[FFmpeg-devel] [PATCHv4 1/4] lavc/h263dsp: add DCT dequantisation functions
James Almer
jamrial at gmail.com
Wed Jun 12 20:28:24 EEST 2024
On 6/10/2024 5:23 PM, Rémi Denis-Courmont wrote:
> Note that optimised implementations of these functions will be taken
> into actual use only if MpegEncContext.dct_unquantize_h263_{inter,intra}
> are *not* overloaded by existing optimisations.
> ---
> libavcodec/h263dsp.c | 25 +++++++++++++++++++++++++
> libavcodec/h263dsp.h | 4 ++++
> 2 files changed, 29 insertions(+)
>
> diff --git a/libavcodec/h263dsp.c b/libavcodec/h263dsp.c
> index 6a13353499..755d7077bf 100644
> --- a/libavcodec/h263dsp.c
> +++ b/libavcodec/h263dsp.c
> @@ -23,6 +23,29 @@
> #include "config.h"
> #include "h263dsp.h"
>
> +static void h263_dct_unquantize_inter_c(int16_t *block, size_t nCoeffs,
> + int qmul, int qadd)
> +{
> + for (size_t i = 0; i <= nCoeffs; i++) {
> + int level = block[i];
> +
> + if (level) {
> + if (level < 0)
> + level = level * qmul - qadd;
> + else
> + level = level * qmul + qadd;
> + block[i] = level;
> + }
> + }
> +}
> +
> +static void h263_dct_unquantize_intra_c(int16_t *block, size_t nCoeffs,
> + int qmul, int qadd)
> +{
> + if (nCoeffs > 0)
> + h263_dct_unquantize_inter_c(block + 1, nCoeffs - 1, qmul, qadd);
I think you can avoid this branch by doing:
for (size_t i = 1; i <= nCoeffs; i++) {
int level = block[i];
if (level) {
if (level < 0)
level = level * qmul - qadd;
else
level = level * qmul + qadd;
block[i] = level;
}
}
> +}
> +
> const uint8_t ff_h263_loop_filter_strength[32] = {
> 0, 1, 1, 2, 2, 3, 3, 4, 4, 4, 5, 5, 6, 6, 7, 7,
> 7, 8, 8, 8, 9, 9, 9, 10, 10, 10, 11, 11, 11, 12, 12, 12
> @@ -116,6 +139,8 @@ static void h263_v_loop_filter_c(uint8_t *src, int stride, int qscale)
>
> av_cold void ff_h263dsp_init(H263DSPContext *ctx)
> {
> + ctx->h263_dct_unquantize_intra = h263_dct_unquantize_intra_c;
> + ctx->h263_dct_unquantize_inter = h263_dct_unquantize_inter_c;
> ctx->h263_h_loop_filter = h263_h_loop_filter_c;
> ctx->h263_v_loop_filter = h263_v_loop_filter_c;
>
> diff --git a/libavcodec/h263dsp.h b/libavcodec/h263dsp.h
> index 2dccd23392..0ecbe83314 100644
> --- a/libavcodec/h263dsp.h
> +++ b/libavcodec/h263dsp.h
> @@ -24,6 +24,10 @@
> extern const uint8_t ff_h263_loop_filter_strength[32];
>
> typedef struct H263DSPContext {
> + void (*h263_dct_unquantize_intra)(int16_t *block /* align 16 */,
> + size_t len, int mul, int add);
> + void (*h263_dct_unquantize_inter)(int16_t *block /* align 16 */,
> + size_t len, int mul, int add);
> void (*h263_h_loop_filter)(uint8_t *src, int stride, int qscale);
> void (*h263_v_loop_filter)(uint8_t *src, int stride, int qscale);
> } H263DSPContext;
More information about the ffmpeg-devel
mailing list