2:ih*2:0:ih[tmp]; [tmp][1:v]overlay=W/2:0[pic]' -map '[pic]' -map 2:a -b:v 3000k output.mp4

If the videos are additionally of different sizes, you'll need a longer version of this command:

W1=$(ffprobe -show_entries stream=width input1.mp4 |grep ^width=|head -1|cut -d= -f2); W2=$(ffprobe -show_entries stream=width input2.mp4 |grep ^width=|head -1|cut -d= -f2); H1=$(ffprobe -show_entries stream=height input1.mp4 |grep ^height=|head -1|cut -d= -f2); H2=$(ffprobe -show_entries stream=height input2.mp4 |grep ^height=|head -1|cut -d= -f2); ffmpeg -i input1.mp4 -i input2.mp4 -i $Audio -filter_complex "[0:v]pad=$[$W1+$W2]:$[$H1+$H2]:0:$H2[tmp]; [tmp][1:v]overlay=$W1:0[pic]" -map '[pic]' -map 2:a -b:v 3000k output.mp4

Recording the desktop

• Omit -f alsa -i pulse for no audio. Region size defaults to 640x480, override with -s. To capture full screen use -f x11grab -s $(xrandr -q|head -1|sed -e 's/.*current//' -e 's/,.*//'|tr -d ' ') -r 25 etc
• Fedora 34+ requires -i pipewire instead of -i pulse (and is likely to give buffer underruns and drop audio---use a different distribution if possible)
• To record a vertical section of camera to the right of the desktop area, with slightly-delayed 'viewfinder' window on the camera section, and a 60-second timeout:
  ffmpeg -f alsa -i pulse -f x11grab -s 480:480 -follow_mouse 100 -show_region 1 -r 25 -i "$DISPLAY" -f video4linux2 -i /dev/video0 -filter_complex '[2:v]crop=160:480:240:0,split=2[d][D];[d]pad=640:480:480:0[c];[c][1:v]overlay=0:0[o]' -map '[o]' -map 0:a -t 60 -y output.mkv -map '[D]' -f matroska -t 60 - | ffplay -autoexit -noborder -left 0 -
• To record just the camera, with viewfinder:
  ffmpeg -f alsa -i pulse -f video4linux2 -i /dev/video0 -filter_complex '[1:v]split=2[d][D]' -map '[d]' -map 0:a -y output.mkv -map '[D]' -f matroska - | ffplay -autoexit -noborder -left 0 -
  (press q on the original command terminal to stop the recording)
• If you then find somebody wanted mp4 format:
  ffmpeg -i output.mkv -codec copy output.mp4
  (but for some applications you might also need to recode h264)

Mac OS X: "QuickTime Player" despite its name is not just a player. Its File menu contains options to record the screen with optional microphone narration, or to record from camera. Results are placed in ~/Movies and I think version 10.9+ of OS X also lets you record part of the screen (otherwise you have to post-process with mencoder's -vf crop=w:h:x:y if you don't want the whole screen).

Series of pictures

Output options

Android, iPhone or Mac

• If you get "MPlayer was compiled without libfaac" try using ffmpeg instead e.g. ffmpeg -i video.avi -b 512k output.mp4 (errors at the very end of the stream can be ignored)
• This can also be used to work around WeChat's error "Unable to share this video due to unspported format"
• If you get "x264encopts is not an MEncoder option" on a Mac, please note the MacPorts and Homebrew versions no longer support x264: you have to compile from SVN source using the instructions at mplayerhq (but you might want to keep the packaged mplayer in case the SVN version segfaults on playing)

Nokia S60, S40 etc

• Don't try sending a multi-megabyte MP4 via Bluetooth to an S40 phone: some models get permanently bricked as a result (infinite reset loop on power-on with no reformatting possible)

Windows 10 or Mac with large screen

• Press Alt-Enter to make WMP play full-screen (in VLC it's F, plus you might need Ctrl-H to hide the controls)

