feat: batch video upscaling with folder upload, directory save, and result comparison (#1051)

* feat: support batch video upscaling with folder upload and directory save

- Add multi-file selection and entire folder upload (webkitdirectory)
- Support drag & drop of both files and folders via FileSystemEntry API
- Add save directory picker using File System Access API (showDirectoryPicker)
- Process videos sequentially with per-file progress and status tracking
- Add right-side result list with click-to-compare functionality
- Add per-video duration and total batch duration display
- Add retry button for failed items with error detail display
- Remove auto-play on comparison viewer load
- Fix worker error handling: handle "error" command to reject stale promises
- Fix event listener accumulation in video comparison (AbortController)
- Fix XSS risk by escaping HTML in all innerHTML injections
- Fix URL revocation timing in download to prevent large file truncation
- Extract writeToSaveDirectory and truncateName helpers to reduce duplication
- Add Usage Guide panel explaining single/multiple/folder upload options

Files changed:
  docs/upscaler/index.html  (+1110/-181)
  docs/upscaler/upscaler.js (+110)

* fix: prevent auto-play and resource consumption during upscaling

- Set preload="metadata" on preview and comparison video elements
- Explicitly pause preview video after setting src in showVideoPreview
- Remove preview video seek sync from batch processing progress callbacks
  (was causing continuous decode during upscaling, wasting GPU resources)
- Remove preview video seek sync from retry progress callback
- All videos now require manual play; no background resource usage

* fix: improve upscaled video quality with higher bitrate and codec support

- Raise base bitrate from 2.5 Mbps (25e5) to 8 Mbps (8e6) for standard and
  firefox processors, preventing quality loss when source videos have high
  bitrates (e.g. 720p @ 16.7 Mbps was producing 1440p @ 10 Mbps, smaller
  than the original file)
- Double the bitrate for mediabunny processor (X.n1 * 2) to account for the
  4x pixel increase from 2x upscaling
- Add H.264 Level 5.1 (avc1.640033) and Level 5.2 (avc1.640034) codecs to
  the fallback lists, since Level 4.0 (avc1.640028, ~24.6 Mbps) cannot
  support the higher bitrates for 1440p+ outputs
- Add latencyMode: "quality" to VideoEncoder configs for both standard and
  firefox processors, prioritizing encoding quality over latency (suitable
  for offline processing)

* feat: add video data comparison panel for original vs upscaled metrics

- Add a comparison data table below the file info bar showing 6 metrics:
  Resolution, File Size, Duration, Est. Bitrate, Pixels, Process Time
- Display per-metric change percentage with color-coded indicators:
  green (↑) for improvements, red (↓) for regressions, gray for neutral
- Estimated bitrate calculated from file size × 8 / video duration
- Table renders after both original and upscaled video metadata loads
- Auto-hide panel on reset

* fix: make video data comparison panel full-width and responsive

- Move comparison data table from inside the left column to the full-width
  area below the left/right layout, so it is no longer constrained by the
  comparison viewer column width
- Remove table-fixed colgroup and overflow-x-auto that caused horizontal
  scrolling on smaller screens
- Table now uses w-full auto-layout, displaying all 4 columns (Metric,
  Original, Upscaled, Change) without requiring horizontal scrolling

