diff --git a/modules/api/video.py b/modules/api/video.py
index 2b34357d2..ff2345214 100644
--- a/modules/api/video.py
+++ b/modules/api/video.py
@@ -38,7 +38,7 @@ class ReqVideo(BaseModel):
     mp4_interpolate: int = Field(default=0, ge=0, le=10, title="Interpolation", description="RIFE interpolation passes between frames")
     mp4_codec: str = Field(default="libx264", title="Codec", description="Video codec; none skips video encoding")
     mp4_ext: str = Field(default="mp4", title="Container", description="Container extension; the muxer is inferred from it")
-    mp4_opt: str = Field(default="crf:16", title="Codec options", description="Encoder options as comma-separated key:value pairs")
+    mp4_opt: str = Field(default="crf=16", title="Codec options", description="Encoder options as key=value pairs separated by : or ,")
     mp4_video: bool = Field(default=True, title="Save video", description="Write the video container to disk")
     mp4_frames: bool = Field(default=False, title="Save frames", description="Write individual frame images to disk")
     mp4_sf: bool = Field(default=False, title="Save safetensors", description="Write raw frames as a safetensors file")
diff --git a/modules/framepack/framepack_api.py b/modules/framepack/framepack_api.py
index 99efdcfb1..9cc2ace1a 100644
--- a/modules/framepack/framepack_api.py
+++ b/modules/framepack/framepack_api.py
@@ -34,7 +34,7 @@ class ReqFramepack(BaseModel):
     mp4_video: bool | None = Field(default=True, title="Save Video", description="Save video")
     mp4_frames: bool | None = Field(default=False, title="Save Frames", description="Save frames for the video")
     mp4_thumb: bool | None = Field(default=True, title="Save Thumbnail", description="Save thumbnail for the video")
-    mp4_opt: str | None = Field(default="crf:16", title="Options", description="Options for the video codec")
+    mp4_opt: str | None = Field(default="crf=16", title="Options", description="Options for the video codec")
     mp4_ext: str | None = Field(default="mp4", title="Format", description="Format for the video")
     mp4_interpolate: int | None = Field(default=0, title="Interpolation", description="Interpolation for the video")
     attention: str | None = Field(default="Default", title="Attention", description="Attention type for the model")
diff --git a/modules/postprocess/seedvr_model.py b/modules/postprocess/seedvr_model.py
index 27f8e775b..6fc51531c 100644
--- a/modules/postprocess/seedvr_model.py
+++ b/modules/postprocess/seedvr_model.py
@@ -248,7 +248,7 @@ class UpscalerSeedVR(Upscaler):
             log.error(f'Upscaler: name="SeedVR2" video="{video_path}" {e}')
             return None, None, None
 
-    def create_video(self, tensor: torch.Tensor, audio, codec: str = 'libx264', codec_opt: str = 'crf:16', interpolate: int = 0):
+    def create_video(self, tensor: torch.Tensor, audio, codec: str = 'libx264', codec_opt: str = 'crf=16', interpolate: int = 0):
         t0 = time.time()
         from modules.video_models.video_save import save_video
         pixels = tensor.permute(3, 0, 1, 2).unsqueeze(0) # from (t, h, w, c) to (n, c, t, h, w)
@@ -281,7 +281,7 @@ class UpscalerSeedVR(Upscaler):
                    offload: bool = True,
                    interpolate: int = 1,
                    codec: str = 'libx264',
-                   codec_opt: str = 'crf:16',
+                   codec_opt: str = 'crf=16',
                    vae_memory: float = 0.5,
                    vae_tile_encode: bool = True,
                    vae_tile_decode: bool = True,
diff --git a/modules/video_models/video_codecs.py b/modules/video_models/video_codecs.py
index 2e07d1eb4..856e7a90b 100644
--- a/modules/video_models/video_codecs.py
+++ b/modules/video_models/video_codecs.py
@@ -26,14 +26,14 @@ codecs_config = {
         'desc': 'Legacy open video format for WebM.',
         'ext': 'webm',
         'allowed_exts': ['webm', 'mkv'],
-        'options': 'crf=10:b:v=0',
+        'options': 'crf=10:b=0',
     },
     'libvpx-vp9': {
         'name': 'VP9 Video',
         'desc': 'Royalty-free web video format.',
         'ext': 'webm',
         'allowed_exts': ['webm', 'mkv'],
-        'options': 'crf=23:b:v=0',
+        'options': 'crf=23:b=0',
     },
     'libsvtav1': {
         'name': 'AV1 (SVT-AV1)',
@@ -47,14 +47,14 @@ codecs_config = {
         'desc': 'Legacy format for old media players.',
         'ext': 'mp4',
         'allowed_exts': ['mp4', 'avi', 'mkv'],
-        'options': 'qscale:v=3',
+        'options': 'qmin=3:qmax=3',
     },
     'mjpeg': {
         'name': 'Motion JPEG',
         'desc': 'Sequence of JPEG frames; minimal CPU load.',
         'ext': 'avi',