Zoom Cloud Meetings

• If nobody at your location needs to view the video full-screen, then it's likely more efficient to feed the video to Zoom at its original size, avoiding an extra level of rescaling. Try a command like:
  echo pause | mplayer $'-as\x73' $'-\x73\x6c\x61\x76e' -noborder video.mp4
  (I've obfuscated the options for enabling subtitle fonts and waiting on standard input, because some might misunderstand these technical terms as a racist insult if accidentally shown on a conference screen---beware they might still show up if you're using a terminal that shows the currently-executing command on its title bar.) Optionally add -ss start-second and/or -endpos length before the video.
  Mplayer then starts paused so you can set up the screen-share on that window.
  • On a recent Mac, the above command is not likely to work. As mentioned above, "Share Screen / Advanced / Video" is better, but if you're running some other video-conferencing software that cannot share video directly, you might still want to play without scaling: if you can run MacPorts you can sudo port install mpv and run something like:
    mpv --geometry=1280x720 --video-unscaled=yes --pause video.mp4
    (needs adjusting for the video size)---and the first use of Share Screen is likely to require a restart of the video-conferencing software after you've been prompted to change the Mac's security settings, so I'd advise running a test meeting first.
  • Due to Zoom's broken accessibility code on the GNU/Linux version, it is not possible to select "share computer sound" and "optimise screen sharing for video clip" without using the mouse: as of December 2020, attempts to press Space or Enter on these checkboxes give the appearance of a tick-mark appearing but do not actually set the underlying variable. (And if it were open-source I could have fixed that for them, but it's closed-source proprietary software, so all I can do is fill in their feedback form---my 17^th bug report to them as it happens; I don't know how many they're managing to process.)
  • This situation also makes the procedure not compatible with high-DPI displays if the monitor is not physically large enough: the desktop Zoom application is notoriously bad at allowing small window sizes, so the controls often end up being off-screen, which means if they are mouse-only then they cannot be operated no matter how many keyboard shortcuts you know. Some window managers e.g. Gnome 3 let you use Alt-F7 + arrow keys (or Super key + drag) to move Zoom windows partially off-screen at the top in order to access off-screen controls at the bottom.
  • If you do have a physically large enough monitor (or if you have enough eyesight to cope with normal DPI settings) and you are able to use the physical mouse, then Share-screen, select the Mplayer window (remembering to share audio, optimise for video unless it's slides, and mute the microphone) and press Space to start Mplayer. This single-window screen-share should then stop automatically when Mplayer closes itself at the end of the video, or press q to stop early.
• If the video should additionally be full-screen at your location then you can use VLC:
  vlc -f --start-paused video.mp4 vlc://quit
  (with optional --start-time and --stop-time after the --start-paused)---VLC starts paused so you can set up the screen-share on that window before pressing Space to play, and VLC quits at the end so the screen-share stops automatically.

"Share computer audio" can silently fail on some Fedora 34 setups, reportedly because Fedora changed from PulseAudio to PipeWire and PipeWire's PulseAudio plugin is not supported as well as real PulseAudio (it seems it works on some machines but not others). It may be necessary to unmute, set "Suppress background noise" as low as possible, be quiet, hope the fan doesn't spin up, and accept degraded audio going from the speaker to the microphone.

To show static pictures (e.g. slides) : VLC can take multiple images on the command line (and can set "minimal interface" on the menus + not full-screen); by default each image is played for 10 seconds, but Space pauses, then on each slide advance, press n and Space to advance to the next slide and re-pause.

Patching one Zoom meeting into another Zoom meeting

Old Windows or Windows Mobile

• For QVGA displays (320x240):
  -ovc lavc -lavcopts vcodec=wmv2 -oac lavc -lavcopts acodec=wmav2 -of lavf -vf dsize=320:240:2,scale=0:0 -o output.wmv
  • If you're using a version of mencoder you haven't tested before (e.g. on a server you're SSH'ing into), be sure to test that sound works when Windows plays the WMV file. Some mencoder installations can generate silent WMVs without warning, and you might need to reinstall mencoder.
• Desktop or high-end WM systems with larger displays might not need the -vf dsize=320:240:2,scale=0:0 option
• Streaming via slow-connection m3u: try substituting vcodec=wmv2:vbitrate=100 and (e.g.) -vf dsize=160:120:2,scale=0:0 but total may still need 150-200kbit/sec (18-24kB/sec); might stream on GSM EDGE but not plain GSM (and the default Windows Mobile installation can't stream from M3U)

