On 27/09/2019 11:04, Roman Arzumanyan wrote:
Hello,
This patch adds multiple reference frames support (part of Video Codec SDK 9.1).
It adds "nb_ref_frames" CLI option to set number of reference frames. Possible
values:
* auto - let encoder decide (default value).
* [0;7] - set value by hand. 0 is equal to auto.
Usage example:
ffmpeg -i big_buck_bunny_1080p_h264.mov -c:v hevc_nvenc -frames:v 128
-nb_ref_frames auto -bf 2 -y big_buck_bunny_1080p_nb_auto.h265
ffmpeg -i big_buck_bunny_1080p_h264.mov -c:v h264_nvenc -frames:v 128
-nb_ref_frames 1 -y big_buck_bunny_1080p_nb_1.h264
Actual number of reference frames will be determined by encoder, but it will not exceed
value of "nb_ref_frames" option.
Thanks!
Two things:
First, this needs SDK Version Guards, since we want to keep supporting
building against older SDKs and thus Driver-Versions.
There are a few examples in nvenc.h already, like
NVENC_HAVE_HEVC_BFRAME_REF_MODE.
It should be done in the same fashion for this feature.
Second, in what way is this different from the existing global
option(avctx->refs), which nvenc.c already uses to set
h264->maxNumRefFrames and hevc->maxNumRefFramesInDPB?
The refs option is documented as "number of reference frames", which
seems fitting for this. Can that option just be re-used to also set this
new parameter, if it's available, or are they doing different things?
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