Addresses a full-project review. Backend correctness and availability:
- ytdl: cancel() only SIGKILLs the child's process group when the child
actually became its own group leader, so a race (or failed setpgrp)
can no longer kill the whole server; kill the group on cancel and on
shutdown to avoid orphaned ffmpeg children
- ytdl: dedicated ThreadPoolExecutor for download supervision so active
downloads can't starve extract_info / live probes on the default pool
- ytdl/main/subscriptions: route fire-and-forget tasks through a
bg_tasks helper that keeps a strong ref and logs failures
- subscriptions: run flat-playlist extraction in an executor and check
feeds with bounded concurrency so one slow feed can't block the loop;
set last_checked on failure so broken feeds aren't retried every 60s
- main: validate ids on /start & /delete and numeric env vars at startup;
return 400 (not 500) on bad subscriptions/update input; serve /history
from memory; move get_custom_dirs off the event loop; restrict t=
stripping to YouTube hosts; drop double percent-decode in state guard
- dl_formats/ytdl: enforce requested caption format via
FFmpegSubtitlesConvertor and strip VTT header metadata only in the
pre-cue region so real dialogue is preserved
- ytdl: throttle progress events, dedup adds against pending, clear
filename/size on error and reject out-of-dir trashcan deletes, pin
fork start-method on Linux only
Frontend:
- retry deletes the done record only after a successful re-add
- surface HTTP errors for delete/start and reset the deleting flag
- ignore late 'updated' events for rows no longer in the queue
- track table rows by map key; FileSizePipe uses base-1024
Also: HTTPS-aware Docker healthcheck, dead-code removal, and shared
helpers for path-containment and yt-dlp option merging. Adds/updates
unit tests throughout (250 backend tests passing).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Allow users to prefer a specific video codec (H.264, H.265, AV1, VP9)
when adding downloads. The selector filters available formats via
yt-dlp format strings, falling back to best available if the preferred
codec is not found. The completed downloads table now shows Quality
and Codec columns.
The iOS-compatible video may not be the best quality. Add a separate quality option to accommodate people who want the best available versus the best compatible with iOS's strict requirements.
Testing with https://www.youtube.com/watch?v=YiRMs5ZhcH4 where the best quality video is 2160p and not iOS-compatible.
With best quality, the VP9 video format is used (better quality but not iOS-compatible):
```
% ffprobe -hide_banner Who\ Can\ Find\ the\ Weirdest\ PC\ Parts\ on\ AliExpress？.mp4
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Who Can Find the Weirdest PC Parts on AliExpress？.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2mp41
encoder : Lavf60.16.100
Duration: 00:19:02.72, start: 0.000000, bitrate: 10941 kb/s
Stream #0:0[0x1](und): Video: vp9 (Profile 0) (vp09 / 0x39307076), yuv420p(tv, bt709), 3840x1920, 10805 kb/s, 29.97 fps, 29.97 tbr, 16k tbn (default)
Metadata:
handler_name : ISO Media file produced by Google Inc. Created on: 06/15/2024.
vendor_id : [0][0][0][0]
Stream #0:1[0x2](eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)
Metadata:
handler_name : ISO Media file produced by Google Inc.
vendor_id : [0][0][0][0]
```
With "Best (iOS)" quality, the H264 video (lower quality but iOS-compatible) is used:
```
% ffprobe -hide_banner Who\ Can\ Find\ the\ Weirdest\ PC\ Parts\ on\ AliExpress？.mp4
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Who Can Find the Weirdest PC Parts on AliExpress？.mp4':
Metadata:
major_brand : isom
minor_version : 512
compatible_brands: isomiso2avc1mp41
encoder : Lavf60.16.100
Duration: 00:19:02.72, start: 0.000000, bitrate: 1846 kb/s
Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x960 [SAR 1:1 DAR 2:1], 1710 kb/s, 29.97 fps, 29.97 tbr, 30k tbn (default)
Metadata:
handler_name : ISO Media file produced by Google Inc.
vendor_id : [0][0][0][0]
Stream #0:1[0x2](eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)
Metadata:
handler_name : ISO Media file produced by Google Inc.
vendor_id : [0][0][0][0]
```
Included a README note about the new quality option.
iOS has strict requirements for video files, requiring h264 or h265 video codec and aac audio codec in MP4 container. This update to the MP4 format string tries to get a fully compatible file first, followed by the right video codec and any M4A audio (audio is much faster to convert if needed), and then falls back to the original behaviour of getting the best available MP4 video and M4A audio.
Alex Shnitman