VLC: An Out-of-the-box Experience

*nix specific usage questions
imhere
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Posts: 8
Joined: 13 Sep 2009 10:42
VLC version: 2.2.2
Operating System: Kubuntu 16.04
Location: Helsinki, Finland

VLC: An Out-of-the-box Experience

Postby imhere » 24 Apr 2017 18:41

HW: Radeon HD 5450 (OSS driver), a Core2-vintage PC
OS: Kubuntu 16.04.2 LTS (AMD64)
VLC 2.2.2

I've been using VLC for quite a few years but this time I've set up a "new old" box for playing media. This is just a list of issues I ran into and tried to find a solution for before the result was mostly satisfactory.

For 90% of the time, my use case is the playback of transport stream video files from a SMB/CIFS mounted nework share, while watching from a secondary display (TV), connected using HDMI (+HDMI audio).

I would have liked to uninstall PulseAudio and use ALSA only since it has been a source of audio glitches in the past, but it seems to be more of a requirement nowadays, especially for Firefox 52. I guess I'm forced to give it a chance.

Issue: There's a severe frame skipping issue when moving in the timeline that takes several seconds to correct itself. Also, none of the deinterlacing filters worked.
Solution: Disable decoding acceleration in 'settings -> Input/Codecs -> HW-accelerated decoding -> disable'.
The CPU is powerful enough to play back 1080p AVC, this is not an issue even if this takes a few watts more.

Issue: The default timeline mode really doesn't work that well for transport streams. The timing information within a ts-file should always be interpreted as relative to start-of-file and not as absolute. Of course there could be gaps in it as well, making the timing information overall less reliable. The file size (combined with bitrate stats) is really the only truly reliable data when estimating stream duration. Anyway, the timeline works terribly with a growing file in the default mode. Playing a this kind of file happens very often in my use case. One can simulate a growing file with 'gzip <video.ts | gunzip >video_copy.ts'.
Solution: Set VLC to percentage mode in 'settings -> all -> input -> demuxers -> mpeg-ts -> seek based on percent'.

Issue: When seeking backward in the timeline, sometimes audio disappears. Using the percent option above seems to make it more likely. Also, it always happens at a DVD cutpoint when editing has been done with TMPGEnc DVD Author 1.5.11.37. This results lots of 'Could not convert timestamp' log messages.
Solution: Seek forward again or cycle through the audio streams, or if there's only one audio stream, disable/enable (no hotkey for this!). Probably a PulseAudio issue (what isn't).

Issue: There's a short gap in audio when the playback speed is adjusted. This could cause one to miss a word or two of dialogue.
Solution: No solution, fortunately it's not too much worse than before. Clearly a PulseAudio issue (what isn't).

Issue: When returning from S3 standby, HDMI audio is silent.
Solution: This is probably a PulseAudio issue (what isn't). Running 'xrandr' without parameters fixes it. A more permanent fix can be applied with '/lib/systemd/system-sleep/fixhdmiaudio.sh' (set as executable with chmod +x):

Code: Select all

#!/bin/sh if [ "$1" = "post" ] ; then export DISPLAY=:0 su - put_your_username_here -c "/usr/bin/xrandr >/dev/null" fi
Issue: Using the 'clone' feature for duplicating the video for a secondary display doesn't seem to work (black video).
Solution: Looks like the easiest solution was not to clone at all but instead assign a KDE hotkey in 'System settings -> Shortcuts -> Global keyboard shortcuts -> KWin -> Window to next desktop'.
This is for moving the active window to next display. It's a good solution as long as you don't really need the video in two displays at once. It works in fullscreen mode as well.

Issue: DVD:s multiplexed and authored using Mediachance DVD-Lab 1.3 don't play back smoothly but show some kind of micro-skipping. This gets logged as "picture might be displayed late" in debug messages. If the video has been multiplexed using different software and only authored using DVD-Lab then there's no skipping.
Solution: This is an old VLC regression that didn't exist at the time of authoring. Some non-standard behaviour might be involved, but PowerDVD, for example, didn't seem to mind. Use another player.

Issue: DVD:s authored using TMPGEnc DVD Author are sometimes played back at double the intended aspect ratio, i.e. 8:3 when the right one is 4:3, or 32:9 for 16:9 material. This happens only when a track is chosen by navigating through the menus, not when directly playing back the VOBs.
Solution: This is an old VLC regression that didn't exist at the time of authoring. Adjust the aspect ratio manually.

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