Repository: yt-dlp
Issue: YT m4a audio DASH stream download corruption
Labels: external issue,site-bug,site:youtube,core:downloader

### DO NOT REMOVE OR SKIP THE ISSUE TEMPLATE

- [x] I understand that I will be **blocked** if I *intentionally* remove or skip any mandatory\* field

### Checklist

- [x] I'm reporting that yt-dlp is broken on a **supported** site
- [x] I've verified that I have **updated yt-dlp to nightly or master** ([update instructions](https://github.com/yt-dlp/yt-dlp#update-channels))
- [x] I've checked that all provided URLs are playable in a browser with the same IP and same login details
- [x] I've checked that all URLs and arguments with special characters are [properly quoted or escaped](https://github.com/yt-dlp/yt-dlp/wiki/FAQ#video-url-contains-an-ampersand--and-im-getting-some-strange-output-1-2839-or-v-is-not-recognized-as-an-internal-or-external-command)
- [x] I've searched [known issues](https://github.com/yt-dlp/yt-dlp/issues/3766) and the [bugtracker](https://github.com/yt-dlp/yt-dlp/issues?q=) for similar issues **including closed ones**. DO NOT post duplicates
- [x] I've read the [guidelines for opening an issue](https://github.com/yt-dlp/yt-dlp/blob/master/CONTRIBUTING.md#opening-an-issue)
- [x] I've read about [sharing account credentials](https://github.com/yt-dlp/yt-dlp/blob/master/CONTRIBUTING.md#are-you-willing-to-share-account-details-if-needed) and I'm willing to share it if required

### Region

US

### Provide a description that is worded well enough to be understood

For a certain period of time after a YouTube live stream ends, the m4a audio is only available as a DASH stream. It eventually gets processed into HTTP. This means it's not really possible to provide a url with a DASH stream. It needs to be caught by monitoring a live stream and downloading the m4a audio DASH stream right after it ends. I don't have a url that currently repros.

The recent regression (which could be a YT change) is that such downloads end up exactly half the expected length and when played (e.g. VLC) are silent.    

### Provide verbose output that clearly demonstrates the problem

- [x] Run **your** yt-dlp command with **-vU** flag added (`yt-dlp -vU <your command line>`)
- [ ] If using API, add `'verbose': True` to `YoutubeDL` params instead
- [x] Copy the WHOLE output (starting with `[debug] Command-line config`) and insert it below

### Complete Verbose Output

```shell
[debug] Command-line config: ['-vU']
[debug] Encodings: locale cp1252, fs utf-8, pref cp1252, out utf-8, error utf-8, screen utf-8
[debug] yt-dlp version nightly@2025.01.16.232854 from yt-dlp/yt-dlp-nightly-builds [164368610] (pip)
[debug] Python 3.13.1 (CPython AMD64 64bit) - Windows-10-10.0.19045-SP0 (OpenSSL 3.0.15 3 Sep 2024)
[debug] exe versions: ffmpeg 5.1.2-full_build-www.gyan.dev (setts), ffprobe 5.1.2-full_build-www.gyan.dev
[debug] Optional libraries: Cryptodome-3.21.0, brotli-1.1.0, certifi-2024.08.30, mutagen-1.47.0, requests-2.32.3, sqlite3-3.45.3, urllib3-2.2.3, websockets-13.1
[debug] Proxy map: {}
[debug] Request Handlers: urllib, requests, websockets
[debug] Loaded 1837 extractors
[debug] Fetching release info: https://api.github.com/repos/yt-dlp/yt-dlp-nightly-builds/releases/latest
Latest version: nightly@2025.01.16.232854 from yt-dlp/yt-dlp-nightly-builds
yt-dlp is up to date (nightly@2025.01.16.232854 from yt-dlp/yt-dlp-nightly-builds)
```