First-party Windows builds do not include SRT support, ffmpeg not compiled with libsrt?

mpv Information

mpv --version
mpv v0.40.0-dev-g95c7599c4 Copyright © 2000-2025 mpv/MPlayer/mplayer2 projects
 built on Dec  8 2025 21:41:30
libplacebo version: v7.358.0
FFmpeg version: f853d12
FFmpeg library versions:
   libavcodec      62.11.100
   libavdevice     62.1.100
   libavfilter     11.4.100
   libavformat     62.3.100
   libavutil       60.8.100
   libswresample   6.1.100
   libswscale      9.1.100

Other Information

- Windows version: Microsoft Windows [Version 10.0.26200.7462]
- GPU model, driver and version: RTX 5070 TI
- Source of mpv: nightly.link first-party build (MSVC)
- Latest known working version: unknown
- Issue started after the following happened: unknown

Reproduction Steps

Attempt to open an SRT stream with mpv from GUI or command line.

mpv --list-protocols appears to show srt:// protocol support is missing, which is a regression from prior builds I have used (from various recommended sources from mpv.io and the mpvnet-player fork).

Protocols:

 mpv://
 avdevice://
 av://
 memory://
 hex://
 null://
 mf://
 edl://
 file://
 appending://
 slice://
 fd://
 fdclose://
 data://
 gopher://
 gophers://
 http://
 dav://
 webdav://
 httpproxy://
 https://
 davs://
 webdavs://
 mmsh://
 mms://
 mmshttp://
 mmst://
 rtmp://
 rtmps://
 rtmpt://
 rtmpts://
 rtp://
 srtp://
 ipfs://
 ipns://
 rtsp://
 rtsps://
 async://
 cache://
 concat://
 concatf://
 crypto://
 fd://
 ffrtmphttp://
 file://
 ftp://
 hls://
 pipe://
 subfile://
 tcp://
 tls://
 dtls://
 udp://
 udplite://
 ffmpeg://
 lavf://

Total: 56 protocols

Expected Behavior

SRT stream should open and play

Actual Behavior

SRT stream does not play, mpv aborts with an error.

Log File

output.txt

Sample Files

Any valid SRT stream. An SRT stream can be trivially produced using MediaMTX with the source published from OBS for example.

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

• I tested with the latest mpv version to validate that the issue is not already fixed.
• 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.

Start by inspecting the first-party Windows MSVC build configuration and run mpv --list-protocols to verify the missing SRT entry. Compare the build's FFmpeg/libsrt support with a working build, then confirm that a valid SRT stream opens and plays.