---------

Co-authored-by: rionzhao <rionzhao@tencent.com>

assets/sample/danmuku-v2.xml

@@ -0,0 +1 @@
+<?xml version="1.0" encoding="UTF-8"?><i><chatserver></chatserver><chatid>11724691</chatid><mission></mission><maxlimit></maxlimit><state></state><real_name></real_name><source></source><d p="0.465,5,25,26214,1480410348,11,e6d2b8ad,2704552969">泷：三叶，请记住我的名字“I LOVE YOU”</d><d p="0.465,5,25,16777215,1480410348,11,e6d2b8ad,2704553613">泷：三叶，请记住我的名字“I LOVE YOU”</d><d p="0.465,5,25,26112,1480410348,11,e6d2b8ad,2704554207">泷：三叶，请记住我的名字“I LOVE YOU”</d><d p="0.465,5,25,153,1480410349,11,e6d2b8ad,2704554619">泷：三叶，请记住我的名字“I LOVE YOU”</d><d p="0.465,5,25,6750054,1480410349,11,e6d2b8ad,2704555293">泷：三叶，请记住我的名字“I LOVE YOU”</d><d p="0,1,25,16777215,1480507709,1,f1118a60,2707380543"> 被秀了一脸恩爱</d><d p="0,1,25,16777215,1480507733,11,71176b2b,2707448679">和素未相识的网友一起配对啦！有点小激动~</d><d p="0.397,1,25,16777215,1480507736,11,30ae2d68,2707456541">配对成功，领到票了！~感谢B站！</d><d p="0.998,4,25,16711680,1480511354,11,784632ed,2707517761">长理携手同行~君之名</d><d p="0.464,5,25,16711680,1480511374,11,b430db82,2707587437">南宁单身狗的愤怒！！！！抢不到票！只能买！！！</d><d p="0,5,25,6750156,1485234066,11,e3205a8,2892019964">真·神作</d><d p="0.659,5,25,16777215,1494846439,11,6f2da951,3360883360">小僚机，我知道你会来看</d><d p="0.216,5,25,15138834,1627771015,1,ec179f6,52758493762945027">十个在哭，九个在狂笑(指鬼畜)</d><d p="1.103,1,25,16777215,1479974691,11,34d8ddf9,2689553545">我要把我欠的票都还了</d><d p="1.101,5,25,15138834,1479982003,11,7a51ca7e,2689798191">新海诚的票该还了！</d><d p="1.186,5,25,16711680,1480179684,11,9b7de097,2697536623">清露，牵手一起看吧</d><d p="1.242,5,25,41194,1480413988,1,1bf2e5d0,2704646713">呐，媳妇，我们一起看吧，然后订婚吧</d><d p="1.236,5,25,16777215,1480507737,1,4c53bc94,2707460573">你们能够理解我找妹子但是她登陆不上</d><d p="1.236,5,25,16777215,1480507737,11,4c53bc94,2707462659">最后迫不得已和室友配对成功，妹子又能登陆了</d><d p="1.984,1,25,16777215,1480842316,1,9ec9710f,2719145455">诚哥已经暴走碾压票房了</d><d p="1.362,5,25,16737843,1480932398,11,11000a3,2722220923">希望下辈子可以做个东京的帅哥</d><d p="1.687,1,25,16776960,1480939732,11,9d428cc8,2722641857">你的名字并出示你的驾驶证，你已经违规超速</d><d p="1.024,5,25,16777215,1481346068,11,a1d2e4fd,2735207423">希望下辈子可以做个东京的帅哥</d><d p="1.382,5,25,16707842,1487761657,9,d1f803de,3034151580">你的名字，茨木童子</d><d p="1.336,5,25,15138834,1501816307,1,116cf666,3647711960">结果跟基友看了。。。</d><d p="1.819,5,25,16777215,1523157002,11,42ca01f4,4446088750">bgm是黄昏之时 32秒开始</d><d p="1.662,4,25,9487136,1563115700,10,234a8c6a,18860487968030784">看的时候几乎从中间就开始哭，哭到坐车回家的路上还是在哭</d><d p="1.415,5,25,15138834,1626699746,1,ec179f6,52196839793360899">一个被鬼畜区玩坏的新海诚作品预告</d><d p="2.977,1,25,16777215,1479711804,8,a95074f6,2681576151">把之前欠诚哥的电影票还了！！！！</d><d p="2.403,1,25,14811775,1479711820,1,540181fb,2681602949">今晚逃晚自习来看</d><d p="2.261,1,25,16777215,1479867045,7,57aabaf6,2686476547">一天看 十次的节奏</d><d p="2.914,1,25,16777215,1479996640,11,6d5943e4,2690508451">已订票！！！坐标成都！！</d><d p="2.746,5,25,65535,1480064712,11,6719b12f,2692368809">清晨，我睁开眼睛时</d><d p="2.542,1,25,16777215,1480158460,7,b69f3e5a,2696198143">看完超级感动！！！！想和喜欢的人一起去看！！！你的名字是——SXY</d><d p="2.363,5,25,16776960,1480165758,5,c160358f,2696604905">钟晋我们一起去看吧</d><d p="2.311,5,25,16777215,1480233862,4,8017a98f,2699305393">荧荧。我们一起去看好吗。</d><d p="2.036,4,18,16777215,1480345885,7,d948d805,2703226509">目が覚めると</d><d p="2.601,1,25,41194,1480413988,1,1bf2e5d0,2704647585">呐，媳妇，我们一起看吧，然后订婚吧</d><d p="2.527,1,25,10079232,1480417658,11,2805d07,2704838747">小祁啊~好想和你一起去看啊</d><d p="2.98,1,25,16777215,1480507716,9,7c74b51c,2707397713">Morphine，其实Sekka想跟你一起去</d><d p="2.683,5,25,14811775,1480507722,9,4c28c99,2707414993">好的 安徒生</d><d p="2.12,5,25,16711680,1480507737,1,3c70614c,2707461715">邓云遥，我们一起去看吧~</d><d p="2.813,1,25,16777215,1480511374,6,1be1c658,2707587439">宝贝，咱俩一起看</d><d p="2.618,5,25,6737151,1480511393,11,2168da58,2707658573">同南宁，估计又得自己去淘票了！</d><d p="2.159,1,25,16777215,1480518663,9,e4a4c1fc,2707915557">不知道为什么只是看见这个开头就有种想哭的感</d><d p="2.03,1,25,14811775,1480536244,9,b647f440,2708348593">没抢到票。。。Line truncated