实现 --save-pattern 选项和智能文件名冲突处理 (Fixes #426)

[outhud]

Description

Fixes #426 - Implements --save-pattern option and smart filename collision handling to avoid uninformative .copy.mp4 filenames when downloading multiple streams.

Problem

When downloading multiple streams of the same type (e.g., 1080p + 720p video) in a single invocation, the second stream would be saved as .copy.mp4, .copy.copy.mp4, etc., making it impossible to identify which file contains which quality.

Solution

1. New --save-pattern Option

Users can now customize output filenames using template variables:

Available variables:

• <SaveName> - User-specified save name
• <Resolution> - Video resolution (e.g., 1920x1080)
• <Bandwidth> - Stream bandwidth/bitrate
• <Codecs> - Codec information (e.g., avc1.64001f)
• <Language> - Language code (e.g., en, zh-CN)
• <MediaType> - VIDEO, AUDIO, or SUBTITLES
• <Channels> - Audio channel configuration
• <FrameRate> - Frame rate
• <VideoRange> - SDR/HDR information
• <GroupId> - Stream group identifier

Example:
```bash
N_m3u8DL-RE --select-video all --save-pattern "_"

Output: video_1920x1080.mp4, video_1280x720.mp4

```

2. Smart Collision Handling

Even without --save-pattern, the tool now automatically uses stream metadata to generate unique filenames when a collision is detected:

• Video streams: Appends resolution and/or bandwidth
  • Examples: .1920x1080.mp4, .5.0Mbps.mp4, .1920x1080.5.0Mbps.mp4
• Audio streams: Appends language, channels, and/or bandwidth
  • Examples: .en.2ch.m4a, .128kbps.m4a, .en.128kbps.m4a
• Subtitle streams: Appends language
  • Examples: .en.srt, .zh-CN.srt
• Falls back to .copy suffix only when all metadata-based approaches fail

Example (automatic handling):
```bash
N_m3u8DL-RE --select-video all --save-name "video"

Old behavior: video.mp4, video.copy.mp4 ❌

New behavior: video.mp4, video.1280x720.mp4 ✅

```

Technical Implementation

New utility methods (src/N_m3u8DL-RE/Util/OtherUtil.cs):

• FormatSavePattern() - Parses template variables and generates filenames
• HandleFileCollision() - Intelligently resolves filename collisions using stream metadata

Updated download managers:

• SimpleDownloadManager.cs - VOD downloads
• SimpleLiveRecordManager2.cs - Live stream recording
• HTTPLiveRecordManager.cs - HTTP-based live recording

Localization:

• Full support for 3 languages: English (en-US), Simplified Chinese (zh-CN), Traditional Chinese (zh-TW)
• Updated StaticText.cs with translations

Documentation:

• Updated README.md with --save-pattern option description
• Added detailed "More Help" section with examples

Changes Summary

• 7 files changed
• +217 lines added, -18 lines removed
• 0 compilation errors
• All existing warnings remain unchanged

Testing

Build & Compilation: ✅
```bash
dotnet build N_m3u8DL-RE.sln -c Debug

Result: Build succeeded, 0 errors

```

Help Output: ✅
```bash
N_m3u8DL-RE --help

--save-pattern option appears with all variables documented

```

Real-world testing: 🔄 Needs community testing with actual multi-quality streams

Example Usage

Download multiple video qualities with custom pattern

```bash
N_m3u8DL-RE "https://example.com/manifest.mpd"
--select-video all
--save-pattern ""
--save-name "video"

Output:

video_1920x1080_5000000.mp4

video_1280x720_2500000.mp4

```

Download multiple audio tracks with languages

```bash
N_m3u8DL-RE "https://example.com/manifest.mpd"
--select-audio all
--save-pattern "_ch"

Output:

en_2ch.m4a

es_2ch.m4a

ja_6ch.m4a

```

Automatic smart collision handling (no pattern needed)

```bash
N_m3u8DL-RE "https://example.com/manifest.mpd"
--select-video "res=1920|res=1280"
--save-name "video"

Output:

video.mp4 (first stream)

video.1280x720.mp4 (second stream, auto-detected)

```

Checklist

• Code follows project style and conventions
• All files compile without errors
• Localization strings added for all supported languages
• Documentation updated (README.md)
• Bilingual commit message (Chinese/English)
• Tested with real multi-quality streams (needs community validation)

Notes

This implementation provides both explicit control (via --save-pattern) and automatic intelligent handling (via smart collision detection), ensuring users never encounter confusing .copy.mp4 filenames again.

---

🤖 Generated with Claude Code

Co-Authored-By: Claude [email protected]

[nilaoda]

感谢您的贡献！等我有空时会仔细审查，确认无误后便会合并。

Thank you for your contribution! I’ll review it carefully when I have time and merge it once everything looks good.