Re: kern/54230: mpv drops video frames with `--ao=oss' (probably after isaki-audio2 merge)

[Tetsuya Isaki <isaki%pastel-flower.jp@localhost>]

The following reply was made to PR kern/54230; it has been noted by GNATS.

From: Tetsuya Isaki <isaki%pastel-flower.jp@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: kern-bug-people%netbsd.org@localhost,
	gnats-admin%netbsd.org@localhost,
	netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/54230: mpv drops video frames with `--ao=oss' (probably after isaki-audio2 merge)
Date: Fri, 31 May 2019 15:18:42 +0900

 > 	Probably since isaki-audio2 merge mpv started to drop several frames
 > 	making video playback hard to follow.
 
 Thank you for your detailed report!
 
 It is not a new problem.
 Please specify --autosync=30 for mpv.  It's suggested by mpv manpage.
 Our audio driver + libossaudio layer have not implemented "a perfect
 audio delay measurement" mechanism that mpv says(or requires).
 
 On 8.99.37 (before merge) with hw.hdafg0.latency=128 (default),
  mpv                -> Dropped: 740
  mpv --autosync=30  -> Dropped: 3..4
 
 On 8.99.37 with hw.hdafg0.latency=16,
  mpv                -> Dropped: 0      [1]
  mpv --autosync=30  -> Dropped: 0
  
 On 8.99.41 (after merge) with hw.audio0.blk_ms=40 (default),
  mpv                -> Dropped: 1906   [2]
  mpv --autosync=30  -> Dropped: 0..1
 
 On 8.99.41 with hw.audio0.blk_ms=10,
  mpv                -> Dropped: 0
  mpv --autosync=30  -> Dropped: 0
 
 Your report compared case [1] and [2].  But this table shows
 the different facts.
 
 (And there is one more note.  The previous audio driver and audio2
 have different relationship between blocksize and latency.  So you
 don't compare them simply.)
 
 Thanks,
 ---
 Tetsuya Isaki <isaki%pastel-flower.jp@localhost / isaki%NetBSD.org@localhost>