         'allowed_exts': ['avi', 'mov', 'mkv'],
-        'options': 'qscale:v=3',
+        'options': 'qmin=3:qmax=3',
     },
 
     # --- Hardware Accelerated: NVIDIA NVENC ---
diff --git a/modules/video_models/video_run.py b/modules/video_models/video_run.py
index cd52c950e..453e6738a 100644
--- a/modules/video_models/video_run.py
+++ b/modules/video_models/video_run.py
@@ -110,7 +110,7 @@ def run(selected: models_def.Model, *,
         mp4_interpolate: int = 0,
         mp4_codec: str = 'libx264',
         mp4_ext: str = 'mp4',
-        mp4_opt: str = 'crf:16',
+        mp4_opt: str = 'crf=16',
         mp4_video: bool = True,
         mp4_frames: bool = False,
         mp4_sf: bool = False,
diff --git a/scripts/postprocessing_seedvr.py b/scripts/postprocessing_seedvr.py
index 0e47eb268..29868cd0c 100644
--- a/scripts/postprocessing_seedvr.py
+++ b/scripts/postprocessing_seedvr.py
@@ -44,7 +44,7 @@ class ScriptSeedVR(scripts_postprocessing.ScriptPostprocessing):
                     from modules.ui_common import create_refresh_button
                     seedvr_codec = gr.Dropdown(label="Video codec", choices=['none', 'libx264'], value='libx264', type='value')
                     create_refresh_button(seedvr_codec, get_codecs, elem_id="video_mp4_codec_refresh")
-                    seedvr_codec_opt = gr.Textbox(label="Video options", value='crf:16', elem_id="video_mp4_opt")
+                    seedvr_codec_opt = gr.Textbox(label="Video options", value='crf=16', elem_id="video_mp4_opt")
 
         return {
             "seedvr_enabled": seedvr_enabled,
diff --git a/test/test-video-codecs.py b/test/test-video-codecs.py
new file mode 100644
index 000000000..3d03581b8
--- /dev/null
+++ b/test/test-video-codecs.py
@@ -0,0 +1,222 @@
+#!/usr/bin/env python
+"""
+Offline unit tests for the video encoder option strings in modules.video_models.
+
+``parse_options`` treats ``:`` and ``,`` as separators and ``=`` as the only assignment, so a
+segment without ``=`` becomes a valueless flag set to ``'1'``. That makes ffmpeg command line
+spellings parse into something legal but wrong: ``crf:16`` yields ``{'crf': '1', '16': '1'}`` and
+``crf=23:b:v=0`` pins the generic bitrate option to 1 bit per second. Neither raises, so the only
+way to catch it is to assert the shape of the strings themselves.
+
+Covers:
+
+- ``parse_options`` semantics for both separators, the flag form, and the dict passthrough
+- every preset in ``codecs_config`` reaching the encoder as the keys it was written with
+- the shipped ``mp4_opt`` default parsing to the value it names
+
+No running server required. Nothing is encoded.
+
+Usage:
+    python test/test-video-codecs.py
+"""
+
+import os
+import sys
+
+script_dir = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+sys.path.insert(0, script_dir)
+os.chdir(script_dir)
+
+os.environ['SD_INSTALL_QUIET'] = '1'
+
+# Bootstrap cmd_args before any module that pulls in shared.py.
+import modules.cmd_args  # pylint: disable=wrong-import-position
+import installer  # pylint: disable=wrong-import-position
+orig_argv = sys.argv
+sys.argv = [sys.argv[0]]
+try:
+    modules.cmd_args.parse_args()
+finally:
+    sys.argv = orig_argv
+installer.add_args(modules.cmd_args.parser)
+modules.cmd_args.parsed, _ = modules.cmd_args.parser.parse_known_args([])
+
+from modules.errors import log                                       # pylint: disable=wrong-import-position
+from modules.video_models.video_codecs import codecs_config          # pylint: disable=wrong-import-position
+from modules.video_models.video_save import parse_options            # pylint: disable=wrong-import-position
+
+
+results: dict[str, dict] = {}
+
+
+def category(name: str):
+    if name not in results:
+        results[name] = {'passed': 0, 'failed': 0, 'tests': []}
+    return name
+
+
+def record(cat: str, passed: bool, name: str, detail: str = ''):
+    status = 'PASS' if passed else 'FAIL'
+    results[cat]['passed' if passed else 'failed'] += 1
+    results[cat]['tests'].append((status, name))
+    msg = f'  {status}: {name}'
+    if detail:
+        msg += f' ({detail})'
+    if passed:
+        log.info(msg)
+    else:
+        log.error(msg)
+
+
+def run_test(cat: str, fn):
+    name = fn.__name__
+    try:
+        ok = fn()
+        if ok is False:
+            record(cat, False, name)
+        else:
+            record(cat, True, name)
+    except AssertionError as e:
+        record(cat, False, name, str(e))
+    except Exception as e:  # pylint: disable=broad-except
+        record(cat, False, name, f'exception: {e}')
+
+
+# ============================================================
+# parse_options semantics
+# ============================================================
