Re: [FFmpeg-devel] [PATCH] avcodec/nvenc: Use CBR filler data consistently across codecs

[Cameron Gutman <aicommander@gmail.com>]

On Sun, Mar 30, 2025 at 10:46 AM Zhao Zhili
<quinkblack-at-foxmail.com@ffmpeg.org> wrote:
>
>
>
> > On Mar 30, 2025, at 23:33, Kieran Kunhya via ffmpeg-devel <ffmpeg-devel@ffmpeg.org> wrote:
> >
> > On Sun, Mar 30, 2025 at 12:04 AM Cameron Gutman <aicommander@gmail.com <mailto:aicommander@gmail.com>> wrote:
> >>
> >> Previously, AV1 used filler data with CBR by default while H.264
> >> and HEVC did not. Make this consistent by using filler data in
> >> CBR mode across all codecs.
> >>
> >> Since there are valid reasons to use CBR with or without filler,
> >> also add a cbr_padding option to allow users to opt out.
> >>
> >> Signed-off-by: Cameron Gutman <aicommander@gmail.com>
> >> ---
> >> libavcodec/nvenc.c      | 16 +++++++++++++---
> >> libavcodec/nvenc.h      |  2 ++
> >> libavcodec/nvenc_av1.c  |  2 ++
> >> libavcodec/nvenc_h264.c |  4 ++++
> >> libavcodec/nvenc_hevc.c |  4 ++++
> >> 5 files changed, 25 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/libavcodec/nvenc.c b/libavcodec/nvenc.c
> >> index 0f5e772b3e..41a4dc55f4 100644
> >> --- a/libavcodec/nvenc.c
> >> +++ b/libavcodec/nvenc.c
> >> @@ -1304,7 +1304,12 @@ static av_cold int nvenc_setup_h264_config(AVCodecContext *avctx)
> >>     h264->idrPeriod = cc->gopLength;
> >>
> >>     if (IS_CBR(cc->rcParams.rateControlMode)) {
> >> -        h264->outputBufferingPeriodSEI = 1;
> >> +        /* Older SDKs use outputBufferingPeriodSEI to control filler data */
> >> +        h264->outputBufferingPeriodSEI = ctx->cbr_padding;
> >> +
> >> +#ifdef NVENC_HAVE_FILLER_DATA
> >> +        h264->enableFillerDataInsertion = ctx->cbr_padding;
> >> +#endif
> >>     }
> >>
> >>     h264->outputPictureTimingSEI = 1;
> >> @@ -1503,7 +1508,12 @@ static av_cold int nvenc_setup_hevc_config(AVCodecContext *avctx)
> >>     hevc->idrPeriod = cc->gopLength;
> >>
> >>     if (IS_CBR(cc->rcParams.rateControlMode)) {
> >> -        hevc->outputBufferingPeriodSEI = 1;
> >> +        /* Older SDKs use outputBufferingPeriodSEI to control filler data */
> >> +        hevc->outputBufferingPeriodSEI = ctx->cbr_padding;
> >> +
> >> +#ifdef NVENC_HAVE_FILLER_DATA
> >> +        hevc->enableFillerDataInsertion = ctx->cbr_padding;
> >> +#endif
> >>     }
> >>
> >>     hevc->outputPictureTimingSEI = 1;
> >> @@ -1625,7 +1635,7 @@ static av_cold int nvenc_setup_av1_config(AVCodecContext *avctx)
> >>     av1->idrPeriod = cc->gopLength;
> >>
> >>     if (IS_CBR(cc->rcParams.rateControlMode)) {
> >> -        av1->enableBitstreamPadding = 1;
> >> +        av1->enableBitstreamPadding = ctx->cbr_padding;
> >>     }
> >>
> >>     if (ctx->tile_cols >= 0)
> >> diff --git a/libavcodec/nvenc.h b/libavcodec/nvenc.h
> >> index e035e123c6..4b12846ed7 100644
> >> --- a/libavcodec/nvenc.h
> >> +++ b/libavcodec/nvenc.h
> >> @@ -61,6 +61,7 @@ typedef void ID3D11Device;
> >> #define NVENC_HAVE_MULTIPLE_REF_FRAMES
> >> #define NVENC_HAVE_CUSTREAM_PTR
> >> #define NVENC_HAVE_GETLASTERRORSTRING
> >> +#define NVENC_HAVE_FILLER_DATA
> >> #endif
> >>
> >> // SDK 10.0 compile time feature checks
> >> @@ -309,6 +310,7 @@ typedef struct NvencContext
> >>     int unidir_b;
> >>     int split_encode_mode;
> >>     int mdm, cll;
> >> +    int cbr_padding;
> >> } NvencContext;
> >>
> >> int ff_nvenc_encode_init(AVCodecContext *avctx);
> >> diff --git a/libavcodec/nvenc_av1.c b/libavcodec/nvenc_av1.c
> >> index 01626113ab..b1b95672f2 100644
> >> --- a/libavcodec/nvenc_av1.c
> >> +++ b/libavcodec/nvenc_av1.c
> >> @@ -156,6 +156,8 @@ static const AVOption options[] = {
> >>                                                             OFFSET(extra_sei),    AV_OPT_TYPE_BOOL,  { .i64 = 1 }, 0, 1, VE },
