Repository: youtube-dl
Issue: Recognizing YouTube "English descriptive"
Labels: question

## Checklist

- [x] I'm asking a question
- [x] I've looked through the README and FAQ for similar questions
- [x] I've searched the bugtracker for similar questions including closed ones

## Question

I am trying to figure out how I can distinguish an "English descriptive" audio track from an "English original" track on YouTube. The reason for this is that [MPC-HC](https://github.com/clsid2/mpc-hc/), using YouTube-dl, picks the "descriptive" audio track, while YouTube-dl itself picks the "original" track by default. According to https://github.com/clsid2/mpc-hc/issues/1268#issuecomment-905925553 there's no info to distinguish them, so MPC-HC picks the first one. However, e.g. [MPC-BE](https://sourceforge.net/projects/mpcbe/) (using YouTube-dl, not its internal YouTube parser) picks the "original" track, just like YouTube-dl from command line.

An example video: https://vimeo.com/284819667

YouTube-dl -F:
```
[youtube] BJ_PrIVI5Ac: Downloading webpage
[info] Available formats for BJ_PrIVI5Ac:
format code  extension  resolution note
249-0        webm       audio only tiny   47k , webm_dash container, opus @ 47k (48000Hz), 759.04KiB
249-1        webm       audio only tiny   49k , webm_dash container, opus @ 49k (48000Hz), 787.40KiB
250-0        webm       audio only tiny   61k , webm_dash container, opus @ 61k (48000Hz), 981.74KiB
250-1        webm       audio only tiny   61k , webm_dash container, opus @ 61k (48000Hz), 986.31KiB
251-0        webm       audio only tiny  121k , webm_dash container, opus @121k (48000Hz), 1.90MiB
251-1        webm       audio only tiny  121k , webm_dash container, opus @121k (48000Hz), 1.90MiB
140-0        m4a        audio only tiny  129k , m4a_dash container, mp4a.40.2@129k (44100Hz), 2.03MiB
140-1        m4a        audio only tiny  129k , m4a_dash container, mp4a.40.2@129k (44100Hz), 2.03MiB
278          webm       256x144    144p  107k , webm_dash container, vp9@ 107k, 30fps, video only, 1.68MiB
160          mp4        256x144    144p  121k , mp4_dash container, avc1.4d400c@ 121k, 30fps, video only, 1.90MiB
242          webm       426x240    240p  232k , webm_dash container, vp9@ 232k, 30fps, video only, 3.64MiB
133          mp4        426x240    240p  261k , mp4_dash container, avc1.4d4015@ 261k, 30fps, video only, 4.10MiB
243          webm       640x360    360p  422k , webm_dash container, vp9@ 422k, 30fps, video only, 6.62MiB
134          mp4        640x360    360p  583k , mp4_dash container, avc1.4d401e@ 583k, 30fps, video only, 9.14MiB
244          webm       854x480    480p  767k , webm_dash container, vp9@ 767k, 30fps, video only, 12.02MiB
135          mp4        854x480    480p 1064k , mp4_dash container, avc1.4d401f@1064k, 30fps, video only, 16.67MiB
247          webm       1280x720   720p 1543k , webm_dash container, vp9@1543k, 30fps, video only, 24.17MiB
136          mp4        1280x720   720p 2068k , mp4_dash container, avc1.64001f@2068k, 30fps, video only, 32.39MiB
248          webm       1920x1080  1080p 2460k , webm_dash container, vp9@2460k, 30fps, video only, 38.54MiB
137          mp4        1920x1080  1080p 4022k , mp4_dash container, avc1.640028@4022k, 30fps, video only, 63.00MiB
271          webm       2560x1440  1440p 6936k , webm_dash container, vp9@6936k, 30fps, video only, 108.63MiB
313          webm       3840x2160  2160p 12774k , webm_dash container, vp9@12774k, 30fps, video only, 200.05MiB
18           mp4        640x360    360p  657k , avc1.42001E, 30fps, mp4a.40.2 (44100Hz), 10.30MiB
22           mp4        1280x720   720p 2317k , avc1.64001F, 30fps, mp4a.40.2 (44100Hz) (best)
```

The format codes ending with `-1` are the "English original" tracks. The question here is whether this is arbitrary, or whether one can safely assume that the `-1` tracks are the "original" tracks and thus should be chosen. How does YouTube-dl choose the track (when no `-f` parameters are given), i.e. why did it choose the (right) `-1` track?