MP3 audio

• Some versions of mencoder say "video stream is mandatory"; in this case try mplayer -ao pcm:file=output.wav and lame
• If the result is to be written to an audio CD, you can skip the MP3 encoding and output a cdda file via sox: -ovc copy -of rawaudio -oac pcm -srate 44100 -really-quiet -o - | sox -t raw -r 44100 -c 2 -s -b 16 - output.cdda (you might want to use -endpos 4797 or whatever on the input side to ensure the result is not too long). cdda files can be recorded with cdrecord -audio on GNU/Linux; on Mac you should specify wav instead, put it in an empty directory and do drutil burn -audio (dirname)
• Some Apple-recorded audio files can't be read by (many installations of) mencoder. Converting these requires a Mac and something like afconvert rec.aif -d LEI16 rec.wav && lame --vbr-new -V 9 rec.wav -o rec.mp3 (afconvert can't directly write mp3, at least not on any Mac I was able to test)

"Play All" bookmarklet

DVDs and VCDs

• For a PAL DVD try this:
  -oac lavc -ovc lavc -of mpeg -mpegopts format=dvd:tsaf -vf expand=:::::16/9,scale=720:576,harddup -srate 48000 -af lavcresample=48000 -lavcopts vcodec=mpeg2video:vrc_buf_size=1835:vrc_maxrate=9800:keyint=15:vstrict=0:acodec=mp2:aspect=16/9 -ofps 25 -o output.mpg
  Check the size of the .mpg (note DVD-5's "4.7G" is 4.38GiB and allow for overheads); if too big, add :vbitrate=4000 or whatever to the -lavcopts list
• Also check the A/V sync; if mencoder can't get it right then you might need to use ffmpeg instead: first convert it to a file if it's not already, then do ffmpeg -i file.avi -aspect 16:9 -target pal-dvd output.mpg (perhaps with -b:v 4000k or similar just before the output filename if the bitrate needs limiting). If this still doesn't work, try a separate run of ffmpeg to fix the video first using -vcodec copy -acodec copy and/or use -ac 4 etc.
  (Ffmpeg's concatenation is more complex than mencoder's: it's best done after all files are converted, and you'd need to do something like ffmpeg -i file1.mpg -i file2.mpg -i file3.mpg -filter_complex '[0:0][0:1] [1:0][1:1] [2:0][2:1] concat=n=3:v=1:a=1[v][a]' -map '[v]' -map '[a]' -target pal-dvd output.mpg which requires ffmpeg 1.1+; the 0..2 and the =3 need changing according to the number of input files, and any bitrate limit might need to be added again. Such concatenation might not be necessary if the dvdauthor command below takes multiple mpgs, but it doesn't always.)
• When you have output.mpg (from either mencoder or ffmpeg), run this (again changing the 16:9 if necessary):
  mkdir DVD/ && export VIDEO_FORMAT=PAL && dvdauthor -o DVD/ -t -v 16:9 output.mpg && dvdauthor -o DVD/ -T && rm output.mpg && mkisofs -dvd-video -v -o DVD.iso DVD && rm -r DVD
• On GNU/Linux, use sudo cdrecord -data DVD.iso; on a Mac, use hdiutil burn DVD.iso (don't use the Finder to right-click on DVD.iso and select "Burn to Disc", as this creates a new filesystem containing just the ISO file, which most DVD players will reject as "CDROM")
• Some (but not all) DVD players can also play VCD. For a PAL VCD (format is constrained, you can't change the bitrate etc):
  -oac lavc -ovc lavc -of mpeg -mpegopts format=xvcd -vf dsize=352:288:2,harddup -srate 44100 -af lavcresample=44100 -lavcopts acodec=mp2:abitrate=224:vcodec=mpeg1video:keyint=15:vrc_buf_size=327:vrc_minrate=1152:vrc_maxrate=1152:vbitrate=1152:aspect=16/9 -ofps 25 -o output.mpg
  Then run vcdimager output.mpg and write with cdrdao write videocd.cue or convert to ISO with bchunk videocd.bin videocd.cue videocd.iso
• If you have less than 35 minutes to put on a video CD then you can try SVCD (if supported by the player), e.g.:
  -oac lavc -ovc lavc -of mpeg -mpegopts format=xsvcd -vf dsize=480:576:2,harddup -srate 44100 -af lavcresample=44100 -lavcopts vcodec=mpeg2video:mbd=2:keyint=15:vrc_buf_size=917:vrc_minrate=600:vbitrate=2500:vrc_maxrate=2500:acodec=mp2:abitrate=224:aspect=16/9 -ofps 25 -o output.mpg
  then run vcdimager -t svcd output.mpg and burn with cdrdao write videocd.cue.