Facilitate 3D frame sequential/alternating frames for 3D output

Hi,

@wm4

I hope I understood better and that it's not a useless issue here like the previous one.

I have a 3D Ready videoprojector named Vivitek Qumi Q7 that supports 3D with 120 Hz frame sequential/alternating frames output.

It seems that ffmpeg and its stereo3d filter don't support frame sequential/alternating frames for the output.

I guess that libav supports frame sequential output with avconv -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT as seen here.

It seems that the --video-stereo-mode mpv parameter does not offer 3D frame sequential output. Am I right? Or am I again completely wrong? I know that some mpv packages are linked to ffmpeg, some others to libav. For example, the Windows package is bundled with ffmpeg, so it can't work for that need.

Could you facilitate in some way the support of frame sequential/alternating frames as a 3D output in the mpv GUI?

(I also know that we can't use right now Plex Media Player for 3D output with frame sequential/alternating frames format)

Thanks in advance,
HLFH

Begin by examining how mpv's --video-stereo-mode option handles output modes, then compare it with the stereo3d and framepack behavior referenced in the issue. Done means the GUI can produce frame-sequential or alternating-frame 3D output, including with the ffmpeg-based Windows package, with a documented way to select it.