Add Webm medium quality preset and fix MP4/Webm presets

CHANGELOG.md

@@ -7,6 +7,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- `VideoWebmMedium` preset: VP9 at 240k with the height capped at 720, a middle ground between `VideoWebmLow` and `VideoWebmHigh` (#271)
+
+### Changed
+
+- `VideoMp4High` now encodes at CRF 28 instead of 20, which regularly produced a file larger than its input, and adds `-movflags +faststart` (#271)
+- All Webm presets (`VideoWebmLow`, `VideoWebmMedium`, `VideoWebmHigh`) now use `-row-mt 1` for faster VP9 encoding (#271)
+- Bumped `VideoWebmLow` to v4 and `VideoWebmHigh` to v3 following the `-row-mt` addition (#271)
+
 ### Fixed
 
 - Fix JS rewriting of `this.<prop>` so it reliably detects a leading newline (and prepends the needed `;`) regardless of the amount of whitespace, and no longer wrongly rewrites `this` when preceded by `.`/`$` and several spaces (#381)

src/zimscraperlib/video/presets.py

@@ -33,7 +33,7 @@ class VideoWebmLow(Config):
     128k target video bitrate but stay within quality boundaries.
     48k audio bitrate"""
 
-    VERSION = 3
+    VERSION = 4
 
     ext = "webm"
     mimetype = f"{preset_type}/webm"
@@ -47,13 +47,44 @@ class VideoWebmLow(Config):
         "-quality": "good",  # codec preset
         "-speed": "4",  # Encoding speed (compromise between quality and encoding time)
         "-vf": "scale='480:trunc(ow/a/2)*2'",  # frame size
+        "-row-mt": "1",
         "-codec:a": "libvorbis",  # audio codec
         "-b:a": "48k",  # target audio bitrate
         "-ar": "44100",  # audio sampling rate
         "-ac": "2",  # force stereo
     }
 
 
+class VideoWebmMedium(Config):
+    """Medium Quality webm video
+
+    720:h format, height capped at 720 and width adjusted to keep aspect
+    ratio, so smaller videos are not upscaled
+    240k target video bitrate but stay within quality boundaries.
+    48k audio bitrate"""
+
+    VERSION = 1
+
+    ext = "webm"
+    mimetype = f"{preset_type}/webm"
+
+    options: ClassVar[dict[str, str | None]] = {
+        "-codec:v": "libvpx-vp9",
+        "-b:v": "240k",
+        "-qmin": "32",
+        "-qmax": "58",
+        "-g": "240",
+        "-quality": "good",
+        "-speed": "3",
+        "-vf": "scale='-2:min(720,ih)':force_original_aspect_ratio=increase",
+        "-row-mt": "1",
+        "-codec:a": "libvorbis",
+        "-b:a": "48k",
+        "-ar": "44100",
+        "-ac": "2",
+    }
+
+
 class VideoMp4Low(Config):
     """Low Quality mp4 video
 
@@ -88,7 +119,7 @@ class VideoWebmHigh(Config):
 
     25 constant quality"""
 
-    VERSION = 2
+    VERSION = 3
 
     ext = "webm"
     mimetype = f"{preset_type}/webm"
@@ -101,6 +132,7 @@ class VideoWebmHigh(Config):
         "-g": "240",  # Number of frames allowed between keyframes
         "-quality": "good",  # codec preset
         "-speed": "1",  # Encoding speed (compromise between quality and encoding time)
+        "-row-mt": "1",
         "-codec:a": "libvorbis",  # audio codec
         "-b:a": "48k",  # target audio bitrate
         "-ar": "44100",  # audio sampling rate
@@ -109,17 +141,18 @@ class VideoWebmHigh(Config):
 
 
 class VideoMp4High(Config):
-    """Low Quality mp4 video
+    """High Quality mp4 video
 
-    20 constant quality"""
+    28 constant quality"""
 
-    VERSION = 1
+    VERSION = 2
 
     ext = "mp4"
     mimetype = f"{preset_type}/mp4"
 
     options: ClassVar[dict[str, str | None]] = {
         "-codec:v": "h264",  # video codec
         "-codec:a": "aac",  # audio codec
-        "-crf": "20",  # constant quality, lower value gives better qual and larger size
+        "-crf": "28",  # constant quality, lower value gives better qual and larger size
+        "-movflags": "+faststart",
     }

tests/video/test_video.py

@@ -13,6 +13,7 @@
     VideoMp4Low,
     VideoWebmHigh,
     VideoWebmLow,
+    VideoWebmMedium,
     VoiceMp3Low,
 )
 
