Bug#816973: mpv: Video freeze or out of sync audio when streaming with --ytdl

[James Murphy]

Package: mpv
Version: 0.14.0-1
Severity: normal

Dear Maintainer,

In the past week or so I have noticed that streaming videos from youtube
no longer works (or works 50% of the time). Example command that can
cause freeze:

mpv --ytdl "https://www.youtube.com/watch?v=e53DDZxOMvM"

If I understand correctly, sometimes youtube-dl downloads the audio and video
separately. In my case what happens is that the entire video downloads
immediately, but only 2-3 seconds worth of audio downloads. Then I see

[cache] Cache is not responding - slow/stuck network connection?

on my stdout. However, from the GUI, there is no indication of slow
network, mpv says "Cache: 10s + 37.6 MB" which presumably corresponds
only to the video cache and not the audio cache. Indeed, if I then set
the audio track to none the video will continue playing. Trying to
reenable the audio sometimes works, sometimes freezes the video,
sometimes plays the audio out of sync with the video, etc. etc.

What I expected is that if youtube-dl desides to download the video and
audio separately, then either

1) there should be separate video cache and audio cache info in the GUI,
e.g. "Cache A/V: 10s + 37.6 MB / 3s + 0.0 MB"

2) or the cache should display the minimum of the two, i.e. if video has 
10s + 20/0 MB and audio has 3s + 0.0 MB it should say "Cache: 3s + 0.0 MB".

That would at least let me know that my network is the problem. On the
other hand, I'm sitting on a 1Gbps line, so my network really shouldn't be
the problem. For whatever reason, sometimes youtube just decides "oh,
you only get 3 seconds of audio" and the download never completes. When
using youtube-dl directly I just ctrl-C and run the command one or two
more times. At some point youtube realizes that I want more than 3 seconds
and downloads the rest all at once. With youtube-dl ctrl-C and running
the command again resumes download where it left off, but it appears
that this is not the case with mpv, it redownloads everything from
scratch. Is there some way to let mpv resume downloads? If not, that
goes on my wishlist.


-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 4.3.0-1-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages mpv depends on:
ii  libasound2                              1.1.0-1
ii  libass5                                 0.13.1-1
ii  libavcodec-ffmpeg56                     7:2.8.6-1+b1
ii  libavdevice-ffmpeg56                    7:2.8.6-1+b1
ii  libavfilter-ffmpeg5                     7:2.8.6-1+b1
ii  libavformat-ffmpeg56                    7:2.8.6-1+b1
ii  libavutil-ffmpeg54                      7:2.8.6-1+b1
ii  libbluray1                              1:0.9.2-2
ii  libc6                                   2.21-9
ii  libcdio-cdda1                           0.83-4.2+b1
ii  libcdio-paranoia1                       0.83-4.2+b1
ii  libcdio13                               0.83-4.2+b1
ii  libdrm2                                 2.4.67-1
ii  libdvdnav4                              5.0.3-1
ii  libdvdread4                             5.0.3-1
ii  libegl1-mesa [libegl1-x11]              11.1.2-1
ii  libenca0                                1.18-1
ii  libgl1-mesa-glx [libgl1]                11.1.2-1
ii  libguess1                               1.2-1.1
ii  libjack-jackd2-0 [libjack-0.116]        1.9.10+20150825git1ed50c92~dfsg-1
ii  libjpeg62-turbo                         1:1.4.2-2
ii  liblcms2-2                              2.6-3+b3
ii  liblua5.2-0                             5.2.4-1
ii  libpulse0                               8.0-1
ii  librubberband2                          1.8.1-6+b1
ii  libsdl2-2.0-0                           2.0.4+dfsg1-2
ii  libsndio6.0                             1.0.1-2
ii  libswresample-ffmpeg1                   7:2.8.6-1+b1
ii  libswscale-ffmpeg3                      7:2.8.6-1+b1
ii  libva-wayland1                          1.6.2-2
ii  libva-x11-1                             1.6.2-2
ii  libva1                                  1.6.2-2
ii  libvdpau1                               1.1.1-3
ii  libwayland-client0                      1.9.0-1
ii  libwayland-cursor0                      1.9.0-1
ii  libwayland-egl1-mesa [libwayland-egl1]  11.1.2-1
ii  libx11-6                                2:1.6.3-1
ii  libxext6                                2:1.3.3-1
ii  libxinerama1                            2:1.1.3-1+b1
ii  libxkbcommon0                           0.5.0-1
ii  libxrandr2                              2:1.5.0-1
ii  libxss1                                 1:1.2.2-1
ii  libxv1                                  2:1.0.10-1+b1
ii  zlib1g                                  1:1.2.8.dfsg-2+b1

Versions of packages mpv recommends:
ii  xdg-utils   1.1.1-1
ii  youtube-dl  2016.02.22-1

mpv suggests no packages.

-- no debconf information