On Sun, Mar 30, 2025 at 12:04 AM Cameron Gutman <aicomman...@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 <aicomman...@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.
Kieran
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