From: =?gb18030?B?0Oy4o8Kh?= <839789740@qq.com>
To: =?gb18030?B?RkZtcGVnIGRldmVsb3BtZW50IGRpc2N1c3Npb25zIGFuZCBwYXRjaGVz?=
<ffmpeg-devel@ffmpeg.org>
Cc: =?gb18030?B?TWFydGluJm5ic3A7U3RvcnNqhDGkNw==?= <martin@martin.st>
Subject: Re: [FFmpeg-devel] [PATCH] avutil/imgutils: optimize image copy efficiency
Date: Fri, 5 May 2023 17:51:33 +0800
Message-ID: <tencent_001EE0F2BF107976530C34A316F87AB65C06@qq.com> (raw)
In-Reply-To: <b3c31c5a-ba2-248e-3c55-668f4ad8f8b6@martin.st>
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There is an if condition "FFALIGN(linesize[i], align) == linesize[i] && src_linesize[i] == linesize[i]".
When src's linesize equals to dst, it has no padding in this case I think. If has padding, it will execute
previous process. As a result, we could ignore the situation of padding in this case.
Thank you
//frank
------------------ Original ------------------
From: "FFmpeg development discussions and patches" <martin@martin.st>;
Date: Thu, May 4, 2023 04:22 PM
To: "FFmpeg development discussions and patches"<ffmpeg-devel@ffmpeg.org>;
Cc: "Ð츣¡"<839789740@qq.com>;
Subject: Re: [FFmpeg-devel] [PATCH] avutil/imgutils: optimize image copy efficiency
On Thu, 4 May 2023, xufuji456 wrote:
> It makes sense when copying 4K/8K video, if linesize
> equals to aligned linesize.
>
> Signed-off-by: xufuji456 <839789740@qq.com>
> ---
> libavutil/imgutils.c | 15 +++++++++++----
> 1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/libavutil/imgutils.c b/libavutil/imgutils.c
> index 9ab5757cf6..1d432e7a57 100644
> --- a/libavutil/imgutils.c
> +++ b/libavutil/imgutils.c
> @@ -525,10 +525,17 @@ int av_image_copy_to_buffer(uint8_t *dst, int dst_size,
> const uint8_t *src = src_data[i];
> h = (height + (1 << shift) - 1) >> shift;
>
> - for (j = 0; j < h; j++) {
> - memcpy(dst, src, linesize[i]);
> - dst += FFALIGN(linesize[i], align);
> - src += src_linesize[i];
> + if (FFALIGN(linesize[i], align) == linesize[i] && src_linesize[i] == linesize[i]) {
> + int size = linesize[i] * h;
For cases like these, I would prefer to use "linesize[i] * (h - 1) + w"
instead. For cases if copying e.g. into an offsetted position within a
buffer, writing the last trailing padding would end up writing out of
bounds.
That said, I'm unsure about how much gain you get from this optimization
here - some numbers to back it up would be useful.
// Martin
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prev parent reply other threads:[~2023-05-05 9:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-04 7:54 xufuji456
2023-05-04 8:22 ` Martin Storsjö
2023-05-04 13:18 ` =?gb18030?B?0Oy4o8Kh?=
2023-05-05 9:51 ` =?gb18030?B?0Oy4o8Kh?= [this message]
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