3D SBSL and ABL option removed so MPV treats everything as HALF SBS/TAB not FULL SBS/TAB

[netExtra]

mpv Information

Every major MPV release for the last few years

Other Information

- Windows version: Windows 10 and 11
- GPU model, driver and version: Nvidia 30,40 and 50 series
- Source of mpv: Zhonfly, Schinchiro and every other release
- Latest known working version: Years ago.
- Issue started after the following happened: Half SBS 3D

Reproduction Steps

SBSL (Full SBS) and ABL (Full TAB) have always been part of the ffmpeg stereo3D. But they was removed from MPV a few major versions back. I tried settings stereo-in=no but there is no stereo-out option and the logs (see below) suggest the "output" is still being sent as as Half SBS.
I'm not sure if the logs show the output as being interpreted as SBS2L which is half SBSL or A=None means that it is doing nothing. My only option to stop this behavior to to remove the 3D SBS tag from the MKV header file. The same applies for ABL as well as SBSR and ABR for right eyes first.

Expected Behavior

PS C:\Users\Admin> mpv --vf=format:stereo-in=help
Valid values for option stereo-in are:
no
mono
sbsl <-- This is what I think is needed
sbs2l
abl <-- This is what I think is needed
ab2r
ab2l
checkr
checkl
irr
irl
icr
icl
arcc
sbs2r
agmc
al
ar

Actual Behavior

PS C:\Users\Admin> mpv --vf=format:stereo-in=help
Valid values for option stereo-in are:
no
mono
---> no sbsl
sbs2l
---> no abl
ab2r
ab2l
checkr
checkl
irr
irl
icr
icl
arcc
sbs2r
agmc
al
ar

Log File

mpv.log

Selected entried below.
[ 4.135][d][mkv] | + StereoMode: sbs2l
...
[ 4.249][v][vf] [in] 3840x1080 d3d11[nv12] bt.709/bt.709/bt.1886/limited/display CL=mpeg2/4/h264 crop=3840x1080+0+0 stereo=sbs2l A=none
[ 4.249][v][vf] [userdeint] 3840x1080 d3d11[nv12] bt.709/bt.709/bt.1886/limited/display CL=mpeg2/4/h264 crop=3840x1080+0+0 stereo=sbs2l A=none
[ 4.249][v][vf] [userdeint] (disabled)
[ 4.249][v][vf] [format] 3840x1080 d3d11[nv12] bt.709/bt.709/bt.1886/limited/display CL=mpeg2/4/h264 crop=3840x1080+0+0 stereo=sbs2l A=none
[ 4.249][v][vf] [autovflip] 3840x1080 d3d11[nv12] bt.709/bt.709/bt.1886/limited/display CL=mpeg2/4/h264 crop=3840x1080+0+0 A=none
[ 4.249][v][vf] [autovflip] (disabled)
[ 4.249][v][vf] [autorotate] 3840x1080 d3d11[nv12] bt.709/bt.709/bt.1886/limited/display CL=mpeg2/4/h264 crop=3840x1080+0+0 A=none
[ 4.249][v][vf] [autorotate] (disabled)
[ 4.249][v][vf] [convert] 3840x1080 d3d11[nv12] bt.709/bt.709/bt.1886/limited/display CL=mpeg2/4/h264 crop=3840x1080+0+0 A=none

Sample Files

No response

I carefully read all instruction and confirm that I did the following:

• I tested and confirmed that the issue exists with the latest release version or newer.
• I provided all required information including system and mpv version.
• I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of --log-file=output.txt.
• I produced the log file while the behaviors described in "Actual Behavior" were actively observed.
• I attached the full, untruncated log file.
• I attached the backtrace in the case of a crash.

[kasper93]

sbsl was never a valid value of stereo-in, it was an option of the old vf_stereo3d conversion filter (removed in 2017), and it still exists in lavfi filter, which you can use directly: --vf=stereo3d=in=sbsl:out=ml.

The stereo-in names come from Matroska StereoMode values, which don't distinguish full from half SBS. StereoMode=1 just means "side by side, left eye first", and mpv's name for that value happens to be sbs2l. The stereo=sbs2l in your log is frame metadata being printed, not a conversion. mpv doesn't convert or rescale anything based on this tag. Your log shows the full 3840x1080 frame reaching the VO untouched. The only thing the tag affects is OSD/subtitle rendering (duplicated per eye), which your stereo-in=no already disables.

Could you clarify what you're actually seeing on screen and what you expect to happen? A screenshot of the wrong result would help.

