[FFmpeg-devel] [PATCH] doc/encoders: add VP9 temporal scalability encoding option

Wonkap Jang wonkap at google.com
Tue Dec 17 00:21:41 EET 2019

Documentation change for adding support for encoding
with temporal scalability in VP9.
 doc/encoders.texi | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/doc/encoders.texi b/doc/encoders.texi
index 4ee518a124..7efc446a6c 100644
--- a/doc/encoders.texi
+++ b/doc/encoders.texi
@@ -1885,16 +1885,14 @@ Enable error resiliency features.
 Increase sharpness at the expense of lower PSNR.
 The valid range is [0, 7].
- at item VP8-specific options
- at table @option
 @item ts-parameters
 Sets the temporal scalability configuration using a :-separated list of
 key=value pairs. For example, to specify temporal scalability parameters
 with @code{ffmpeg}:
 ffmpeg -i INPUT -c:v libvpx -ts-parameters ts_number_layers=3:\
-ts_periodicity=4:ts_layer_id=0,2,1,2 OUTPUT
+ts_periodicity=4:ts_layer_id=0,2,1,2:ts_layering_mode=3 OUTPUT
 @end example
 Below is a brief explanation of each of the parameters, please
 refer to @code{struct vpx_codec_enc_cfg} in @code{vpx/vpx_encoder.h} for more
@@ -1903,13 +1901,28 @@ details.
 @item ts_number_layers
 Number of temporal coding layers.
 @item ts_target_bitrate
-Target bitrate for each temporal layer.
+Target bitrate for each temporal layer in kbps.
+(bitrate should be inclusive of the lower temporal layer).
 @item ts_rate_decimator
 Frame rate decimation factor for each temporal layer.
 @item ts_periodicity
 Length of the sequence defining frame temporal layer membership.
 @item ts_layer_id
 Template defining the membership of frames to temporal layers.
+ at item ts_layering_mode
+(optional) Selecting the temporal structure from a set of pre-defined temporal layering modes.
+Currently supports the following options.
+ at table @option
+ at item 0
+No temporal layering flags are provided internally,
+relies on flags being passed in using metadata in AVFrame.
+ at item 2
+Two temporal layers. 0-1...
+ at item 3
+Three temporal layers. 0-2-1-2...; with single reference frame.
+ at item 4
+Same as option "3", except there is a dependency between
+the two temporal layer 2 frames within the temporal period.
 @end table
 @end table

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