> >>     { "a53cc",        "Use A53 Closed Captions (if available)", OFFSET(a53_cc),   AV_OPT_TYPE_BOOL,  { .i64 = 1 }, 0, 1, VE },
> >>     { "s12m_tc",      "Use timecode (if available)",        OFFSET(s12m_tc),      AV_OPT_TYPE_BOOL,  { .i64 = 1 }, 0, 1, VE },
> >> +    { "cbr_padding",  "Pad the bitstream to ensure bitrate does not drop below the target in CBR mode",
> >> +                                                            OFFSET(cbr_padding),  AV_OPT_TYPE_BOOL,  { .i64 = 1 }, 0, 1, VE },
> >> #ifdef NVENC_HAVE_H264_AND_AV1_TEMPORAL_FILTER
> >>     { "tf_level",     "Specifies the strength of the temporal filtering",
> >>                                                             OFFSET(tf_level),     AV_OPT_TYPE_INT,   { .i64 = -1 }, -1, INT_MAX, VE, .unit = "tf_level" },
> >> diff --git a/libavcodec/nvenc_h264.c b/libavcodec/nvenc_h264.c
> >> index 21d25d643a..4845d0422d 100644
> >> --- a/libavcodec/nvenc_h264.c
> >> +++ b/libavcodec/nvenc_h264.c
> >> @@ -231,6 +231,10 @@ static const AVOption options[] = {
> >>                                                             OFFSET(max_slice_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, VE },
> >>     { "constrained-encoding", "Enable constrainedFrame encoding where each slice in the constrained picture is independent of other slices",
> >>                                                             OFFSET(constrained_encoding), AV_OPT_TYPE_BOOL,  { .i64 = 0 }, 0, 1, VE },
> >> +#ifdef NVENC_HAVE_FILLER_DATA
> >> +    { "cbr_padding",  "Pad the bitstream to ensure bitrate does not drop below the target in CBR mode",
> >> +                                                            OFFSET(cbr_padding),  AV_OPT_TYPE_BOOL,  { .i64 = 1 }, 0, 1, VE },
> >> +#endif
> >> #ifdef NVENC_HAVE_H264_AND_AV1_TEMPORAL_FILTER
> >>     { "tf_level",     "Specifies the strength of the temporal filtering",
> >>                                                             OFFSET(tf_level),     AV_OPT_TYPE_INT,   { .i64 = -1 }, -1, INT_MAX, VE, .unit = "tf_level" },
> >> diff --git a/libavcodec/nvenc_hevc.c b/libavcodec/nvenc_hevc.c
> >> index c74eca9bb3..8648f4f3a9 100644
> >> --- a/libavcodec/nvenc_hevc.c
> >> +++ b/libavcodec/nvenc_hevc.c
> >> @@ -206,6 +206,10 @@ static const AVOption options[] = {
> >>                                                             OFFSET(max_slice_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, VE },
> >>     { "constrained-encoding", "Enable constrainedFrame encoding where each slice in the constrained picture is independent of other slices",
> >>                                                             OFFSET(constrained_encoding), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, VE },
> >> +#ifdef NVENC_HAVE_FILLER_DATA
> >> +    { "cbr_padding",  "Pad the bitstream to ensure bitrate does not drop below the target in CBR mode",
> >> +                                                            OFFSET(cbr_padding),  AV_OPT_TYPE_BOOL,  { .i64 = 1 }, 0, 1, VE },
> >> +#endif
> >> #ifdef NVENC_HAVE_TEMPORAL_FILTER
> >>     { "tf_level",     "Specifies the strength of the temporal filtering",
> >>                                                             OFFSET(tf_level),     AV_OPT_TYPE_INT,   { .i64 = -1 }, -1, INT_MAX, VE, .unit = "tf_level" },
> >> --
> >> 2.49.0
> >
> >
> > This should be off by default in FFmpeg. We don't do this in any other encoder.
>
> I agree.
>

Timo specifically asked for filler enabled by default, but I don't
mind defaulting disabled either if that's the consensus here.

Will send a v2 shortly.

> >
> > Kieran
> > _______________________________________________
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> >
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