[netExtra]

sbsl was never a valid value of stereo-in, it was an option of the old vf_stereo3d conversion filter (removed in 2017), and it still exists in lavfi filter, which you can use directly: --vf=stereo3d=in=sbsl:out=ml.

The stereo-in names come from Matroska StereoMode values, which don't distinguish full from half SBS. StereoMode=1 just means "side by side, left eye first", and mpv's name for that value happens to be sbs2l. The stereo=sbs2l in your log is frame metadata being printed, not a conversion. mpv doesn't convert or rescale anything based on this tag. Your log shows the full 3840x1080 frame reaching the VO untouched. The only thing the tag affects is OSD/subtitle rendering (duplicated per eye), which your stereo-in=no already disables.

Could you clarify what you're actually seeing on screen and what you expect to happen? A screenshot of the wrong result would help.

Not really coz it's in 3D. But for Full SBS the output should be 1920x1080 per eye and the equivalent for Full TAB. If mpv is only outputing Half SBS/TAB then for the output will be 960x1080 per eye. The only solution currently is to completely bypass MPV 3D processing and remove the 3D tags from the MKV header so MPV outputs it as 3840x1080 with no conversion and my software will do the rest. But I'm not sure why SBSL/R and ABL/R were removed in the first place.

[kasper93]

mpv outputs the video identically whether the tag is present or not, always the full 3840x1080 frame, no scaling, no conversion. There is no "3D processing" to bypass. Nothing halves the frame to 960x1080 per eye. SBSL/R and ABL/R were never removed, because they never existed as tag values. Matroska has no full-vs-half distinction, and mpv never acted on it either way.

The full-vs-half distinction is not expressed by StereoMode at all. Per the Matroska spec (RFC 9559), DisplayWidth/DisplayHeight apply to the whole stored frame, with no per-eye interpretation. "half SBS" only exists implicitly as an anamorphic display aspect (e.g. 1920x1080 frame with 16:9 DAR). Your file has PixelWidth=DisplayWidth=3840 and PixelHeight=DisplayHeight=1080, so mpv displays it 1:1, which is exactly full SBS.

The only thing the tag changes is OSD/subtitle rendering (drawn once per eye). If your external software behaves differently with vs. without the tag, the difference is on its side, not in mpv's video output.

Take screenshot of what you believe is rendering you want, and what you get, with stats page in both cases.

[netExtra]

mpv outputs the video identically whether the tag is present or not, always the full 3840x1080 frame, no scaling, no conversion. There is no "3D processing" to bypass. Nothing halves the frame to 960x1080 per eye. SBSL/R and ABL/R were never removed, because they never existed as tag values. Matroska has no full-vs-half distinction, and mpv never acted on it either way.

The full-vs-half distinction is not expressed by StereoMode at all. Per the Matroska spec (RFC 9559), DisplayWidth/DisplayHeight apply to the whole stored frame, with no per-eye interpretation. "half SBS" only exists implicitly as an anamorphic display aspect (e.g. 1920x1080 frame with 16:9 DAR). Your file has PixelWidth=DisplayWidth=3840 and PixelHeight=DisplayHeight=1080, so mpv displays it 1:1, which is exactly full SBS.

The only thing the tag changes is OSD/subtitle rendering (drawn once per eye). If your external software behaves differently with vs. without the tag, the difference is on its side, not in mpv's video output.

Take screenshot of what you believe is rendering you want, and what you get, with stats page in both cases.

Thanks for the clarification. This is why I asked the question about the logs. So what exactly are the logs entries (see below) showing when they say stereo output is sbs2l. That is half SBS. When I remove all 3D processing, those log messages go away.

[ 4.135][d][mkv] | + StereoMode: sbs2l
...
[ 4.249][v][vf] [in] 3840x1080 d3d11[nv12] bt.709/bt.709/bt.1886/limited/display CL=mpeg2/4/h264 crop=3840x1080+0+0 stereo=sbs2l A=none
[ 4.249][v][vf] [userdeint] 3840x1080 d3d11[nv12] bt.709/bt.709/bt.1886/limited/display CL=mpeg2/4/h264 crop=3840x1080+0+0 stereo=sbs2l A=none
[ 4.249][v][vf] [userdeint] (disabled)
[ 4.249][v][vf] [format] 3840x1080 d3d11[nv12] bt.709/bt.709/bt.1886/limited/display CL=mpeg2/4/h264 crop=3840x1080+0+0 stereo=sbs2l A=none