Interface `loadvid` doesn't work while `loadvid_frame_nums` does

[oyiadin]

Hi, I've been trying to test lintel by excuting lintel_test, only to got a strange result.

lintel_test --filename xxx.mp4 --width 0 --height 0 works perfectly, but lintel_test --filename xxx.mp4 --width 0 --height 0 --loadvid went wrong and reported:

AVERROR: -1094995529, message: Invalid data found when processing input
Stream index not found.

By diving into the source code of lintel, I've found that Stream index not found. comes out here, but it seems like the preparation of loadvid and loadvid_frame_nums are very similar in a way. Completely confused :(

Here are some of my environment information:

• Platform: macOS mojave 10.14.6
• Python 3.7.3
• (mini)conda 4.7.12
• lintel v1.0, installed via (mini)conda
• ffmpeg v4.0.2, installed via brew
• the mp4 file (from hmdb51, previously converted to mp4 using ffmpeg)