[FFmpeg-devel] [PATCH 10/10] lavc/hevc_ps: compactify ShortTermRPS
James Almer
jamrial at gmail.com
Thu Apr 11 15:35:37 EEST 2024
On 4/10/2024 10:31 AM, Anton Khirnov wrote:
> Do not use larger fields than needed, use size-1 bitfields for flags.
>
> Reduces sizeof(HEVCSPS) by 1280 bytes.
> ---
> libavcodec/hevc_ps.c | 6 +++---
> libavcodec/hevc_ps.h | 19 +++++++++++--------
> libavcodec/vulkan_hevc.c | 2 +-
> 3 files changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/libavcodec/hevc_ps.c b/libavcodec/hevc_ps.c
> index 76fe507e7b..7b486ce0af 100644
> --- a/libavcodec/hevc_ps.c
> +++ b/libavcodec/hevc_ps.c
> @@ -143,11 +143,11 @@ int ff_hevc_decode_short_term_rps(GetBitContext *gb, AVCodecContext *avctx,
> for (i = 0; i <= rps_ridx->num_delta_pocs; i++) {
> used[k] = get_bits1(gb);
>
> - rps->use_delta_flag = 0;
> + rps->use_delta = 0;
> if (!used[k])
> - rps->use_delta_flag = get_bits1(gb);
> + rps->use_delta = get_bits1(gb);
>
> - if (used[k] || rps->use_delta_flag) {
> + if (used[k] || rps->use_delta) {
> if (i < rps_ridx->num_delta_pocs)
> delta_poc = delta_rps + rps_ridx->delta_poc[i];
> else
> diff --git a/libavcodec/hevc_ps.h b/libavcodec/hevc_ps.h
> index 92b85115f7..a8d07aa1b2 100644
> --- a/libavcodec/hevc_ps.h
> +++ b/libavcodec/hevc_ps.h
> @@ -70,16 +70,19 @@ typedef struct HEVCHdrParams {
> } HEVCHdrParams;
>
> typedef struct ShortTermRPS {
> - uint8_t rps_predict;
> - unsigned int delta_idx;
> - uint8_t use_delta_flag;
> - uint8_t delta_rps_sign;
> - unsigned int abs_delta_rps;
> - unsigned int num_negative_pics;
> - int num_delta_pocs;
> - int rps_idx_num_delta_pocs;
> int32_t delta_poc[32];
> uint32_t used;
> +
> + uint8_t delta_idx;
> + uint8_t num_negative_pics;
> + uint8_t num_delta_pocs;
> + uint8_t rps_idx_num_delta_pocs;
> +
> + uint16_t abs_delta_rps;
> + unsigned delta_rps_sign:1;
Wont the compiler add two bytes of padding if you put this here?
> +
> + unsigned rps_predict:1;
> + unsigned use_delta:1;
> } ShortTermRPS;
>
> typedef struct HEVCWindow {
> diff --git a/libavcodec/vulkan_hevc.c b/libavcodec/vulkan_hevc.c
> index c2b65fc201..b109475194 100644
> --- a/libavcodec/vulkan_hevc.c
> +++ b/libavcodec/vulkan_hevc.c
> @@ -359,7 +359,7 @@ static void set_sps(const HEVCSPS *sps, int sps_idx,
> .delta_rps_sign = sps->st_rps[i].delta_rps_sign,
> },
> .delta_idx_minus1 = sps->st_rps[i].delta_idx - 1,
> - .use_delta_flag = sps->st_rps[i].use_delta_flag,
> + .use_delta_flag = sps->st_rps[i].use_delta,
> .abs_delta_rps_minus1 = sps->st_rps[i].abs_delta_rps - 1,
> .used_by_curr_pic_flag = 0x0,
> .used_by_curr_pic_s0_flag = 0x0,
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