testsrc

MP4 subtitles in Chinese, Japanese and Korean

edge/tx3g-cjk.mp4MP4Edge case

MP4 text subtitles in Chinese, Japanese and Korean, as phone recordings and downloaded episodes carry them.

How it should play

字幕 · 자막 · Sub

What a broken player shows

□□ · □□ · ???
An illustration of the symptom, not a frame from the file.

What goes wrong

Garbled characters, missing glyphs, or no subtitles at all.

The file

Container
MP4, 6 s
Size
5.5 MB
Video
H.264, 1920x1080, 30 fps
Audio
AAC, stereo, 48,000 Hz
Expected
plays correctly in any player

How it was verified

Built by the testsrc generator (gen v0.2) and verified with FFmpeg 7.1.5-0+deb13u1 and GStreamer 1.26.2 in snapshot 2026-11-02, before it was published: the file has the property this page describes, and decoding it gives the expected result.

With a token: the file, how exactly it was built, the full fact sheet, and the expected result the checker judges a player against.

Use it

# the public facts
curl https://testsrc.com/v1/cases/edge/tx3g-cjk.mp4

# the full fact sheet and the file, with your token
curl -H "Authorization: Bearer $TESTSRC_TOKEN" \
  https://testsrc.com/v1/cases/edge/tx3g-cjk.mp4/facts
curl -H "Authorization: Bearer $TESTSRC_TOKEN" -o tx3g-cjk.mp4 \
  https://testsrc.com/v1/files/edge/tx3g-cjk.mp4

# play it through your player and check what it showed
testsrc run --player libvlc edge/tx3g-cjk.mp4

See the API reference for tokens, quotas and snapshots.

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More on subtitles

2 more cases on this with a token.