@@ -178,9 +179,9 @@ def test_preset_has_mime_and_ext():
 
 def test_preset_video_webm_low():
     config = VideoWebmLow()
-    assert config.VERSION == 3
+    assert config.VERSION == 4
     args = config.to_ffmpeg_args()
-    assert len(args) == 26
+    assert len(args) == 28
     options_map = [
         ("codec:v", "libvpx-vp9"),
         ("codec:a", "libvorbis"),
@@ -191,6 +192,7 @@ def test_preset_video_webm_low():
         ("qmin", "30"),
         ("qmax", "40"),
         ("vf", "scale='480:trunc(ow/a/2)*2'"),
+        ("row-mt", "1"),
         ("g", "240"),
         ("speed", "4"),
         ("ac", "2"),
@@ -210,11 +212,49 @@ def test_preset_video_webm_low():
     assert idx != -1 and args[idx + 1] == "25"
 
 
+def test_preset_video_webm_medium():
+    config = VideoWebmMedium()
+    assert config.VERSION == 1
+    args = config.to_ffmpeg_args()
+    assert len(args) == 28
+    options_map = [
+        ("codec:v", "libvpx-vp9"),
+        ("codec:a", "libvorbis"),
+        ("b:v", "240k"),
+        ("ar", "44100"),
+        ("b:a", "48k"),
+        ("quality", "good"),
+        ("qmin", "32"),
+        ("qmax", "58"),
+        (
+            "vf",
+            "scale='-2:min(720,ih)':force_original_aspect_ratio=increase",
+        ),
+        ("row-mt", "1"),
+        ("g", "240"),
+        ("speed", "3"),
+        ("ac", "2"),
+    ]
+    for option, val in options_map:
+        idx = args.index(f"-{option}")
+        assert idx != -1
+        assert args[idx + 1] == val
+
+    # test updating values
+    config = VideoWebmMedium(**{"-speed": "4"})
+    config["-b:v"] = "300k"
+    args = config.to_ffmpeg_args()
+    idx = args.index("-speed")
+    assert idx != -1 and args[idx + 1] == "4"
+    idx = args.index("-b:v")
+    assert idx != -1 and args[idx + 1] == "300k"
+
+
 def test_preset_video_webm_high():
     config = VideoWebmHigh()
-    assert config.VERSION == 2
+    assert config.VERSION == 3
     args = config.to_ffmpeg_args()
-    assert len(args) == 24
+    assert len(args) == 26
     options_map = [
         ("codec:v", "libvpx-vp9"),
         ("codec:a", "libvorbis"),
@@ -224,6 +264,7 @@ def test_preset_video_webm_high():
         ("quality", "good"),
         ("qmin", "26"),
         ("qmax", "54"),
+        ("row-mt", "1"),
         ("g", "240"),
         ("speed", "1"),
         ("ac", "2"),
@@ -279,13 +320,14 @@ def test_preset_video_mp4_low():
 
 def test_preset_video_mp4_high():
     config = VideoMp4High()
-    assert config.VERSION == 1
+    assert config.VERSION == 2
     args = config.to_ffmpeg_args()
-    assert len(args) == 8
+    assert len(args) == 10
     options_map = [
         ("codec:v", "h264"),
         ("codec:a", "aac"),
-        ("crf", "20"),
+        ("crf", "28"),
+        ("movflags", "+faststart"),
     ]
     for option, val in options_map:
         idx = args.index(f"-{option}")
@@ -355,6 +397,18 @@ def test_preset_voice_mp3_low():
             VideoWebmLow().to_ffmpeg_args(),
             {"codecs": ["vp9", "vorbis"], "duration": 2},
         ),
+        (
+            "video.mp4",
+            "video.webm",
+            VideoWebmMedium().to_ffmpeg_args(),
+            {"codecs": ["vp9", "vorbis"], "duration": 2},
+        ),
+        (
+            "video.mkv",
+            "video.mp4",
+            VideoMp4High().to_ffmpeg_args(),
+            {"codecs": ["h264", "aac"], "duration": 2},
+        ),
         (
             "video.webm",
             "video.mkv",