+
+def test_assignment_uses_equals():
+    assert parse_options('crf=16') == {'crf': '16'}
+
+
+def test_colon_separates_pairs():
+    assert parse_options('crf=18:preset=medium') == {'crf': '18', 'preset': 'medium'}
+
+
+def test_comma_separates_pairs():
+    assert parse_options('crf=18,preset=medium') == {'crf': '18', 'preset': 'medium'}
+
+
+def test_bare_item_becomes_a_flag():
+    assert parse_options('fastseek') == {'fastseek': '1'}
+
+
+def test_whitespace_is_stripped():
+    assert parse_options(' crf = 18 : preset = medium ') == {'crf': '18', 'preset': 'medium'}
+
+
+def test_empty_and_dict_inputs():
+    assert parse_options('') == {}
+    assert parse_options('   ') == {}
+    assert parse_options(None) == {}
+    assert parse_options({'crf': '16'}) == {'crf': '16'}
+
+
+def test_ffmpeg_cli_spelling_does_not_assign():
+    # the failure this suite exists for: legal parse, wrong meaning, no exception
+    assert parse_options('crf:16') != {'crf': '16'}
+
+
+# ============================================================
+# shipped presets
+# ============================================================
+
+def test_every_preset_segment_assigns():
+    broken = []
+    for name, cfg in codecs_config.items():
+        options = cfg.get('options', '')
+        if not options:
+            continue
+        for segment in options.replace(',', ':').split(':'):
+            if segment.strip() and '=' not in segment:
+                broken.append(f'{name}="{options}" segment="{segment}"')
+    assert not broken, f'segments parse as flags instead of assignments: {broken}'
+
+
+def test_no_preset_key_is_numeric():
+    numeric = []
+    for name, cfg in codecs_config.items():
+        for key in parse_options(cfg.get('options', '')):
+            if key.isdigit():
+                numeric.append(f'{name}: {key}')
+    assert not numeric, f'a value was parsed as a key: {numeric}'
+
+
+def test_no_preset_sets_a_degenerate_bitrate():
+    # b is a generic AVCodecContext option, so a stray b=1 caps the encoder at 1 bit per second
+    bad = []
+    for name, cfg in codecs_config.items():
+        bitrate = parse_options(cfg.get('options', '')).get('b', None)
+        if bitrate is not None and bitrate != '0':
+            bad.append(f'{name}: b={bitrate}')
+    assert not bad, f'bitrate pinned to a nonzero value: {bad}'
+
+
+def test_every_preset_keeps_its_key_count():
+    for name, cfg in codecs_config.items():
+        options = cfg.get('options', '')
+        if not options:
+            continue
+        segments = [s for s in options.replace(',', ':').split(':') if s.strip()]
+        parsed = parse_options(options)
+        assert len(parsed) == len(segments), f'{name}="{options}" parsed to {parsed}'
+
+
+# ============================================================
+# shipped defaults
+# ============================================================
+
+def test_run_default_names_its_own_value():
+    import inspect
+    from modules.video_models import video_run
+    default = inspect.signature(video_run.run).parameters['mp4_opt'].default
+    assert parse_options(default) == {'crf': '16'}, f'default "{default}" parsed to {parse_options(default)}'
+
+
+def run_all():
+    log.warning('=== Video codec options ===')
+    cat = category('parser')
+    for fn in [
+        test_assignment_uses_equals,
+        test_colon_separates_pairs,
+        test_comma_separates_pairs,
+        test_bare_item_becomes_a_flag,
+        test_whitespace_is_stripped,
+        test_empty_and_dict_inputs,
+        test_ffmpeg_cli_spelling_does_not_assign,
+    ]:
+        run_test(cat, fn)
+    cat = category('presets')
+    for fn in [
+        test_every_preset_segment_assigns,
+        test_no_preset_key_is_numeric,
+        test_no_preset_sets_a_degenerate_bitrate,
+        test_every_preset_keeps_its_key_count,
+    ]:
+        run_test(cat, fn)
+    cat = category('defaults')
+    for fn in [
+        test_run_default_names_its_own_value,
+    ]:
+        run_test(cat, fn)
+
+    log.warning('=== Results ===')
+    total_passed = 0
+    total_failed = 0
+    for cat_name, info in results.items():
+        ok = info['failed'] == 0
+        status = 'PASS' if ok else 'FAIL'
+        log.info(f"  {cat_name}: {info['passed']} passed, {info['failed']} failed [{status}]")
+        total_passed += info['passed']
+        total_failed += info['failed']
+    log.warning(f'Total: {total_passed} passed, {total_failed} failed')
+    return total_failed == 0
+
+
+if __name__ == '__main__':
+    import time
+    t0 = time.time()
+    ok = run_all()
+    log.warning(f'Total time: {time.time() - t0:.2f}s')
+    sys.exit(0 if ok else 1)