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[Savannah-cvs] [777] Use more properly researched ffmpeg settings
From: |
iank |
Subject: |
[Savannah-cvs] [777] Use more properly researched ffmpeg settings |
Date: |
Mon, 1 Apr 2024 22:08:21 -0400 (EDT) |
Revision: 777
http://svn.savannah.gnu.org/viewvc/?view=rev&root=administration&revision=777
Author: iank
Date: 2024-04-01 22:08:19 -0400 (Mon, 01 Apr 2024)
Log Message:
-----------
Use more properly researched ffmpeg settings
Removed useless options:
* cluster_time_limit=5100 cluster_size_limit=2M: these come from a very
old xiph.org wiki page, it claims that once upon a time they were
needed for icecast compatibility. Nowadays, they are undocumented in
ffmpeg, but greping source code, they are used in dash and mkv, not
the webm we are using.
* minrate=1.5M maxrate=1.5M, found some reference to say say this pushes
vpx into stricter cbr mode, but it is unclear if that is actually
true. Most sources do not recommend this when using realtime, and I
suspect it is largely superflous and not beneficial.
* crf=30 this does nothing in the mode we are using.
Modified Paths:
--------------
trunk/sviki/fsf/tools/OBS.mdwn
Modified: trunk/sviki/fsf/tools/OBS.mdwn
===================================================================
--- trunk/sviki/fsf/tools/OBS.mdwn 2024-04-01 12:46:17 UTC (rev 776)
+++ trunk/sviki/fsf/tools/OBS.mdwn 2024-04-02 02:08:19 UTC (rev 777)
@@ -50,18 +50,22 @@
* File path or URL:
`icecast://source:PASSWORD@live-master.fsf.org:8000/stream-room-NAME.webm`
* Note: Password has an O as in Opal. Not a zero.
* Container format: `webm`
-* Muster settings (if any): `content_type=video/webm cluster_time_limit=5100
cluster_size_limit=2M`
+* Muster settings (if any): `content_type=video/webm`
* Video Bitrate: `1500 Kbps`
-* Keyframe interval (frames): `150`
+* Keyframe interval (frames): `60`
* Rescale Output: greyed out, not settable.
* Show all codecs (even if potentially incompatible): checked
* Video Encoder: `libvpx`
-* Video Encoder Settings (if any): `rt cpu-used=5 threads=2 error-resilient=1
crf=30 g=150 minrate=1.5M maxrate=1.5M`
+* Video Encoder Settings (if any): `quality=realtime cpu-used=5 threads=2
error-resilient=1`
+** For vp9, which we will test in LP2024: `quality=realtime cpu-used=5
threads=4 row-mt=1 tile-columns=2 frame-parallel=1`
+** background notes: man ffmpeg-codecs says -g is group of picture size, but
online sources call it the "keyframe interval." In vp9, at roughly > 2 seconds
worth of frames, it starts to increase latency at a corresponding rate. If cpu
struggles, adjust cpu-used upward, max is 8 which uses the lowest cpu.
* Audio Bitrate: `96 Kbps`
* Audio Track: check mark on 1.
* Audio Encoder: `libvorbis`
* Audio Encoder Settings (if any): empty
+
+
#### Audio
* Desktop Audio: (Set to your output device such that you see sound levels
when there is audio playing on your system)
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