Video resolution for live YouTube stream

[leftwing]

I have used information from the forum to write a C++ app that displays live YouTube streams. For every live YouTube URL I've tried to use, I always receive 256x144 video but I know other resolutions are available. Here is output from youtube-dl that shows 6 available resolutions for the popular NASA live channel.

$ youtube-dl -F RtU_mdL2vBM -v
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'-F', u'RtU_mdL2vBM', u'-v']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2017.12.31
[debug] Python version 2.7.12 - Linux-4.10.0-42-generic-x86_64-with-Ubuntu-16.04-xenial
[debug] exe versions: ffmpeg 3.3.3-2, ffprobe 3.3.3-2, rtmpdump 2.4
[debug] Proxy map: {}
[youtube] RtU_mdL2vBM: Downloading webpage
[youtube] RtU_mdL2vBM: Downloading video info webpage
[youtube] RtU_mdL2vBM: Extracting video information
[youtube] RtU_mdL2vBM: Downloading m3u8 information
[youtube] RtU_mdL2vBM: Downloading MPD manifest
[info] Available formats for RtU_mdL2vBM:
format code extension resolution note
91 mp4 256x144 HLS 197k , avc1.42c00b, 30.0fps, mp4a.40.5@ 48k
92 mp4 426x240 HLS 338k , avc1.4d4015, 30.0fps, mp4a.40.5@ 48k
93 mp4 640x360 HLS 829k , avc1.4d401e, 30.0fps, mp4a.40.2@128k
94 mp4 854x480 HLS 1380k , avc1.4d401f, 30.0fps, mp4a.40.2@128k
95 mp4 1280x720 HLS 2593k , avc1.4d401f, 30.0fps, mp4a.40.2@256k
96 mp4 1920x1080 HLS 4715k , avc1.640028, 30.0fps, mp4a.40.2@256k (best)

However, using the usual method based on extracting the first libvlc_media_t item from a libvlc_media_list_t list (note that libvlc_media_list_count() says there is only one item in the list), I always get the lowest resolution. Below is the MRL for the libvlc_media_t item that is in position 0 in the list.

https://manifest.googlevideo.com/api/ma ... 35.124.33/itag/0/ei/WwZRWt6QNrishwbS-aeoDA/maudio/1/hfr/1/ipbits/0/signature/6014B5FB2BCAD858AF9429921A3F89AE05A41D43.3DB953211F5956EA7CC0BCA76BE5233DFBCE7240/playlist_type/DVR/dover/8/keepalive/yes/playlist_duration/30/manifest_duration/30/file/index.m3u8

I think the itag/0 field results in selection of a default resolution. I would like to use format code 93 shown in the youtube-dl output. Is there any way I can do that programming with the libvlc API?

[Jean-Baptiste Kempf]

When you play with VLC, does it take the correct version?

[leftwing]

When I play with VLC the 256x144 stream is also used. However when I play from the YouTube site the 640x360 stream is used. For my current purposes, that's the one I actually want.

[Jean-Baptiste Kempf]

Then the issue is the VLC lua script for youtube.

[leftwing]

I got youtube.lua from GitHub @ https://github.com/videolan/vlc/blob/ma ... outube.lua and I think it's a recent revision. I don't know LUA or enough VLC internals so I decided to try to solve this problem another way. I found that information about the available streams at different resolutions, usually about 5 or 6, is posted to the log file. I examine the strings passed to my log_callback and I pick the MRL for the resolution I want. The process involves starting at the resolution I get from the media list, which has always been 256x144 for live streams, and then switching to a higher-res steam when information about the streams is available in the log.

It works fine right now but it will break if log entries change in the future. Maybe if I learn more I'll look at the LUA script.